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A FT IR Study of a Transitory Product in the Gas-Phase Ozone-Ethylene Reaction
Further kinetic and spectroscopic characterization was made with the FT IR method for the transistory species (compound X) detected originally by Heath et al. and more recently Su et al. in the gas-phase reaction between O3 and C2H4.The results obtained support the earlier suggestion of Su et al. that compound X is HOCH2OCHO formed by the secondary reaction of the thermally stabilized CH2OO entity with CH2O.
Niki, H.,Maker, P. D.,Savage, C. M.,Breitenbach, L. P.
p. 1024 - 1027
(1981)
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HYDROFORMYLATION OF FORMALDEHYDE CATALYSED BY RHODIUM COMPLEXES
The hydroformylation of formaldehyde to glycol aldehyde (OHCCH2OH) catalysed by rhodium complexes has been studied.The hydrogenation product, methanol, is also formed.The ratio of hydroformylation to hydrogenation is very dependent on the solvent.Hydroformylation is favoured only in N,N-disubstituted amides, with methanol formation predominating in other solvents.This is attributed to the electronic effect of coordinated amide.Complexes of the type RhCl(CO)L2, (L=PPh3, P(p-tol)3, P(m-tol)3 (tol=tolyl) P(p-FC6H4)3 radical) are most efficient as catalysts.Deuteration studies show that the mechanism is analogous to that of alkene hydroformylation.A detailed reaction mechanism is proposed.
Spencer, A.
p. 113 - 124
(1980)
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Pyrolysis of inulin, glucose, and fructose
The pyrolytic behavior of inulin, a (2->1)-linked fructofuranan, is described.Parallel investigations of the pyrolysis of glucose and of fructose were conducted to supplement the inulin results and to aid comparison with previous results from glucans.Effects of neutral and basic additives are emphasized.As with glucans, the addition of such additives (especially basic) increases the yields of the one-, two-, and three-carbon products (as well as of hexosaccharinolactones), while generally decreasing the yields of anhydro sugar and furan derivatives.The former products include glycolaldehyde, acetol, dihydroxyacetone, acetic acid, formic acid, and lactic acid.Mechanistic speculations are made regarding the origins of these compounds, as well as of furan derivatives and saccharinic acid lactones.Parallels with alkaline degradation are considered.
Ponder, Glenn R.,Richards, Geoffrey N.
p. 341 - 360
(1993)
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Laboratory and theoretical study of the oxy radicals in the OH- and Cl-initiated oxidation of ethene
The products of the OH-initiated oxidation mechanism of ethene have been studied as a function of temperature (between 250 and 325 K) in an environmental chamber, using Fourier transform infrared spectroscopy for end product analysis. The oxidation proceeds via formation of a peroxy radical, HOCH2CH2O2. Reaction of this peroxy radical with NO is exothermic and produces chemically activated HOCH2CH2O radicals, of which about 25% decompose to CH2OH and CH2O on a time scale that is rapid compared to collisions, independent of temperature. The remainder of the HOCH2CH2O radicals are thermalized and undergo competition between decomposition, HOCH2CH2O → CH2OH + CH2O (6), and reaction with O2, HOCH2CH2O + O2 → HOCH2-CHO + HO2 (7). The rate constant ratio, k6/k7, for the thermalized radicals was found to be (2.0 ± 0.2) × 1025 exp[-(4200 ± 600)/T] molecule cm-3 over the temperature range 250-325 K. With the assumption of an activation energy of 1-2 kcal mol-1 for reaction 7, the barrier to decomposition of the HOCH2CH2O radical is found to be 10-11 kcal mol-1. A study of the Cl-atom-initiated oxidation of ethene was also carried out; the main product observed under conditions relevant to the atmosphere was chloroacetaldehyde, ClCH2CHO Theoretical studies of the thermal and "prompt" decomposition of the oxy radicals were based on a recent ab initio characterization that highlighted the role of intramolecular H bonding in HOCH2CH2O. Thermal decomposition is described by transition state and the Troe theories. To quantify the prompt decomposition of chemically activated nascent oxy radicals, the energy partitioning in the initially formed radicals was described by separate statistical ensemble theory, and the fraction of activated radicals dissociating before collisional stabilization was obtained by master equation analysis using RRKM theory. The barrier to HOCH2CH2O decomposition is inferred independently as being 10-11 kcal mol-1, by matching both of the theoretical HOCH2CH2O decomposition rates at 298 K with the experimental results. The data are discussed in terms of the atmospheric fate of ethene.
Orlando, John J.,Tyndall, Geoffrey S.,Bilde, Merete,Ferronato, Corinne,Wallington, Timothy J.,Vereecken, Luc,Peeters, Jozef
p. 8116 - 8123
(1998)
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KINETICS AND MECHANISM OF THE OXIDATION OF SOME DIOLS BY CHROMIUM(VI) IN PERCHLORIC ACID MEDIUM
Chromic acid oxidations of some diols have been studied in perchloric acid medium.The reactions are firstorder with respect to the diols and acid chromate ion.The rate increases with the increase in acidity but the orders with respect to perchloric acid are different (1.25-2.0).The rate of the oxidation reactions at = 1.0 M and temperature = 35 deg C, follow the order pinacol > 2.3-butane diol > ethylene glycol.The activation parameters of the oxidation reactions have been calculated.Plausible reaction mechanisms have been suggested.
Gupta, Kalyan Kali Sen,Samanta, Tapashi,Basu, Samarendra Nath
p. 5707 - 5714
(1986)
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Tuning Ca-Al-based catalysts' composition to isomerize or epimerize glucose and other sugars
One of the key reactions to achieve good productivity in the transformations of cellulose derived from biomass feedstocks is the isomerization of glucose to fructose, the latest being the platform molecule for obtaining other important derivatives. In this work, Ca-Al containing catalysts based on hydrotalcite-type derived materials were used to perform the selective isomerization of glucose to fructose, and the selective epimerization of glucose to mannose, using water as the solvent under mild reaction conditions. The catalysts showed high activity (conversion = 51-87%), and excellent selectivity (63-88%) towards fructose, compared with the current industrial process based on the glucose transformation via biocatalysis. It was also possible to modulate the selectivity towards fructose or mannose by tuning the amount of basic sites of the catalysts and their composition. The combination of basic and acid sites present in the Ca-Al-based catalysts plays a key role in the reaction, a fact that is discussed in the text together with other important operational parameters. The stability and recyclability of the catalysts were tested, detecting only a small activity loss after 5 consecutive runs. The synthesis of the catalysts and their characterization are also discussed since they are one of the few cases found in the literature of this kind of hydrotalcite-type material with such a high level of Ca incorporation. Some green metrics, such as E-factor, have been calculated to evaluate our system as an environmentally friendly process.
Ventura, Maria,Cecilia, Juan A.,Rodríguez-Castellón, Enrique,Domine, Marcelo E.
p. 1393 - 1405
(2020)
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Catalytic conversion of xylose to furfural over the solid acid SO 42-/ZrO2-Al2O3/SBA-15 catalysts
Al-promoted SO42--/ZrO2/SBA-15 catalysts were prepared and characterized by XRD, BET, ICP and NH3-TPD techniques. The influence of introducing aluminum on the structure and surface properties of the catalyst and the catalytic activity for dehydration of xylose to furfural has been investigated. The introduction of the Al stabilizes the tetragonal phase of the ZrO2 and thus increases the number and intensity of acid sites. Based on the characterization of the deactivated catalyst, the accumulation of byproducts is the main reason for the deactivation of the catalyst. Regeneration with H2O2 can completely recover the catalytic activity of the deactivated catalyst.
Shi, Xuejun,Wu, Yulong,Li, Panpan,Yi, Huaifeng,Yang, Mingde,Wang, Gehua
p. 480 - 487
(2011)
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Study of hydroformylation of formaldehyde in the presence of rhodium catalysts by in situ IR spectroscopy and the kinetic technique
Carbonylrhodium complexes formed during hydroformylation of CH2O from various rhodium precursors were investigated by in situ IR spectroscopy.It was found that under the conditions of the hydroformylation of CH2O in N,N-dimethylacetamide (DMAA), RhH(CO)(PPh3)3, RhCl(CO)(PPh3)2, RhCl(PPh3)3, RhCl(CO)(PBu3)2, and 2 form complex systems that necessarily contain anionic complexes, - (L = PPh3, PBu3, x = 1 to 2, Y = 1 to 0; -).The participation of ionic structures in the hydroformylation of CH2O, most likely, in the step of the activation of CH2O, was proven by kinetic techniques. - Key words: formaldehyde, hydroformylation, rhodium complexes, in situ IR spectroscopy.
Ezhova, N. N.,Korneeva, G. A.,Kurkin, V. I.,Slivinsky E. V.
p. 1027 - 1030
(1995)
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Kinetics and mechanisms of OH-initiated oxidation of small unsaturated alcohols
Smog chamber relative rate techniques were used to measure rate coefficients of (5.00 ± 0.54) × 10-11, (5.87 ± 0.63) × 10-11, and (6.49 ± 0.82) × 10 -11 cm3 molecule-1 s-1 in 700 Torr air at 296 ± 1 K for reactions of OH radicals with allyl alcohol, 1-buten-3-ol, and 2-methyl-3-buten-2-ol, respectively; the quoted uncertainties encompass the extremes of determinations using two different reference compounds. The OH-initiated oxidation of allyl alcohol in the presence of NOx gives glycolaldehyde in a molar yield of 0.85 ± 0.08; the quoted uncertainty is two standard deviations. Oxidation of 2-methyl-3-buten-2- ol gives acetone and glycolaldehyde in molar yields of 0.66 ± 0.06 and 0.56 ± 0.05, respectively. The reaction of OH radicals with allyl alcohol, 1-buten-3-ol, and 2-methyl-3-buten-2-ol proceeds predominately via addition to the >C=CH2 double bond with most of the addition occurring to the terminal carbon.
Takahashi, Kenshi,Hurley, Michael D.,Wallington, Timothy J.
p. 151 - 158
(2010)
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Study of the photoinduced formose reaction by flash and stationary photolysis
The chemical condensation of formaldehyde into more complex aldehydes (glycolaldehyde and glyceraldehyde) and monosaccharides (glucose, lyxose, erythrose and erythrulose) under UV irradiation was found to proceed in acidic aqueous solutions in the absence of catalysts and initial primers.
Snytnikova, Olga A.,Simonov, Alexandr N.,Pestunova, Oxana P.,Parmon, Valentin N.,Tsentalovich, Yuri P.
p. 9 - 11
(2006)
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Catalytic fast pyrolysis of cellulose using nano zeolite and zeolite/matrix catalysts in a GC/micro-pyrolyzer
