20246-26-8Relevant articles and documents
Phenolic compounds from the leaves of Cornus controversa
Lee, Dongho,Kang, Shin-Jung,Lee, Seung-Ho,Ro, Jaiseup,Lee, Kyongsoon,Kinghorn, A. Douglas
, p. 405 - 407 (2000)
Two novel phenolic compounds from the leaves of Cornus controversa (Cornaceae) were characterized as (-)-2,3-digalloyl-4(E)-caffeoyl-L-threonic acid and (-)-2-galloyl-4-(E)-caffeoyl-L-threonic acid, using spectroscopic methods. (C) 2000 Elsevier Science Ltd.
Oxidation of threose-series, pentose and hexoses by N-arylbromosulphonamides in alkaline medium
Shashikala,Rangappa
, p. 1907 - 1914 (2007/10/03)
Kinetic studies of the oxidation of D-galactose, L-sorbose and D-xylose by bromamine-T (sodium-N-bromo-p-toluenesulphonamide or BAT) and bromamine-B (sodium-N-bromobenzene sulphonamide or BAB) in alkaline medium has been investigated at 303 K. The rate of the reaction is first order both with respect to oxidant and sugar, and second order with respect to [HO-]. The addition of the reaction product p-toluenesulphonamide (PTS) or benzenesulphonamide (BSA) and the variation of ionic strength of the medium have no effect on the rate. The rate decreases with the decrease in dielectric constant of the medium and values of dAB, the size of activated complex are calculated. Proton inventory studies in H2O · D2O mixtures suggest a single transition state. Product analysis for D-galactose, L-sorbose and D-xylose reveal that hexoses give mainly mixture of lyxonic and threonic acids with minor proportions of hexonic, xylonic and glyceric acids, whereas xylose yields a mixture of lyxonic, threonic and glyceric acids with minor amounts of xylonic and hexonic acids. From the results of kinetic studies, reaction stoichiometry and product analysis, a possible mechanism for the oxidation of threose-series sugars is suggested.
Kinetics and mechanism of oxidation of erythro-series pentoses and hexoses by N-chloro-p-toluenesulfonamide
Rangappa, Kanchugarakoppal S.,Raghavendra, Manikanahally P.,Mahadevappa, Dandinasivara S.,Gowda, D. Channe
, p. 57 - 67 (2007/10/03)
The kinetics and mechanism of oxidation of D-glucose, D-mannose, D- fructose, D-arabinose, and D-ribose with chloramine-T in alkaline medium were studied. The rate law, rate = k [Chloramine-T] [Sugar] [HO-]2, was observed. The rate of the reaction was influenced by a change in ionic strength of the medium, and the dielectric effect was found to be negative. The latter enabled the computation of d(AB), the size of the activated complex. The reaction rate was almost doubled in deuterium oxide. Activation energies were calculated from the Arrhenius plots. HPLC and GLC-MS analyses of the products indicated that the sugars were oxidized to a mixture of aldonic acids, consisting of arabinonic, ribonic, erythronic, and glyceric acids. Based on these data, a plausible mechanism involving the aldo-enolic anions of pentoses and keto-enolic anions of hexoses is suggested.
