C:Corrosive;
107-92-6Relevant articles and documents
Aqueous-phase hydrogenation of biomass-derived itaconic acid to methyl-γ-butyrolactone over Pd/C catalysts: Effect of pretreatments of active carbon
Li, Sha,Wang, Xicheng,Liu, Xiaoran,Xu, Guoqiang,Han, Sheng,Mu, Xindong
, p. 92 - 96 (2015)
The effect of active carbon pretreatment on the catalytic performance of Pd/C catalysts in the hydrogenation of itaconic acid was studied. The catalysts were prepared by deposition-precipitation and characterized by XRD, BET, NH3-TPD, TEM and F
A series of crystal structures of a meta-cleavage product hydrolase from Pseudomonas fluorescens IP01 (CumD) complexed with various cleavage products
Fushinobu, Shinya,Jun, So-Young,Hidaka, Masafumi,Nojiri, Hideaki,Yamane, Hisakazu,Shoun, Hirofumi,Omori, Toshio,Wakagi, Takayoshi
, p. 491 - 498 (2005)
Meta-cleavage product hydrolase (MCP-hydrolase) is one of the key enzymes in the microbial degradation of aromatic compounds. MCP-hydrolase produces 2-hydroxypenta-2,4-dienoate and various organic acids, according to the C6 substituent of the substrate. Comprehensive analysis of the substrate specificity of the MCP-hydrolase from Pseudomonas fluorescens IP01 (CumD) was carried out by determining the kinetic parameters for nine substrates and crystal structures complexed with eight cleavage products. CumD preferred substrates with long non-branched C6 substituents, but did not effectively hydrolyze a substrate with a phenyl group. Superimposition of the complex structures indicated that benzoate was bound in a significantly different direction than other aliphatic cleavage products. The directions of the bound organic acids appeared to be related with the kcat values of the corresponding substrates. The Ile139 and Trp143 residues on helix α4 appeared to cause steric hindrance with the aromatic ring of the substrate, which hampers base-catalyzed attack by water.
The Rhodium-Catalyzed Carbonylation of Linear Primary Alcohols
Deklewa, Thomas W.,Forster, Denis
, p. 3565 - 3567 (1985)
The results of a comprehensive kinetic, spectroscopic, and analytical study into the rhodium-catalyzed carbonylation of primary linear alcohols (R = Me, Et, and n-Pr) are reported.In all cases, the reaction rate is first order in both and added and independent of CO pressure.The only rhodium species observed under catalytic conditions was RhI2(CO)21-.The rates of carbonylation of the alcohols decreased in the order MeOH > EtOH >n-Pr with relative rates at 170 deg C of 21:1:0.47.Apparent activation parameters have been determined.All the data are consistent with the rate-determining step being nucleophilic attack by the rhodium ion on the corresponding alkyl iodide, in agreement with the previous interpretation of the methanol system.Important information was also obatained regarding the stability of the intermediate rhodium alkyl species.Carbonylation of n-PrOH gave a mixture of the two isomeric product butyric acids, the composition of which depended on the CO pressure.The isobutyric acid appears to arise from the isomerization of the initially formed n-alkyl species, and the pressure dependence of this process suggests that loss of CO from the alkyldicarbonylrhodium(III) species is competitive with the migratory insertion reaction which forms the analogous monocarbonyl acyl species observed previously.
Aerobic oxidation of alcohols to carbonyl compounds catalyzed by N-hydroxyphthalimide (NHPI) combined with Co(acac)3
Iwahama, Takahiro,Sakaguchi, Satoshi,Nishiyama, Yutaka,Ishii, Yasutaka
, p. 6923 - 6926 (1995)
Aerobic oxidation of various alcohols has been accomplished by using a new catalytic system. N-hydroxyphthalimide (NHPI) combined with Co(acac)3. The oxidation of alcohols by NHPI was found to be markedly enhanced by adding a slight amount of Co(acac)3 (0.05 equiv. to NHPI). Thus, secondary alcohols and vic-diols which are difficult to be oxidized by NHPI alone were smoothly oxidized with molecular oxygen (1 atm) to the corresponding carbonyl compounds under relatively mild conditions (65 ~ 75 °C).
An unexplored O2-involved pathway for the decarboxylation of saturated carboxylic acids by TiO2 photocatalysis: An isotopic probe study
Wen, Bo,Li, Yue,Chen, Chuncheng,Ma, Wanhong,Zhao, Jincai
, p. 11859 - 11866 (2010)
The aerobic decarboxylation of saturated carboxylic acids (from C 2 to C5) in water by TiO2 photocatalysis was systematically investigated in this work. It was found that the split of C 1-C2 bond of the acids to release CO2 proceeds sequentially (that is, a C5 acid sequentially forms C4 products, then C3 and so forth). As a model reaction, the decarboxylation of propionic acid to produce acetic acid was tracked by using isotopic-labeled H218O. As much as ≈42% of oxygen atoms of the produced acetic acids were from dioxygen (16O2). Through diffuse reflectance FTIR measurements (DRIFTS), we confirmed that an intermediate pyruvic acid was generated prior to the cut-off of the initial carboxyl group; this intermediate was evidenced by the appearance of an absorption peak at 1772 cm-1 (attributed to C=O stretch of α-keto group of pyruvic acid) and the shift of this peak to 1726 cm -1 when H216O was replaced by H 218O. Consequently, pyruvic acid was chosen as another model molecule to observe how its decarboxylation occurs in H2 16O under an atmosphere of 18O2. With the α-keto oxygen of pyruvic acid preserved in the carboxyl group of acetic acid, ≈24% new oxygen atoms of the produced acetic acid were from molecular oxygen at near 100% conversion of pyruvic acid. The other ≈76% oxygen atoms were provided by H2O through hole/OH radical oxidation. In the presence of conduction band electrons, O2 can independently accomplish such C1-C2 bond cleavage of pyruvic acid to generate acetic acid with ≈100% selectivity, as confirmed by an electrochemical experiment carried out in the dark. More importantly, the ratio of O2 participation in decarboxylation increased along with the increase of pyruvic acid conversion, indicating the differences between non-substituted acids and α-keto acids. This also suggests that the O 2-dependent decarboxylation competes with hole/OH-radical-promoted decarboxylation and depends on TiO2 surface defects at which Ti 4c sites are available for the simultaneous coordination of substrates and O2. Acid aerobics! An O2-involved pathway for the decarboxylation of saturated carboxylic acids by TiO2 photocatalysis is clarified, and has been found to be composed of two major tandem steps. An oxygen atom of O2 is incorporated into the product acid in the second step (see scheme).
