Infrared study of the adsorption of 1,2-dimethoxyethane on silica

Abstract

Interactions between suface hydroxyl groups on silica and 1,2-dimethoxyethane (DME) have been studied by infrared spectroscopy. Interactions for isolated silanol groups involved the formation of hydrogen bonds between single silanol groups and single methoxy groups in adsorbed molecules. For weakly adsorbed DME only one methoxy group in each molecule was bonded to the surface at a silanol group site. A stronger mode of adsorption involved both methoxy groups in each DME molecule bonded to the surface and constituted the dominant mode of adsorption at low surface coverages during absorption or after partial desorption induced by evacuation. Conversion of the doubly bonded species to the singly bonded species occurred in the presence of excess DME and was reversed by evacuation. Only ca. 11 % of the adjacent interacting silanol groups on silica acted as sites for the adsorption of DME under conditions for which coverage of isolated silanol groups was complete.