Silica supported Brönsted acids as catalyst in organic transformations: A comprehensive review

Brönsted acid catalysts have been used in a number of organic transformations. To overcome limitations, such as toxicity, volatility, high price and hazardous nature of the conventional methods, the catalysts are adsorbed on silica gel to give the benefits and advantages of ready availability, simple work-up procedure, long catalytic life, environment-friendliness, good to excellent yields and recyclability. The uses of such catalysts have gained importance worldwide. This article describes some of the important silicated catalysts, namely, heteropolyacids, polyphosphoric acid, perchloric acid, fluoroboric acid, and silicated sulphuric acid. These catalysts have been used in a number of organic reactions to yield compounds that are important in the chemical and pharmaceutical industries. We summarize the beneficial effects of these catalysts and the reports that have been published on them in the past several years. In the present review, the description of the catalysts are introduced followed by a recent research history, and a comparison between the silica supported catalysts and other (polymer) supported catalysts. The article ends up giving the advantages of these catalytic systems over the conventional catalyst.

Graphical AbstractThe present review is an assemblage of various organic transformations utilising silica adsorbed Brönsted acids as efficient, user friendly, non-toxic and recyclable catalytic system and its advantage over the catalysts adsorbed on other support media.Figure optionsDownload full-size imageDownload as PowerPoint slide