Cellulose, as a model compound of biomass, was catalyzed over zeolite (HY, HZSM-5) and zeolite/matrix (HY/Clay, HM/Clay) in a GC/micro-pyrolyzer at 500 °C, to produce the valuable products. The catalysts used were pure zeolite and zeolite/matrix including 20 wt% matrix content, which were prepared into different particle sizes (average size; 0.1 mm, 1.6 mm) to study the effect of the particle size of the catalyst for the distribution of product yields. Catalytic pyrolysis had much more volatile products as light components and less content of sugars than pyrolysis only. This phenomenon was strongly influenced by the particle size of the catalyst in catalytic fast pyrolysis. Also, in zeolite and zeolite/matrix catalysts the zeolite type gave the dominant impact on the distribution of product yields.
Lee, Kyong-Hwan
p. 4631 - 4637
(2016)
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REACTIONS RETRODIENIQUES XIII - THERMOLYSE ECLAIR DES (Z) ET (E) DIHYDROXY-11,12 ETHANO-9,10 ANTHRACENES : SYNTHESE DES (Z) ET (E) ETHENEDIOLS-1,2.
The flash vacuum thermolysis of diols 3 and 4 affords, via a retro-Diels-Alder cleavage, the simplest enediols 1 and 2 for which the NMR and IR spectra as well as their thermal evolution are reported.
Lasne, Marie-Claire,Ripoll, Jean-Louis
p. 1587 - 1588
(1982)
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Effects of B group vitamins on reactions of various α-hydroxyl- containing organic radicals
Effects of vitamins B1, B2, B6, and pyridoxal phosphate (PPh) on final product formation in radiolysis of aqueous solutions of ethanol, ethylene glycol, α-methylglycoside, and maltose were studied. It has been found that vitamin B2 and PPh effectively oxidize R.CHOH species, while suppressing their recombination and fragmentation reactions, thereby increasing the yields of the respective oxidation products. Vitamins B1 and B2 are capable of reducing alcohol radicals to the respective initial molecules, decreasing the yields of the radical transformation products.
Lagutin,Shadyro
p. 3797 - 3800
(2005)
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Atmospheric fate of methyl vinyl ketone: Peroxy radical reactions with NO and HO2
First generation product yields from the OH-initiated oxidation of methyl vinyl ketone (3-buten-2-one, MVK) under both low and high NO conditions are reported. In the low NO chemistry, three distinct reaction channels are identified leading to the formation of (1) OH, glycolaldehyde, and acetyl peroxy R2a, (2) a hydroperoxide R2b, and (3) an α-diketone R2c. The α-diketone likely results from HOx-neutral chemistry previously only known to occur in reactions of HO2 with halogenated peroxy radicals. Quantum chemical calculations demonstrate that all channels are kinetically accessible at 298 K. In the high NO chemistry, glycolaldehyde is produced with a yield of 74 ± 6.0%. Two alkyl nitrates are formed with a combined yield of 4.0 ± 0.6%. We revise a three-dimensional chemical transport model to assess what impact these modifications in the MVK mechanism have on simulations of atmospheric oxidative chemistry. The calculated OH mixing ratio over the Amazon increases by 6%, suggesting that the low NO chemistry makes a non-negligible contribution toward sustaining the atmospheric radical pool.
Praske, Eric,Crounse, John D.,Bates, Kelvin H.,Kurtén, Theo,Kjaergaard, Henrik G.,Wennberg, Paul O.
p. 4562 - 4572
(2015)
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Convergent Functional Groups: Catalysis of Hemiacetal Cleavage in a Synthetic Molecular Cleft
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Wolfe, J.,Nemeth, D.,Costero, A.,Rebek, J. Jr.
p. 983 - 984
(1988)
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Selective oxidation of alcohols over Ag-containing Si3N 4 catalysts
Ag-containing ceramic catalysts modified or unmodified with Zr and Al were studied in selective catalytic oxidation of ethylene glycol and ethanol into the corresponding carbonyl compounds. The influence of phase and chemical composition of ceramic supports prepared by the self-propagating high-temperature synthesis (SHS) on the basis of silicon nitride was considered. The catalysts were characterized by X-ray diffraction, using scanning electron microscope (SEM) equipped with energy dispersive X-ray analysis (EDX) unit, and tested in selective oxidation of ethanol and ethylene glycol into acetaldehyde and glyoxal, respectively. It was shown that the presence of ZrO2 and Si3Al12O9N10 phases in the support composition allowed increasing glyoxal selectivity up to 50% at 87% conversion of glycol. Ag-containing ceramic catalysts also demonstrated high selectivity/activity in ethanol oxidation (95% acetaldehyde selectivity and 100% ethanol conversion at 300 °C), while the support phase composition did not influence the catalytic performance.
Vodyankina, Olga V.,Blokhina,Kurzina,Sobolev,Koltunov, K.Yu.,Chukhlomina,Dvilis
p. 127 - 132
(2013)
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Separating Thermodynamics from Kinetics—A New Understanding of the Transketolase Reaction
Transketolase catalyzes asymmetric C?C bond formation of two highly polar compounds. Over the last 30 years, the reaction has unanimously been described in literature as irreversible because of the concomitant release of CO2 if using lithium hydroxypyruvate (LiHPA) as a substrate. Following the reaction over a longer period of time however, we have now found it to be initially kinetically controlled. Contrary to previous suggestions, for the non-natural conversion of synthetically more interesting apolar substrates, the complete change of active-site polarity is therefore not necessary. From docking studies it was revealed that water and hydrogen-bond networks are essential for substrate binding, thus allowing aliphatic aldehydes to be converted in the charged active site of transketolase.
Marsden, Stefan R.,Gjonaj, Lorina,Eustace, Stephen J.,Hanefeld, Ulf
p. 1808 - 1814
(2017)
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Design of a synthetic enzyme cascade for the: In vitro fixation of a C1carbon source to a functional C4sugar
Realizing a sustainable future requires intensifying the waste stream conversion, such as converting the greenhouse gas carbon dioxide into value-added products. In this paper, we focus on utilizing formaldehyde as a C1 carbon source for enzymatic C-C bond formation. Formaldehyde can be sustainably derived from other C1 feedstocks, and in this work, we designed a synthetic enzyme cascade for producing the functional C4 sugar erythrulose. This involved tailoring the enzyme formolase, which was optimized for fusing formaldehyde, from a three-carbon producer (dihydroxyacetone) to sets of variants with enhanced two-carbon (glycolaldehyde) or four-carbon (erythrulose) activity. To achieve this, a high-throughput combinatorial screening was developed, and every single variant was evaluated in terms of glycolaldehyde, dihydroxyacetone and erythrulose activity. By applying the two most promising variants in an enzyme cascade, we were able to show for the first time production of ERY starting from a C1 carbon source. In addition, we demonstrated that one of our tailored formolase variants was able to convert 25.0 g L-1 glycolaldehyde to 24.6 g L-1 erythrulose (98% theoretical yield) in a fully atom-economic biocatalytic process. This represents the highest achieved in vitro concentration of erythrulose to date.
Güner, Samed,Pick, André,Sieber, Volker,Wegat, Vanessa
p. 6583 - 6590
(2021)
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The Enhancement of Formose Formation with 2-Hydroxyacetophenone. A mechanism Involving Aldol and Retro-aldol Reactions
The rapid aldol addition of formaldehyde to 2-hydroxyacetophenone (HAP), an efficient accelerator for formose formation, took place to yield addition products of HAP with one and two molecules of formaldehyde at 35 deg C in an aqueous 40percent methanol mixture of formaldehyde, HAP, and Ca(OH)2.No further addition product with more than two molecules of formaldehyde attached to HAP was detected throughout the reaction.On the contrary, benzaldehyde and benzoic acid were formed, accompanied by formose sugars.The initial molar amount of HAP corresponded to the sum of the compounds substituted with the phenyl group including benzaldehyde and benzoic acid.The retro-aldol reaction of the HAP derivatives is likely to be involved in the overall reaction to yield glycolaldehyde or trioses, which are good accelerators for formose formation.
Sakai, Tomoya,Ishizaki, Masahiko,Goto, Masafumi
p. 2409 - 2414
(1982)
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Mead,Bartron
p. 1287
(1948)
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Manganese(III) oxidation of L-serine in aqueous sulfuric acid medium: Kinetics and mechanism
Kinetics and mechanism of oxidation of L-serine by manganese(III) ions have been studied in aqueous sulfuric acid medium at 323 K. Manganese(III) sulfate was prepared by an electrolytic oxidation of manganous sulfate in aqueous sulfuric acid. The dependencies of the reaction rate are: an unusual one and a half-order on [Mn(III)], first-order on [ser], an inverse first-order on [H+], and an inverse fractional-order on [Mn(II)]. Effects of complexing agents and varying solvent composition were studied. Solvent isotope studies in D2O medium were made. The dependence of the reaction rate on temperature was studied and activation parameters were computed from Arrhenius-Eyring plots. A mechanism consistent with the observed kinetic data has been proposed and discussed.
Chandraju,Rangappa,Made Gowda
p. 525 - 530
(1999)
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Efficient immobilization of yeast transketolase on layered double hydroxides and application for ketose synthesis
Transketolase (TK) from S. cerevisiae was successfully immobilized on layered double hydroxides (LDH) using simple, affordable and efficient adsorption and coprecipitation based immobilization procedures. Optimization of the preparation was performed using zinc aluminium nitrate (Zn 2Al-NO3) and magnesium aluminium nitrate (Mg 2Al-NO3) LDH as immobilization supports, and the protein-to-LDH weight ratio (Q) was varied. The highest immobilization yields (98-99%) and highest relative specific activities (4.2-4.4 U·mg -1 for the immobilized enzyme compared to 4.5 U·mg -1 for the free enzyme) were both achieved when using a protein-to-LDH weight ratio (Q) of 0.38. Efficient lyophilization of the LDH-TK bionanocomposites thus synthesized was proven to allow easy use and storage of the supported TK with no significant loss of activity over a three-month period. The kinetic parameters of the LDH-TK enzyme were comparable to those of the free TK. The LDH-TK enzyme was finally tested for the synthesis of L-erythrulose starting from hydroxypyruvate lithium salt (Li-HPA) and glycolaldehyde (GA) as substrates. L-erythrulose was characterized and obtained with an isolated yield of 56% similar to that obtained with free TK. The reusability of the LDH-TK biohybrid material was then investigated, and we found no loss of enzymatic activity over six cycles. Copyright
Benaissi, Karima,Helaine, Virgil,Prevot, Vanessa,Forano, Claude,Hecquet, Laurence
p. 1497 - 1509
(2011)
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Catalysis and Stability Effect of Solvent Alcohol on the C6 Aldose Conversion toward Tetrose
