2-Mercaptoethanol → HCID 53980131, Verbindung

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A solution of 2-mercaptoethanol (58.5 g.) in anhydrous ethanol (220 cc.) is added, at about 10° C. and over the course of one hour, to a solution of sodium ethoxide in ethanol [prepared by reacting sodium (17.2 g.) with anhydrous ethanol (570 cc.)]. After having heated the reaction mixture to 45°-50° C., ethyl γ-bromoacetoacetate (157 g.) is added over the course of 45 minutes, and then the reaction mixture is stirred for 2 hours at a temperature of about 25° C. After filtration, the solvent is evaporated at about 50° C. under reduced pressure (20 mm.Hg). The residue is dissolved in anhydrous toluene (1,000 cc.) and, after filtration of the resulting solution, toluene-p-sulphonic acid monohydrate (1.5 g.) is added. The reaction mixture is heated under reflux until complete dehydration has taken place (the water formed being removed in a Dean-Stark apparatus) and then toluene (200 cc.) is distilled. After cooling, the toluene solution is filtered and washed twice with a saturated aqueous solution of sodium bicarbonate (200 cc.) and then with water (2 × 200 cc.); it is then dried over sodium sulphate, treated with decolourizing charcoal, filtered and evaporated under reduced pressure (20 mm.Hg). A residue (131.9 g.) is obtained and is chromatographed on alumina (550 g.). Elution is effected using a mixture (2.5 liters) of ethyl acetate and cyclohexane (1-19 by volume) and the eluates are concentrated to dryness under reduced pressure (20 mm.Hg). Ethyl (5,6-dihydro-1,4-oxathiin-2-yl )acetate (75.7 g.) is obtained in the form of an oil.

Herkunft & Nachweise