Natural Kaolinitic Clay: A Mild and Efficient Catalyst for the Tetrahydropyranylation and Trimethylsilylation of Alcohols

Potential Genotoxic and Cytotoxic Effects of Plant Extracts

“…The most common ones use higher plants (Allium cepa, Allium sativum, Vicia faba, Tradescantia virginiana) or rodents (mice, rats) in vivo as test systems for monitoring chromosomal aberrations (Hsu, 1982;Kihlman, 1971;Levan, 1949;Naismith, 1987;. Root tip cells of V. faba constitute an excellent system for such cytogenetic tests (Abraham & John 1989;Gowrisankar et al, 1993;John & Abraham 1991;Upadhya et al, 1996;Wuu & Grant 1967). However WHO (1971) andCommittee 17 (1975) argued that a single test system is not sufficient to come to the conclusion that a particular agent is mutagenic or not.…”

Tetrahydropyranyl protection and deprotection of alcohols using a niobium-based Brønsted acid catalyst

“…However, literature precedents using other heterogeneous supports have lacked study on the recyclability of these materials. [8][9][10][11] Given NbPO4 is a very much a Canadian resource, the development and application of this material within common, catalytically induced organic transformations is important for both economic and environmental sustainability.…”

“…Heterogeneous-derived catalytic pathways have gained considerable attention due the advantageous ease of separation and catalyst reusability, as compared with their homogeneous counterparts. With regards to the THP protection of alcohols, catalysts such as Amberlyst-15, [7] natural Kaolinitic Clays, [8] sepiolite, [9] HY zeolites [10] and ZnCl2 supported on alumina [11] have been successfully used. When considering the deprotection of THP-ehters both homogenous [3,12] and heterogeneous [9,13] approaches have also been used in the past.…”

Effect of Acid Activation on the De-Tert-Butylation Activity of Some Jordanian Clays

“…Natural clays are increasingly used in industry as catalysts or catalyst supports in many organic reactions (Auer and Hofmann, 1993;Li and Jin, 1996;Ravichandran et al, 1996, Upadhya et al, 1996Chitnis and Sharma, 1997;Clark et al, 1997). For example, montmorillonite and kaolinite are two clays commonly used in these reactions.…”

“…The catalytic properties can be improved by different acid treatment and/or pillaring methods (Auer and Hofmann, 1993;Ravichandran et al, 1996;Upadhya et al, 1996;Chitnis and Sharma, 1997;Clark et al, 1997). For example, the alkylation of many organic compounds, including phenols, aromatics, and other hydrocarbons, is catalyzed by acid-treated clays (Chitnis and Sharma, 1997).…”