Conversions of biomass feedstock into various valuable chemicals are of great significance. As a typical route, retro-aldol condensation of monosaccharide greatly expands the variety of biomass-derived platform chemicals via a selective C?C splitting. Herein, we describe a solvent-catalysed strategy to high-selectively accumulate tetrose (four-carbon platform chemical) from C6 aldoses via the retro-aldol/aldol process. We find that alcohol solvents with Lewis acidity facilitate the C?C splitting process of hexose under the catalyst-free condition. The conversion is the fastest in methanol while it is the slowest in isopropanol. The product distribution is greatly influenced by the alcohols through shifting the equilibrium between tetrose and glycolaldehyde (GA). The addition of catalyst only accelerates the reaction rate, and does not change the product distribution. On the one hand, the acetalization of GA with methanol or ethanol shifts the equilibrium from tetrose toward GA, which results in a low yield of tetrose in methanol or ethanol solvent. On the other hand, tetrose can be well accumulated in isopropanol or n-butanol, and the yield of tetrose in isopropanol is higher than in n-butanol because tetrose can be well solvated and stabilized in it. This solvent-dependent reaction strategy provides a new possibility which contributes to the conversion of biomass feedback into valuable platform chemicals and accumulation of target products by utilizing the solvation effect.
Hou, Wenrong,Yan, Yueer,Li, Gang,Zhan, Yulu,Feng, Lei,Zhang, Ruohong,Hua Li, Zhen,Zhang, Yahong,Tang, Yi
p. 4182 - 4188
(2019)
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Enhancing tungsten oxide/SBA-15 catalysts for hydrolysis of cellobiose through doping ZrO2
The number of strong acid sites on a hydrolysis catalyst accessible by the bulky cellulose limits its efficiency in the conversion and utilization of biomass-based resources. In this work, high surface area WZr/SBA-15 catalysts (>400?m2/g) were prepared by hydrothermal method and characterized using XRD, N2 adsorption, TEM, Raman, UV–vis, XPS and FTIR of pyridine adsorption. The results showed that doping a moderate amount of ZrO2 into the WO3/SBA-15 catalyst stabilized the tungstate species in the form of a polytungstate species as a result of the strong ZrOx-WOx interaction as well as increased the surface area of the catalyst. The resulting polytungstate species provided strong Br?nsted acid sites for hydrolysis. Consequently, the cellobiose conversion was maximized at 5% ZrO2 loading, corresponding to a maximized surface area and density of Br?nsted acid sites. This catalytic activity is significantly higher than that of a WO3/ZrO2 catalyst prepared using the conventional impregnation method, indicating the importance of mesoporous structure to the dispersion of active species and to the accessibility of the active sites by the bulky reactant. This result indicates that the density of the strong Br?nsted acid sites with improved accessibility by the bulky reactant is essential to achieve a high hydrolysis activity.
Wang, Hua,Guo, Yingge,Chang, Cuirong,Zhu, Xinli,Liu, Xiao,Han, Jinyu,Ge, Qingfeng
p. 182 - 192
(2016)
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Products of the gas-phase reaction of the OH radical with 3-methyl-1-butene in the presence of NO
The products of the gas-phase reaction of the OH radical with 3-methyl-1-butene in the presence of NO have been investigated at room temperature and 740 torr total pressure of air by gas chromatography with flame ionization detection, in situ Fourier transform infrared absorption spectroscopy, and direct air sampling atmospheric pressure ionization tandem mass spectrometry. The products identified and quantified by GC-FID and in situ FT-IR absorption spectroscopy were HCHO, 2-methylpropanal, acetone, glycolaldehyde, and methacrolein, with formation yields of 0.70±0.06, 0.58±0.08, 0.17±0.02, 0.18±0.03, and 0.033±0.007, respectively. In addition, IR absorption bands due to organic nitrates were observed, consistent with API-MS observations of product ion peaks attributed to the β-hydroxynitrates (CH3)2CHCH(ONO2)CH2OH and/or (CH3)2CHCH(OH)CH2ONO2 formed from the reactions of the corresponding β-hydroxyalkyl peroxy radicals with NO. A formation yield of ca. 0.15 for these nitrates was estimated using IR absorption band intensities for known organic nitrates. These products account for essentially all of the reacted 3-methyl-1-butene. Analysis of the potential reaction pathways involved shows that H-atom abstraction from the allylic C-H bond in 3-methyl-1-butene is a minor pathway which accounts for 5-10% of the overall OH radical reaction.
Atkinson,Tuazon,Aschmann
p. 577 - 587
(1998)
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Comparative study on the photocatalytic oxidation of glycerol using ZnO and TiO2
Herein, we have compared the behavior of ZnO and TiO2 in the photocatalytic oxidation of glycerol through detection of the main products. ZnO showed higher selectivity for the products where the carbon chain was preserved, such as glyceraldehyde (GAD) and dihydroxyacetone (DHA). TiO2 generated more products from the cleavage of the glycerol molecule, such as formaldehyde (FORM) and glycolaldehyde (GCOL). ZnO yielded about 16 times more GAD and 2.5 times more DHA than did TiO2.
Hermes, Natanael A.,Corsetti, Andre,Lansarin, Marla A.
p. 143 - 145
(2014)
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Transformations of formaldehyde and glycolaldehyde during the hydroformylation of formaldehyde in the presence of rhodium catalysts
Hydroformylation of formaldehyde to give glycolaldehyde (GA) in the presence of RhCl(PPh3)3, RhCl(CO)(PPh3)2, or the RhCl3 + PPh3 system in N,N-dimethylacetamide was studied.The hydroformylation is accompanied by the Cannizzaro-Tishchenko reaction, condensation of CH2O with GA to give C3-C16 polyoxyladehydes (POA), and dimerization of GA.THe formation of POA, which probably occurs through coordination of GA with a Rh atom, predominates among the side reactions.The optimum conditions for hydroformylation of CH2O were found to be: RhCl3 + PPh3 as the catalyst, T CO+H2 >/= 12 MPa, -1, -3 g-at.L-1, and -1.At a substrate conversion of 62 - 67percent, the selectivity of GA formation reaches 96percent, and the yield is 60 - 65percent. - Key words: formaldehyde, hydroformylation; glycolaldehyde; rhodium catalysts.
Ezhova, N. N.,Korneeva, G. A.,Slivinsky, E. V.,Aronovich, R. A.
p. 69 - 73
(1995)
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Gas-phase reaction of two unsaturated ketones with atomic Cl and O3: Kinetics and products
The rate constants and products for the reactions of atomic Cl and O3 molecule with 3-methyl-3-buten-2-one (MBO332) and 3-methyl-3-penten-2-one (MPO332) were determined in a 100 L Teflon chamber at 293 ± 1 K and atmospheric pressure. For MBO332 and MPO332, the rate constants measured with atomic Cl were (2.38 ± 0.26) × 10-10 and (3.00 ± 0.34) × 10-10 cm3 molecule-1 s-1 using the relative rate method. Using the absolute rate method, the rate constants with O3 measured were (1.18 ± 0.21) × 10-17 and (4.07 ± 0.45) × 10-17 cm3 molecule-1 s-1. The products of these reactions were investigated by the proton-transfer-reaction mass spectrum (PTR-MS). The results indicated that the major products observed in the atomic Cl reaction were formaldehyde together with chloroacetone for MBO332, and acetaldehyde and CH3C(O)C(O)Cl for MPO332. For O3 reactions, butanedione and formaldehyde were the main products of MBO332, while butanedione and acetaldehyde were the main products of MPO332. Possible reaction mechanisms were proposed and discussed and the atmospheric implications of these reactions were also discussed.
Wang, Jing,Zhou, Li,Wang, Weigang,Ge, Maofa
p. 12000 - 12012
(2015)
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Governing chemistry of cellulose hydrolysis in supercritical water
At extremely low reaction times (0.02 s), cellulose was hydrolyzed in supercritical water (T=400°C and P=25 MPa) to obtain a sugar yield higher than 95 wt %, whereas the 5-hydroxymethylfurfural (5-HMF) yield was lower than 0.01 wt %. If the reaction time was increased to 1 s, the main product was glycolaldehyde (60 wt %). Independently of the reaction time, the yield of 5-HMF was always lower than 0.01 wt %. To evaluate the reaction mechanism of biomass hydrolysis in pressurized water, several parameters (temperature, pressure, reaction time, and reaction medium) were studied for different biomasses (cellulose, glucose, fructose, and wheat bran). It was found that the H+ and OH- ion concentration in the reaction medium as a result of water dissociation is the determining factor in the selectivity. The reaction of glucose isomerization to fructose and the further dehydration to 5-HMF are highly dependent on the ion concentration. By an increase in the pOH/pH value, these reactions were minimized to allow control of 5-HMF production. Under these conditions, the retroaldol condensation pathway was enhanced, instead of the isomerization/dehydration pathway. Just add water: A reaction mechanism for cellulose hydrolysis that can explain the huge selectivity of biomass hydrolysis in supercritical water is presented. The model of the reaction mechanism has been validated by several experiments carried out in a continuous pilot plant capable at various conditions. It was found that the proton and hydroxide anion concentration in the medium due to water dissociation (represented by the ionic product of water, Kw) is the determining factor in the selectivity of the process.
Cantero, Danilo A.,Bermejo, M. Dolores,Cocero, M. José
p. 1026 - 1033
(2015)
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Direct conversion of C6 sugars to methyl glycerate and glycolate in methanol
The present work deals with the one-pot conversion of C6 sugars to methyl glycerate and glycolate via a cascade of retro-aldol condensation and oxidation processes catalyzed by using MoO3 as the Lewis acid catalyst and Au/TiO2 as the oxidation catalyst in methanol. Methyl glycerate (MGLY) is the product of C6 ketose (fructose), while methyl glycolate (MG) is produced from C6 aldose (mannose, glucose). It is found that a good one-pot match between two reactive processes is the key to the production of MGLY and MG with high yield (27.6% MGLY and 39.2% MG). A separated retro-aldol condensation and oxidation process greatly decreases their yields, and even no MGLY can be obtained in this separated process. We attribute this to high instability of glyceraldehyde/glycolaldehyde and their different reaction pathways which mainly depend on whether acetalization of retro-aldol products (glyceraldehyde and glycolaldehyde) occurs with methanol or not. This result opens a new prospect on the accumulation of C3 products other than lactate from biomass-derived carbohydrates.
Feng, Lei,Li, Gang,Yan, Yueer,Hou, Wenrong,Zhang, Yahong,Tang, Yi
p. 30163 - 30170
(2018)
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Revealing the chemistry of biomass pyrolysis by means of tunable synchrotron photoionisation-mass spectrometry
