298-12-4Relevant articles and documents
Radiation Chemical Studies of Nickel-Glycine. Hydrogen Abstraction by OH Radicals and Oxidation by Br2-1
Bhattacharyya, S.N,Neta, P.
, p. 1527 - 1529 (1981)
Reactions of hydroxyl radicals with Ni(II)-glycine complexes were studied by pulse radiolysis and by product analysis.Radiolytic degradation of the complexes in N2O-saturated solutions leads to the formation of carbonyl compounds.The nature and the yield of these products indicate that the transient formed by reaction of OH with the complex undergoes disproportionation.The optical absorption spectrum of this transient exhibits a maximum below 250 nm, which is similar to that observed with glycine alone.The reaction of Br2- with the complex is found to be too slow to be observed by pulse radiolysis.However, the reaction occurs in steady-state radiolysis and yield products different from those observed with OH.Specifically, the yield of formaldehyde is appreciably higher in the presence of Br-.It is concluded that Br2- oxidizes the metal center of the Ni(II)-glycine complex to Ni(III), whereas OH reacts by hydrogen abstraction to form Ni(II)-coordinated glycine radical.
Formation of Two-Carbon Acids from Carbon Dioxide by Photoreduction on Cadmium Sulphide
Eggins, Brian R.,Irvine, John T. S.,Murphy, Eileen P.,Grimshaw, James
, p. 1123 - 1124 (1988)
Aqueous solutions of CO2 containing tetramethylammonium chloride were photolysed with visible light in the presence of colloidal CdS to yield glyoxylic acid as well as formic and acetic and CH2O.
Combination of Sodium Dodecylsulfate and 2,2′-Bipyridine for Hundred Fold Rate Enhancement of Chromium(VI) Oxidation of Malonic Acid at Room Temperature: A Greener Approach
Malik, Susanta,Mondal, Monohar Hossain,Ghosh, Aniruddha,De, Sourav,Mahali, Kalachand,Bhattacharyya, Shuvendu Sekhar,Saha, Bidyut
, p. 1043 - 1060 (2016)
Chromic acid oxidation of malonic acid in aqueous media has been investigated spectrophotometrically at 303?K. The product glyoxylic acid has been characterized by 13C-NMR and FTIR spectroscopy. Three representative N-heteroaromatic nitrogen base promoters, 2-picolinic acid, 2,2′-bipyridine (bpy) and 1,10-phenanthroline, in combination with the anionic surfactant sodium dodecylsulfate (SDS) enhanced the rate of the oxidation reaction compared to the unpromoted reaction.?2,2′-Bipyridine produced the maximum rate enhancement of the three promoters used. The mechanism of the reaction has been proposed with the help of kinetic results and spectroscopic studies. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. The SDS and bpy combination is suitable for malonic acid oxidation.
An Unusual Oxidative Ring Transformation of Purine to Imidazo[1,5-c] imidazole
Poje, Nevenka,Poje, Mirko
, p. 4265 - 4268 (2003)
(Equation presented) Reevaluation of products derived from 3, 9-dimethyluric acid in a chlorination-reductive dechlorinaton sequence has demonstrated unequivocally that they are not purines. Spectroscopic and degradative evidence, in conjunction with position-labeling NMR studies, revealed an unprecedented oxidative ring transformation pathway involving the key purine-to-imidazo[1,5-c]imidazole rearrangement.
Formation of Glyoxylic Acid by Oxidative Dehydrogenation of Glycolic Acid
Ai, Mamoru,Ohdan, Kyoji
, p. 1995 - 2000 (1997)
Iron phosphates with a P/Fe atomic ratio of 1.2 were found to be effective as catalysts for a vapor-phase oxidative dehydrogenation of glycolic acid to glyoxylic acid.The effects of the reaction variables on the conversion and selectivity were studied.The optimum reaction temperature was around 240 deg C and the optimum feed rate of oxygen was in the range of 10 to 25 mmol h-1 when the feed rate of glycolic acid was 12.3 mmol h-1.The reaction was not affected by a variation in the feed rate of water vapor in the range of 86 to 480 mmol h-1.The selectivity to glyoxylic acid remained unchanged at 74 molpercent with an increase in the conversion of glycolic acid up to 70percent; the highest yield of glyoxylic acid was 56.5 molpercent at the conversion of 80percent.
Mechanistic investigation of the oxidative cleavage of the carbon-carbon double bond in α,β-Unsaturated compounds by hexachloroiridate(iv) in acetate buffer
Pal, Biswajit
, p. 31 - 40 (2014)
The hexachloroiridate(IV) oxidation of α,β-unsaturated compounds such as acrylic acid, acrylamide, and acrylonitrile (CH2=CHX; X = -COOH, -CONH2, and -CN) was carried out in NaOAc-AcOH buffer medium. The reaction follows complex kinetics, being first order in [IrIV] and complex order in [CH2=CHX]. H+ ion has no effect on the reaction rate in the pH range 3.42-4.63. The pseudo-first-order rate constant decreases with a decrease in the dielectric constant and with a decrease of ionic strength of the medium. The oxidation rate follows the sequence: acrylonitrile > acrylamide > acrylic acid. A mechanism is proposed involving the formation of an unstable intermediate complex between the substrate and the oxidant which is transformed to the radical cation in a slow rate-determining step with the concomitant reduction of Ir(IV) to Ir(III). The radical cation subsequently decomposes to the aldehyde that appears as the ultimate product of the carbon-carbon double bond cleavage. The major product of oxidation was identified as HCHO by 1H NMR. Activation parameters for the slow rate-determining step and thermodynamic parameters associated with the equilibrium step of the proposed mechanism have been evaluated. The enthalpy of activation is linearly related to the entropy of activation, and this linear relationship confirms that the oxidation of all the α,β-unsaturated compounds follows a common mechanism.
