反应详情

19.8 g (0.353 mol) of potassium hydroxide was dissolved in 5.1 ml of water and 830 ml of ethanol, and 39.6 g (0.236 mol) of 3,4-dihydroxybenzohydrazide and 99 ml (1.65 mol) of carbon disulfide was added thereto. The mixture was heated for 24 hours under reflux. The reaction solution was stirred for 1.5 hours under cooling with ice. The precipitated crystals were collected by filtration and washed with 200 ml of ethanol. The crystals were dissolved in 3 liter of water and adjusted to pH1.5 with 6N hydrochloric acid under cooling with ice. The solution was extracted with 1 liter of ethyl acetate and 400 ml of ethyl acetate. The organic layers were put together, washed twice with 300 ml of a saturated sodium chloride aqueous solution, dried over anhydrous magnesium sulfate and concentrated under reduced pressure to obtain 42.8 g (yield: 86.5%) of 2-mercapto-5-(3,4-dihydroxyphenyl)-1,3,4-oxadiazole.

1. temperatureThe mixture was heated for 24 hours
2. temperatureunder reflux
3. temperatureunder cooling with ice
4. filtrationThe precipitated crystals were collected by filtration
5. washwashed with 200 ml of ethanol
6. dissolutionThe crystals were dissolved in 3 liter of water
7. temperatureunder cooling with ice
8. extractionThe solution was extracted with 1 liter of ethyl acetate and 400 ml of ethyl acetate
9. washwashed twice with 300 ml of a saturated sodium chloride aqueous solution
10. dry with materialdried over anhydrous magnesium sulfate
11. concentrationconcentrated under reduced pressure