3,3-二甲基丁醛的合成工艺研究

Abstract

3,3-二甲基丁醛是合成新型强力甜味剂纽甜的重要中间体,其生产成本对纽甜的生产和应用影响重大.报道了一种简便和经济的3,3-二甲基丁醛合成工艺,以3,3-二甲基丁酸为原料,经氯化反应和常压催化氢化反应,合成了3,3-二甲基丁醛.研究了反应的工艺条件.3,3-二甲基丁酸的氯化反应以氯化亚砜为氯化剂,较为适宜的工艺条件为n(氯化亚砜)∶n(3,3-二甲基丁酸)=1.3∶1,反应温度80℃、反应时间3 H,3,3-二甲基丁酰氯的收率为92%.3,3-二甲基丁酰氯的常压催化氢化反应在二甲苯溶剂中进行,以Pd/C为催化剂,较为适宜的工艺条件为M(二甲笨)∶M(3,3-二甲基丁酰氯)=6.5∶1,催化剂用量W=15%(基于3,3-二甲基丁酰氯),氢气流量90 Ml/MIn,搅拌转速500 r/MIn,反应温度120℃,反应时间6 H,3,3-二甲基丁醛的收率为73.4%.催化剂重复使用6次,3,3-二甲基丁醛收率仍达到71%,显示良好的稳定性.

3,3-Dimethylbutyraldehyde(DMBD) is an important intermediate which is useful in the preparation of the novel high-intensity sweetener neotame.The cost of DMBD has a great influence on the production and application of neotame,therefore,a cost reduction is highly desirable.A convenient and economical method for preparation of DMBD is developed.DMBD was synthesized from 3,3-dimethylbutanoic acid by chlorination and catalytic hydrogenation under atmospheric pressure.Appropriate operation conditions for the reactions were researched.A yield of 92% for 3,3-dimethylbutanoyl chloride was achieved by chlorination of 3,3-dimethylbutanoic acid with thionyl chloride under following conditions:molar ratio of thionyl chloride to 3,3-dimethylbutanoic acid being 1.3∶1,reaction at 80℃ for 3 h.The catalytic hydrogenation of 3,3-dimethylbutanoyl chloride was carried out using xylene as a sovlent and Pd/C as catalyst.Yield of DMBD was reached up to 73.4% after reaction for 6 h under following conditions:mass ratio of xylene to 3,3-dimethybutanoyl chloride being 6.5∶1,the catalyst dosage 15%(by mass of 3,3-dimethylbutanoyl chloride),stirring speed 500 r/min,hydrogen flow rate 90 mL/min and temperature 120℃.A yield of 71% for DMBD was still achieved with the catalyst recycled for six times,which indicated good stability for the catalyst.