Imaging biomass conversion: pyrolysis is the first reaction involved in all thermal processes for biofuels and green chemicals production. Synchrotron light ionisation and mass spectrometry is used for the first time to investigate biomass pyrolysis. The soft and tunable ionisation source coupled with ab initio calculations reveals chemical mechanisms and new major intermediate species. This methodology could be extended to the thermal and catalytic conversion of all other materials. Primary volatile products are analysed online as a function of photon energy, biomass composition (cellulose, xylan, lignin), reactor temperature and time of conversion. Hydroxyacetaldehyde was detected at very minor yields for cellulose pyrolysis confirming that it is a secondary product. The effect of cellulose structure and ash content on primary tar formation was also studied. The mechanism of levoglucosan dissociative photoionisation is depicted. A new major intermediate product which could be a precursor of furanone-based species from cellulose is evidenced thanks to the soft ionisation and MSMS structural analysis of ions. Different lignin markers and evolutions upon time of conversion are shown for miscanthus and oak pyrolysis.
Dufour, Anthony,Weng, Junjie,Jia, Liangyuan,Tang, Xiaofeng,Sirjean, Baptiste,Fournet, Rene,Gall, Herve Le,Brosse, Nicolas,Billaud, Francis,Mauviel, Guillain,Qi, Fei
p. 4786 - 4792
(2013)
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Photochemistry and Photophysics of Glycolaldehyde in Solution
The end products for the photolysis of glycolaldehyde in aqueous solution have been monitored by mass spectrometric, FTIR, 1H NMR, 13C NMR, and UV-vis spectroscopic techniques.Methanol, carbon monoxide, formaldehyde, and malonaldehyde are the major photochemical products and are in accord with earlier CIDNP studies.The quantum yields of fluorescence for glycolaldehyde and a series of related alkanal compounds in solution are reported for the first time; they are all in the range ΦF = 0.71-0.84E-3.The singlet state decay kinetics for glycolaldehyde and ethanal were followed in more detail by measurement of their fluorescence lifetimes in solution with use of a synchrotron radiation source.The results may be explained in terms of emission from "free" and hydrogen-bonded singlet n?* excited states of the carbonyl compounds in water.
Beeby, Andrew,Mohammed, Dahlan Bin Hj.,Sodeau, John R.
p. 857 - 861
(1987)
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Borate-Stabilized Transformation of C6 Aldose to C4 Aldose
Highly efficient transformations of biomass-derived sugars into various valuable chemicals are of topical interest. Tetrose with a four-carbon bone is the root of most of biomass-derived C4 products, but its extreme instability obstructs the blossoming of C4 products presently. Herein, we describe a borate-stabilized catalytic strategy to accumulate erythrose from C6 aldose in a highly selective manner via retro-aldol and aldol processes in alcohol solvent. In our proposed mechanism, borate can stabilize erythrose and avoid its further retro-aldol splitting or isomerization, and induce the production of erythrose again via the aldol condensation of the above-generated glycolaldehyde.
Yan, Yueer,Feng, Lei,Li, Gang,Lin, Shaoying,Sun, Zhen,Zhang, Yahong,Tang, Yi
p. 4473 - 4478
(2017)
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Influence of substituents of the mechanism of oxidation of amino acids
The kinetics of oxidation of amino acids (AA) by peroxomonosulphate in aqueous alkaline medium at 35°C is studied. Based on the experimental results, a reaction scheme is proposed in which the electrophilic attack of HSO5- occurs at the amino nitrogen. The break down of the intermediate is influenced by the nature of the substituent at the amino carbon atom. The formation of imine/imino acid is supported by the absorption spectra of the intermediate.
Ramachandran,Eswaramoorthy,Sureshkumar
p. 9495 - 9504
(1994)
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Products from the gas-phase reaction of some unsaturated alcohols with nitrate radicals
Five structurally similar unsaturated alcohols, 2-propene-1-ol (allyl alcohol), 3-butene-2-ol, 2-methyl-3-butene-2-ol (MBO232), 2-butene-1-ol (crotyl alcohol) and 3-methyl-2-butene-1-ol (MBO321), were examined to clarify their atmospheric degradation pathways via oxidation initiated by NO3 radicals. The reactions were investigated using a 0.153 m3 static glass reactor equipped with long-path FTIR spectroscopy. The experiments were performed at a pressure of 1020 ± 5 mbar and at a temperature of 297 ± 2 K in air or nitrogen as the bath gas. The identified and quantified gas phase products were small carbonyl compounds such as acetone, formaldehyde, acetaldehyde, glycolaldehyde and 2-nitrooxy acetaldehyde. The specific products and their yields varied for the five studied alcohols as follows: formaldehyde 37(±1)% and 2-nitrooxy acetaldehyde 41(±7)% from allyl alcohol; acetaldehyde 28(±6)%, formaldehyde 2(±1)% and 2-nitrooxy acetaldehyde 33(±4)% from 3-butene-2-ol; acetone 63(±6)% and 2-nitrooxy acetaldehyde 67(±8)% from MBO232; acetaldehyde 12(±2)%, formaldehyde 10(±3)% and glycolaldehyde 7(±2)% from 2-butene-1-ol; acetone 21(±6)%, formaldehyde 11(±3)% and glycolaldehyde 29(±10)% from MBO321. In addition, yields were estimated for total organic nitrates using an average integrated absorption cross section of unspecified organic nitrates. Tentative reaction schemes were proposed from the yielded products. The distribution between bond breakage and other processes such as abstraction of a hydrogen atom from the alkoxy radical, formed in the degradation process, was estimated. The small carbonyl compounds were produced by the bond breakage mechanisms. Large multi-functional organic compounds e.g. 1-hydroxy-3-nitrooxy-3-methyl-2- butanone from MBO321 were proposed to be formed by hydrogen abstraction. From the product distribution, the contribution of the number of methyl group substituents at the α and γ carbon atoms, influencing the bond breakage pattern, is discussed. The observed bond cleavage trends are correlated to a substitution pattern where electron donating methyl substituents increase the stability of the leaving radical groups.
Noda,Hallquist,Langer,Ljungstroem
p. 2555 - 2564
(2000)
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Promoted Hydroformylation of Formaldehyde By Electronic Metal–Support Interactions in N-Group Functionalized Silica Supported Rhodium Catalyst
The influence of surface modification of SiO2 carrier by grafting method and its effects for Rh supporting was investigated on formaldehyde hydroformylation reaction. The relationship between the structure of catalysts and their performance was characterized in detail by X-ray diffraction, N2 adsorption–desorption, temperature programmed reduction with H2, X-ray photoelectron spectroscopy, and in situ infrared. After grafting the amino organic functional group, the surface circumstance of SiO2 was altered, and moreover, sites available for metal loading was enriched on the carrier that distribute a high dispersion of Rh species Under the same Rh loading, the Rh@N–SiO2 catalyst exhibits better catalytic activity than pristine SiO2 supported Rh catalysts. Spectroscopic evidences suggest the presence of an electronic perturbation between Rh and modified SiO2 which promotes the hydroformylation of formaldehyde by maintaining Rh at proper Rh0/(Rh3+ + Rhδ+) ratio. Graphic Abstract: Diagram of the effect of surface modified with amino group on metal rhodium loading. [Figure not available: see fulltext.].
Chen, Jie,Qiao, Luyang,Zhou, Zhangfeng,Wu, Xiaoman,Guo, Xiaxin,Zong, Shanshan,Ding, Yifan,He, Yuntao,Yao, Yuangen
p. 3664 - 3674
(2021)
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A point mutation converts dihydroneopterin aldolase to a cofactor-independent oxygenase
Dihydroneopterin aldolase (DHNA) catalyzes the conversion of 7,8-dihydroneopterin (1) to 6-hydroxymethyl-7,8-dihydropterin (4) in the folate biosynthetic pathway. Substitution of a conserved tyrosine residue at the active site of DHNA by phenylalanine converts the enzyme to a cofactor-independent oxygenase, which generates mainly 7,8-dihydroxanthopterin (6) rather than 4. 6 is generated via the same enol intermediate as in the wild-type enzyme-catalyzed reaction, but this species undergoes an oxygenation reaction to form 6. The conserved tyrosine residue plays only a minor role in the formation of the enol reaction intermediate but a critical role in the protonation of the enol intermediate to form 4.
Wang, Yi,Scherperel, Gwynyth,Roberts, Kade D.,Jones, A. Daniel,Reid, Gavin E.,Yan, Honggao
p. 13216 - 13223
(2006)
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Roth,Orchin
p. C27
(1979)
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Reactions of the peroxo intermediate of soluble methane monooxygenase hydroxylase with ethers
Soluble methane monooxygenase (sMMO) isolated from Methylococcus capsulatus (Bath) utilizes a carboxylate-bridged diiron center and dioxygen to catalyze the conversion of methane to methanol. Previous studies revealed that a di(μ-oxo)diiron(IV) intermediate termed Q is responsible for the catalytic activity with hydrocarbons. In addition, the peroxodiiron(III) intermediate (Hperoxo) that precedes Q formation in the catalytic cycle has been demonstrated to react with propylene, but its reactivity has not been extensively investigated. Given the burgeoning interest in the existence of multiple oxidants in metalloenzymes, a more exhaustive study of the reactivity of Hperoxo was undertaken. The kinetics of single turnover reactions of the two intermediates with ethyl vinyl ether and diethyl ether were monitored by single- and double-mixing stopped-flow optical spectroscopy. For both substrates, the rate constants for reaction with Hperoxo are greater than those for Q. An analytical model for explaining the transient kinetics is described and used successfully to fit the observed data. Activation parameters were determined through temperature-dependent studies, and the kinetic isotope effects for the reactions with diethyl ether were measured. The rate constants indicate that Hperoxo is a more electrophilic oxidant than Q. We propose that Hperoxo reacts via two-electron transfer mechanisms, and that Q reacts by single-electron transfer steps.
Beauvais, Laurance G.,Lippard, Stephen J.
p. 7370 - 7378
(2005)
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Fenton
p. 375
(1897)
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Selective Reductive Dimerization of CO2into Glycolaldehyde
The selective dimerization of CO2 into glycolaldehyde is achieved in a one-pot two-step process via formaldehyde as a key intermediate. The first step concerns the iron-catalyzed selective reduction of CO2 into formaldehyde via formation and controlled hydrolysis of a bis(boryl)acetal compound. The second step concerns the carbene-catalyzed C-C bond formation to afford glycolaldehyde. Both carbon atoms of glycolaldehyde arise from CO2 as proven by the labeling experiment with 13CO2. This hybrid organometallic/organic catalytic system employs mild conditions (1 atm of CO2, 25 to 80 °C in less than 3 h) and low catalytic loadings (1 and 2.5%, respectively). Glycolaldehyde is obtained in 53% overall yield. The appealing reactivity of glycolaldehyde is exemplified (i) in a dimerization process leading to C4 aldose compounds and (ii) in a tri-component Petasis-Borono-Mannich reaction generating C-N and C-C bonds in one process.
Zhang, Dan,Jarava-Barrera, Carlos,Bontemps, Sébastien
p. 4568 - 4575
(2021/05/04)

