Xi:Irritant;106-68-3Relevant articles and documents
Ruthenium complexes with dendritic ferrocenyl phosphanes: Synthesis, characterization, and application in the catalytic redox isomerization of allylic alcohols
Neumann, Paul,Dib, Hanna,Sournia-Saquet, Alix,Grell, Toni,Handke, Marcel,Caminade, Anne-Marie,Hey-Hawkins, Evamarie
, p. 6590 - 6604 (2015)
An efficient system for the catalytic redox isomerization of the allylic alcohol 1-octen-3-ol to 3-octanone is presented. The homogeneous ruthenium(II) catalyst contains a monodentate phosphane ligand with a ferrocene moiety in the backbone and provides 3-octanone in quantitative yields. The activity is increased by nearly 90 % with respect to the corresponding triphenyl phosphane ruthenium(II) complex. By grafting the catalyst at the surface of a dendrimer, the catalytic activity is further increased. By introducing different spacers between ferrocene and phosphorus, the influence on the electronic properties of the complexes is shown by evaluating the electrochemical behavior of the compounds.
Symmetric triazolylidene Ni(II) complexes applied as oxidation catalysts
Mncube, Siyabonga G.,Bala, Muhammad D.
, p. 467 - 473 (2019)
A set of related Ni(II) complexes of N-heterocyclic carbene ligands (NHC) [trans-X2Ni(NHC)2] (X = Cl, I) bearing linear straight chain alkyl wingtip substituents have been synthesised and fully characterised. Single crystal XRD data revealed symmetrically aligned Ni(II) centres within square planar coordination of trans halide, trans NHC ligands. The complexes were used for the catalytic oxidation of alkanes under mild conditions in conjunction with tert-butyl hydroperoxide as an oxidant. Under optimised reaction conditions, the catalytic results pointed to good activities of circa 15% and 19% for cyclohexane and n-octane respectively. Furthermore, the catalytic systems are shown to be very efficient for the oxidation of linear alcohols to corresponding ketones.
Selective Synthesis of Alkynes by Catalytic Dehydrogenation of Alkenes over Polymer-supported Palladium Acetate in the Liquid Phase
Cum, Giampietro,Gallo, Raffaele,Ipsale, Salvatore,Spadaro, Agatino
, p. 1571 - 1573 (1985)
A heterogenized palladium acetate catalyst, in the presence of oxygen and perchloric acid in ethanol-water caused the direct conversion of terminal and internal monoalkenes into the corresponding alkynes, under mild conditions and in high yields; Wacker-type ketonization occurs with the same reagents in dioxane-water.
Arachidonic acid-dependent carbon-eight volatile synthesis from wounded liverwort (Marchantia polymorpha)
Kihara, Hirotomo,Tanaka, Maya,Yamato, Katsuyuki T.,Horibata, Akira,Yamada, Atsushi,Kita, Sayaka,Ishizaki, Kimitsune,Kajikawa, Masataka,Fukuzawa, Hideya,Kohchi, Takayuki,Akakabe, Yoshihiko,Matsui, Kenji
, p. 42 - 49 (2014)
Eight-carbon (C8) volatiles, such as 1-octen-3-ol, octan-3-one, and octan-3-ol, are ubiquitously found among fungi and bryophytes. In this study, it was found that the thalli of the common liverwort Marchantia polymorpha, a model plant species, emitted high amounts of C8 volatiles mainly consisting of (R)-1-octen-3-ol and octan-3-one upon mechanical wounding. The induction of emission took place within 40 min. In intact thalli, 1-octen-3-yl acetate was the predominant C8 volatile while tissue disruption resulted in conversion of the acetate to 1-octen-3-ol. This conversion was carried out by an esterase showing stereospecificity to (R)-1-octen-3-yl acetate. From the transgenic line of M. polymorpha (des6KO) lacking arachidonic acid and eicosapentaenoic acid, formation of C8 volatiles was only minimally observed, which indicated that arachidonic and/or eicosapentaenoic acids were essential to form C8 volatiles in M. polymorpha. When des6KO thalli were exposed to the vapor of 1-octen-3-ol, they absorbed the alcohol and converted it into 1-octen-3-yl acetate and octan-3-one. Therefore, this implied that 1-octen-3-ol was the primary C8 product formed from arachidonic acid, and further metabolism involving acetylation and oxidoreduction occurred to diversify the C8 products. Octan-3-one was only minimally formed from completely disrupted thalli, while it was formed as the most abundant product in partially disrupted thalli. Therefore, it is assumed that the remaining intact tissues were involved in the conversion of 1-octen-3-ol to octan-3-one in the partially disrupted thalli. The conversion was partly promoted by addition of NAD(P)H into the completely disrupted tissues, suggesting an NAD(P)H-dependent oxidoreductase was involved in the conversion.
