Novel mesoporous organic−inorganic spherical hybrid particles are described that contain
a 3-hydroxypropyl organic functionality which is integral to the pore surface. The 3-hydroxypropyl hybrid particle is synthesized in three steps starting from a 4:1 (mol/mol) mixture of
tetraethoxysilane and [3-(methacryloxy)propyl]trimethoxysilane, where the monomers are
polymerized to a poly(organoalkoxysilane) oil, followed by sol−gel reaction to the hybrid
silicate bead, which is finally subjected to an alkaline hydrothermal treatment to liberate
the alcohol from the ester protecting group. The silicate precursor and final product were
characterized by NMR spectroscopy and nitrogen sorption analysis. The heterogeneous
surface chemistry of the hybrid's alcohol functionality was explored by running a series of
classical alcohol reactions including bromination, esterification (carbamic and carbonic), and
etherification (Williamson, epoxide ring opening). The brominated analogue was further
converted via cyanation and Grignard couplings. Nuances to the heterogeneous surface
chemistry are discussed as well as product characterizations by NMR spectroscopy and
combustion analysis. A stability study was further conducted on the 3-hydroxypropyl hybrid
silicate using an alkaline resistance test under HPLC packed column conditions. The hybrid
material was found to be over 10-fold more stable than a comparable silica gel material. In
a second HPLC test, the cyano derivatized hybrid material was found to be more resistant
to acid-induced siloxane cleavage vs a comparable (3-cyanopropyl)silane grafted silica gel.
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