NEW BED MATERIAL FOR THERMOLYTIC FRAGMENTATION OF SUGARS
The present invention relates to a process for thermolytic fragmentation of a sugar into a composition comprising C1-C3 oxygenates. In particular, it relates to the use of heat carrying particles providing improved yields of C1-C3 oxygenates and improved fluidization characteristics making it suitable for industrial scale production of e.g. glycolaldehyde. It also regards a circulating fluidized bed system comprising the heat carrying particles.
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(2021/02/26)

PROCESSES FOR PREPARING C-4 SUGARS AND KETOSE SUGARS
Various processes for preparing C4 aldoses and/or ketones thereof are described. Various processes are described for preparing C4 aldoses and/or ketones thereof from feed compositions comprising glycolaldehyde. Also, various processes for preparing useful downstream products and intermediates, such as erythritol and erythronic acid, from the C4 aldoses and/or ketones thereof are described.
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(2021/11/20)

PROCESSES FOR THE PYROLYSIS OF CARBOHYDRATES
Various processes for the pyrolysis of carbohydrates to prepare products such as glycolaldehyde are described. Also, various catalysts and processes for preparing catalysts useful for carbohydrate pyrolysis are described.
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(2021/11/20)

Efficiently selective oxidation of glycerol by BiQDs/BiOBr-Ov: promotion of molecular oxygen activation by Bi quantum dots and oxygen vacancies
Selective oxidation of biomass resource glycerol to produce high value-added formic acid, dihydroxyacetone and other fine chemicals is in line with the current development concept of green and sustainable chemistry. A Bi quantum dot and oxygen vacancy modified BiOBr photocatalyst was applied to the selective aerobic oxidation of glycerol. A series of characterization results showed that the introduction of Bi quantum dots and oxygen vacancies can promote the effective transfer of photo-generated electrons and the adsorption of molecular oxygen on the catalyst surface to promote the activation of molecular oxygen, thereby significantly improving the photocatalytic efficiency of BiOBr. BiQDs/BiOBr-Ovcan efficiently catalyze the oxidation of glycerol to yield FA and DHA (FA selectivity 46.2%, DHA selectivity 26.9% at 98.4% glycerol conversion) under mild conditions, which is around 2.9 times that of normal BiOBr. In addition, the relevant reaction mechanism and path were systematically studied: two reaction paths to yield FA and DHA independently were found, where photo-generated holes and superoxide radicals played important roles. This work provided an efficient catalyst modification scheme by promoting the activation of molecular oxygen to improve the photocatalytic oxidation efficiency of biomass resources.
Dong, Yuming,Fan, Mingming,Haryono, Agus,Jiang, Pingping,Leng, Yan,Li, Chenhao,Yue, Chengguang,Zhang, Pingbo
p. 12938 - 12944
(2021/08/03)

AEROBIC ELECTROCATALYTIC OXIDATION OF HYDROCARBONS
This invention is directed to a method of oxygenating hydrocarbons with molecular oxygen, O2, as oxidant under electrochemical reducing conditions, using polyoxometalate compounds containing copper such as Q10 [Gu4(H2O)2(B-α-PW9O)2] or Q12{ [Cu(H2O)]3[(A-α- PW9O34)2(NO3)-] } or solvates thereof as catalysts, wherein Q are each independently selected from alkali metal cations, alkaline earth metal cations, transition metal cations, NH4+,H+ or any combination thereof.
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(2022/01/04)

Tin, molybdenum and tin-molybdenum oxides: Influence of Lewis and Bronsted acid sites on xylose conversion
In this study, tin oxide (SnO2), molybdenum oxide (MoO3) and a mixed oxide based on tin and molybdenum (respectively, Sn100, Mo100 and SnMo25, synthesized by the impregnation method) were applied in xylose conversion. The best results were obtained employing Mo100 and SnMo25. In the presence of SnMo25, after 0.5 h, xylose conversions of 39.5%, 34.1% and 63.4% were obtained, respectively, at 110, 130 and 150 °C. For Mo100, conversions of 49.6%, 71.8% and 85.3% were attained under the same reaction conditions, showing that Mo100 provided the best conversion results. However, with the use of this catalyst there was an increase in the amount of soluble and insoluble polymeric material. In terms of the soluble products formed from xylose, depending on the reaction condition were detected xylulose (X), lyxose (L) and furfural (FUR), glyceraldehyde (GL), pyruvaldehyde (PYR), glycoaldehyde (GLYC), dihydroxyacetone (DHA), lactic acid (AL), levulinic acid (LA) and acetic acid (AA). However, with the use of Sn100 or without a catalyst (systems with low conversions) there was mainly the formation of lyxose. The use of Mo100 and SnMo25 (systems which exhibit high acidity) leads mainly to isomerization, epimerization and dehydration reactions, as in the case of the retro-aldol pathway and furfural conversion, highlighting the importance of Lewis and Bronsted acid sites in relation to modulating the selectivity of the systems.
Meneghetti, Mario R.,Meneghetti, Simoni M. P.,Pryston, Dhara B. A.,da Silva Avelino, Débora Olimpio,dos Santos, Thatiane V.
(2021/11/16)

Kinetics and mechanism of quinolinium dichromate mediated oxidation of sugar alcohols in Bronsted acid media
Bronsted acid catalyzed oxidation of certain sugar alcohols (polyols) has been studied by quinolinium dichromate (QDC) using aqueous sulfuric, perchloric, and hydrochloric acids at different temperatures. At constant acidity, reaction kinetics revealed the second-order kinetics with a first order in [Alcohol] and [QDC]. Zucker-Hammett, Bunnett, and Bunnett-Olsen criteria were used to analyze acid-dependent rate accelerations. Bunnett-Olsen plots of (log k + Hν) versus (Hν + log [H+]), and (log k) versus (Hν + log [H+]) afforded slope values (? and ?*, respectively)?>?0.47, suggesting that a water molecule acts as a prton transfer agent in the slow step of the mechanism in the oxidation of alcohols by QDC in the presence of aqueous sulfuric, perchloric, and hydrochloric acids.
Kodali, Satish Babu,Jakku, Narendar Reddy,Kamatala, Chinna Rajanna,Yerraguntla, Rajeshwar Rao
p. 167 - 177
(2019/12/27)

CATALYST SYSTEMS AND METHODS FOR THEIR USE IN SELECTIVE HYDROFORMYLATION OF FORMALDEHYDE TO GLYCOLALDEHYDE
A method of producing glycolaldehyde through hydroformylation of formaldehyde in the presence of a rhodium-amine or rhodium-phosphine ligand complex catalyst. The reaction can be performed in aqueous and/or ionic liquid solvent-based reaction systems.
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(2020/06/01)

Pd-Catalyzed Decarboxylative Olefination: Stereoselective Synthesis of Polysubstituted Butadienes and Macrocyclic P-glycoprotein Inhibitors
The efficient and stereoselective synthesis of polysubstituted butadienes, especially the multifunctional butadienes, represents a great challenge in organic synthesis. Herein, we wish to report a distinctive Pd(0) carbene-initiated decarboxylative olefination approach that enables the direct coupling of diazo esters with vinylethylene carbonates (VECs), vinyl oxazolidinones, or vinyl benzoxazinones to afford alcohol-, amine-, or aniline-containing 1,3-dienes in moderate to high yields and with excellent stereoselectivity. This protocol features operational simplicity, mild reaction conditions, a broad substrate scope, and gram-scalability. Notably, a structurally unique allylic Pd(II) intermediate was isolated and characterized. DFT calculation and control experiments demonstrated that a rare Pd(0) carbene intermediate could be involved in this reaction. Moreover, the polysubstituted butadienes as novel building blocks were unprecedentedly assembled into macrocycles, which efficiently inhibited the P-glycoprotein and dramatically reversed multidrug resistance in cancer cells by 190-fold.
Chen, Xiangyang,Hao, Jiping,Houk, K. N.,Li, Yingzi,Lou, Liguang,Quan, Haitian,Song, Bichao,Wang, Lu,Xia, Yuanzhi,Xie, Peipei,Xu, Zhongliang,Yang, Weibo
supporting information
p. 9982 - 9992
(2020/06/27)

Reductive Electrochemical Activation of Molecular Oxygen Catalyzed by an Iron-Tungstate Oxide Capsule: Reactivity Studies Consistent with Compound i Type Oxidants
The reductive activation of molecular oxygen catalyzed by iron-based enzymes toward its use as an oxygen donor is paradigmatic for oxygen transfer reactions in nature. Mechanistic studies on these enzymes and related biomimetic coordination compounds designed to form reactive intermediates, almost invariably using various "shunt" pathways, have shown that high-valent Fe(V)=O and the formally isoelectronic Fe(IV) =O porphyrin cation radical intermediates are often thought to be the active species in alkane and arene hydroxylation and alkene epoxidation reactions. Although this four decade long research effort has yielded a massive amount of spectroscopic data, reactivity studies, and a detailed, but still incomplete, mechanistic understanding, the actual reductive activation of molecular oxygen coupled with efficient catalytic transformations has rarely been experimentally studied. Recently, we found that a completely inorganic iron-tungsten oxide capsule with a keplerate structure, noted as {Fe30W72}, is an effective electrocatalyst for the cathodic activation of molecular oxygen in water leading to the oxidation of light alkanes and alkenes. The present report deals with extensive reactivity studies of these {Fe30W72} electrocatalytic reactions showing (1) arene hydroxylation including kinetic isotope effects and migration of the ipso substituent to the adjacent carbon atom ("NIH shift"); (2) a high kinetic isotope effect for alkyl C - H bond activation; (3) dealkylation of alkylamines and alkylsulfides; (4) desaturation reactions; (5) retention of stereochemistry in cis-alkene epoxidation; and (6) unusual regioselectivity in the oxidation of cyclic and acyclic ketones, alcohols, and carboxylic acids where reactivity is not correlated to the bond disassociation energy; the regioselectivity obtained is attributable to polar effects and/or entropic contributions. Collectively these results also support the conclusion that the active intermediate species formed in the catalytic cycle is consistent with a compound I type oxidant. The activity of {Fe30W72} in cathodic aerobic oxidation reactions shows it to be an inorganic functional analogue of iron-based monooxygenases.
Bugnola, Marco,Shen, Kaiji,Haviv, Eynat,Neumann, Ronny
p. 4227 - 4237
(2020/05/05)

