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 Synthesis of Phenyl vinyl sulfone and sulfoxide
  • Synthesis of Phenyl vinyl sulfone and sulfoxide
  • and sulfoxide could be produced through the following synthetic routes.

    Synthesis of Phenyl vinyl sulfone and sulfoxide

    A. (CAS NO.: ). In a 1-L, three-necked, round-bottomed flask fitted with magnetic stirrer, condenser, addition funnel, and nitrogen-inlet tube is placed 400 mL of ethanol. metal (23 g, 1 g-atom), cut into small pieces, is added with stirring. When conversion to sodium ethoxide is complete (5–15 min), the stopper of the addition funnel is removed under a positive flow of nitrogen, and benzenethiol (110 g, 1 mol) is poured into the addition funnel. The stopper is put in place, and the benzenethiol is added over 15–20 min to the cloudy, gray sodium ethoxide solution. The reaction mixture warms spontaneously and becomes clear brown. At 25°C this solution is transferred by stainless-steel cannula over 45 min to a stirred solution of 1,2-dibromoethane (272 g, 1.45 mol) in ethanol (28 mL) contained in a 2-L, three-necked round-bottomed flask equipped with a mechanical stirrer, addition funnel, reflux condenser, nitrogen-inlet tube, and internal thermometer. The reaction temperature is maintained at 25–30°C by cooling with an ice bath. The mixture is stirred under nitrogen for 30 min and treated for an additional 30 min with ethanolic sodium ethoxide prepared from 40 g (2.17 g-atom) of sodium and 800 mL of ethanol. The resulting mixture is stirred at reflux for 8 hr, cooled, and treated with 750 mL of benzene and 750 mL of water. The organic layer is separated, washed with water (2 × 50 mL) and brine (100 mL), and concentrated by rotary evaporation. The yellow oil that results is distilled to give 70–87 g (50–65%) of phenyl vinyl sulfide, bp 91–93°C/20 mm.

    B. Phenyl vinyl sulfone (CAS NO.: ). In a 250-mL, three-necked, round-bottomed flask fitted with a magnetic stirrer, condenser, addition funnel, and thermometer is placed 19.7 g(0.145 mol) of phenyl vinyl sulfide dissolved in 70 mL of glacial acetic acid. peroxide (30%, 56 mL, 0.5 mol) is added slowly at such a rate to maintain a reaction temperature of 70°C. The reaction mixture is heated at reflux for 20 min, cooled, and treated with ether (150 mL) and water (200 mL). The organic phase is separated, washed with water (50 mL) and brine (50 mL), and concentrated at 70°C/0.3 mm for 3 hr to afford 18–19 g (74–78%) of phenyl vinyl sulfone as a colorless solid, mp 64–65°C. Although this material is sufficiently pure for most purposes, recrystallization from hexane affords colorless crystals, mp 66–67°C.

    C. Phenyl vinyl sulfoxide (CAS NO.: ). A 500 mL, three-necked, round-bottomed flask equipped with a dropping funnel and magnetic stirrer is charged with 20 g (0.147 mol) of phenyl vinyl sulfide and 250 mL of dichloromethane. The solution is stirred and cooled to -78°C while a solution of m-chloroperbenzoic acid (25.4 g, 1.0 equiv) in 200 mL of dichloromethane is added dropwise during a 30-min period. The mixture is stirred and warmed to room temperature for 1 hr in a water bath at 30°C. The mixture is then poured into 300 mL of saturated sodium bicarbonate solution, and the mixture is extracted with three 250-mL portions of dichloromethane. The combined organic extracts are washed with three 250-mL portions of water and dried over anhydrous magnesium sulfate. The solvent is removed by rotary evaporation and the residual liquid is distilled to afford 15–16 g (68–70%) of phenyl vinyl sulfoxide as a colorless liquid, bp 98°C/0.6 mm.

    Notice: Reactions and subsequent operations involving peracids and peroxy compounds should be run behind a safety shield. Peroxy compounds should be added to the organic material, never the reverse. For relatively fast reactions, the rate of addition of the peroxy compound should be slow enough so that it reacts rapidly and no significant unreacted excess is allowed to build up. The reaction mixture should be stirred efficiently while the peroxy compound is being added, and cooling should generally be provided since many reactions of peroxy compounds are exothermic. New or unfamiliar reactions, particularly those run at elevated temperatures, should be run first on a small scale.

    Caution! 1-Phenylthio-2-bromoethane is a powerful alkylating agent that causes severe skin blistering. Although the present one-pot procedure eliminates the cumbersome handling of this intermediate, due care must be exercised to avoid exposure to this substance.


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