An Efficient Synthesis of Optically Active 4-Methyloxetan-2-one: Asymmetric Hydrogenation of Diketene catalysed by binap-Ruthenium(II) Complexes
Ohta, Tetsuo,Miyake, Tsutomu,Takaya, Hidemasa
, p. 1725 - 1726 (1992)
Highly enantioselective hydrogenation of diketene with the catalytic system derived from (benzene)>Cl and triethylamine or with Ru2Cl42(NEt3) in tetrahydrofuran gives optically active 4-methyloxetan-2-one in up to 97percent selectivity and 92percent enantiomeric excess (e.e.).
Lid hinge region of Penicillium expansum lipase affects enzyme activity and interfacial activation
Tang, Lianghua,Su, Min,Yan, Junzhe,Xie, Sheng,Zhang, Wenhuang
, p. 1218 - 1223 (2015)
Saturation mutagenesis at sites displaying the highest B factors in the lid and the hinge regions of Penicillium expansum lipase (PEL) has been employed to improve the efficiency of the lipase in biocatalysis. Replacements of amino acid on beneficial mutants were identified as T66L/D70N, T66V/D70N, E83K, E83H and E83N. In substrate specificity assays, T66L/D70N was significantly more active than wild-type PEL on substrates with medium and long chain lengths. In addition this mutant also displayed a 136.4-fold increase in activity on p-nitrophenyl palmitate. Remarkably, E83K lacked interfacial activation while it was observed in wild-type PEL and the other mutants. Insight into the relation between the mutations and enzymatic properties was gained by modeling and docking studies. All these mutants showed an enhanced catalytic activity, indicating their potential in further application. Therefore, these results indicate the amino acid composition of the lid hinge region plays an extremely important role in the interfacial activation, activity and substrate specificity of PEL. Moreover, the results in this work provide a new clue for selecting critical amino acid residues for the enzyme design.
Effects of diluents on the reaction hazards of tributyl phosphate with nitric acid
Sreekantan, Smitha Velayuthan,Mahadevan, Surianarayanan,Jala, Samuel Vara Kumar,Seshadri, Hariharan,Mandal, Asit Baran
, p. 1821 - 1827 (2014)
A proportion of 30 wt % of tributyl phosphate (TBP) in suitable diluents is the workhorse in the extraction of U and Pu in the plutonium uranium extraction (PUREX) process. Accelerating rate calorimetric (ARC) studies of effects of diluents on TBP behavior reveal a similar thermal behavior irrespective of the nature of diluents. The reactive thermal hazards of 30 wt % of TBP with 4N HNO3 in different diluents show onset temperatures in the range of 105-130 °C with a significant pressure rise. Although the onset points are closer to the operating temperature range of the PUREX process, the heat rates are small. However, the process poses pressurization hazards due to the breakdown of the structure of TBP. Oxidation of butanol to butanoic acid is the main cause for exothermic behavior in all cases.
HYDROCARBONYLATION DE LACTONES EN PRESENCE DE CATALYSEURS A BASE DE COBALT ET DE RHODIUM
Bitsi, Gustave,Kheradmand, Houchang,Jenner, Gerard
, p. 115 - 120 (1986)
The hydrocarbonylation of lactones catalysed by rhodium and cobalt complexes is discussed.Rhodium catalysts promote the formation of mono- and di-acids, but with cobalt catalysts homologation takes place yielding lactones and acids.The addition of iodine promotors is essential.
Adsorption and degradation of Congo red on a jarosite-type compound
Dong, Yu,Wang, Ziting,Yang, Xin,Zhu, Meiying,Chen, Rufen,Lu, Bin,Liu, Hui
, p. 102972 - 102978 (2016)
Natrojarosite particles were prepared by forced hydrolysis. X-ray diffraction and field-emission scanning electron microscopy were used to characterize the resulting products. Degradation of the azo dye Congo red (CR) by natrojarosite was investigated under various conditions, such as in the presence or absence of visible-light irradiation, catalyst loading, H2O2 concentration, and initial pH. Total organic carbon determination, UV-visible spectroscopy, and direct infusion-electrospray ionization mass spectrometry in the negative ion mode provided insight into the nature of the degradation products. Moreover, a complete degradation mechanism of CR on natrojarosite was presented. The degradation of CR in the current system occurred even at neutral pH, and the total degradation rate was close to 99.1% for a 30 mg L-1 CR solution. Approximately 80% of the samples were completely mineralized and the other 20% were degraded to small-molecule products. The novel natrojarosite catalysts are potentially valuable for industrial applications because of their high activity, low iron leaching, and low cost.
