Efficient synthesis of epoxybutane from butanediol via a two-step process

Xin Niu; Liguo Wang; Junya Cao; Yan Cao; Peng He; Junya Zhou; Huiquan Li

doi:10.1039/c9ra01220f

Efficient synthesis of epoxybutane from butanediol via a two-step process

RSC Adv. 2019 Mar 29;9(18):10072-10080. doi: 10.1039/c9ra01220f. eCollection 2019 Mar 28.

Authors

Xin Niu^{1

2}, Liguo Wang^{2

3

4}, Junya Cao¹, Yan Cao², Peng He², Junya Zhou^{1

2}, Huiquan Li^{2

3}

Affiliations

¹ China University of Mining &Technology, Beijing Beijing 100083 P. R. China.
² CAS Key Laboratory of Green Process and Engineering, National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences Beijing 100190 P. R. China lgwang@ipe.ac.cn hqli@ipe.ac.cn.
³ Sino-Danish College University, Chinese Academy of Sciences, Beijing 100049 P. R. China.
⁴ Dalian National Laboratory for Clean Energy Dalian 116023 China.

Abstract

A novel approach for the synthesis of epoxybutane via decarboxylation of butenyl carbonate derived from butanediol was developed for the first time. For the carbonylation of butanediol with dimethyl carbonate, NaAlO₂ has exhibited excellent catalytic activity under mild reaction conditions. The yield of butenyl carbonate reached as high as 96.2%. NaAlO₂ provides suitable acid-base active sites to promote the transesterification reaction of butanediol and dimethyl carbonate. For the following step of decarboxylation of butenyl carbonate, ionic liquid 1-butyl-3-methylimidazolium bromide could effectively catalyze the decarboxylation process both in batch or continuous processes. Moreover, the catalytic mechanism for the crucial step of decarboxylation of butenyl carbonate over 1-butyl-3-methylimidazolium bromide was explored using DFT calculations. The results showed that the electrostatic and hydrogen-bond effects of 1-butyl-3-methylimidazolium bromide played a crucial role for the generation of epoxybutane. Briefly, the Br anion of the ionic liquid attacks the methylene of the ring and the H of the ionic liquid cation attacks the carbonyl oxygen, which facilitated the five-ring opening and subsequent decarboxylation to form BO. This study not only provided a new and green synthetic route for producing epoxybutane, but also contributed to the effective utilization of butanediol, which is inevitably produced as by-product in the process of coal to ethylene glycol, suggesting a promising application in the clean manufacture of epoxybutane with inexpensive cost.