The Novel Process Of 5-substituted 1-H-tetrazole

5-Substituted 1-H-tetrazoles are important intermediates for fine chemistry,Whichcan be used to synthesize new drugs or pesticides such as Olmesartan medoxomil,Candesartan cilexeti,Azimsulfuron.5-Substituted tetrazoles are traditionally prepared by sodium azide and nitriles using zinc bromide as accelerator.Thisprocess suffers from the low reaction yield,long reaction-time,complex post-processing of product,and much waterwaste.On the basis of civil and foreign literatures,two processes were studied for5-subsutited-tetrazoles catalyzed by ytterbium triflate or accelerated by zinc bromide.The processes were optimized and the better parameters were obtained.The main contents were as follows:1)A variety of methods for the synthesis and application of5-substituted-tetrazole were summarized,analyzed and compared.2)The synthesis of 5-substituted-tetrazole catalyzed by ytterbium triflate:Benzonitrile was reacted with sodium azide at 110^oC for 16h using ytterbium triflate as catalyst and DMF as solvent.Their mole ratios were 1:2:0.1.The yield of5-phenyl-tetrazole was 99%.Other 5-Substituted tetrazoles were obtained by above optimized conditions,including 5-p-chlorophenyl tetrazole,5-p-bromophenyl triazole,5-p-fluorophenyl tetrazole,5-o-tolyl tetrazole,5-m-tolyl tetrazole,5-o-chlorophenyl tetrazole,5,5'-phenyl-1,2-bis(1H-tetrazole),5,5'-phenyl-1,3 bis(1H-tetrazole)and5-methyl tetrazole.The yields were 37-99%.The yield of 5-methyl-tetrazole was50%.3)The synthesis of 5-substituted-tetrazole accelerated by zinc bromide:Acetonitrile was reacted with sodium azide at 170^oC for 12h using zinc bromide as accelerator and H₂O as solvent.Their mole ratios were 1:1.1:1.The yield of5-methyl-tetrazole was 87%.The yield of 5-Phenyl-tetrazole was 83%.In summary,the former new process has advantages of high reaction yield,easy operation and less waste.It is suitable for the preparation of 5-p-substituted1-H-tetrazole.The latter process has advantages of high reaction yield and safe operation.It is suitable for the preparation of 5-methyl-1-H-tetrazole.