Glucose oxidation to formic acid and methyl formate in perfect selectivity
We report the highly remarkable discovery that glucose oxidation catalysed by polyoxometalates (POMs) in methanolic solution enables formation of formic acid and methyl formate in close to 100percent combined selectivity, thus with only negligible sugar oxidation to CO2. In detail, we report oxidation of a methanolic glucose solution using H8[PV5Mo7O40] (HPA-5) as catalyst at 90 °C and 20 bar O2 pressure. Experiments with 13C-labelled glucose confirm unambiguously that glucose is the only source of the observed formic acid and methyl formate formation under the applied oxidation conditions. Our results demonstrate a very astonishing solvent effect for the POM-catalysed glucose oxidation. In comparison to earlier work, a step-change in product yield and selectivity is achieved by applying an alcoholic reaction medium. The extremely high combined yields of formic acid and methyl formate greatly facilitate product isolation as low-boiling methyl formate (bp = 32 °C) can simply be isolated from the reaction mixture by distillation.
Albert, Jakob,Bukowski, Anna,Kumpidet, Chiraphat,Maerten, Stephanie,Vo?, Dorothea,Wasserscheid, Peter
p. 4311 - 4320
(2020/07/14)

Reduction of carbon dioxide at a plasmonically active copper-silver cathode
Electrochemically deposited copper nanostructures were coated with silver to create a plasmonically active cathode for carbon dioxide (CO2) reduction. Illumination with 365 nm light, close to the peak plasmon resonance of silver, selectively enhanced 5 of the 14 typically observed copper CO2 reduction products while simultaneously suppressing hydrogen evolution. At low overpotentials, carbon monoxide was promoted in the light and at high overpotentials ethylene, methane, formate, and allyl alcohol were enhanced upon illumination; generally C1 products and C2/C3 products containing a double carbon bond were selectively promoted under illumination. Temperature-dependent product analysis in the dark showed that local heating is not the cause of these selectivity changes. While the exact plasmonic mechanism is still unknown, these results demonstrate the potential for enhancing CO2 reduction selectivity at copper electrodes using plasmonics.
Corson, Elizabeth R.,Subramani, Ananya,Cooper, Jason K.,Kostecki, Robert,Urban, Jeffrey J.,McCloskey, Bryan D.
supporting information
p. 9970 - 9973
(2020/09/23)

Totally atom-economical synthesis of lactic acid from formaldehyde: combined bio-carboligation and chemo-rearrangement without the isolation of intermediates
Non-fermentative chemoenzymatic transformations have attracted great interest from both academia and industry. Here, we report a green chemoenzymatic cascade reaction that converts the C1 compound formaldehyde into lactic acid using a newly identified formolase variant and NaOH as catalysts with 100% atom economy and 82.9% overall yield under near-ambient conditions. The engineered formolase variant in this study exhibits a 19-fold substantially improved activity and improved formaldehyde resistance (up to 500 mM) and alters the main product from two-carbon glycolaldehyde (GA) to three-carbon dihydroxyacetone (DHA). The crystal structures of the parent formolase and identified variants were resolved to elucidate the molecular reason for the obtained improvement. Molecular dynamics simulation and molecular mechanics/generalized born surface area (MM/GBSA) analysis suggested that the identified amino acid substitutions allow more stable TPP-GA complexes in the active center of the dimeric formolase which is beneficial for the subsequent DHA generation. This journal is
Jiang, Huifeng,Li, Jinlong,Li, Tianzhen,Lin, Jianping,Liu, Haifeng,Liu, Pi,Liu, Weidong,Ma, Yanhe,Tan, Zijian,Tang, Zijing,Wei, Hongli,Zheng, Yingying,Zhu, Leilei
supporting information
p. 6809 - 6814
(2020/11/10)

Method for producing glycolaldehyde
The present invention relates to a method for preparing glycolaldehyde by condensation of formaldehyde. The method uses amidine or immobilized amidine and triazole salt as catalysts, uses alkali as areaction auxiliary agent, and converts formaldehyde to glycolaldehyde, glyceraldehyde and low carbon sugar. The raw material formaldehyde in a reaction system is cheap and easily available, the catalyst synthesis is simple, and a target product glycolaldehyde has a high yield. The production process involved in the present application is simple, easy to operate, and environmentally friendly, and creates favorable conditions for industrial scale production of the product.
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(2019/01/10)

VALORIZATION OF SYNGAS VIA FORMALDEHYDE – HYDROFORMYLATION OF FORMALDEHYDE USING HETEROGENIZED ORGANOMETALLIC COMPLEXES OF GROUP VIII METALS
Disclosed is a process and catalyst for the production of glycolaldehyde from mixtures of formaldehyde, carbon monoxide, and hydrogen. The process disclosed herein employs a heterogenized catalyst complex for the production of glycolaldehyde with high levels of formaldehyde conversion. The heterogenized catalyst complexes can be recovered in relatively high amounts as compared to other glycolaldehyde-production catalysts.
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(2019/07/13)

Photochemical reductive homologation of hydrogen cyanide using sulfite and ferrocyanide
Photoredox cycling during UV irradiation of ferrocyanide ([FeII(CN)6]4-) in the presence of stoichiometric sulfite (SO32-) is shown to be an extremely effective way to drive the reductive homologation
Xu, Jianfeng,Ritson, Dougal J.,Ranjan, Sukrit,Todd, Zoe R.,Sasselov, Dimitar D.,Sutherland, John D.
supporting information
p. 5566 - 5569
(2018/06/04)

The desA and desB genes from Clostridium scindens ATCC 35704 encode steroid-17,20-desmolase
Clostridium scindens is a gut microbe capable of removing the side-chain of cortisol, forming 11?-hydroxyandrostenedione. A cortisol-inducible operon (desABCD) was previously identified in C. scindens ATCC 35704 by RNA-Seq. The desC gene was shown to encode a cortisol 20?-hydroxysteroid dehydrogenase (20?-HSDH). The desD encodes a protein annotated as a member of the major facilitator family, predicted to function as a cortisol transporter. The desA and desB genes are annotated as N-terminal and C-terminal transketolases, respectively. We hypothesized that the DesAB forms a complex and has steroid-17,20-desmolase activity. We cloned the desA and desB genes from C. scindens ATCC 35704 in pETDuet for overexpression in Escherichia coli. The purified recombinant DesAB was determined to be a 142 ± 5.4 kDa heterotetramer. We developed an enzyme-linked continuous spectrophotometric assay to quantify steroid- 17,20-desmolase. This was achieved by coupling DesABdependent formation of 11?-hydroxyandrostenedione with the NADPH-dependent reduction of the steroid 17-keto group by a recombinant 17?-HSDH from the filamentous fungus, Cochliobolus lunatus. The pH optimum for the coupled assay was 7.0 and kinetic constants using cortisol as substrate were Km of 4.96 ± 0.57 μM and kcat of 0.87 ± 0.076 min?1. Substrate- specificity studies revealed that rDesAB recognized substrates regardless of 11?-hydroxylation, but had an absolute requirement for 17,21-dihydroxy 20-ketosteroids.- Devendran, S., S. M. Mythen, and J. M. Ridlon. The desA and desB genes from Clostridium scindens ATCC 35704 encode steroid-17,20-desmolase.
Devendran, Saravanan,Mythen, Sean M.,Ridlon, Jason M.
p. 1005 - 1014
(2018/06/22)

Gas-phase sugar formation using hydroxymethylene as the reactive formaldehyde isomer
Carbohydrates (CH2O)n are the formal adducts of carbon (atoms) to water with a repeating unit that structurally resembles H–C?–OH (hydroxymethylene). Although hydroxymethylene has been suggested as a building block for sugar formation, it is a reactive species that had escaped detection until recently. Here we demonstrate that formaldehyde reacts with its isomer hydroxymethylene to give glycolaldehyde in a nearly barrierless reaction. This carbonyl–ene-type transformation operates in the absence of base and solvent at cryogenic temperatures similar to those found in extraterrestrial environments or interstellar clouds. Hydroxymethylene acts as a building block for an iterative sugar synthesis, as we demonstrate through the formation of the triose glyceraldehyde. The thermodynamically preferred ketose dihydroxyacetone does not form, and the formation of further branched sugars in the iterative synthesis presented here is unlikely. The results therefore provide a link between the well-known formose (Butlerow) reaction and sugar formation under non-aqueous conditions.
Eckhardt, André K.,Linden, Michael M.,Wende, Raffael C.,Bernhardt, Bastian,Schreiner, Peter R.
p. 1141 - 1147
(2019/04/25)

PRODUCTION OF GLYCOLALDEHYDE BY THERMOLYTIC FRAGMENTATION
The present invention relates to a process for the production of glycolaldehyde by thermolytic fragmentation of a carbohydrate feedstock comprising mono- and/or di-saccharide(s) and a system suitable for performing the process. The process and the system are suitable for industrial application, and the process may be performed in a continuous process.
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(2018/06/30)

Formation of Chiral Structures in Photoinitiated Formose Reaction
The possibility to synthesize biologically important sugars and other chiral compounds without any initiators in the UV-initiated reaction of formaldehyde in aqueous solution has been shown for the first time. An optically active condensed phase due to an
Stovbun,Skoblin,Zanin,Tverdislov,Taran,Parmon
p. 108 - 116
(2018/04/05)

Production of Primary Amines by Reductive Amination of Biomass-Derived Aldehydes/Ketones
Transformation of biomass into valuable nitrogen-containing compounds is highly desired, yet limited success has been achieved. Here we report an efficient catalyst system, partially reduced Ru/ZrO2, which could catalyze the reductive amination of a variety of biomass-derived aldehydes/ketones in aqueous ammonia. With this approach, a spectrum of renewable primary amines was produced in good to excellent yields. Moreover, we have demonstrated a two-step approach for production of ethanolamine, a large-market nitrogen-containing chemical, from lignocellulose in an overall yield of 10 %. Extensive characterizations showed that Ru/ZrO2-containing multivalence Ru association species worked as a bifunctional catalyst, with RuO2 as acidic promoter to facilitate the activation of carbonyl groups and Ru as active sites for the subsequent imine hydrogenation.
Liang, Guanfeng,Wang, Aiqin,Li, Lin,Xu, Gang,Yan, Ning,Zhang, Tao
supporting information
p. 3050 - 3054
(2017/03/14)

