基于1-甲基-2,4-苯二脲路径的尿素法合成甲苯-2,4-二氨基甲酸甲酯反应研究

Synthesis of Dimethyl Toluene-2,4-Dicarbamate by Urea Route via 1-Methyl-2,4-Phenyl Bisurea Intermediate

采用尿素法合成甲苯-2,4-二氨基甲酸甲酯(TDC)是一条绿色的工艺路线。其反应路径之一是以1-甲基-2,4-苯二脲(TBU)为中间产物,即2,4-二氨基甲苯(TDA)与尿素反应生成TBU,TBU再与甲醇反应得到TDC。首先对该路径进行了热力学分析,然后分别对两步反应进行了研究。对于TBU合成反应,适宜溶剂和催化剂分别为环丁砜(CBS)和乙酸锌;适宜反应条件为:反应温度130℃,反应时间7 h,n(TDA):n(Zn(OAc)2):n(Urea):n(CBS)=1:0.05:3.5:10。此时TDA转化率为54.3%,TBU选择性为73.3%。对于TDC合成反应,基于液相色谱-质谱和气相色谱分析结果,确定了反应组分。适宜的反应条件为:反应温度140℃,反应时间5 h,反应压力1.1 MPa,甲醇与TBU摩尔比为110:1。在该反应条件下,TBU转化率为100%,TDC选择性为60.4%。

The synthesis of dimethyl toluene-2,4-dicarbamate（TDC） by urea route is a green technology.One of the plausible paths in the urea route is via 1-methyl-2,4-phenyl bisurea（TBU） intermediate.This path consists of two reactions： the reaction between 2,4-diamino toluene（TDA） and urea to form TBU and then the formation of TDC from the reaction of TBU and methanol.In this paper the two reactions in this path were thermodynamically studied and then experimentally investigated.As for the reaction for TBU synthesis,the suitable solvent and catalyst were separately cyclobutylsulfone（CBS） and zinc acetate.Under the suitable conditions of reaction temperature 130℃,reaction time 7 h,and the molar ratio of TDA/zinc acetate/urea/CBS =1/0.05/3.5/10,the conversion of TDA and selectivity of TBU were respectively 54.3% and 73.3%.As for the reaction of TBU with methanol to form TDC,the components were determined based on the analyses of HPLC-MS and GC.Under the suitable conditions of reaction temperature 140℃,reaction time 5 h,reaction pressure 1.1 MPa,and molar ratio of methanol to TBU = 110：1,the conversion of TBU and the selectivity of TDC were respectively 100% and 60.4%.