新型ILs催化H2S制备β-巯基丙酸

Preparation of β-mercaptopropionic acid catalyzed by novel ionic liquids

摘要:

选择羧乙基硫代丁二酸（CETSA）作为阴离子，一步法合成四种亲水性的新型离子液体，经处理后分别采用1H NMR、13C NMR、TG、MS和FTIR对其结构进行了表征，确认离子液体催化剂合成成功。以丙烯酸和原位生成的硫化氢（H2S）为原料，进行迈克尔加成反应合成β-巯基丙酸，从而考察离子液体的催化效果。最佳工艺条件为：四氢呋喃用量35 g，丙烯酸用量2.16 g，通过原位生成足量硫化氢代替传统气瓶，离子液体3 mmol，在水热合成反应釜中反应温度90 ℃，反应时间4.5 h。此时，1,5-二氮杂双环[4.3.0]-5-壬烯羧乙基硫代丁二酸盐（[DBNH]CETSA）的催化效果最佳，丙烯酸转化率100%，产物选择性为90.57%。[DBNH]CETSA 重复使用 7 次仍具有较高的活性，丙烯酸的转化率仍达 98.97%，说明该离子液体催化剂在反应中比较稳定。

Abstract:

Carboxyethiosuccinic acid (CETSA) was selected as anion and four kinds of novel ionic liquids were synthesized by one-step method. Their structures were characterized by 1H NMR、13C NMR、TG、MS and FTIR respectively, confirming the successful synthesis of ionic liquid catalysts. β-mercaptopropionic acid was synthesized by Michael addition reaction from acrylic acid and hydrogen sulfide (H2S). The catalytic effect of ionic liquid was investigated. The optimal process conditions are: tetrahydrofuran (THF) of 35 g, acrylic acid of 2.16 g, sufficient hydrogen sulfide in situ to replace the traditional gas cylinder, the ionic liquid of 3mmol, the reaction temperature was 90 ℃, and the reaction time was 4.5 h in the hydrothermal synthesis reaction reactor. At this time, the results showed that 1,5-diazabicyclo[4.3.0]-5-nonene carboxyethyl thioglycoate ([DBNH]CETSA) showed the best catalytic effect, and the conversion rate of acrylic acid was 100% and the selectivity of product was 90.57%. [DBNH]CETSA still has high activityafter repeated use for 7 times, and the conversion rate of acrylic acid still reached 98.97%, indicating that the ionic liquid catalyst was relatively stable in the reaction.