Making H2 from light and biomass-derived alcohols: The outstanding activity of newly designed hierarchical MWCNT/Pd@TiO2 hybrid catalysts
Hydrogen evolution is among the most investigated catalytic processes given the importance of H2 from an industrial and an energy perspective. Achieving H2 production through green routes, such as water splitting or more realistically photoreforming of alcohols, is particularly desirable. In this work, we achieve a remarkable H2 productivity through photoreforming of either ethanol or glycerol as a sacrificial electron donor by employing a hybrid nanocatalyst where the properties of multi-walled carbon nanotubes (MWCNTs), Pd nanoparticles and crystalline TiO2 are optimally merged through appropriate engineering of the three components and an optimised synthetic protocol. Catalysts were very active both under UV (highest activity 25 mmol g-1 h-1) and simulated solar light (1.5 mmol h-1 g-1), as well as very stable. Critical to such high performance is the intimate contact of the three phases, each fulfilling a specific task synergistically with the other components.
Beltram,Melchionna,Montini,Nasi,Fornasiero,Prato
supporting information
p. 2379 - 2389
(2017/07/15)

Photocatalytic coupling of formaldehyde to ethylene glycol and glycolaldehyde over bismuth vanadate with controllable facets and cocatalysts
Bismuth vanadate (BiVO4) single crystals with controllable facets and cocatalysts were synthesized and studied for photocatalytic coupling of formaldehyde into C2 compounds mainly including ethylene glycol and glycolaldehyde. By using chloride anions as a morphology-controlling agent, we succeeded in synthesizing BiVO4 single crystals with a uniform truncated tetragonal bipyramidal morphology enclosed with {010} and {110} facets. The ratio of exposed {010} and {110} facets could be regulated by changing the concentration of Cl-. BiVO4 with an equal fraction of exposed {010} and {110} facets exhibited the highest capability of electron-hole separation and the highest C2-compound yield. The loading of core-shell structured Pt@MoOx and MnOx particles onto {010} and {110} facets, respectively, further enhanced the formation of C2 compounds. Our studies suggested that the Pt core and the MnOx particles accelerated the separation of photogenerated electron-hole pairs, whereas the MoOx shell catalyzed the coupling of HCHO possibly via a redox mechanism. The yields of C2 compounds and ethylene glycol reached 21% and 11%, respectively, under irradiation with UV-vis light for 12 h. Quantum yields of 11% and 4.8% were achieved for the coupling products under ultraviolet (350 nm) and visible (450 nm) light irradiation, respectively.
Xie, Shunji,Shen, Zebin,Zhang, Huamin,Cheng, Jun,Zhang, Qinghong,Wang, Ye
p. 923 - 933
(2017/08/16)

Catalytic conversion of glucose into alkanediols over nickel-based catalysts: A mechanism study
The conversion of isotope-labeled glucose (d-1-13C-glucose) into alkanediols was carried out in a batch reactor over a Ni-MgO-ZnO catalyst to reveal the C-C cleavage mechanisms. The unique role of the MgO-ZnO support was highlighted by 13C NMR and GC-MS analysis qualitatively and the MgO-ZnO favored isomerization of glucose to fructose. 13C NMR, GC-MS and HPLC analysis demonstrated that the C1 position of ethylene glycol, the C1 and C3 positions of 1,2-propanediol and the C1 position of glycerin were labeled with 13C, which is attributed to a C-C cleavage at d-1-13C-glucose's corresponding positions through retro-aldol condensation. A hydrogenolysis followed by hydrogenation pathway was proposed for glucose converted into alkanediols at 493 K with 6.0 MPa of H2 pressure over Ni based catalysts.
Tan, Zhichao,Miao, Gai,Liu, Chang,Luo, Hu,Bao, Liwei,Kong, Lingzhao,Sun, Yuhan
p. 62747 - 62753
(2016/07/13)

Catalytic routes and oxidation mechanisms in photoreforming of polyols
Photocatalytic reforming of biomass-derived oxygenates leads to H2 generation and evolution of CO2 via parallel formation of organic intermediates through anodic oxidations on a Rh/TiO2 photocatalyst. The reaction pathways and kinetics in the photoreforming of C3–C6 polyols were explored. Polyols are converted via direct and indirect hole transfer pathways resulting in (i) oxidative rupture of C–C bonds, (ii) oxidation to α-oxygen functionalized aldoses and ketoses (carbonyl group formation) and (iii) light-driven dehydration. Direct hole transfer to chemisorbed oxygenates on terminal Ti(IV)-OH groups, generating alkoxy-radicals that undergo ?-C–C-cleavage, is proposed for the oxidative C–C rupture. Carbonyl group formation and dehydration are attributed to indirect hole transfer at surface lattice oxygen sites [Ti?O?Ti] followed by the generation of carbon-centered radicals. Polyol chain length impacts the contribution of the oxidation mechanisms favoring the C–C bond cleavage (internal preferred over terminal) as the dominant pathway with higher polyol carbon number.
Sanwald, Kai E.,Berto, Tobias F.,Eisenreich, Wolfgang,Gutiérrez, Oliver Y.,Lercher, Johannes A.
p. 806 - 816
(2016/12/09)

The role of phosphate in a multistep enzymatic reaction: Reactions of the substrate and intermediate in pieces
Several mechanistically unrelated enzymes utilize the binding energy of their substrate's nonreacting phosphoryl group to accelerate catalysis. Evidence for the involvement of the phosphodianion in transition state formation has come from reactions of the substrate in pieces, in which reaction of a truncated substrate lacking its phosphorylmethyl group is activated by inorganic phosphite. What has remained unknown until now is how the phosphodianion group influences the reaction energetics at different points along the reaction coordinate. 1-Deoxy-d-xylulose-5-phosphate (DXP) reductoisomerase (DXR), which catalyzes the isomerization of DXP to 2-C-methyl-d-erythrose 4-phosphate (MEsP) and subsequent NADPH-dependent reduction, presents a unique opportunity to address this concern. Previously, we have reported the effect of covalently linked phosphate on the energetics of DXP turnover. Through the use of chemically synthesized MEsP and its phosphate-truncated analogue, 2-C-methyl-d-glyceraldehyde, the current study revealed a loss of 6.1 kcal/mol of kinetic barrier stabilization upon truncation, of which 4.4 kcal/mol was regained in the presence of phosphite dianion. The activating effect of phosphite was accompanied by apparent tightening of its interactions within the active site at the intermediate stage of the reaction, suggesting a role of the phosphodianion in disfavoring intermediate release and in modulation of the on-enzyme isomerization equilibrium. The results of kinetic isotope effect and structural studies indicate rate limitation by physical steps when the covalent linkage is severed. These striking differences in the energetics of the natural reaction and the reactions in pieces provide a deeper insight into the contribution of enzyme-phosphodianion interactions to the reaction coordinate.
Kholodar, Svetlana A.,Allen, C. Leigh,Gulick, Andrew M.,Murkin, Andrew S.
p. 2748 - 2756
(2015/03/04)

BACTERIA ENGINEERED FOR CONVERSION OF ETHYLENE TO N-BUTANOL
The present disclosure provides recombinant bacteria with elevated production of ethanol and/or n-butanol from ethylene. Methods for the production of the recombinant bacteria, as well as for use thereof for production of ethanol and/or n-butanol are also provided.
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Paragraph 0102

(2016/01/01)

Conformationally constrained 2-methylidene 1,3-oxathiane S-oxides: Synthesis and nucleophilic additions
The properties of vinyl sulfoxides are significantly influenced by stereoelectronic effects, where the relative orientation of sulfoxide group and alkene moiety is responsible for reactivity and selectivity, e.g., in the addition of nucleophiles. Conformationally constrained derivatives of 2-methylidene 1,3-oxathiane S-oxides allow the quantification of stereoelectronic effects. Suitable substrates were prepared by oxidation of 2-hydroxymethyl-1,3-oxathianes and pyrolysis of the respective xanthogenates. Nucleophilic additions of ethyl thiolate, piperidine, and dimethyl malonate anion are over 100 times faster to axial sulfoxides than to the respective equatorial substrates. The oxathiane derivatives turned out to be about 1000 times less reactive than the respective 1,3-dithianes.
Weingand, Daniel,Kiefer, Claude,Podlech, Joachim
p. 1261 - 1268
(2015/03/05)

Formation of complex organic molecules in methanol and methanol-carbon monoxide ices exposed to ionizing radiation - A combined FTIR and reflectron time-of-flight mass spectrometry study
The radiation induced chemical processing of methanol and methanol-carbon monoxide ices at 5.5 K exposed to ionizing radiation in the form of energetic electrons and subsequent temperature programmed desorption is reported in this study. The endogenous formation of complex organic molecules was monitored online and in situ via infrared spectroscopy in the solid state and post irradiation with temperature programmed desorption (TPD) using highly sensitive reflectron time-of-flight (ReTOF) mass spectrometry coupled with single photoionization at 10.49 eV. Infrared spectroscopic analysis of the processed ice systems resulted in the identification of simple molecules including the hydroxymethyl radical (CH2OH), formyl radical (HCO), methane (CH4), formaldehyde (H2CO), carbon dioxide (CO2), ethylene glycol (HOCH2CH2OH), glycolaldehyde (HOCH2CHO), methyl formate (HCOOCH3), and ketene (H2CCO). In addition, ReTOF mass spectrometry of subliming molecules following temperature programmed desorption definitely identified several closed shell C/H/O bearing organics including ketene (H2CCO), acetaldehyde (CH3COH), ethanol (C2H5OH), dimethyl ether (CH3OCH3), glyoxal (HCOCOH), glycolaldehyde (HOCH2CHO), ethene-1,2-diol (HOCHCHOH), ethylene glycol (HOCH2CH2OH), methoxy methanol (CH3OCH2OH) and glycerol (CH2OHCHOHCH2OH) in the processed ice systems. Additionally, an abundant amount of molecules yet to be specifically identified were observed sublimating from the irradiated ices including isomers with the formula C3H(x=4,6,8)O, C4H(x=8,10)O, C3H(x=4,6,8)O2, C4H(x=6,8)O2, C3H(x=4,6)O3, C4H8O3, C4H(x=4,6,8)O4, C5H(x=6,8)O4 and C5H(x=6,8)O5. The last group of molecules containing four to five oxygen atoms observed sublimating from the processed ice samples include an astrobiologically important class of sugars relevant to RNA, phospholipids and energy storage. Experiments are currently being designed to elucidate their chemical structure. In addition, several reaction pathways were identified in the irradiated ices of mixed isotopes based upon the results of both in situ FTIR analysis and TPD ReTOF gas phase analysis. In general, the results of this study provide crucial information on the formation of a variety of classes of organics including alcohols, ketones, aldehydes, esters, ethers, and sugars within the bulk ices upon exposure to ionizing radiation that are relevant to the molecular clouds within the interstellar medium.
Maity, Surajit,Kaiser, Ralf I.,Jones, Brant M.
p. 3081 - 3114
(2015/02/05)

