醋酸锌催化碳酸二甲酯胺解合成六亚甲基二氨基二甲酸甲酯

METHOXYCARBONYLATION OF 1,6-HEXANEDIAMINE WITH DIMETHYL CARBONATE TO DIMETHYLHEXANE-1,6-DICARBAMATE CATALYZED BY Zn(OAc)_2

在醋酸锌催化作用下,对碳酸二甲酯(DMC)胺解合成六亚甲基二氨基二甲酸甲酯的工艺条件进行了优化,并对催化机理进行了推测。结果表明,Zn(OAc)_2对DMC甲氧羰基化具有较好的催化活性,在n(DMC):n(HDA)=6、反应温度353 K、反应时间6 h、n(Zn(OAc)_2):n(HDA)=0.04的反应条件下,HDA转化率达92%,六亚甲基二氨基二甲酸甲酯收率达82%。其催化实质是过醋酸锌中Zn^(2+)与DMC中显电负性的羰基氧配位,并通过电子传递效应,籍此引发DMC中羰基碳的正离子化;然后1,6-己二胺中氮负离子再亲核进攻DMC中的羰基碳正离子,发生加成消去反应,进而得到六亚甲基二氨基二甲酸甲酯。

The methoxycarbonylation of 1,6-hexanediamine （HDA） with dimethyl carbonate （DMC） was studied, using Zn（OAc）2 as a catalyst. Under the conditions of reaction temperature 343 K, reaction time 6 h and n（Zn（OAc）2） ： n（HDA） of 0.04, up to 92 % yield of dimethylhexane-l,6-dicar- bamate was obtained. The mechanistic studies suggest that the catalytic recycle may consist of several key steps as follows. At first, the coordination of DMC molecules to Zn2＋ cations, thereby activates the carbonyl group of DMC; then, Zn2＋-coordinated DMC reacts with HDA to form carbamate.