反应详情

温度

80 °C

Potassium carbonate (36 g, 0.26 mol) was added to a stirred mixture of 3,5-dichloro-4-fluorobenzoic acid (27.6 g, 0.13 mol), ethyl iodide (41.2 g- 0.26 moles) and dry dimethylformamide (300 ml) under nitrogen. The reaction was heated to 80° C. for 6 hours. The dimethylformamide was removed in vacuo and the residue treated with water (200 ml) acidified with dilute hydrochloric acid and extracted with ethylacetate (2×250 ml). The organic layer was washed with water, dried over magnesium sulphate and evaporated in vacuo, to give an orange oil which was purified by chromatography on silica, using a 4:1 mixture of petrol and diethylether as eluent. The pink oil obtained crystallised on standing, and washing with ice-cold 40-60 petrol gave white crystals of ethyl 3,5-dichloro-4-fluorobenzoate (29 g).

1. customThe dimethylformamide was removed in vacuo
2. additionthe residue treated with water (200 ml)
3. extractionextracted with ethylacetate (2×250 ml)
4. washThe organic layer was washed with water
5. dry with materialdried over magnesium sulphate
6. customevaporated in vacuo
7. customto give an orange oil which
8. customwas purified by chromatography on silica
9. additiona 4:1 mixture of petrol and diethylether as eluent
10. customThe pink oil obtained
11. customcrystallised
12. washwashing with ice-cold 40-60 petrol