Barium hydroxide, octahydrate → 6-(4-Toluoyl)pyridine-2-sulphonic acid

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Reaction Steps

This thiol (9.16 g) was dissolved in a solution of barium hydroxide octahydrate (12.62 g) in water (250 ml) and the solution filtered. To the stirred and ice-cooled solution was then added dropwise 30% aqueous hydrogen peroxide (14.0 ml). After allowing to warm to room-temperature the mixture was heated on the steam bath for one hour with stirring. The resultant solution was filtered hot and then allowed to cool whereupon the barium salt of the sulphonic acid crystallised from solution. To the suspension of the barium salt was added with stirring 1.0N aqueous sulphuric acid (40 ml) and the resultant mixture heated on the steam bath for 15 minutes and then allowed to cool. The precipitate of barium sulphate was filtered off and the filtrate concentration to dryness in vacuo and the residue treated with ethanol and reconcentrated to dryness. Trituration with ethanol, filtration and washing with acetone gave 6-(4-toluoyl)pyridine-2-sulphonic acid (8.93 g) as a yellow solid. M.p.>300°.

Provenance & Evidence