PREPARATION OF PHENYLPIPERAZINE DERIVATIVE

PURPOSE:To prepare the titled substance useful as a synthetic intermidiate for pharmaceuticals, without producing by-products, with easy operation, in high yield, by reacting an aniline derivative with diethanolamine in the presence of a condensing agent comprising a polyphosphoric acid, phosphoric acid, and/or phosphorus pentoxide. CONSTITUTION:An aniline derivative formula I [R is halogen, lower alkoxy, lower alkyl, lower alkanoyl, lower alkoxycarbonyl, lower alkylthio, etc.; n is 0-3; two adjacent Rs in -(R)n may together form a lower alkylenedioxy group], e.g. aniline, 2-chloroaniline, etc. is made to react with diethanolamine in the presence of at least one condensing agent selected from the group of polyphosphoric acids, phosphoric acid and phosphorus pentoxide, to afford the compound of formula II. The amount of the condensing agent is usually more than the catalytic amount to the compound of formula I, pref. 0.5-1.5 times mole.