氯铝酸室温离子液体介质中正十二碳烯的选择环化反应

Highly Selective Cyclization of 1-Dodecene Using Ethanol-Buffered Chloroaluminate Ionic Liquids as Reaction Medium

在氯化 1 丙基 3 甲基咪唑 (PMImCl)、氯化 1 丁基 3 甲基咪唑 (BMImCl)、氯化 1 丁基吡啶 (BPCl)和溴化 1 乙基吡啶(EPBr)季铵盐与AlCl3 构成的室温离子液体介质中 ,首次发现正十二碳烯 (简称十二烯 )可以高选择性地发生环化反应生成环十二烷 .依次在反应管中加入氯铝酸室温离子液体、乙醇和十二烯 ,其中AlCl3 的量为 0 0 1mol,AlCl3 与季铵盐的摩尔比为 2 ,乙醇为 10ml,十二烯为 2ml (9 3mmol) .当反应体系中不添加乙醇时 ,十二烯转化率和环十二烷选择性仅分别为 4 2 %和73 1% .这是由于十二烯和氯铝酸离子液体形成两相体系而不易充分接触 ,故十二烯转化率和环十二烷选择性较低 .当反应体系中加入乙醇时 ,十二烯和氯铝酸离子液体体系变为单相 ,使得十二烯和氯铝酸离子液体可以充分接触 ,十二烯转化率和环十二烷选择性可分别达到 12 4 %和 82 9% .压力对提高十二烯转化率和环十二烷选择性有很大的影响 .p(N2 ) =3 0～ 6 0MPa下反应 12h ,十二烯转化率和环十二烷选择性可分别达到 2 7 2 %和 93 8% .反应结束后加热除去乙醇 ,产物自动与离子液体分层 ,便于分离 。

Ethanol-buffered chloroaluminate ionic liquids consisted of AlCl3 with 1-alkyl pyridinium or 1-alkyl-3-methyl imidazolium quaternary ammonium salts (QAS), such as 1-butylpyridinium chloride, 1-butyl-3-methylimidazolium chloride, 1-propyl-3-methylimidazolium chloride and 1-ethylpyridinium bromide, are novel reaction medium for selective cyclization of 1-dodecene to cyclododecane. In a typical experiment, the chloroaluminate ionic liquid with n (AlCl3) = 0.01 mol, n (AlCl3) /n (QAS) = 2, V(EtOH) = 10 ml and V(C-12) = 2 ml were successively added into a stainless autoclave with magnetic stirring. Kept the reaction at 80 similar to 140 degreesC for 6 similar to 12 h. With the addition of a small amount of ethanol, the bi-phasic 1-dodecene and ionic liquid are converted into a homogenous solution including ionic liquid. 1-dodecene and ethanol, which greatly facilitated the reaction. Owing to the immiscibility, 1-dodecene and cyclododecane can be separated from ionic liquids after the reaction with removal of ethanol, resulted in easy recovery of the product and the substrate. The conversion of 1-dodecene and selectivity for cyclododecane increased remarkably when the reaction was carried out under p (N-2) = 3.0 similar to 6.0 MPa. The ionic liquids as reaction medium can be repeatedly used.