反应详情

The hydrazone (20 g.) was then refluxed for 3 hours with a solution containing water (200 ml.), ethanol (40 ml.), benzaldehyde (25 ml.) and benzoic acid (2.5 g.). The solution was cooled and then decanted from benzaldehyde phenylhydrazone, extracted three times with chloroform, decolorized with carbon and concentrated at reduced pressure. The resulting syrup was further evaporated with several portions of absolute ethanol to remove residual water and the resulting syrup (10 g.) was left to crystallize. The crystals were filtered with ethanol to give α-L-mannopyranose, m.p. 125°-126°, [α]D -26.9°→-14.4° (24 hr., c 2.0, water) compared to m.p. 128°-132°, [α]D -14.5° (equilibrium, c 3.4, water).

1. temperatureThe solution was cooled
2. customdecanted from benzaldehyde phenylhydrazone
3. extractionextracted three times with chloroform
4. concentrationconcentrated at reduced pressure
5. customThe resulting syrup was further evaporated with several portions of absolute ethanol
6. customto remove residual water
7. waitthe resulting syrup (10 g.) was left
8. customto crystallize
9. filtrationThe crystals were filtered with ethanol