The Effect of the Reaction Medium on the Coverage Density of C₁₈ Chemically Bonded Phase

Abstract

A wide-pore silica for HPLC (S_BET = 360 m² g⁻¹, D = 20 nm, V_p = 2.1 cm³ g⁻¹) was silanized with n-octadecyl dimethylchlorosilane in the presence of several base activators. It has been found that the density of bonded octadecyl ligands is not only a function of reaction time and temperature, but also depends upon the structure of the organic base used as reaction activator. The reproducible synthesis of silica bearing more than 4/umol m^–2 of octadecyl ligands is described.