Recent advances and actual challenges in late transition metal catalyzed hydrosilylation of olefins from an industrial point of view

Hydrosilylation of olefins is the key catalytic reaction for the production of industrially important organosilicon compounds such as organofunctional silanes and silicones. Moreover catalytic hydrosilylation is used for crosslinking of silicone polymers to elastomers and silicone-based release coatings, and for coupling of silanes and siloxanes to organic polymers. Industrially relevant aspects of hydrosilylation are dominated by the selectivity, activity (defined by the turnover frequency (TOF)), and stability (defined by the turnover number (TON)) of hydrosilylation catalysts as well as switchable catalyses. Furthermore, the high and volatile price of platinum as the industrially most important catalytic metal is a strong motivation for the reduction of precious metal consumption, such as homogeneous catalyst recycling or increasing the TOF resp. TONs of established hydrosilylation catalysts, or employing lower-priced transition metal catalysts. The selectivity of hydrosilylation determines yield and production costs of functional silanes, e.g. hydrosilylation products of allyl chloride, but is of equal importance for the product quality of silane-modified organic polymers and hybrid polymers. As industrial applications of hydrosilylation curing silicones, such as release coatings and elastomers, continuously move towards higher production speed, this requires catalytic systems capable of very high activity resp. turnover frequencies at temperatures typically above 100 degrees C, but allowing shelf-stable silicone compositions and therefore requiring suppression of any catalytic activity at ambient conditions prior use. This form of switchable catalysis employs carefully designed catalytic systems, which are activated by heating or photoactivation in a very short period of time, demanding very high standards of industrial hydrosilylation chemistry. (C) 2011 Elsevier B.V. All rights reserved.