Solvent-free conditions organic synthesis

Ionic liquids have been a popular topic of interest in 2002 and a review of the applications of these solvents in organic synthesis has been published (02ACA75>. New, densely functionalized fluoroalkyl-substituted imidazolium ionic liquids have been reported <02TL9497>. An ultrasound-assisted preparation of a series of ambient-temperature ionic liquids, l-alkyl-3-methylimidazolium halides, which proceeds via efficient reactions of 1-methyl imidazole with alkyl halides/terminal dihalides under solvent-free conditions, has been described <02OL3161>. New hydrophilic poly(ethyleneglycol)-ionic liquids have been synthesized from... 

The development and use of environmentally friendly methods for the synthesis of quinolines and dihydroquinolines were represented in variety of publications in 2006. Many of the reports incorporated solvent free conditions. Perumal et al. showed that silica-supported NaHSO as a heterogeneous catalyst for the cyclization of 2-amino-chalcones 71 under solvent free microwave conditions results in a variety of 2,3-dihydroquinolin-4-ones 72 in high yields <06CJC1079>. Lier et al. also utilized a silica supported TaBrs catalyst to cyclize 2-amino-chalcones 71 forming a variety of 2,3-dihydroquinolin-4-ones 72 under solvent free thermal conditions <06TL2725>. The use of silica gel supported TaBrs under solvent free thermal conditions showed considerable improvement in yield for this cyclization compared to the reaction conducted in organic solvents. 

Microwave energy is a key enabling technology in achieving the objective of sustainable (green) chemistry. It has been shown that solvent-free conditions are especially suited to microwave-assisted organic synthesis, because reactions can be run... 

The development of modem and reliable procedures for microwave-assisted organic synthesis has also been used advantageously for 1,2,4-oxadiazole synthesis by avoiding time-consuming steps, using green solvents or solvent-free conditions, or by directly employing acids rather... 

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