反应详情

温度

10 °C

29 g of L-valine is dissolved in 250 ml of 1N aqueous NaOH, and to the solution is added water so that 400 ml of the solution is obtained. To the solution is added 150 ml of tetrahydrofuran. Then, while vigorously stirring at 10° C., to the solution are added 100 ml of Boc-Cl by 1/5 amounts at intervals of ten minutes, while 2N aqueous NaOH is added after every addition of Boc-Cl in such amount as will provide a pH value of about 8 to 9. Two hours later, the mixture is extracted with diethyl ether. The aqueous layer is acidified with an aqueous solution of 0.5 M aqueous citric acid, whereby an oily substance is precipitated. The precipitate is extracted with ethyl acetate. The extract is washed with a small amount of water, dried over Na2SP4, and concentrated under reduced pressure. To the concentrated extract is added petroleum ether, and the mixture is allowed to stand in a refrigerator, whereby a crystal is formed. The crystal is filtered off and dried. Thus, there is obtained 30 g of Boc-valine having a melting point of 78° C. The yield of the product is 55%.

1. customis obtained
2. customas will provide a pH value of about 8 to 9
3. extractionTwo hours later, the mixture is extracted with diethyl ether
4. customis precipitated
5. extractionThe precipitate is extracted with ethyl acetate
6. washThe extract is washed with a small amount of water
7. dry with materialdried over Na2SP4
8. concentrationconcentrated under reduced pressure
9. extractionTo the concentrated extract
10. additionis added petroleum ether
11. customis formed
12. filtrationThe crystal is filtered off
13. customdried