反应详情

Sodium (12.5 g, 0.54 g-atoms) was gradually added in small pieces to absolute ethanol (375 ml) while stirring under an inert (N2) atmosphere until complete solution of the sodium has taken place. Diethyl methylmalonate (95.5 g, 570 mmol) was then added dropwise to the sodium ethoxide solution over 20 minutes and the mixture was heated at reflux for about 15 minutes. After cooling to room temperature, 1-bromooctane (99 g, 512 mmol) was added dropwise over 15 minutes; the mixture was heated at reflux for 2 hours, cooled and neutralized by adding a few drops of glacial acetic acid. About two-thirds of the alcohol was removed by distillation and the residue was washed with 500 ml of water. The organic phase was separated and the aqueous phase extracted with three 50 ml portions of benzene. The organic phase and extracts were combined, washed with water, and dried over anhydrous magnesium sulfate. The residue obtained upon evaporation of the solvent was treated with a solution of 115 g of 86% potassium hydroxide Pellets in 900 ml of reagent ethanol and the mixture heated at reflux, with stirring, for 4 hours. About two-thirds of the solvent was removed by distillation, 750 ml water was added, followed by sufficient (520 ml) 6N sulfuric acid to bring the pH of the solution to 1-2. The organic phase was separated and the aqueous phase was extracted with two portions of ether. The organic phase and extracts were combined, washed with water, then with saturated sodium chloride solution, and finally dried over magnesium sulfate. The residue obtained upon evaporation of the solvent was heated to 180°-190° C. at which temperature decarboxylation occurred smoothly over a period of several minutes. The crude acid was then distilled through a short Vigreux column to give 64 g of product (73% yield), b.p. 143°/5.8 mm (lit. b.p. 137°/4.4 mm), which showed a purity of >99% by GC.

1. temperaturethe mixture was heated
2. temperatureat reflux for about 15 minutes
3. temperaturethe mixture was heated
4. temperatureat reflux for 2 hours
5. temperaturecooled
6. customAbout two-thirds of the alcohol was removed by distillation
7. washthe residue was washed with 500 ml of water
8. customThe organic phase was separated
9. extractionthe aqueous phase extracted with three 50 ml portions of benzene
10. washwashed with water
11. dry with materialdried over anhydrous magnesium sulfate
12. customThe residue obtained upon evaporation of the solvent
13. temperaturethe mixture heated
14. temperatureat reflux
15. customAbout two-thirds of the solvent was removed by distillation, 750 ml water
16. additionwas added
17. customThe organic phase was separated
18. extractionthe aqueous phase was extracted with two portions of ether
19. washwashed with water
20. dry with materialwith saturated sodium chloride solution, and finally dried over magnesium sulfate
21. customThe residue obtained upon evaporation of the solvent
22. temperaturewas heated to 180°-190° C. at which temperature decarboxylation
23. waitoccurred smoothly over a period of several minutes
24. distillationThe crude acid was then distilled through a short Vigreux column