Biocatalytic oxidative kinetic resolution of sec-alcohols: Stereocontrol through substrate-modification
Stampfer, Wolfgang,Kosjek, Birgit,Faber, Kurt,Kroutil, Wolfgang
, p. 275 - 280 (2003)
Whole lyophilised cells of Rhodococcus ruber DSM 44541 were employed for the oxidative kinetic resolution of sec-alcohols using acetone as hydrogen acceptor. The enantioselectivity of this process could be controlled effectively by introducing C-C multiple bonds into substrates, which were inefficiently recognised, in particular short-chain (ω-1)-alcohols and (ω-2)-analogs. Thus, the enantioselectivities of rac-2-pentanol (E=16.8) and rac-3-octanol (E=13.3) were significantly improved by introducing a C=C bond adjacent to the alcohol moiety to give racemic (E)-pent-3-en-2-ol and 4-(E)-octen-3-ol, which were resolved with excellent selectivities (E >100 and 50, respectively). In addition, it was found that high stereodifferentiation between the E- and Z-configured double bonds occurred, as the corresponding (Z)-isomers were not converted. Similar selectivity-enhancing effects were observed with acetylenic analogs.
Vanadium phosphorus oxide as an efficient catalyst for hydrocarbon oxidations using hydrogen peroxide
Pillai, Unnikrishnan R.,Sahle-Demessie, Endalkachew
, p. 525 - 528 (2003)
Calcined vanadium phosphorus oxide (VPO) prepared by an organic route is found to be an active and effective catalyst for the oxidation of various alkanes such as cyclopentane, cyclohexane, n-hexane, cycloheptane, cyclooctane, cyclodecane and adamantane in acetonitrile solvent using the environmentally benign oxidant, hydrogen peroxide, where the oxidation mechanism is believed to involve a reversible V4+/V5+ redox cycle.
μ-Chlorido-bridged dimanganese(II) complexes of the schiff base derived from [2+2] condensation of 2,6-diformyl-4-methylphenol and 1,3-bis(3- aminopropyl)tetramethyldisiloxane: Structure, magnetism, electrochemical behaviour, and catalytic oxidation of secondary alcohols
Alexandru, Mihaela,Cazacu, Maria,Arvinte, Adina,Shova, Sergiu,Turta, Constantin,Simionescu, Bogdan C.,Dobrov, Anatolie,Alegria, Elisabete C. B. A.,Martins, Luísa M. D. R. S.,Pombeiro, Armando J. L.,Arion, Vladimir B.
