顺/反-异戊烯基-3-甲基丁二烯醚的合成研究

Study on Synthesis of Citral Intermediate

以异戊烯醛和异戊烯醇为原料,经异戊烯酸催化缩醛化反应得到3-甲基-2-丁烯醛二异戊烯基缩醛,再经磷酸催化消除反应得到顺/反-异戊烯基-3-甲基丁二烯醚。对缩醛化反应条件和消除反应条件等工艺条件进行了详细研究。结果表明,以0.3%异戊烯酸为酸性催化剂,70~75℃共沸脱水反应8 h,异戊烯醛的单程转化率达到63%~64%,处理后可得含量为97.5%的3-甲基-2-丁烯醛二异戊烯基缩醛,收率96.8%;以100×10-6磷酸为催化剂,90~120℃,2.66 kPa下反应并及时将反应产物蒸出,处理后得到含量为95.7%的顺/反-异戊烯基-3-甲基丁二烯醚,收率97.0%。

For search the effective method of synthesis of citral intermediate,prenal and prenol was taken as starting material,using cetalization reaction 3-methyl-2-butenal diprenyl acetal was synthesized by senecioic acid catalysis and elimination reaction cis/trans-prenyl-3-methylbutadienyl ether with phosphoric acid catalysis.The conditions of acetalization reaction and elimination reaction were investigated in detail.It was found that with 0.3% senecioic acid as catalysis,acetalization reacting at 70~75℃ for 8 hrs by azeotropism,one-way conversion for prenal was 63~64%;after treatment 3-methyl-2-butenal diprenyl acetal yield was 96.8% with 97.5% purity.Using 100×10-6 phosphoric acid as catalyst,elimination reacting at 90~120℃ and 2.66 kPa and vaporizing out of the reaction products in a timely manner,after treatment cis/trans-prenyl-3-methylbutadienyl ether yield was 97% with 95.7% purity.