Novel alcohol oxidase with glycolate oxidase activity from Ochrobactrum sp. AIU 033
Yamada, Miwa,Higashiyama, Takanori,Kishino, Shigenobu,Kataoka, Michihiko,Ogawa, Jun,Shimizu, Sakayu,Isobe, Kimiyasu
, p. 41 - 48 (2014)
We revealed that Ochrobactrum sp. AIU 033, which accumulated a high concentration of glyoxylate from glycolate, produced an enzyme catalyzing oxidation of glycolate to glyoxylate. The enzyme further oxidized lactate and primary alcohols (C2-C10), but did not oxidize glyoxylate, ethylene glycol, glycerol, or methanol. The Km value for glycolate (167 mM) was higher than that for primary alcohols. The glycolate oxidase activity was optimum at pH 5.5, and more than 80% of the enzyme activity remained in the pH range from 5.5 to 6.5 and at below 35 °C. The enzyme had a molecular mass of 130 kDa and was composed of an α2β2 structure, in which the α subunit was 52 kDa and the β subunit was 14 kDa. The enzyme was a flavoprotein and contained two iron atoms. The N-terminal sequences of the 52 kDa subunit and 14 kDa subunit had high similarity to those of putative glucose-methanol-choline oxidoreductases and putative 2-keto-gluconate dehydrogenase. These findings implied that the enzyme was a novel type of alcohol oxidase exhibiting glycolate oxidase activity. The enzyme accumulated glyoxylate with time, but oxalate, which is the oxidation product of glyoxylate, was not detected. This result also indicated that the enzyme catalyzed the formation of glyoxylate in the resting cell-reaction and thus could be useful in the enzymatic production of glyoxylate.
Selective Oxidation of Glyoxal to Glyoxalic Acid by Air over Mesoporous Silica Supported Pd Catalysts
Liu, Junchi,Qin, Feng,Huang, Zhen,Huang, Liang,Liao, Zhenan,Xu, Hualong,Shen, Wei
, p. 1894 - 1902 (2019)
Abstract: A series of mesoporous silica (KIT-6, MCM-41 and SBA-15) supported Pd catalysts were successfully synthesized and applied for selective oxidation of glyoxal. All of these catalysts exhibited significantly higher activity than commercial Pd/C. Among them, Pd/KIT-6 exhibited the best activity and selectivity with 41.3% glyoxal conversion and 57.0% selectivity to glyoxalic acid. The better performance of Pd/KIT-6 was attributed to its three-dimensional mesoporous structure. The three-dimensional mesoporous structure of KIT-6 could enhance Pd dispersion, providing sufficient accessible active sites which improved the conversion of glyoxal. Meanwhile, the better mass transfer capability of Pd/KIT-6 allowed glyoxalic acid to leave the catalyst easily, reducing the probability of over-oxidation. The ratio of kI (rate constant of initial oxidation reaction) to kII (rate constant of over-oxidation) was compared among three catalysts. The kI/kII of Pd/KIT-6 (0.50) was higher than that of Pd/MCM-41 (0.39) and Pd/SBA-15 (0.34), which reflected its best selectivity from kinetic aspect. Graphical Abstract: [Figure not available: see fulltext.]
Aluminum(III) triflate-catalyzed selective oxidation of glycerol to formic acid with hydrogen peroxide
Kong, Kang,Li, Difan,Ma, Wenbao,Zhou, Qingqing,Tang, Guoping,Hou, Zhenshan
, p. 534 - 542 (2019)
Glycerol is a by-product of biodiesel production and is an important readily available platform chemical. Valorization of glycerol into value-added chemicals has gained immense attention. Herein, we carried out the conversion of glycerol to formic acid and glycolic acid using H2O2 as an oxidant and metal (III) triflate-based catalytic systems. Aluminum(III) triflate was found to be the most efficient catalyst for the selective oxidation of glycerol to formic acid. A correlation between the catalytic activity of the metal cations and their hydrolysis constants (Kh) and water exchange rate constants was observed. At 70 °C, a formic acid yield of up to 72% could be attained within 12 h. The catalyst could be recycled at least five times with a high conversion rate, and hence can also be used for the selective oxidation of other biomass platform molecules. Reaction kinetics and 1H NMR studies showed that the oxidation of glycerol (to formic acid) involved glycerol hydrolysis pathways with glyceric acid and glycolic acid as the main intermediate products. Both the [Al(OH)x]n+ Lewis acid species and CF3SO3H Br?nsted acid, which were generated by the in-situ hydrolysis of Al(OTf)3, were responsible for glycerol conversion. The easy availability, high efficiency, and good recyclability of Al(OTf)3 render it suitable for the selective oxidation of glycerol to high value-added products.
Stereochemistry of the decarboxylation of glyoxylic acid by yeast pyruvate decarboxylase
Vegad, Hiran,Lobell, Mario,Bornemann, Stephen,Crout, David H.G.
, p. 2317 - 2324 (2000)
Tritiated glyoxylic acid was incubated with pyruvate decarboxylase. The hydroxymethylthiamine diphosphate formed was ozonolysed to give tritiated glycolic acid, the absolute configuration of which was investigated by analysis using glycolate oxidase. The tritiated glycolic acid proved to be racemic. The implications of this result are discussed in relation to models for the mechanism of pyruvate decarboxylase.
