[C:1](=[S:3])=[O:2].[CH3:4][CH:5]([CH3:7])[O-:6].[K+].[CH3:9][S:10][CH:11](Cl)[CH3:12]>C(OCC)C>[C:1](=[O:2])([S:3][CH:11]([S:10][CH3:9])[CH3:12])[O:6][CH:5]([CH3:7])[CH3:4]In a two-necked round bottomed flask equipped with a gas introducing tube and a condenser, gaseous carbonyl sulphide (6 g or 0.1 mole) was introduced into a suspension of potassium isopropoxide (9.9 g or 0.1 mole) in diethyl ether (60 ml). The reaction mixture refluxed by the reaction heat. After the addition of carbonyl sulphide was completed, the mixture was cooled and the precipitate was collected by filtration and suspended in dichloromethane (100 ml). The suspension was cooled to 0°C and while stirring, 1-methylthio-1-chloroethane (11.0 g or 0.1 mole, prepared according to H. Bohme and H. Bentler, Chem. Ber. 89 (1956) pages 1464-1468) was added dropwise in 30 min. The mixture was then kept overnight at 0° C and filtered. The filtrate was dried over anhydrous magnesium sulphate. The solvent was evaporated off at 30°C and 10 mm Hg. Fractional distillation of the residue yielded 11.0 g (57%) O-isopropyl S-[1-methylthioethyl] thiocarbonate, b.p. 62-64°C at 0.1 mm Hg. nD20 = 1.4914. Infrared absorptions (liquid film) were at 2980, 2939, 2920, 2878, 2862, 2828, 1708, 1700, 1465, 1444, 1436, 1422, 1384, 1373, 1340, 1330, 1230, 1155, 1095, 1055, 974, 951, 911, 847, 810, 728, 697, 673, 520 and 510 cm-1. The NMR spectrum (in CCl4, internal standard Si (CH3)4) had signals at δ = 1.25 (doublet), δ = 1.62 (doublet), δ = 2.14 (singlet), δ = 4.32 (quadruplet) and δ = 5.01 ppm (septet).
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