The invention concerns an improved method for preparing catalysts for hydrosilylation
reactions of compounds with ethylene or acetylene unsaturation (for example olefins
or acetylene derivatives), in particular but not exclusively those involving polyorganosiloxanes
(POS) bearing Si—H units and POS bearing Si-(ethylene or acetylene unsaturation)
units. Said preparation corresponds to the following synthesis (I), wherein: A=B=carbon:
T1, T2=cyclohexyl, t-butyl or methyl; T3, T4=H;
DVTMS=divinyltetramethylsiloxane; t-BuOK=potassium tert-butylate; T.A=room temperature.
The invention is characterised in that it consists in carrying out said synthesis
in a single step by bringing together salt (III) above, Karstedt (IV) in the presence
of a solvent (V) (THF) and a base (VI) (t-BuOK) at room temperature.
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