Retardation Effect by Acetylene Derivatives on Hydrosilylation Estimation of the Retarder's Capability by Differential Thermal Analysis Method

Abstract

The hydrosilylation by using metal-complex catalysts is the most useful reaction and especially platinum-catalyzed hydrosilylation is widely applied to commercial silicones, such as room-temperature vulcanization rubber (RTV) and release paper. From a practical point of view, however, retarders ha+e been used to control hydrosilylation effectively.
In this article, we made a study of the retarder of platinum-catalyzed hyd rosilylation reaction for the estimation of the retarder's capability. Differential scanning calorimetry (DSC) method was used in this study. In particular, acetylene derivatives were selected as the retarder, and exothermic curve of hydrosilylation was measured by DSC method.
As a result, DSC method was useful for evaluation of retarder's effectivenes s. Both the initial temperature of hydrosilylation and the shape of theexthermic curve depended up o n the structure of acetylene derivative (Fig.1). The hydrosilylation was controlled effectively by acetylene alcohols and their silylated derivatives, but not by alkynes with no functional group. The acetylene alcohols containing a bulky substituent on the a-carbon was the most effective.
The content of triple bond in the acetylene derivative was defined acetylene value (molfg). The peak temperature of the exothermic curve was related to the acetylene value. It was found that the effective retarder had the structure of C-C multiple b ond and oxygen atom or nitrogen atom on the carbon atom next to C-C multiple bond. The distance between the multiple bond and the functional group on the effective retarder was estimated to be 2.0Å.