Solvent-free reactions

For reasons of economy and pollution, solvent-free methods are of great int erest in order to modernize classical procedures making them more clean, sa fe and easy to perform. Reactions on solid mineral supports, reactions with out any solvent/support or catalyst, and solid-liquid phase transfer cataly sis can be thus employed with noticeable increases in reactivity and select ivity. A comprehensive review of these techniques is presented here. These methodologies can moreover be improved to take advantage of microwave activ ation as a beneficial alternative to conventional heating under safe and ef ficient conditions with large enhancements in yields and savings in time.