Adsorption and Reaction of 2-Chloroethylethyl Sulfide with Al2O3 Surfaces

Abstract

The reaction of 2-chloroethylethyl sulfide (CEES) with a high-area Al2O3 surface was investigated. Two different reactive sites were created by thermally pretreating the Al2O3 powder: isolated hydroxyl sites and Lewis acid−base pair sites. The reaction of CEES with the isolated hydroxyl groups at 303 and 473 K produced a surface-bound species, which is characterized by a carbon−oxygen stretching mode near 1100 cm-1. This assignment was confirmed by isotopic substitution of 18O into the isolated hydroxyl groups prior to reaction with CEES. The other reaction product detected at 473 K was HCl. For a more highly dehydroxylated Al2O3 surface, the reaction of CEES with the Lewis acid−base pairs produced a surface−bound species also exhibiting a carbon−oxygen stretching mode near 1100 cm-1. This species is postulated to form at O2- Lewis base sites as Al3+−Cl- bonds form on adjacent Lewis acid sites. The adsorption of pyridine onto the Lewis acid sites prior to CEES exposure effectively closes this reaction pa...