Preparation of dihydrazides of dicarboxylic acids

Claim 1

IN THE MANUFACTURE OF DIHYDRAZIDES OF DIBASIC ACIDS, THE STEPS OF ESTERFYING A DIBASIC ACID, OF THE FORMULA HOOC(CH2)NX(CH2)MCOOH WHEREIN X IS SELECTED FROM THE GROUP CONSISTING OF OXYGEN, SULFUR AND METHYLENE AND N AND M ARE INTEGERS OF FROM 1 TO 2, WITH N-BUTANOL BY CONTACTING THE ACID AND N-BUTANOL IN THE PRESENCE OF A SUBSTANTIAL STOICHIOMETRIC EXCESS OF N-BUTANOL AND AN ACIDIC ION EXCHANGE CATALYST WITH REMOVAL OF WATER OF ESTERIFICATION AS AN AZEOTROPE OF WATER AND N-BUTANOL FROM THE REACTION MIXTURE UNTIL AT LEAST ABOUT 99% OF THE ACID HAS BEEN ESTERIFIED TO PROVIDE A FIRST REACTION MIXTURE CONSISTING ESSENTIALLY OF A MIXTURE OF THE CATALYST, DI-N-BUTYL ESTER OF THE ACID AND N-BUTANOL, SEPARATING THE CATALYST FROM THE FIRST REACTION MIXTURE, ADMIXING THE REMAINDER OF THE FIRST REACTION MIXTURE WITH HYDRAZINE IN AN AMOUNT SUFFICIENT TO PROVIDE A SMALL STOICHIOMETRIC EXCESS OF DI-NBUTYL ESTER OVER HYDRAZINE WHEREBY THE ESTER AND HYDRAZINE REACT AND A SECOND REACTION MIXTURE CONTAINING THE DIHYDRAZIDE OF THE DIBASIC ACID IS FORMED, AND SEPARATING THE DIHYDRAZIDE FROM THE SECOND REACTION MIXTURE.