Identification of Oxidation Products and Oxidation Pathways of High Molecular Weight Dicarboxylic Acids under Hydrothermal Condition

Abstract

CAO, J.; ENOMOTO, H.; MORIYA, T.; J. Supercrit. Fluids 39 (2006) 1, 80-88; Dep. Environ. Stud., Grad. Sch. Environ. Stud., Tohoku Univ., Aoba, Sendai 980, Japan; Eng.) -Meier 12-252

Rapid and highly selective conversion of biomass into value-added products in hydrothermal conditions: chemistry of acid/base-catalysed and oxidation reactions

“…The mechanism via decarboxylation of hexonic acids was tested in glucose experiments by changing the oxygen supply. 37 If a mechanism via decarboxylation of hexonic acid exists, then the addition of oxygen should promote not only the oxidation of glucose into hexonic acid, but also the decarboxylation of hexonic acid, whose mechanism has been explained elsewhere, 15 and thus lead to an increase in the formation of xylose or 2-FA. In these experiments, neither gluconic acid nor xylose were detected, and no significant difference in the yield of 2-FA was observed.…”

“…Hydrothermal oxidation of organic compounds is generally thought to proceed through a free radical mechanism. [82][83][84][85][86][87] On the basis of the oxidation mechanism of carboxylic acids in supercritical water 12,15 and the oxidation mechanism of secondary alcohols in a liquid phase, 82,83 as well as on experimental results that the oxidation of all of cellulose, starch and glucose yielded a considerably high quantity of formic acid, a possible reaction scheme shown in Fig. 8 was proposed to explain the oxidation pathways of carbohydrates.…”

“…Extensive research on the hydrothermal conversion of organic waste and low-value organic materials into fuels and chemicals has demonstrated that hydrothermal reactions can convert various natural organic materials directly and efficiently into useful chemicals, [11][12][13][14][15][16][17][18][19][20][21][22][23] synthetic organic materials like plastics into oil 24 and ultra-heavy crude oil like bitumen into light oil. 25 Some works on the hydrothermal conversion of biomass, the chemical reactions for specified compounds and the roles of HTW in chemical reactions have been described in review articles.…”

Reactivity of Aliphatic Dicarboxylic Acids in Wet Air Oxidation Conditions

“…They proposed that the main oxidation sites (α-, β-, and γ-carbon from the carbonyl group) and major intermediates are short-chain DCAs, (ω − 1)-oxo acids, and γ-lactones. 39,40 Still, there is no sufficient quantitative information about the effect of pH and other additives on the oxidation. First we studied the stability of a DCA artificial mixture in water at different O 2 concentrations (21% O 2 (air), a 50% O 2 (with N 2 ), and 100% O 2 ) and determined the quantity of each DCA after oxidation.…”

Hydrothermal Lactic Acid Production from Glucose over Feldspars as Solid Base Catalysts in Water

“…They are made of SUS-316 stainless steel. The details of this reactor system have been described in previous publication [6][7] . The general experimental procedure was as follows: the desired amount of glucose, feldspars and 2ml of water prepared in advance were added into the batch reactor and the sealed reactor was pleased into a salt bath preheated to the desired temperature.…”