The Letter describes the investigation of an industrial reaction of N-methylphenylpiperazine and chloronicotinonitrile, under microwave heating. Besides the formation of the expected 2- (4-methyl-2-phenylpiperazinyl) pyridine-3-carbonitrile (4), extension of the scale leads to unexpected by-products. A specific pathway due to the formation of a reactive 'ionic alkylating intermediate'formed in situ under microwave conditions is proposed to explain ...