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采用理论计算方法研究了果糖脱水转化为5-羟甲基糠醛(HMF)的反应历程,系统考察了环果糖经历环状呋喃衍生物中间体转化为HMF和链果糖经历烯二醇中间体转化为HMF的反应机理。结果表明,该转化过程由质子化、脱水和去质子等一系列基元反应组成。环果糖易于被质子化,去质子化反应由于能垒较高成为转化过程的决速步骤。在链果糖的转化过程中,质子化反应则成为决速步骤。反应体系中水的存在会促进环果糖的转化,但对链果糖的转化却表现出一定的抑制作用。
The reaction process of dehydration of fructose to 5-hydroxymethylfurfural (HMF) was studied by using theoretical calculation method. The conversion of cyclic fructose to HMF and fructose through cyclic furan derivatives was investigated systematically. HMF reaction mechanism. The results show that the conversion process consists of a series of elementary reactions such as protonation, dehydration and deprotonation. Cyclic fructose is easily protonated, deprotonation due to the higher energy barrier as the rate step of the conversion process. During the conversion of the chain fructose, the protonation reaction becomes the rate-fixing step. The presence of water in the reaction system will promote the conversion of cyclofructose, but the conversion of chain fructose has shown some inhibition.