Improved Rapid and Green Synthesis of N-Aryl Piperazine Hydrochlorides Using Synergistic Coupling of Hydrated Task Specific Ionic Liquid ([BbIm]OH) and Microwave Irradiation

An improved and rapid green synthesis of N-alkyl/aryl piperazine hydrochlorides using synergistic coupling of hydrated Task Specific Ionic Liquid ([BbIm]OH) and Microwave Irradiation (MWI) has been described. The protocol worked well with good yields for electron withdrawing as well as electron donating groups in aryl amines to provide the respective aryl piperazine hydrochlorides. Presence of other labile groups like hydroxyl and thiol in the aryl amines remained unaffected. The said TSIL could be reused upto five cycles without an appreciable loss of the catalytic activity. It is proposed that [BbIm]OH along with a water molecule is able to catalyse the reaction due to symphoria. The proposed mechanism is supported by DFT and molecular dynamics studies. The use of hydrated TSIL like ([BbIm]OH) as reaction media may open new gates in green organic syntheses.