Clay Catalysis: Synthesis of Organosulphur Synthons

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Abstract
The Montmorillonite KSF catalyses the synthesis of a large variety of organic sulphur compounds from carbonyl compounds: dithianes, thioacetals, thioketals, thiochromanes. Clay minerals are known to cataiyse a variety of organic reactions(1). In these reaction, the clay catalyst acts as a solid Bronsted acid. One of the most acidic, Montmorillonite manufactured by Sud Chemie, is the KSF catalyst. Clay is inexpensive and offers several advantages to the classic acid: a strong acidity (Ho = −8 to −9), no corrosive action, selectivity and easy work-up. We report here, that KSF clay is a convenient catalyst for the synthesis of useful thio-organic reagents : dithianes, thioketals, trithioorthoformiates, thiochromanes. The condensations of the thiol with the carbonyl compounds were completed in refluxing toluene in presence of KSF with the azeotropic separation of water. Generally the pure compound was obtained in these reactions and the work-up very simple.