GB636145A - Stabilizers for photographic silver-halide emulsions - Google Patents

Abstract

Compounds of the general formula <FORM:0636145/IV (b)/1> wherein R is a carbalkoxy group, R1 is an alkyl, aryl, or heterocyclic group, R2 is H or an alkyl, aryl, or aralkyl group, and Y is OH, are prepared by condensing a b -keto ester with a 3-amino-5-carbalkoxy-1 : 2 : 4-triazole. 7 - Hydroxy - 5 - methyl - 2 - carbethoxy-1 : 3 : 4-triazaindolizine is prepared by refluxing together 3-amino-5-carbethoxy-1 : 2 : 4-triazole and ethyl acetoacetate in glacial acetic acid. The 5-phenyl, 5-methyl-6-propyl, and 5-b -pyridyl-derivatives, and 7-hydroxy-5-ethyl-2-carbmethoxy-1 : 3 : 4-triazaindolizine are similarly prepared. Compounds of the general formula wherein R is a carbalkoxy group and Y is NH2 are prepared by condensing a b -iminonitrile with a 3 - amino - 5 - carbalkoxy - 1 : 2 : 4 - triazole. Compounds referred to are the 5-methyl, 5-phenyl, and 5-b -pyridyl derivatives of 7-amino - 2 - carbethoxy - 1 : 3 : 4 - triazaindolizine. Compounds of the general formula wherein R is a carboxy group and Y is OH or NH2 are prepared by hydrolysing the corresponding compounds wherein R is a carbalkoxy group. 7 - Hydroxy - 5 - methyl - 2 - carboxy - 1 : 3 - 4-triazaindolizine is prepared by refluxing 7-hydroxy - 5 - methyl - 2 - carbethoxy - 1 : 3 : 4-triazaindolizine with aqueous NaOH and acidifying. 7 - Hydroxy - 5 - phenyl - 2 - carboxy-1 : 3 : 4 - triazaindolizine and 7 - amino - 5-methyl - 2 - carboxy - 1 : 3 : 4 - triazaindolizine are similarly prepared. Specification 628,994 is referred to.