反应详情

A mixture of 2,3-dichloro-4-formylphenol (5.73 g., 0.03 mole), ethyl 4-bromobutyrate (11.7 g., 0.06 mole) and potassium carbonate (8.28 g., 0.06 mole) in dimethylformamide (25 ml.) is heated at 50°-60° C. for 11/2 hours. Water (50 ml.) is added and the mixture is extracted with ether. The ether extract is dried and evaporated. To the residue is added a solution composed of 48 ml. of 40% sodium bisulfite and 12 ml. of alcohol. The precipitated 4isulfite addition compound then is washed with alcohol and ether. The solid is suspended in water heated in a steam bath. An oily layer of the free aldehyde is formed. The hot water then is decanted and the oily layer is extracted with ether and the ether evaporated. The residue is heated to 80° C. in a mixture of potassium hydroxide (2.8 g.), methanol (30 ml.) and water (5 ml.), the resulting solution is evaporated to dryness and the residue dissolved in water. Upon acidification a solid separates. The solid is crystallized from benzene to obtain 2.9 g. of 4-(2,3-dichloro-4-formylphenoxy)butyric acid, M.P. 147°-148° C.

1. temperatureis heated at 50°-60° C. for 11/2 hours
2. extractionthe mixture is extracted with ether
3. extractionThe ether extract
4. customis dried
5. customevaporated
6. additionTo the residue is added a solution
7. washThe precipitated 4isulfite addition compound then is washed with alcohol and ether
8. temperatureheated in a steam bath