Formation of Si–H groups during the functionalization of mesoporous silica with Grignard reagents

A Grignard reaction is carried out upon halogenated SBA-15 type mesoporous silica, with different alkyl groups and reaction conditions, in order to modify its surface with these groups. The resulting solids are analyzed by infrared, thermal analysis, 19F MAS NMR, 1H MAS NMR and elemental analysis. Parallel to the Grignard reaction an unusual reaction producing hydrosilane end groups (Si–H) is observed. A possible mechanism for the production of these groups from the fluorinated material is proposed, which involves a transition state of a six members ring formed with two Grignard molecules and a silicon bonded to at least two fluorine atoms.