, p. 120 - 131 (2014)
The reaction of 2,6-diformyl-4-methylphenol with 1,3-bis(3-aminopropyl) tetramethyldisiloxane in the presence of MnCl2 in a 1:1:2 molar ratio in methanol afforded a dinuclear μ-chlorido-bridged manganese(II) complex of the macrocyclic [2+2] condensation product (H2L), namely, [Mn 2Cl2(H2L)(HL)]Cl·3H2O (1). The latter afforded a new compound, namely, [Mn2Cl2(H 2L)2][MnCl4]·4CH3CN·0. 5CHCl3·0.4H2O (2), after recrystallisation from 1:1 CHCl3/CH3CN. The co-existence of the free and complexed azomethine groups, phenolato donors, μ-chlorido bridges, and the disiloxane unit were well evidenced by ESI mass spectrometry and FTIR spectroscopy and confirmed by X-ray crystallography. The magnetic measurements revealed an antiferromagnetic interaction between the two high-spin (S = 5/2, g = 2) manganese(II) ions through the μ-chlorido bridging ligands. The electrochemical behaviour of 1 and 2 has been studied, and details of their redox properties are reported. Both compounds act as catalysts or catalyst precursors in the solvent-free low-power microwave-assisted oxidation of selected secondary alcohols, for example, 1-phenylethanol, cyclohexanol, 2- and 3-octanol, to the corresponding ketones in the absence of solvent. The highest yield of 72 % was achieved for 1-phenylethanol by using a maximum of 1 % molar ratio of catalyst relative to substrate. Copyright
Catalytic Double Bond Isomerization by Polystyrene-Anchored RuCl2(PPh3)3
Zoran, Amikam,Sasson, Yoel,Blum, Jochanan
, p. 255 - 260 (1981)
Dichlorotris(triphenylphosphine)ruthenium has been anchored to diphenylphosphinated styrene-divinylbenzene copolymer.The resulting leaching-resistant catalyst was employed successfully for the isomerization of allylbenzenes and allyl alcohols in numerous turnovers.The stability of the catalyst was examined in different media, and its performances were compared with those of homogeneous RuCl2(PPh3)3 and with those of polymer-bound as well as of free RhCl(PPh3)3 and IrCl(CO)(PPh3)2
Wacker-type oxidation of internal olefins using a PdCl2/N,N- dimethylacetamide catalyst system under copper-free reaction conditions
Mitsudome, Takato,Mizumoto, Keiichi,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
, p. 1238 - 1240 (2010)
(Figure Presented) A simple catalyst system consisting of PdCl2 and N,N-dimethylacetamide (DMA) as the solvent can successfully promote Wacker-type oxidation of internal olefins. This catalyst system does not require copper compounds and is tolerant of a wide range of substrates having internal olefins.
Utilisation of new NiSNS pincer complexes in paraffin oxidation
Soobramoney, Lynette,Bala, Muhammad D.,Friedrich, Holger B.
, p. 97 - 105 (2018)
Two series of closely related SNS pincer ligands (L) were synthesised with the major structural variation on the nitrogen backbone containing either the methyl [L = (RSCH2CH2)2NMe: where R = Me (1), Et (2), Bu (3)] or the phenyl [L = (RSCH2CH2)2NPh: where R = Me (4), Et (5), Cy (6)] functional group. When ligands 1–3 were complexed to Ni by reaction with Ni(DME)Cl2 (DME = dimethoxyethane), they respectively yielded three new cationic dimeric [LNi(μ-Cl)3NiL]+ complexes (7–9), whilst ligands 4–6 on reaction with Ni(PPh3)2Br2 respectively yielded neutral mononuclear (LNiBr2) complexes 10–12. All the new compounds were characterised by IR, HRMS, elemental analysis and in addition, single crystal X-ray diffraction for complexes 9–12. X-ray structural data of 9 revealed an unusual three chlorido-bridged Ni dimer with the SNS ligand coordinated in a facial binding mode to the two pseudo-octahedral Ni centres. Molecular structures of complexes 10, 11 and 12 each displayed five-coordinate distorted trigonal bipyramidal geometry around the nickel(II) metal centres. When utilised as catalysts in the tert-butyl hydroperoxide oxidation of n-octane, all the complexes showed activity to mainly products of internal carbon activation (octanones and secondary octanols) with 11 as the most active (10% total substrate to oxygenates yield), whereas 10 was the least active, but most selective towards alcohols (alcohol/ketone = 2.13).
