692-29-5Relevant academic research and scientific papers
Rearrangements and Tautomeric Transformations of Heterocyclic Compounds in Homogeneous Reaction Systems Furfural–Н2О2–Solvent
Badovskaya,Poskonin
, p. 1568 - 1579 (2018/11/10)
General information on the reactions of furfurals with hydrogen peroxide is given. We have discussed the Baeyer–Villiger rearrangement of furan 2-hydroxyhydroperoxides and tautomeric transformations with proton transfer of 2-hydroxyfuran and β-formylacrylic acid formed in a homogeneous reaction system furfural–Н2О2–solvent under the catalysis with the formed acids. The factors affecting these rearrangements and tautomeric transformations as well as their specificity in comparison with benzene type compounds, and the pathway of the reactions of furan aldehydes with Н2О2 in water have been analyzed. Ketoenol tautomerism of cyclic hemiacetal form of β-formylacrylic acid leading to its transformation into succinic anhydride has been described for the first time.
Hydrogenations without hydrogen: Titania photocatalyzed reductions of maleimides and aldehydes
Manley, David W.,Buzzetti, Luca,MacKessack-Leitch, Andrew,Walton, John C.
, p. 15324 - 15338 (2015/01/16)
A mild procedure for the reduction of electron-deficient alkenes and carbonyl compounds is described. UVA irradiations of substituted maleimides with dispersions of titania (Aeroxide P25) in methanol/acetonitrile (1:9) solvent under dry anoxic conditions led to hydrogenation and production of the corresponding succinimides. Aromatic and heteroaromatic aldehydes were reduced to primary alcohols in similar titania photocatalyzed reactions. A mechanism is proposed which involves two proton-coupled electron transfers to the substrates at the titania surface.
Inhibition of 1,4-butanediol metabolism in human liver in vitro
Lenz, Daniel,Juebner, Martin,Bender, Katja,Wintermeyer, Annette,Beike, Justus,Rothschild, Markus A.,Kaeferstein, Herbert
scheme or table, p. 647 - 654 (2012/06/01)
The conversion of 1,4-butanediol (1,4-BD) to gamma-hydroxybutyric acid (GHB), a drug of abuse, is most probably catalyzed by alcohol dehydrogenase, and potentially by aldehyde dehydrogenase. The purpose of this study was to investigate the degradation of 1,4-BD in cytosolic supernatant of human liver in vitro, and to verify involvement of the suggested enzymes by means of gas chromatography-mass spectrometry. The coingestion of 1,4-BD and ethanol (EtOH) might cause complex pharmacokinetic interactions in humans. Therefore, the effect of EtOH on 1,4-BD metabolism by human liver was examined in vitro. Additionally, the influence of acetaldehyde (AL), which might inhibit the second step of 1,4-BD degradation, was investigated. In case of a 1,4-BD intoxication, the alcohol dehydrogenase inhibitor fomepizole (4-methylpyrazole, FOM) has been discussed as an antidote preventing the formation of the central nervous system depressing GHB. Besides FOM, we tested pyrazole, disulfiram, and cimetidine as possible inhibitors of the formation of GHB from 1,4-BD catalyzed by human liver enzymes in vitro. The conversion of 1,4-BD to GHB was inhibited competitively by EtOH with an apparent K i of 0.56 mM. Therefore, the coingestion of 1,4-BD and EtOH might increase the concentrations and the effects of 1,4-BD itself. By contrast AL accelerated the formation of GHB. All antidotes showed the ability to inhibit the formation of GHB. In comparison FOM showed the highest inhibitory effectiveness. Furthermore, the results confirm strong involvement of ADH in 1,4-BD metabolism by human liver.
Aggregation in oxidation of aspartic and glutamic acids by chloramine-T in presence of surfactants: A kinetic study
Pandey, Ekta,Grover, Neeti,Kambo, Neelu,Upadhyay, Santosh K.
, p. 1186 - 1192 (2007/10/03)
The kinetics of oxidation of aspartic and glutamic acids by chloramine-T in HClO4 medium have been investigated in the absence and presence of anionic (sodium lauryl sulphate), cationic (cetyltrimethylammonium bromide) and non-ionic (Brij 35) surfactants. In the absence of surfactant the rate of oxidation may be represented as, d[Chloramine-T]/dt=k[Chloramine-T] 2[Amino acid]/(1+K[H+]) where k and K are constants. The presence of a small amount of surfactant (below its critical micelle concentration) strongly enhances the rate of oxidation and the observed rate constant attains constancy at higher surfactant concentration. Using Piszkiewicz's cooperativity model, the cooperative index n has been calculated for these reactions to be between 1-3, indicating the existence of catalytically productive submicellar aggregates. The values of n have been used to calculate the binding constants of reactants with the surfactant using Raghvan and Srinivasan's model proposed for biomolecular micellar catalysed reactions. The evaluated binding constants are in good agreement from those obtained by Piszkiewicz's model. The formation of aggregate is further supported by the enhancement of rate in presence of a common hydrotrope, namely, sodium benzoate.
