反应详情

温度

60 °C

80.0 g (0.35 mol) of recrystallized 3-hydroxy-3-(2-methyl-5-pyridyl)-propionic acid methyl ester was dissolved in 100 ml of toluene. 60.0 g (0.588 mol) of acetic anhydride and 0.1 g (0.0009 mol) of 4-dimethyl-aminopyridine were added, and the solution was stirred for 1 hour at 60° C. Then 20 ml of methanol was added. After 15 minutes, the solution was diluted with 250 ml of acetic acid, 1.5 g of 5 percent palladium on activated carbon was added, and the solution was poured into the autoclave. The hydrogenation was performed under 8 bars of hydrogen at 65° C. for 5.5 hours. At the end of the hydrogenation, the autoclave was cooled, and the solution was filtered and evaporated. The evaporation residue was dissolved in 100 ml of water and 100 ml of methylene chloride and adjusted to pH 7 with 87.9 g of 40 percent sodium hydroxide solution. The phases were separated, the aqueous phase was extracted with methylene chloride, and the combined organic extracts were evaporated. 71.5 g of raw 2-methylpyridine-5-propionic acid methyl ester was obtained. (Content according to GC, 91.5 percent; yield, 92.1 percent in relation to the 3-hydroxy-3-(2-methyl-5-pyridyl)-propionic acid methyl ester used.) The product was distilled to obtain a 97 percent product having with a boiling point of 100°-113° C./1-2 mbar. The yield of distilled product was 88.5 percent, in relation to the 3-hydroxy-3-(2-methyl-5-pyridyl)propionic acid methyl ester used.

1. waitAfter 15 minutes
2. additionwas added
3. additionthe solution was poured into the autoclave
4. temperatureAt the end of the hydrogenation, the autoclave was cooled
5. filtrationthe solution was filtered
6. customevaporated
7. dissolutionThe evaporation residue was dissolved in 100 ml of water
8. customThe phases were separated
9. extractionthe aqueous phase was extracted with methylene chloride
10. customthe combined organic extracts were evaporated