In Situ Spectroscopic Investigation of the Rhenium-Catalyzed Deoxydehydration of Vicinal Diols
Dethlefsen, Johannes R.,Fristrup, Peter
, p. 1184 - 1196 (2015)
The mechanism of the CH3ReO3-catalyzed deoxydehydration of a vicinal diol to an alkene driven by oxidation of a secondary alcohol was investigated by time-resolved, in situ IR spectroscopy and was found to occur in three steps: 1) reduction of the catalytically active methyltrioxorhenium(VII) to a rhenium(V) complex (the rate-limiting step), 2) condensation of the diol and the rhenium(V) complex to a rhenium(V) diolate, and 3) extrusion of the alkene accompanied by oxidation of the Re center and thus regeneration of CH3ReO3. The reaction follows zero-order kinetics initially but, unexpectedly, accelerates towards the end, which is explained in terms of a deactivating pre-equilibrium, in which the catalytically active CH3ReO3 condenses reversibly with the diol to form an inactive rhenium(VII) diolate. This conclusion is supported by the direct observation of a catalytically inactive species as well as DFT calculations of the IR spectra of the relevant compounds.
A collaborative effect between gold and a support induces the selective oxidation of alcohols
Abad, Alberto,Concepcion, Patricia,Corma, Avelino,Garcia, Hermenegildo
, p. 4066 - 4069 (2005)
Ceria nanoparticles as a support stabilize positive gold species and provide oxygen vacancies. The resulting solid exhibits an exceedingly high efficiency for the solventless aerobic oxidation of primary and secondary alcohols to carbonyl compounds (see picture). (Chemical Equation Presented)
Selective aerobic oxidation of alcohols with a combination of a polyoxometalate and nitroxyl radical as catalysts
Ben-Daniel,Alsters,Neumann
, p. 8650 - 8653 (2001)
-
Synthesis and Occurrence of Oxoaldehydes in Used Frying Oils
Takeoka, Gary R.,Buttery, Ron G.,Perrino, Charles T.
, p. 22 - 26 (1995)
As part of our efforts to identify volatile decomposition products in used frying oils, a series of 4- and 5-oxoaldehydes were synthesized, purified, and characterized by gas chromatography, gas chromatography-mass spectrometry, gas-chromatography-Fourier transform infrared spectrometry, and nuclear magnetic resonance spectrometry.Oxoaldehydes have been proposed as possible precursors of alkylfurans, which have potential anticancer effects.In a model reaction 4-oxononanal was refluxed in hexane for 40 days and only trace amounts of 2-pentylfuran were produced, suggesting that it is not a major precursor of the furan.The volatile constituents of used frying oils obtained from commercial food processors were studied, and 4-oxohexanal, 4-oxooctanal, 4-oxononanal, and 4-oxodecanal were identified.Keywords: Oxoaldehydes; odor threshold; frying oil
Atmospheric hydrogenation of Α Β-unsaturated ketones catalyzed by highly efficient and recyclable Pd nanocatalyst
Chen, Pu,Li, Wenjiang,Wang, Yanhua
, p. 10 - 14 (2019)
A thermoregulated phase-transfer Pd nanocatalyst was explored firstly and shown to be highly efficient and recyclable in the atmospheric hydrogenation of α β-unsaturated ketones. Under optimized reaction conditions, the conversion of chalcone and the selectivity of dihydrochalcone were 99% and 98%, respectively. The catalyst can be easily separated from the product and used directly for four times without evident loss in activity and selectivity. The turnover frequency (TOF) for the atmospheric hydrogenation of chalcone was 870 h?1, which to the best of our knowledge was the highest value ever reported among transition metal nanocatalysts.
