Supported Heteropolyacids Assisted Selective Nitration of Toluene with N_2O_5

Toluene nitration was carried out with supported heteropolyacids as catalysts and N2O5 as nitrating agent.Many factors were investigated,including the type of heteropolyacid and carrier,loading of heteropolyacid,and recycle times of the catalyst.Results shows that the nitration with N2O5 is an acid catalyzed reaction,and the supported heteropolyacids can highly enhance the nitration ability of N2O5;the catalysts can be directly reused after recycle,and their activity is not obviously decreased.Under the optimum conditions,the yield of nitration was 34%,and the para-selectivity was up to 58.9%,which indicated that N2O5 is a prospective nitration agent,and the process meets the environmental protection requirements.