Abstract:

The preparation of benzyl alcohol and benzoic acid from benzaldehyde by Cannizarro reaction was the common content of organic chemistry laboratory teaching. Nevertheless, due to its time consuming, low yield and inefficient isolating method, this experimental design was far from satisfactory in teaching. The following improvements have been made:Microwave radiation method was introduced, and the synthesis conditions was optimized by orthogonal test design. Under optimized conditions which was 50% KOH, microwave radiation at 500 W for 15 min, the reaction was completed. The yield of benzyl alcohol could reach 82.0%. Benzyl alcohol was isolated by column chromatography instead of distillation, to avoid the formation of distillation by-products. The yield of benzyl alcohol in crude products was determined quickly and accurately by spectrophotometry without separation. The comparison showed that the improved method could reduce the time by 99% and increase the yield by 15%. In addition, the extraction agent was more safe. The improvement was more responsive to the increasing requirements of laboratory training development.

Key words: Microwave radiation, Orthogonal test, Spectrophotometry, Improvement and innovation