Preparation of $\alpha $-hydroxyphenylacetic acid with cyclodextrins as an effective phase-transfer catalyst and its reaction mechanism

Authors: BING REN TIAN, RUI XIA ZHANG, HUI MIN CHU, QING HUANG, ZHI ZhONG WANG

Abstract: An effective procedure for the synthesis of $\alpha $-hydroxyphenylacetic acid with cyclodextrin (CD) catalysts was developed. The phase-transfer catalyst types, catalyst loadings, reaction times, reaction temperatures, and substrate molar ratios were investigated to optimize the reaction conditions. In addition, the factors that affect the reaction were studied, and the relationship between benzaldehyde and $\beta $-cyclodextrin ($\beta $-CD) was analyzed through 2D-ROESY. The equilibrium constant when $\beta $-CD was used as the catalyst was calculated. The results indicated that $\beta $-CD is the optimal catalyst for the reported reaction (yield: 69.08%). Furthermore, the mechanism underlying the reported reaction was proposed.

Keywords: Yclodextrin, benzaldehyde, $\alpha $-hydroxyphenylacetic acid, equilibrium constant, reaction mechanism

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