On triazoles. XL - Non catalytic dehalogenation of some 5-chloro-1,2,4-triazolo[1,5-a]pyrimidine derivatives

A non catalytic dehalogenation method of type 4 5-chloro-1,2,4-triazolo[1,5 -a]pyrimidine derivatives based on the hydrolysis of the corresponding type 5 p-toluenesulphonyl hydrazones with diluted aqueous sodium carbonate solu tion was elaborated. The method provides the required 5-unsubstituted deriv atives 6 also in those cases when the simple hydrogenation is not possible. Using deuterium oxide as the solvent of the hydrolysis, deuterium atoms al so could be inserted into position 5 of derivatives 6. Different by-product s of the reactions were also isolated, and a possible explanation was given for their formation.