Synthesis and structure of grafted layer of silicas modified with alkanesulfonic acid

Author： Alekseev S.A. Zaitsev V.N. Fraissard J.

ISSN： 1066-5285

Source： Russian Chemical Bulletin, Vol.52, Iss.2, 2003-02, pp. : 364-369

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Abstract

A convenient method for preparation of silicas modified with alkanesulfonic acid through the reaction of NaHSO₃ with the C₂H₃ groups grafted on the SiO₂ surface was proposed. The influence of the carrier and the structure of the grafted layer on the modification process was studied by DRIFT, MAS NMR, and temperature-programmed desorption mass spectrometry (TPD-MS). It was found that at most 40% of the C₂H₃ groups transform to the acid sites, which mostly have the structure of 2-Si-ethanesulfonic acid. The mechanism of the thermal decomposition of the grafted groups, which are stable up to 240 °C, was proposed. The monomeric structure of the grafted layer leads to partial olygomerization of the C₂H₃ groups through the N=N bonds.