PREPARATION OF SURFACE-MODIFIED ADSORBENTS .1. REACTION ON PHENYLTRICHLOROSILANE WITH SILICA GEL

The surface reaction of phenyltrichlorsilane with three different species of silica gel of definite pore structure and known concentration of hydroxyl groups on the surface was studied in the temperature range of 20-350 °C. On the basis of the analytical results of the modified silica gel species it is suggested that phenyltrichlorosilane reacts selectively with two hydroxyl groups forming a phenyl-monochloro-silyl surface layer at all reaction temperatures under investigation. This result was confirmed by the determination of the concentration of the hydroxyl groups on the surface before and after the reaction. The maximum yield of the surface coverage attained under the best reaction conditions was 3,6 μmole phenyl-monochloro-silyl groups m-2 indicating that 75% of the total amount of the hydroxyl groups had reacted. Hydrolysis of the modified silica gel yielded a white hydrophobic adsorbens. For the wide-pored silical gel and for the species with pores in the transitional range (20<d<400 Å) the value of the specific surface and the mean pore diameter remained unchanged by the modification. The silica gel with narrow pores gave a non porous adsorbent by the modification. The phenylated silica gels were tested as packing materials for GSC- and GPC columns. Furthermore, they were employed for the preparation of synthetic cationexchangers. © 1969 Dr. Dietrich Steinkopff Verlag.