Microsome-bound alcohol oxidase catalyzed production of carbonyl compounds from alcohol substrates
Kakoti, Ankana,Kumar, Adepu Kiran,Goswami, Pranab
, p. 98 - 104 (2012)
High yield conversion of a wide range of alcohol substrates to their corresponding aldehydes was demonstrated using a microsomal alcohol oxidase (AOx) from Aspergillus terreus. The microsome bound AOx preparation was then immobilized into polyurethane foam matrix following a simple adsorption technique. The successful immobilization of the enzyme into the foam matrix was demonstrated microscopically and by biological staining. The enzyme loading was measured as ～2.02 U mg-1 (76.6 mg protein %) of polyurethane foam. The optimum activity of the immobilized enzyme was detected in the pH range 7.0-8.0. The catalytic activity of the immobilized AOx was utilized for the production of n-heptanal. A maximum n-heptanal yield of 20.7 ± 1.2% (w/w) was achieved at a substrate concentration of 10 mM n-heptanol; beyond this concentration substrate dependent inhibition of the catalytic reaction was observed. The operational stability of the immobilized enzyme was determined and found to be ～60% of the initial activity till the fifth reaction cycle, thus providing high cumulative yield of the product. The deactivation (k d) and half-life time (t1/2) of the immobilized enzyme were 5.17 × 10-5 min-1 and ～9 days, respectively. The results demonstrated the potential application of the polyurethane foam immobilized microsomal AOx-based environmentally benign biocatalytic process for the production of industrially important n-heptanal.
Efficient isomerization of allylic alcohols to saturated carbonyl compounds by activated rhodium and ruthenium complexes
Uma, Ramalinga,Davies, Maxwell K.,Crevisy, Christophe,Gree, Rene
, p. 3141 - 3146 (2001)
A range of readily available rhodium complexes of the general structures Rh(PPh3)3+ PF6- and RhX(PPh3)3 (X = H, Me, Ph) have been prepared and used in situ for the isomerization of allylic alcohols to their corresponding saturated carbonyl compounds. The isomerization of octen-3-ol, selected as a model, yielded octan-3-one in good yield. This reaction has been extended to the corresponding ruthenium complexes of the general structures [RuCl(PPh3)3]+ PF6-, RuXCl(PPh3)3 and RuX2(PPh3)3 (X = H, Me, Ph). It is noteworthy that many of these complexes have not been employed previously for this isomerization. The scope and efficiency of the process has been demonstrated by four representative complexes [RhH(PPh3)3, RuH2(PPh3)3, RuPh2(PPh3)3, RuCl(PPh3)3+ PF6-] with a wide variety of allylic alcohols. The reaction of primary allylic alcohols in the presence of RuCl(PPh3)3+ PF6- in methanol yields aldehydes protected as their methyl acetals. Deuterium labelling experiments are in agreement with a 1,3-hydride shift mechanism.
Gold nanoparticles onto cerium oxycarbonate as highly efficient catalyst for aerobic allyl alcohol oxidation
Oberhauser, Werner,Evangelisti, Claudio,Marelli, Marcello,Santo, Vladimiro Dal,Cepek, Cinzia,Bellini, Marco
, (2020)
Au nanoparticles, generated by the metal vapor synthesis technique, were supported onto cerium oxycarbonate monohydrate (Ce2O(CO3)2·H2O) giving Au@Ce2O(CO3)2·H2O. The obtained heterogeneous catalyst was used in the aerobic allyl alcohol oxidation reaction performed in toluene, showing a notably higher catalytic substrate conversion and isomerization activity compared to Au onto ceria, which is the reference catalyst for this type of catalysis. Results originating from catalytic recycling experiments and PXRD, HRTEM and XPS measurements carried out on recovered Au@Ce2O(CO3)2·H2O, confirmed the stability of the catalyst under aerobic oxidation reaction conditions and hence its recyclability, without the need of a regeneration step.
