p-Toluenesulfonic acid monohydrate → HCID 86735408, compound

Participants

Reaction Conditions

Reaction Steps

Ethyl 2-hydroxyimino-4-(2-mercapto-ethylthio)-3-oxo-butyrate (655 g.) is suspended in toluene (3,500 cc.) in the presence of p-toluenesulphonic acid monohydrate (22 g.). The mixture is heated under reflux (the water being removed at the rate of which it is formed, in a Dean and Stark apparatus) for 40 minutes, then cooled to 60° C., and concentrated to dryness under reduced pressure (20 mm.Hg). The residue is dissolved in ethyl acetate (200 cc.) and the solution is washed twice with a saturated sodium bicarbonate solution (700 cc.), and with water (twice 700 cc.) and is then dried over magnesium sulphate and finally treated with decolourising charcoal. The solution is filtered and the filtrate is concentrated to dryness under reduced pressure (20 mm.Hg). The residue obtained is dissolved hot in chloroform (450 cc.) and carbon tetrachloride (800 cc.). The mixture is cooled to 0° C., for 16 hours and the crystals obtained are filtered off. Ethyl α-hydroxyimino-(5,6-dihydro-1,4-dithiin-2-yl)-acetate (173 g.) is thus obtained in the form of white crystals melting at 142° C.

Provenance & Evidence