METHOD FOR THE ENZYMATIC PRODUCTION OF D-ERYTHROSE AND ACETYL PHOSPHATE
Described is a method for the production of D-erythrose and acetyl phosphate comprising the enzymatic conversion of D-fructose into D-erythrose and acetyl phosphate by making use of a phosphoketolase. The produced D-erythrose can further be converted into glycolaldehyde by a method for the production of glycolaldehyde comprising the enzymatic conversion of D-erythrose into glycolaldehyde by making use of an aldolase, wherein said aldolase is a 2- deoxyribose-5-phosphate aldolase (EC 4.1.2.4) or a fructose-bisphosphate aldolase (EC 4.1.2.13). The produced glycolaldehyde can finally be converted into acetyl phosphate by the enzymatic conversion of the thus produced glycolaldehyde into acetyl phosphate by making use of a phosphoketolase or a sulfoacetaldehyde acetyltransferase.
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(2015/12/17)

Products of the OH radical-initiated reactions of furan, 2- and 3-methylfuran, and 2,3- and 2,5-dimethylfuran in the presence of NO
Products of the gas-phase reactions of OH radicals with furan, furan-d 4, 2- and 3-methylfuran, and 2,3- and 2,5-dimethylfuran have been investigated in the presence of NO using direct air sampling atmospheric pressure ionization tandem mass spectrometry (API-MS and API-MS/MS), and gas chromatography with flame ionization and mass spectrometric detectors (GC-FID and GC-MS) to analyze samples collected onto annular denuders coated with XAD solid adsorbent and further coated with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine for derivatization of carbonyl-containing compounds to their oximes. The products observed were unsaturated 1,4-dicarbonyls, unsaturated carbonyl-acids and/or hydroxy-furanones, and from 2,5-dimethylfuran, an unsaturated carbonyl-ester. Quantification of the unsaturated 1,4-dicarbonyls was carried out by GC-FID using 2,5-hexanedione as an internal standard, and the measured molar formation yields were: HC(O)CH=CHCHO (dominantly the E-isomer) from OH + furan, 75 ± 5%; CH3C(O)CH=CHCHO (dominantly the E-isomer) from OH + 2-methylfuran, 31 ± 5%; HC(O)C(CH3)=CHCHO (a E-/Z-mixture) from OH + 3-methylfuran, 38 ± 2%; and CH 3C(O)C(CH3)=CHCHO from OH + 2,3-dimethylfuran, 8 ± 2%. In addition, a formation yield of 3-hexene-2,5-dione from OH + 2,5-dimethylfuran of 27% was obtained from a single experiment, in good agreement with a previous value of 24 ± 3% from GC-FID analyses of samples collected onto Tenax solid adsorbent without derivatization.
Aschmann, Sara M.,Nishino, Noriko,Arey, Janet,Atkinson, Roger
p. 457 - 466
(2014/02/14)

High-pressure fast-pyrolysis, fast-hydropyrolysis and catalytic hydrodeoxygenation of cellulose: Production of liquid fuel from biomass
A lab-scale, high-pressure, continuous-flow fast-hydropyrolysis and vapor-phase catalytic hydrodeoxygenation (HDO) reactor has been successfully designed, built and tested with cellulose as a model biomass feedstock. We investigated the effects of pyrolysis temperature on high-pressure cellulose fast-pyrolysis, hydrogen on high-pressure cellulose fast-hydropyrolysis, reaction pressure (27 bar and 54 bar) on our reactor performance and candidate catalysts for downstream catalytic HDO of cellulose fast-hydropyrolysis vapors. In this work, a liquid chromatography-mass spectrometry (LC-MS) method has been developed and utilized for quantitative characterization of the liquid products. The major compounds in the liquid from cellulose fast-pyrolysis (27 bar, 520 °C) are levoglucosan and its isomers, formic acid, glycolaldehyde, and water, constituting 51 wt%, 11 wt%, 8 wt% and 24 wt% of liquid respectively. Our results show that high pressures of hydrogen do not have a significant effect on the fast-hydropyrolysis of cellulose at 480 °C but suppress the formation of reactive light oxygenate species like glycolaldehyde and formic acid at 580 °C. The formation of permanent gases (CO, CO2, CH4) and glycolaldehyde and formic acid increased with increasing pyrolysis temperature in the range of 480 °C-580 °C in high-pressure cellulose fast-pyrolysis, in the absence of hydrogen. Candidate HDO catalysts Al 2O3, 2% Ru/Al2O3 and 2% Pt/Al 2O3 resulted in extents of deoxygenation of 20%, 22% and 27%, respectively, but led to carbon loss to gas phase as CO and CH4. These catalysts provide useful insights for other candidate HDO catalysts for improving the extent of deoxygenation with higher carbon recovery in the liquid product.
Venkatakrishnan, Vinod Kumar,Degenstein, John C.,Smeltz, Andrew D.,Delgass, W. Nicholas,Agrawal, Rakesh,Ribeiro, Fabio H.
p. 792 - 802
(2014/02/14)

SiO2-, Cu-, and Ni-supported Au nanoparticles for selective glycerol oxidation in the liquid phase
We tested for the first time the efficiency of SiO2-, Cu-, and Ni-supported Au in deep glycerol oxidation in a diluted and viscous H2O2/H2O liquid phase. Acetic acid (AA), the C2 oxidate, was preferentially formed in such a system. High conversion (100%) and AA yields (90%) were observed for the sol-gel SiO2-supported Au in diluted solutions. Although with the increase of glycerol concentration in the viscous liquid phase these values decreased to ca. 40% (conversion) and 20% (AA yield), the addition of acetonitrile improved the AA yield to ca. 40%, while the surfactants were found to be capable of a many-fold enhancement of the catalyst activity at the room temperature highly viscous liquid phase. High performances were also observed for the bimetallic Au/Cu and Au/Ni catalysts obtained by nano-Au transfer; however, these catalysts were destroyed during the reaction by the Cu or Ni leaching effect.
Kapkowski, Maciej,Bartczak, Piotr,Korzec, Mateusz,Sitko, Rafal,Szade, Jacek,Balin, Katarzyna,Lel?tko, Józef,Polanski, Jaroslaw
p. 110 - 118
(2015/09/28)

Selective photocatalytic conversion of glycerol to hydroxyacetaldehyde in aqueous solution on facet tuned TiO2-based catalysts
Glycerol is selectively converted to hydroxyacetaldehyde (HAA) and H 2 in aqueous solution on TiO2-based photocatalysts. The product selectivity was verified to be strongly dependent on the facets of TiO2. Rutile with high percentage of {110} facets results in over 90% superior selectivity of HAA, while anatase with {001} or {101} facets gives only 16% and 49% selectivity for HAA, respectively.
Chong, Ruifeng,Li, Jun,Zhou, Xin,Ma, Yi,Yang, Jingxiu,Huang, Lei,Han, Hongxian,Zhang, Fuxiang,Li, Can
supporting information
p. 165 - 167
(2014/01/06)

Atmospheric aqueous phase radical chemistry of the isoprene oxidation products methacrolein, methyl vinyl ketone, methacrylic acid and acrylic acid-kinetics and product studies
Kinetic and mechanistic studies were conducted on the isoprene oxidation products methacrolein, methyl vinyl ketone, methacrylic and acrylic acid reacting with hydroxyl and nitrate radicals and sulfate radical anions in aqueous solution by use of the laser flash photolysis technique and a reversed-rate method for kinetics. High-performance liquid chromatography/mass spectrometry was applied for product analysis. The kinetic investigations show the highest reactivity of the hydroxyl radical followed by sulfate and nitrate radicals. For methacrolein and methyl vinyl ketone the following rate constants have been determined at 298 K: k(OH+methacrolein) = (9.4 ± 0.7) × 109 M-1 s-1, k (OH+methylvinylketone) = (7.3 ± 0.5) × 109 M-1 s-1, k(NO3+methacrolein) = (4.0 ± 1.0) × 107 M-1 s-1, k(NO 3+methylvinylketone)= (9.7 ± 3.4) × 106 M-1 s-1, k (SO4-+methacrolein) = (9.9 ± 4.9) × 107 M-1 s-1 and k (SO4-+methylvinylketone) = (1.0 ± 0.2) × 108 M-1 s-1. Temperature and pH dependencies of the reactions of OH, NO3 and SO4 - with methacrolein, methyl vinyl ketone, methacrylic and acrylic acid as well as Arrhenius parameters have been obtained and discussed. Product studies were performed on the OH radical induced oxidation of methacrolein and methyl vinyl ketone. In the reaction of methacrolein + OH methylglyoxal and hydroxyacetone were identified as first oxidation products with yields of 0.099 and 0.162. Methylglyoxal was primarily produced in the oxidation of methyl vinyl ketone with a yield of 0.052. For both precursor compounds the formation of glycolaldehyde was observed for the first time with yields of 0.051 and 0.111 in the oxidation of methacrolein and methyl vinyl ketone, respectively. Furthermore, highly functionalised C4 compounds were determined from the oxidation of both precursor compounds, but for the first time for methyl vinyl ketone. Reaction schemes were developed based on known peroxyl radical reaction mechanisms. The aqueous phase conversion of the first generation isoprene oxidation products can potentially contribute to tropospheric aqueous phase budgets of important carbonyl and dicarbonyl components which are expected to be conducive to the formation of aqSOA. This journal is
Schoene, Luisa,Schindelka, Janine,Szeremeta, Edyta,Schaefer, Thomas,Hoffmann, Dirk,Rudzinski, Krzysztof J.,Szmigielski, Rafal,Herrmann, Hartmut
p. 6257 - 6272
(2014/04/03)

Transformations of polyols to organic acids and hydrogen in aqueous alkaline media
In this paper we show that carbon nanofiber supported copper and nickel nanoparticles can selectively transform ethylene glycol and glycerol into value added oxygenates (organic acids) under anaerobic aqueous conditions. During aqueous phase oxidation Cu based catalysts showed a nearly quantitative yield (96% selectivity at 82% conversion) of glycolic acid from ethylene glycol. The reaction was carried out under alkaline conditions at relatively mild temperatures (150-180 °C) and produced H2 as co-product. The high selectivity towards glycolic acid was independent of the temperature. For glycerol oxidation a high selectivity (67% at full conversion) towards lactic acid was observed using Cu with competitive formation of glyceric acid, 1,2-propanediol tartronic acid and formation of H2 as co-product. The activity of Ni was comparable to that of Cu but it was less selective for the formation of desired oxygenates, glycolic acid (31%) and lactic acid (24%), due to the formation of formic acid.
Van Haasterecht,Van Deelen,De Jong,Bitter
p. 2353 - 2366
(2014/07/22)