3608 J. Org. Chem., Vol. 37, No. 93, 1979
CONDON
Some Aspects of the Selective Acetylation of Methylhydrazine. 1-Acetyl-1-methyl- and lnAcetyl-2-methylhydrazine F. E. CONDON Department of Chemistry, The City College of the City University of New York, New York, New York 10031 Received June RR, 1971 The selective acetylation of methylhydrazine-with acetic anhydride to give chiefly l-acetyl-l-methylhydrazine (1) and with ethyl acetate to give chiefly 1-acetyl-2-methylhydrazine (2)-was studied, with nmr spectroscopy as the method of analysis. The ratio, 1/2, was found to be -0.30 with ethyl acetate as acetylating agent, -38 with acetic anhydride in pyridine or triethylamine as solvent, and >lo0 with acetic anhydride in acetic acid. The ratios result from kinetic control. The equilibrium ratio, 1/2, was found to be 0.39 at 27' and 0.49 at 87", from which AH0 = 785 f.40 cal/mol and ASo = 0.75 i 0.6 cal/deg mol for the process 2 + 1. The isomerization is -1/8 as fast as the acetylation of methylhydrazine with ethyl acetate at 80-90'. Isomer 2 is -1.5 times as rapidly acetylated as 1 with acetic anhydride to give 1,2-diacetyl-l-methylhydrazine,and, as reactive as methylhydrazine judging from the compositions of reaction mixtures, 1 and 2 appeared to be
