Reversed endcapping and bonding of chromatographic stationary phases using hydrosilanes

A chromatographic stationary phase for use in reversed-phase chromatography, prepared according to a process comprising:

• providing an inorganic oxide support material comprising surface hydroxyl groups;
• reacting the surface hydroxyl groups with at least one endcapping reagent having a formula selected from the group consisting of formulas I, II, and III:
• wherein, R1 is hydrogen or methyl, X is halogen, OR2 or NR3R4, and Z is —NH— or —NR5—, wherein R2 is C1 to C30 alkyl, R3 and R4 are independently hydrogen or C1 to C30 alkyl, and R5 is methyl or ethyl, to provide a modified particulate support material having at least one endcap Si—H group;
• converting at least one endcap Si—H group to an endcap silanol group;
• and
• reacting the endcap silanol group with at least one silane coupling agent selected from the group consisting of formulas IV, V, VI, and VII:
• wherein
• R6-15 are independently hydrogen or C1 to C30 hydrocarbyl, optionally substituted with at least one reversed-phase chromatography ligand;
• Y is halogen, OR2 or NR3R4, wherein R2 is C1 to C30 alkyl, and R3 and R4 are independently hydrogen or C1 to C30 alkyl;
• m is 1 or greater;
• and
• n is 1 or greater to provide a functionalized particulate support material.