Use
Purify 1-acetylpiperazine by recrystallisation from 40% aqueous EtOH or from EtOH/Et2O. It is an irritant, and is hygroscopic. The hydrochloride has m 191o (from EtOH), and the tosylate salt has m 148-149o (from EtOH/EtOAc, 1:16). The free base, however, cannot be isolated by basifying the tosylate salt and extraction with CH2Cl2. [Jacobi Chem Ber 66 113 1933, Mosher et al. J Am Chem Soc 75 4949 1953, Hall J Am Chem Soc 78 2570 1956, Beilstein 23 IV 1786.]