Elucidation of chemical synthesis from sugar and solvent effect on the reaction using supercritical microreactor

我们研究了在超临界水中以糖为原料的化学合成，重点是乙二醇酸作为一种可生物降解的材料。本研究考察了回收乙二醇醛的工艺条件。首先，分析了微反装置中乙二醇的分解过程。通过逆醛醇缩合反应，甘油醛分解为赤藓糖和乙二醇醛。乙二醇醛通过互变异构转化为果糖，最后分解为甘油醛和异戊醛。这些反应都伴随着脱水，我们估计的反应速率及其对温度的依赖性，使用微型反应器，并揭示了较高的温度和较低的水浓度促进逆醛醇反应，而不是脱水和互变异构。反应温度450℃，反应介质为密度为0.1g/cm^3的水，乙二醇酸的产率为89%。我们还证实了乙二醇醛通过Cannizzaro反应生成乙二醇酸，反应速率估计为几十毫秒，这表明需要小型反应器才能实现工业化过程。研究表明，在微反应器中制备乙二醇酸的反应条件、工业浓缩反应物的反应和其它工业热量的利用是有待进一步研究的课题，并进一步探讨了溶剂对反应时间的影响以及利用微反应器合成糖、纤维素、氨基酸和木质素的可能性。

We investigated chemical synthesis from sugar in supercritical water, focusing on glycol acid as a bio-degradable material. In this research, process conditions are surveyed to recover glycol aldehyde.First of all, we analyzed decomposition process of glycol using micro-reactors. Glycols decomposed to erythrose and then glycol aldehyde by retroaldol reaction. Glycol aldehyde is converted into fructose by tautomerism and finally decomposed into glyceraldehyde and pyruvaldehyde. These reactions were accompanied with dehydration.We estimated the reaction rate and its dependency on temperature, using micro-reactors, and revealed that higher temperature and lower water concentration promotes retroaldol reaction instead of dehydration and tautomerism. The reaction at 450℃ in water with a density of 0.1g/cm^3 produced glycol acid with a yield of 89%. We also confirmed glycol aldehyde reacted into glycol acid by Cannizzaro reaction.The reaction rate was estimated as several tens msec, indicating that small reactor is required to enable industrial processes. We showed that the remained research theme are reaction conditions for conversion to glycol acid, reaction of concentrated reactants for industrial process, and utilization of heat from other industry.We, further, estimated solvent effect on reaction time and the possibility of a new synthesis method for sugar, cellulose, amino acids, and lignin, using micro-reactors.