Carbonylation of Dinitrotoluene to Dimethyl Toluenedicarbamate; High Efficiency of Phosphorus Acids as Promoters for the Palladium-Phenanthroline Catalytic System
作者:Michela Gasperini、Fabio Ragaini、Chiara Cazzaniga、Sergio Cenini
DOI:10.1002/adsc.200404151
日期:2005.1
Phosphorus acids are excellent promoters for the palladium-phenanthroline catalyzed carbonylation of 2,4-dinitrotoluene to 2,4-toluenedicarbamate. For the first time, all intermediate nitrocarbamates and aminocarbamates have been independently synthesized and their amount after every catalytic reaction precisely quantified. An extensive optimization of all experimental variables has been carried out
磷酸是钯-菲咯啉催化的2,4-二硝基甲苯羰基化为2,4-甲苯二氨基甲酸酯的极好促进剂。第一次,所有中间体硝基氨基甲酸酯和氨基甲酸酯都被独立合成,并且在每次催化反应后它们的数量都被精确地定量了。已经对所有实验变量进行了广泛的优化。最好的酸是苯基膦酸和4-甲苯基膦酸。添加2,2-二甲氧基丙烷作为内部干燥剂是非常有益的。衍生自起始二硝基芳烃的胺的加入提高了羰基化反应的速率和选择性。配合物[Pd(Phen)2 ] [SbF 6 ]和[Pd(Phen)2 ] [BAr F 4首次制备了[Ar F= 3,5-(CF 3)2 C 6 H 3 ]。后者显示出比所有其他[Pd(Phen)2 ] 2+复合物明显更高的溶解度。还研究了几种可能的启动子的作用。在优化的实验条件下,当以二硝基甲苯/ Pd = 2920的摩尔比工作时,在二氨基甲酸酯中的选择性为77.6%。在反应结束时,冷却后,二氨基甲酸酯自发从溶液中