Hydroxyl-type specificity of diborane chemisorbed on the surface of silica gel

Abstract

The reaction of diborane with the surface of silica gel has been investigated by volumetric monitoring of the hydrogen evolved. The chemisorption of diborane features two phenomena. Diborane reveals hydroxyl-type specificity for the free hydroxyl groups on the surface. Diborane reacts quantitatively with all free hydroxyl groups, but, above this free hydroxyl number, chemisorption at bridged hydroxyl groups also occurs. The absolute magnitude of the reacted bridged hydroxyl groups in excess of the amount of free hydroxyl groups is determined by the relative coverage of the two hydroxyl types.