Phenyl hydrazine react with acetophenone in presence of glacial acetic acid
Answers
. Acetophenone N,N-dimethylhydrazone. A mixture of acetophenone (12.0 g., 0.100 mole), anhydrous N,N-dimethylhydrazine (18.0 g., 0.300 mole) (Note 1), absolute ethanol (25 ml.), and glacial acetic acid (1 ml.) (Note 2) is heated at reflux for 24 hours. During this period the colorless solution becomes bright yellow. The volatile reactants and solvent are removed under reduced pressure and the residual oil is fractionally distilled through a 10-cm. Vigreux column, giving a small forerun of unreacted acetophenone, b.p. 30–40° (0.15 mm.), followed by 14.6–15.2 g. (90–94%) of acetophenone N,N-dimethylhydrazone, b.p. 55–56° (0.15 mm.), nD25 1.5443 (Note 3) and (Note 4).
B. Acetophenone hydrazone. A mixture of acetophenone N,N-dimethylhydrazone (8.1 g., 0.050 mole) and anhydrous hydrazine (6.4 g., 0.20 mole) (Note 5) in absolute ethanol (15 ml.) is heated at reflux until the reaction mixture turns colorless (Note 6). The volatile materials are removed on a rotary evaporator without allowing the flask temperature to rise above 20° (Note 7). The colorless residual acetophenone hydrazone, which solidifies as the last traces of solvent are removed, weighs 6.5–6.6 g. (97–99%) and is sufficiently pure for most purposes, m.p. 24–25° (