Chamosite, a naturally occurring clay as a versatile catalyst for various organic transformations

Author： Arundhathi R. Sreedhar B. Parthasarathy G.

ISSN： 1471-8030

Source： Clay Minerals, Vol.45, Iss.3, 2010-09, pp. : 281-299

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Abstract

The chlorite-group mineral chamosite occurs in nanocrystalline form (∼200 nm grain size) as a naturally occurring clay in the Quaternary marine sedimentary deposits near Kudiamozhi, Tuticorin District, Tamil Nadu, India; samples were used in this study as a reusable catalyst. The clay has the usual alternating tetrahedral-octahedral-tetrahedral silicate/aluminate/silicate layer structural arrangement (sometimes called the 2:1 silicate or talc layer structure). The interlayer and the t-o-t layer are bound together by both electrostatic and hydrogen-bonding forces. This natural clay catalyst has been well characterized by various techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD), temperature programmed desorption (TPD), thermal analysis and BET surface area measurements (Sreedhar et al., 2009); it has been utilized for various organic transformations such as acylation of alcohols and amines, cyclization of arylaldehydes with O-phenylenediamines and C-O bond formation reactions.