Role of chloride in the oxidative decarboxylation of amino acids by chloramine-T
Gowda, B. Thimme,Quine, S. Darlin,Krishna Kumar
, p. 413 - 420 (2007/10/03)
Kinetics of oxidative decarhoxylation of amino acids by chloramine-T in the presence of chloride have been studied in aqueous perchloric acid over a wide range. The rate-[H+] plots show nearly bell-shaped profiles in the presence of added chloride. The rate-dependence in [CAT] changes from second order to first order as [H+] and [Cl-] are varied. The reactions generally show fractional order kinetics in [AA] and inverse dependence in [H+] except in the acid range 0.05-0.20 mol dm-3. Mechanisms consistent with the observed results are discussed. The rate-limiting steps have been identified and constants of these steps calculated. Activation parameters corresponding to these steps have also been computed. Validity of Taft equation has been tested. The study establishes the significant role of chloride in chloramine-T oxidations in acid medium. The chloride effect is more pronounced at high acid concentrations.
Aerosol formation in the cyclohexene-ozone system
Seinfeld,Kalberer,Yu,Cocker,Flagan
, p. 4894 - 4901 (2007/10/03)
Atmospheric oxidation of certain VOCs can yield products with low vapor pressure resulting in the partitioning of the products into the aerosol phase, producing secondary organic aerosol. As cyclohexene is known to produce aerosol upon photooxidation, it was used as a model system for the molecular identification of gas- and aerosol-phase products via derivatization and MS detection. Adipic acid, hydroxyglutaric acid, and hydroxyadipic acid were among the compounds identified in the aerosol phase. Pentanal was the predominant product in the gas phase at a molar yield of 17%. Possible explanations for the presence of relatively high vapor pressure compounds in the aerosol phase are presented.
Catalytic oxidation of furan and hydrofuran compounds. 2. Oxidation of furfural in the hydrogen peroxide-vanadyl sulfate-sodium acetate system
Poskonin,Badovskaya
, p. 646 - 650 (2007/10/03)
The characteristics of the oxidation of furfural in the hydrogen peroxide-VOSO4-sodium acetate system and the composition of the products were studied. The principal stages of the reaction occur at pH ～7. The direction of the reaction is very different from the process in an acidic medium, where β-formylacrylic and maleic acids are mainly formed. The main oxidation products in the acetate buffer solution in the presence of VOSO4 are succinic and β-formylpropionic acids and 2(5H)-furanone; without the catalyst the main product is 2-furancarboxylic acid. A mechanism is proposed for the transformations of furfural in the investigated system. 1998 Plenum Publishing Corporation.
Coenzyme A hemithioacetals as easily prepared inhibitors of CoA ester-utilizing enzymes
Schwartz, Benjamin,Vogel, Kurt W.,Drueckhammer, Dale G.
, p. 9356 - 9361 (2007/10/03)
Hemithioacetals are formed by reactions of coenzyme A (CoA) with aldehydes in aqueous solution. Equilibria for hemithioacetal formation with four commercially available aldehydes and rate constants for hemithioacetal dissociation have been studied. The hemithioacetals are viewed as acyl-CoA analogs having a tetrahedral center in place of the planar trigonal thioester carbonyl carbon. These compounds may serve as mimics of the tetrahedral intermediate or transition state in the reactions of acyl-CoA dependent acyltransferase enzymes. The hemithioacetal generated by reaction of CoA with formaldehyde is a poor inhibitor of chloramphenicol acetyltransferase, with a K(i) more than 6-fold higher than the K(m) for the substrate acetyl-CoA. The hemithioacetals formed by reaction of CoA with acetaldehyde and trifluroacetaldehyde are substantially better inhibitors, with K(i) values approximately 2.4-fold and 10-fold lower than the K(m) values for acetyl-CoA, respectively. The hemithioacetal formed by reaction of CoA with succinic semialdehyde inhibits succinic thiokinase, with a K(i) 4-fold lower than the K(m) for the substrate succinyl-CoA. The CoA hemithioacetals provide a novel readily accessible new class of acyl-CoA analogs for use in mechanistic and structural studies of CoA ester-utilizing enzymes.
EFFECT OF HALOGEN SUBSTITUTION OF INDOLE-3-ACETIC ACID ON BIOLOGICAL ACTIVITY IN PEA FRUIT
Reinecke, Dennis M.,Ozga, Jocelyn A.,Magnus, Volker
, p. 1361 - 1366 (2007/10/02)
Auxins (a class of plant growth hormones naturally present in all plants) have been implicated in fruit growth of pea.Pea (Pisum sativum L.) fruit contain the auxins indole-3-acetic acid (IAA) and 4-chloroindole-3-acetic acid (4-Cl-IAA).Fruits grow poorly and subsequently abscise when seeds are removed two days after anthesis, but 4-Cl-IAA can substitute for the seeds in maintaining growth of deseeded fruit (perciarp) in planta.Applications of 4-Cl-IAA promoted pericarp growth, the effect increasing with concentration from 1 to 100 μM, but IAA was ineffective in stimulating growth when tested from 0.1 to 100 μM.The effect of the position of the halogen on pericarp growth was examined by assaying the activities of 4-, 5-, 6- and 7-chloro- and fluoro-substituted IAA.The position and type of halogen dramatically affected auxin activity, with the natural product 4-Cl-IAA being most effective.Of the other compounds tested, only 5-Cl-IAA stimulated pea pericarp elongation, and then only moderately.Fluoro-substituted IAAs did not stimulate pericarp growth, and 4-F-IAA was inhibitory.This study is unique in that it reports the biological activity of 4-Cl-IAA and halogen-IAA analogues in tissues of intact plants known to contain 4-Cl-IAA.The relative activity of the compounds is discussed in reference to previous reports of auxin activity in other systems, and 4-Cl-IAA's possible importance in pea fruit growth. - Key words: Pisum sativum; Leguminosae; pea pericarp; auxin; IAA; 4-chloroindole-3-acetic acid; helogenated-IAA analogues.
