Monoglycerylcetyldimethylammonium chloride was synthesized from 3-chloro-1,2-propanediol (CP) and N,N-dimethylhexadecylamine (DMHA) in 2-propanol solvent and in solvent-free conditions to examine microwave specific effects. None were evident in homogeneous 2-propanol media under temperature conditions identical to conventional heating. In contrast, heterogeneous solvent-free conditions brought out specific microwave effects as evidenced by variant product yields (130 degrees C; 30 min): 62% by microwave and 47% by conventional heating. This variance is attributed to thermal conduction and localized hot spots formed under microwave irradiation. The model proposed for the solvent-free synthesis considers hydrophilic 3-chloro-1,2-propanediol molecules form H-bonded domains (size, 2-20 mu m) preferentially heated by the microwaves and dispersed in a sea of hydrophobic N, N-dimethylhexadecylamine molecules. (C) 2010 Elsevier B. V. All rights reserved.