Sodium Hydroxide → Retinol

Temperatur

-20 °C

Retinol was prepared in a high degree of purity from commercial retinyl acetate for use as a reference retinoid in certain bioassays and as a precursor of retinyl ethers. A solution of 100 g of commercial all-trans-retinyl acetate in 1.5 L of a methanol solution of sodium hydroxide (2%) was stirred under a nitrogen atmosphere at room temperature. After 2 h, retinyl acetate was not observable by TLC. The orange solution was concentrated under reduced pressure, and at 30° C., to about 300 mL; the concentrated solution was poured, with stirring, into cold water (1.5 L); and hexane (1 L) was added to dissolve the precipitated retinol. The organic layer was separated and washed with three portions of water, saturated aqueous NaCl being added (as required) to separate emulsions. The organic solution was washed further with saturated aqueous NaCl, dried (MgSO4), and concentrated under reduced pressure to an orange syrup. A solution of the syrup in ethyl formate (100 mL) was cooled to −20° C., seeded with pure retinol, and stored (under a nitrogen atmosphere) at −20° C. The crystalline retinol was collected by filtration under nitrogen, washed with cold (−70° C.) ethyl formate, and dried in vacuo: yield, 47 g (54%); mp 60-62° C. [lit. Robeson et al., 1955), 62-64° C.]; HPLC, 99.4%: UV λmax 325 (ε 53 000) and 250 nm (ε 5000); 1H NMR in accord with the structure.

1. concentrationThe orange solution was concentrated under reduced pressure
2. customat 30° C.
3. additionthe concentrated solution was poured
4. additionand hexane (1 L) was added
5. dissolutionto dissolve the precipitated retinol
6. customThe organic layer was separated
7. washwashed with three portions of water, saturated aqueous NaCl being
8. additionadded (as required)
9. customto separate emulsions
10. washThe organic solution was washed further with saturated aqueous NaCl
11. dry with materialdried (MgSO4)
12. concentrationconcentrated under reduced pressure to an orange syrup
13. customat −20° C
14. filtrationThe crystalline retinol was collected by filtration under nitrogen
15. washwashed with cold (−70° C.) ethyl formate
16. customdried in vacuo
17. customyield
18. custom62-64° C.

ORD-Eintrag

ord-832d96c497064719880e1f64b2bb1127

Quelldatensatz

uspto-grants-2001_08

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US06281250B1