New Polymer Colloidal and Carbon Nanospheres: Stabilizing Ultrasmall Metal Nanoparticles for Solvent-Free Catalysis
Wang, Tao,Zhang, Pengfei,Sun, Yan,Liu, Bing,Liu, Yunling,Qiao, Zhen-An,Huo, Qisheng,Dai, Sheng
, p. 4044 - 4051 (2017)
Herein, we report the synthesis of new colloidal polydiaminopyridine (PDAP) nanospheres with uniform particle size tuned from 76 to 331 nm. The polymer colloidal nanospheres and thin films assembled by the nanospheres exhibit amphiphilic or superhydrophilic properties, originated from the different polymer surfactants. In addition, the polymer nanospheres can be easily carbonized into microporous carbon nanospheres with high N content up to 24 wt %, thus enabling a preferred basicity for CO2 adsorption. As-synthesized PDAP show good compatibility that can not only encapsulate typical nanoparticles to form core-shell composite nanospheres but also stabilize noble metal ions to obtain ultrasmall metal nanoparticles (e.g., Pd and Au) during the thermal reduction process by the nitrogen sites from sphere frameworks. The nanocomplex Pd/PDAP-500 shows exceptional activity and high selectivity in the solvent-free oxidation of alcohols with O2.
Reactivity of the Dimer [{RuCl(μ-Cl)(η3:η3-C10H16)}2] (C10H16 = 2,7-Dimethylocta-2,6-diene-1,8-diyl) toward Guanidines: Access to Ruthenium(IV) and Ruthenium(II) Guanidinate Complexes
Menéndez-Rodríguez, Lucía,Tomás-Mendivil, Eder,Francos, Javier,Crochet, Pascale,Cadierno, Victorio,Anti?olo, Antonio,Fernández-Galán, Rafael,Carrillo-Hermosilla, Fernando
, p. 2796 - 2809 (2015)
The novel bis(allyl)ruthenium(IV) guanidinate complexes [RuCl{κ2(N,N′)-C(NR)(NiPr)-NHiPr}(η3:η3-C10H16)] (C10H16 = 2,7-dimethylocta-2,6-diene-1,8-diyl; R = Ph (3a), 4-C6H4F (3b), 4-C6H4Cl (3c), 4-C6H4Me (3d), 3-C6H4Me (3e) 4-C6H4tBu (3f)) have been synthesized by treatment of the dimeric precursor [{RuCl(μ-Cl)(η3:η3-C10H16)}2] (1) with 4 equiv of the corresponding guanidine (iPrHN)2C=NR (2a-f). The easily separable guanidinium chloride salts [(iPrHN)2C(NHR)][Cl] (4a-f) are also formed in these reactions. Attempts to generate analogous Ru(IV) guanidinate complexes from (iPrHN)2C=NR (R = 2-C6H4Me (2g), 2,4,6-C6H2Me3 (2h), 2,6-C6H3iPr2 (2i)) failed, due probably to the steric hindrance associated with the aryl group in these guanidines. On the other hand, the reaction of the dimer [{RuCl(μ-Cl)(η3:η3-C10H16)}2] (1) with (iPrHN)2C=N-4-C6H4C≡N (2j) led to the selective formation of the mononuclear derivative [RuCl2(η3:η3-C10H16){N≡C-4-C6H4-N=C(NHiPr2)2}] (5), in which the guanidine coordinates to ruthenium through the pendant nitrile unit. This result contrasts with that obtained by employing the related Ru(II) dimer [{RuCl(μ-Cl)(η6-p-cymene)}2] (6), whose reaction with 2j afforded the expected guanidinate complex [RuCl{κ2(N,N′)-C(N-4-C6H4C≡N)(NiPr)-NHiPr}(η6-p-cymene)] (7). Treatment of 7 with dimer 1 yielded the dinuclear Ru(II)/Ru(IV) derivative 8, via cleavage of the chloride bridges of 1 by the C≡N group of 7. Reductive elimination of the 2,7-dimethylocta-2,6-diene-1,8-diyl chain in [RuCl{κ2(N,N′)-C(NR)(NiPr)-NHiPr}(η3:η3-C10H16)] (3a-f) readily took place in the presence of an excess of 2,6-dimethylphenyl isocyanide, thus allowing the high-yield preparation of the octahedral ruthenium(II) compounds mer-[RuCl{κ2(N,N′)-C(NR)(NiPr)-NHiPr}(CN-2,6-C6H3Me2)3] (9a-f). The structures of [RuCl{κ2(N,N′)-C(N-4-C6H4Me)(NiPr)-NHiPr}(η3:η3-C10H16)] (3d), [RuCl{κ2(N,N′)-C(N-4-C6H4C≡N)(NiPr)-NHiPr}(η6-p-cymene)] (7), and mer-[RuCl{κ2(N,N′)-C(N-4-C6H4tBu)(NiPr)-NHiPr}(CN-2,6-C6H3Me2)3] (9f), as well as those of the guanidinium chloride salts 4a-c, were unequivocally confirmed by X-ray diffraction methods. In addition, the catalytic behavior of the guanidinate complexes 3a-f and 9a-f in the redox isomerization of allylic alcohols was also explored.
