反应详情

To a three necked flask (2 L , equipped with an ice/water bath, mechanical stirrer and vented to a trap containing an aqueous solution of potassium hydroxide, was added potassium (D)-lyxonate (177.18 g, 0.87 mol) and isopropanol (1.2 L). To this cooled vigorously stirred slurry was introduced gaseous HCl, via a sparge tube, at such a rate that the temperature did not exceed 40° C. HCl sparging was continued for 40 min at which time HCl fumes were detected at the caustic trap and the internal temperature began to fall. Sparging was discontinued and the mixture slowly heated to reflux (Caution: HCl fumes were vigorously expelled when the mixture approached the reflux temperature). After refluxing for 10 min, the mixture was cooled and concentrated under reduced pressure to a volume of about 250 mL. The residue was heated to attain solution and allowed to slowly cool to room temperature, during which time crystallization occurred. This highly crystalline product was filtered, washed with cold isopropanol (75 mL), air dried for 1 h and then vacuum dried overnight to provide 90.9 g of desired 2. The mother liquor and washings were reduced in volume to 75 mL, crystallized, filtered and dried as described above to give an additional 9.74 g of 2. The first and second crops were combined to provide 100.64 g of D-lyxono-1,4lactone 2 (77.6): DISC mp 112.51° C. [lit. (1), (2) mp 110-112 and 114° C.]; Analysis calculated for C5H8O5 : C, 40.54; H, 5.44. Found: C, 40.38; H, 5.51%

1. customTo a three necked flask (2 L , equipped with an ice/water bath, mechanical stirrer
2. customvented to a trap
3. temperatureTo this cooled vigorously stirred slurry
4. customvia a sparge tube, at such a rate that the temperature did not exceed 40° C
5. customSparging
6. temperaturethe mixture slowly heated
7. temperatureto reflux (Caution
8. temperatureAfter refluxing for 10 min
9. temperaturethe mixture was cooled
10. concentrationconcentrated under reduced pressure to a volume of about 250 mL
11. temperatureThe residue was heated
12. filtrationThis highly crystalline product was filtered
13. washwashed with cold isopropanol (75 mL), air
14. customdried for 1 h
15. customvacuum dried overnight
16. customto provide 90.9 g
17. customcrystallized
18. filtrationfiltered
19. customdried