Piperazine-1,4-diium bromide

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 4-(=- 1)piperazine dihydrobromide may be prepared in the following manner: the experiment is carried out as in Example 8 for the preparation of 4-(4hydroxyphenyl)piperazine dihydrobromide, starting with 4-(2-methoxypheny)piperazine (25 g) and 47% aqueous solution of hydrdromic acid (360 cc). The mixture is heated at boiling point for 9 hours, the cooled to a temperature close to 20° C. Stirring is maintained for 15 hours at this temperature, then the mixture is concentrated at 40° C underreduced pressure (20 mm g; 2.7 kPa). The residual oil is redissolved in acetonitrile (40 cc) and isopropyl oxide (40 cc); the precipitate formed is separated by filtration, washed with oxide (2×50 cc). 4-(2-Hydroxyphenyl)piperazine dihydrobromide (m.p.: 235° C.) (18g) is obtained, which is used in the crude state in the subsequent syntheses. The mixture is heated for 9 hours the cooled to a temperature close to 20° C is maintained for 15 hours at this temperature the mixture is concentrated at 40° C underreduced pressure (20 mm g; 2.7 kPa) The residual oil is redissolved in acetonitrile (40 cc) the precipitate formed is separated by filtration washed with oxide (2×50 cc)