A process for preparing diazopyridone compounds which comprises (a) admixing in the absence of a solvent (1) a diamine of the formula H2N???R1???NH2 wherein R1 is an alkylene group, an arylene group, an arylalkylene group, or an alkylarylene group, and (2) a first ester of the formula wherein R2 is an electron withdrawing group and R3 is an alkyl group; (b) heating the mixture containing the amine