反应详情

A solution of 3.15 g (0.017 mol) of 2-carbethoxymethyl-1,3,4-oxadiazole-5-thiol in 25 ml of water and 25 ml of ethanol was stirred for 5 hours while maintaining the pH at 10-11 by addition of 10% aqueous sodium hydroxide solution. The mixture was neutralized to pH 7.0 then evaporated to dryness. The residue was dissolved in 15 ml of water, 50 ml of ethyl acetate was added and the solution was acidified to pH 1.5 with 3N hydrochloric acid. The layers were separated and the aqueous phase was extracted twice with ethyl acetate. The combined extracts were dried (Na2SO4) and the solvent was evaporated to give a residue which was recrystallized from ether-cyclohexane to give 2-carboxymethyl-1,3,4-oxadiazole-5-thiol, m.p. 167° -169° (dec.)

1. temperaturewhile maintaining the pH at 10-11
2. customthen evaporated to dryness
3. dissolutionThe residue was dissolved in 15 ml of water
4. addition50 ml of ethyl acetate was added
5. customThe layers were separated
6. extractionthe aqueous phase was extracted twice with ethyl acetate
7. dry with materialThe combined extracts were dried (Na2SO4)
8. customthe solvent was evaporated
9. customto give a residue which
10. customwas recrystallized from ether-cyclohexane