Effect of the functionalisation route on a Zr-MOF with an Ir-NHC complex for catalysis
Carson, Fabian,Martínez-Castro, Elisa,Marcos, Rocío,Miera, Greco González,Jansson, Kjell,Zou, Xiaodong,Martín-Matute, Belén
, p. 10864 - 10867 (2015)
A new iridium N-heterocyclic carbene (NHC) metallolinker has been synthesised and introduced into a metal-organic framework (MOF), for the first time, via two different routes: direct synthesis and postsynthetic exchange (PSE). The two materials were compared in terms of the Ir loading and distribution using X-ray energy dispersive spectroscopy (EDS), the local Ir structure using X-ray absorption spectroscopy (XAS) and the catalytic activity. The materials showed good activity and recyclability as catalysts for the isomerisation of an allylic alcohol.
Synthesis and characterization of Co3O4 immobilized on dipeptide-functionalized silica-coated magnetite nanoparticles as a catalyst for the selective aerobic oxidation of alcohols
Khodaei, Mohammad Mehdi,Dehghan, Mahsa
, p. 11381 - 11389 (2018)
Synthesis and characterization of a new silica-coated magnetite nanocatalyst are described. This catalyst was prepared through a multistep procedure consisting of surface modification, functionalization with the product of an Ugi multicomponent reaction, and immobilization of Co3O4 on silica-coated magnetite nanoparticles. The prepared nanocatalyst was characterized using various techniques such as Fourier-transform infrared and energy-dispersive X-ray spectroscopies, thermal and elemental analyses, X-ray diffraction, and field-emission scanning and transmission electron microscopies. The catalyst showed high catalytic activity for the aerobic oxidation of alcohols in acetonitrile as the solvent at mild temperatures and reusability for five repeated runs without loss of its activity.
Oxygen transfer from sulfoxides: Selective oxidation of alcohols catalyzed by polyoxomolybdates
Khenkin, Alexander M.,Neumann, Ronny
, p. 7075 - 7079 (2002)
Benzylic, allylic, and aliphatic alcohols are oxidized to aldehydes and ketones in a reaction catalyzed by Keggin-type polyoxomolybdates, PVxMo(12-x)O40-(3+x) (x = 0, 2), with DMSO as a solvent. The oxidation of benzylic alcohols is quantitative within hours and selective, whereas that of allylic alcohols is less selective. Oxidation of aliphatic alcohols is slower but selective. Further mechanistic studies revealed that, for H3PMo12O40 as a catalyst and benzylic alcohols as substrates, the sulfoxide is in fact an oxygen donor in the reaction. Postulated reaction steps as determined from isotopelabeling experiments, kinetic isotope effects, and Hammett plots include (a) sulfoxide activation by complexation to the polyoxometalate and (b) oxygen transfer from the activated sulfoxide and elimination of water from the alcohol. The mechanism is supported by the reaction kinetics.
