反应详情

温度

5 °C

To 50 grams of a solution of 20% ethyl 1,4-dimethyl-3-ethoxycarbonylpyrrole-2-acetate (10 grams, 40 mmoles) in toluene containing 2.4 ml of absolute ethanol (1.9 grams, 41 mmoles) were added, dropwise, over 20 minutes, 8.6 ml of 96% sulfuric acid (15 grams, 160 mmoles, containing 0.63 gram, 35 mmoles of water). During the addition, the temperature of the reaction mixture rose to about 50° C., and the mixture became heterogeneous. The reaction mixture was then heated in an oil bath at 75°-80° C. for 75 minutes with stirring. Gas evolution was observed. The reaction mixture was then diluted with 25 ml of toluene and cooled to 5° C. Then 75 ml of ice water was added in one portion with vigorous stirring. After five minutes, the organic layer was separated and dried with magnesium sulfate. Gas chromatographic analysis indicates the toluene contained 9% ethyl 1,4-dimethylpyrrole-2 -acetate. The toluene was removed by vacuum distillation at 100 mm of mercury followed by vacuum distillation of the residue at 1 mm of mercury to give a fraction which weighed 5.5 grams. This corresponds to a 78% yield of ethyl 1,4-dimethylpyrrole-2-acetate.

1. additionDuring the addition
2. customrose to about 50° C.
3. temperatureThe reaction mixture was then heated in an oil bath at 75°-80° C. for 75 minutes
4. waitAfter five minutes
5. customthe organic layer was separated
6. dry with materialdried with magnesium sulfate
7. customThe toluene was removed by vacuum distillation at 100 mm of mercury
8. distillationfollowed by vacuum distillation of the residue at 1 mm of mercury
9. customto give a fraction which