Li Zhihui, Wang Tingting, Qi Xudong, Yang Qiusheng, Gao Liya, Zhang Dongsheng, Zhao Xinqiang, Wang Yanji
Hebei Provincial Key Lab of Green Chemical Technology and High Efficient Energy Saving, Hebei University of Technology Tianjin 300130 China
School of Energy and Environmental Engineering, Hebei University of Technology Tianjin 300401 China.
RSC Adv. 2019 Jun 5;9(31):17631-17638. doi: 10.1039/c9ra02296a. eCollection 2019 Jun 4.
Preparation of benzonitrile from benzaldehyde and hydroxylamine hydrochloride is one of the most advantageous approaches. Nevertheless, it suffers from various constraints such as longer reaction time, corrosion and recovery of hydrochloric acid, the use of metal salt catalysts and their separation. For these reasons, a novel green benzonitrile synthetic route was proposed with ionic liquid as the recycling agent in this study. The results indicated that hydroxylamine 1-sulfobutyl pyridine hydrosulfate salt ((NHOH)·[HSO--Py]·HSO) was an expert alternative to hydroxylamine hydrochloride. Meanwhile, the ionic liquid [HSO--Py]·HSO exhibited the multiple roles of co-solvent, catalysis and phase separation, thus the use of metal salt catalyst was eliminated, and no additional catalyst was needed. Hence, the separation process was greatly simplified. When the molar ratio of benzaldehyde to (NHOH)·[HSO--Py]·HSO was 1 : 1.5, the volume ratio of paraxylene to [HSO--Py]·HSO was 2 : 1, the benzaldehyde conversion and benzonitrile yield were both 100% at 120 °C in 2 h. Even better, the ionic liquid could be recovered easily by phase separation, and recycled directly after reaction. Additionally, this novel route is applicable to the green synthesis of a variety of aromatic, heteroaromatic and aliphatic nitriles with excellent yields.
由苯甲醛和盐酸羟胺制备苯甲腈是最具优势的方法之一。然而，它存在各种限制，如反应时间长、盐酸的腐蚀和回收、金属盐催化剂的使用及其分离。基于这些原因，本研究提出了一种以离子液体作为循环剂的新型绿色苯甲腈合成路线。结果表明，硫酸氢1-磺酸丁基吡啶羟胺盐（(NHOH)·[HSO-Py]·HSO）是盐酸羟胺的理想替代品。同时，离子液体[HSO-Py]·HSO发挥了共溶剂、催化和相分离的多重作用，因此无需使用金属盐催化剂，也不需要额外的催化剂。因此，分离过程大大简化。当苯甲醛与(NHOH)·[HSO-Py]·HSO的摩尔比为1∶1.5，对二甲苯与[HSO-Py]·HSO的体积比为2∶1时，在120℃下反应2小时，苯甲醛转化率和苯甲腈产率均为100%。更优的是，离子液体可通过相分离轻松回收，并在反应后直接循环使用。此外，这条新路线适用于多种芳香族、杂芳香族和脂肪族腈的绿色合成，产率优异。
