盐酸盐助剂对硫酸催化合成二苯甲烷二氨基甲酸甲酯的影响

二苯甲烷二氨基甲酸甲酯（MDC）是非光气法合成二苯甲烷二异氰酸酯（MDI）的中间体。以硫酸为催化剂，盐酸盐为助剂，研究了苯氨基甲酸甲酯（MPC）与甲醛缩合制备MDC的反应。对助剂盐酸盐进行了筛选，发现氯化铜的效果较好，其MPC转化率达96%，4,4′-MDC产率可达76.7%。反应条件为：m(硫酸)∶m(MPC)=4∶1，n(MPC)∶n(HCHO)=1∶1，氯化铜用量为MPC物质的量的5.4%，100 ℃下反应3 h。将氯化铜分别与氯化镧和氯化亚铈以物质的量的比1∶1复合使用，发现单独使用氯化铜的效果好于复合盐酸盐的效果。分别使用甲醛溶液、三聚甲醛和多聚甲醛为亚甲基化剂，发现价廉易得的甲醛溶液效果最好。

Synthesis of methyl methylene di(phenyl carbamate)catalyzed by sulfuric acid with chloride as the promoter

Methyl methylene di(phenylene carbamate) (MDC) was the intermediate for synthesis of diphenylmethane diisocyanate via non-phosgene route. Condensation of methyl N-phenyl carbamate(MPC) with formaldehyde to methyl methylene di(phenylene carbamate) catalyzed by sulfuric acid with chloride as the promoter was investigated. CuCl₂ was found to be an effective promoter. 4，4′-MDC yield of 76.7% and MPC conversion of 96% were obtained under the following condition: m(30% H2SO4)∶m(MPC) = 4∶1; n(inorganic salt)∶n(MPC) = 5.4∶100; n(MPC)∶n(HCHO) = 1∶1, reaction time 4 h, temperature 100 ℃. Effects of different promoters(CuCl₂-LaCl₃, CuCl₂-CeCl₂, CuCl₂) were compared, which showed that CuCl₂ was superior to CuCl₂-LaCl₃ and CuCl₂-CeCl₂. Formaldehyde, as methylene agent, was superior to trioxymetylene and paraformaldehyde.