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Article
Hydrophobic effect of silica functionalized with silylated Ti-salicylaldimine complex on limonene oxidation by aqueous hydrogen peroxide
Journal of Chemical Sciences (2015)
  • Lai Sin Yuan, University Technology Malaysia
  • Sheela Chandren, University Technology Malaysia
  • Jon Efendi, University Technology Malaysia
  • Chin Siong Ho, University Technology Malaysia
  • Hadi Nur, University Technology Malaysia
Abstract
This research work describes the effect of hydrophobicity in inducing the diffusion of alkene substrates to the catalytic active sites. The aim of this research is to improve the catalytic activity by tailoring the degree of hydrophobicity of the catalyst. Silica functionalized with solid non-silylated Ti-salicylaldimine complex was prepared at room temperature by mixing imine ligand and Ti(IV) sulphate solution. The amorphous, solid complex formed was further silylated with octadecyltrimethoxysilane (OTMS) to induce hydrophobicity. The composition of the resulting silica functionalized with silylated Ti-salicylaldimine complex was varied with Ti:OTMS molar ratio in the range of 1:1/4 to 1:4 at room temperature. The successful attachment of alkylsilyl groups to silica functionalized with Ti-salicylaldimine complex was proven by the FTIR and 29Si solid state NMR spectra. The FTIR spectra showed increasing peak area for sp3 C-H stretching mode (ca. 2919 cm−1 and 2850 cm−1) and decreasing peak area for Si-OH band with increasing amount of OTMS. TGA showed less water content with higher amount of alkylsilyl groups in the catalyst. This is in agreement with the lower kinetic rate of water adsorption capacity for the hydrophobic catalysts prepared. It was observed that the hydrophobic, silica functionalized with silylated Ti-salicylaldimine complex exhibited higher substrate conversion and reusability compared to the non-silylated catalyst.
Keywords
  • Hydrophobicity,
  • silylation,
  • silica functionalized with silyated Ti-salicylaldimine complex,
  • limonene oxidation,
  • octadecyltrimethoxysilane
Publication Date
Winter November 4, 2015
DOI
10.1007/s12039-015-0965-0
Citation Information
Lai Sin Yuan, Sheela Chandren, Jon Efendi, Chin Siong Ho, et al.. "Hydrophobic effect of silica functionalized with silylated Ti-salicylaldimine complex on limonene oxidation by aqueous hydrogen peroxide" Journal of Chemical Sciences Vol. 127 Iss. 11 (2015) p. 1905 - 1917
Available at: http://works.bepress.com/hadi_nur/169/