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

研究了糖在超临界水中的化学合成，重点研究了乙二醇作为生物可降解材料。本研究考察了回收乙二醇醛的工艺条件。首先，分析了乙二醇在微反应器中的分解过程。乙二醇经反醛醇反应分解为红血球，再分解为乙二醇醛。乙二醇醛经互变异构作用转化为果糖，最后分解为甘油醛和丙酮醛。这些反应伴有脱水。我们利用微反应器估算了反应速率及其对温度的依赖性，发现较高的温度和较低的水浓度促进了反醛醇反应，而不是脱水和互变异构。在密度为0.1g/cm^3的水中，反应温度为450℃，生成乙二醇酸，收率为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，表明工业过程需要小型反应器。研究表明，剩余的研究主题是转化为乙二醇酸的反应条件、工业过程中浓缩反应物的反应以及其他工业热的利用。我们进一步估计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、氨基酸和木质素的新方法的可能性。

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.