Nitrosation of 4-amino-1-phenacyl-1,2,4-triazolium bromides and ?-(1,2,4-triazol-1-yl)acetophenones
作者:I. M. Shtyrkov、G. V. Roitburd、V. P. Tashchi、M. Z. Krimer
DOI:10.1007/bf00959722
日期:1991.12
The reaction of 4-amino-1-phenacyl-1,2,4-triazolium bromides with an excess of nitrous acid leads to a mixture of the corresponding omega-(1,2,4-triazol-1-yl)acetophenones and omega-hydroximino-omega-(1,2,4-triazol-1-yl)acetophenones. Products of the latter type are formed during nitrosation at the methylene group of both the intermediate omega-triazolylacetophenones, and the starting 4-amino-1-phenacyl-1,2,4-triazolium bromides. The role of Br- as a catalyst is significant for both nitrosation paths. In the reaction of omega-(1,2,4-triazol-1-yl)acetophenones with HNO2, SCN- is a more active catalyst than Br-. During the nitrosation of para-substituted 4-amino-1-phenacyl-1,2,4-triazolium bromides, the yield of omega-hydroximino-omega-(1,2,4-triazol-1-yl)acetophenones increases with increase in the acceptor properties of the aryl substituent, which is explained by the increase in the CH-acidity of the nitrosation substrates.