A convenient synthesis of a porphyrin cross-linked polymer, its application as a size selective heterogeneous catalyst and a comparison with a porphyrin-cored hyperbranched polymer
Twyman, Lance J.,Zheng, Xinwei
, p. 617 - 623 (2016)
This paper describes how the polymeric structure and environment surrounding supported catalysts can be used to affect the product outcome from a reaction. As well as reporting a size/shape selectivity, we also describe a significant effect on product distribution. Specifically, how the polymeric environment can favour or disfavour particular products. As such, these results illustrate how it may be possible to target more or less of a specific compound (from a possible mix) by careful choice of the polymer architecture surrounding a catalyst.
Thermoregulated phase-transfer iridium nanoparticle catalyst: Highly selective hydrogenation of the CO bond for α,β-unsaturated aldehydes and the CC bond for α,β-unsaturated ketones
Li, Wenjiang,Wang, Yanhua,Chen, Pu,Zeng, Min,Jiang, Jingyang,Jin, Zilin
, p. 7386 - 7390 (2016)
In the same catalytic system, thermoregulated ligand Ph2P(CH2CH2O)22CH3-stabilized iridium nanoparticles exhibited a totally different orientation for the hydrogenation of unsaturated carbonyl compounds, namely, highly selective hydrogenation of the CO bond for α,β-unsaturated aldehydes and the CC bond for α,β-unsaturated ketones.
The effects of metals and ligands on the oxidation of n-octane using iridium and rhodium “PNP” aminodiphosphine complexes
Naicker, Dunesha,Alapour, Saba,Friedrich, Holger B
, p. 282 - 289 (2020/12/01)
Ir and Rh “PNP” complexes with different ligands are utilized for the oxidation of n-octane. Based on the obtained conversion, selectivity, and the characterized recovered catalysts, it is found that the combination of Ir and the studied ligands does not promote the redox mechanism that is known to result in selective formation of oxo and peroxo compounds [desired species for C(1) activation]. Instead, they support a deeper oxidation mechanism, and thus higher selectivity for ketones and acids is obtained. In contrast, these ligands seem to tune the electron density around the Rh (in the Rh-PNP complexes), and thus result in a higher n-octane conversion and improved selectivity for the C(1) activated products, with minimized deeper oxidation, in comparison to Ir-PNP catalysts.
Expanding the Biocatalytic Toolbox with a New Type of ene/yne-Reductase from Cyclocybe aegerita
Karrer, Dominik,Gand, Martin,Rühl, Martin
, p. 2191 - 2199 (2021/02/26)
This study introduces a new type of ene/yne-reductase from Cyclocybe aegerita with a broad substrate scope including aliphatic and aromatic alkenes/alkynes from which aliphatic C8-alkenones, C8-alkenals and aromatic nitroalkenes were the preferred substrates. By comparing alkenes and alkynes, a ～2-fold lower conversion towards alkynes was observed. Furthermore, it could be shown that the alkyne reduction proceeds via a slow reduction of the alkyne to the alkene followed by a rapid reduction to the corresponding alkane. An accumulation of the alkene was not observed. Moreover, a regioselective reduction of the double bond in α,β-position of α,β,γ,δ-unsaturated alkenals took place. This as well as the first biocatalytic reduction of different aliphatic and aromatic alkynes to alkanes underlines the novelty of this biocatalyst. Thus with this study on the new ene-reductase CaeEnR1, a promising substrate scope is disclosed that describes conceivably a broad occurrence of such reactions within the chemical landscape.
Oxidation of Alkenes by Water with H2 Liberation
Ben-David, Yehoshoa,Milstein, David,Tang, Shan
supporting information, p. 5980 - 5984 (2020/04/27)
Oxidation by water with H2 liberation is highly desirable, as it can serve as an environmentally friendly way for the oxidation of organic compounds. Herein, we report the oxidation of alkenes with water as the oxidant by using a catalyst combination of a dearomatized acridine-based PNP-Ru complex and indium(III) triflate. Compared to traditional Wacker-type oxidation, this transformation avoids the use of added chemical oxidants and liberates hydrogen gas as the only byproduct.
