SiO_2催化合成甲苯二氨基甲酸丁酯反应研究

Synthesis of dibutyl toluene dicarbamate catalyzed by SiO_2

以2,4-二氨基甲苯(TDA)、尿素和正丁醇为原料,在催化剂作用下合成甲苯二异氰酸酯的前体甲苯-2,4-二氨基甲酸丁酯(BTDC).从几种催化剂的催化活性及重复使用性综合考虑,SiO2是较适宜的合成BTDC催化剂.优化了催化剂的焙烧温度和反应条件,结果表明,在SiO2焙烧温度400℃、反应温度200℃、反应时间6 h、催化剂的用量为TDA质量的30%、TDA∶尿素∶正丁醇=1∶5∶65的较好条件下,TDA的转化率可达96.5%,BTDC收率达81.7%.考察了反应条件对反应结果的影响,并对催化剂结构进行了表征.

Dibutyl toluene-2,4-dicarbamate （BTDC） which is a precursor of toluene diisocyanate was synthesized from 2,4-diamino-toluene （TDA）, urea and butyl alcohol. The catalytic behavior and the stability of several catalysts were evaluated in the reaction of BTDC synthesis, and the results show that SiO2 presents better catalytic performance. Over SiO2 catalyst, the optimal conditions are as follows： calcination temperature 400 ℃, reaction temperature 200 ℃, reaction time 6 h, catalyst mass fraction 30% （based on TDA） and n（TDA） ： n（urea） ： n（butyl alcohol） =1 ： 5 ： 65. Under these conditions, TDA conversion can reach 96.5% and BTDC yield can reach 81.7%. The effects of the varieties of the reaction conditions on the BTDC yield were analyzed, and the structure of SiO2 catalyst was characterized by BET.