At 200 ℃ and 50 mPa, the oxidative carbonylation of amines catalyzed by organic gold complexes HAuCl 4, Au(PPh 3)Cl, Au(PPh 3) 2Cl, Au(PPh 3)NO 3 and [Au(PPh 3)] 2S afforded R(NHCO 2CH 3) n with a high conversion and selectivity. The best results were obtained when using the catalyst Au(PPh 3)Cl in the presence of PPh 3. The catalytic efficiency of catalytic Au(PPh 3)Cl was compared to Pd(PPh 3) 2Cl 2, e.g. the conversion was 97.2% and selectivity was 89% when using catalyst Au(PPh 3)Cl in the presence of PPh 3, while the conversion was 98.8% and selectivity was 86% when using catalyst Pd(PPh 3) 2Cl 2 in the presence of PPh 3. The experimental results suggested that Au complexes might be promising catalysts instead of Pd catalysts for the oxidative carbonylation of amines to carbamates.
Novel resin supported gold catalysts were developed for the synthesis of carbamates by oxidative carbonylation of aniline and its derivatives. At 175 ℃ and 5.0 MPa, the oxidative carbonylation of aniline to the corresponding carbamates over these catalysts could be proceeded with a high conversion(96%), selectivity(99%) and 532 for TOF was achieved. The resin supported gold castalyst would be reusable and the catalytic performance was much better than that of the resin supported Pd catalyst.
