還流法による高沸点飽和炭化水素中でのシリカゲルの脱水とアルコールによる表面処理

抄録

The reflux method has been used to modify the silica gel surface with alcohols, in which the water produced through the treatment was taken out of the reaction system by collecting it on the bottom of side tube and the long chain hydrocarbons (with high boiling point) including the unreacted alcohols were refluxed and recycled into the reaction vessel. The following two procedures were performed to investigate the effect of the above-described reflux method; (1) the silica gels were initially dehydrated in tetradecane at various temperatures and then treated with cetyl alcohol in tetradecane at the same temperature as that of the dehydration and (2) the silica gels were initially dehydrated in the various hydrocarbons at their respective boiling points and then the alcohols with boiling point similar to that of hydrocarbon used were added to treat the silica gels at their boiling points. It was found from the data of elementary analysis and argon surface areas of surface-treated silica gels that the effective surface-treatment has been performed by the dehydration and the surface-treatment at 200°C or higher in the procedure (1) and by the dehydration in hydrocarbons with the boiling point of ca. 200°C or higher and the surface-treatment with alcohols with boiling point similar to that of hydrocarbon used in procedure (2). The silica gels after dehydration at 200°C or higher in the long chain hydrocarbons have shown the existence of residual and this residue cannot be completely eliminated even after well-washing with n-hexane. These gels have shown nearly 10% decrease in argon surface areas.