A:
Finely powder a number of Tablets,equivalent to about 200mg of piperazine citrate,mix with 5mLof 3Nhydrochloric acid,and filter.To the filtrate add,with stirring,1mLof sodium nitrite solution (1in 2).Chill in an ice bath for 15minutes,stirring if necessary,to induce crystallization,filter the precipitate on a sintered-glass funnel,wash with 10mLof cold water,and dry at 105

:the N,N
¢-dinitrosopiperazine so obtained melts between 156

and 160

.