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温度

0 °C

407 mmol (42.4 g) alanine hydroxamic acid were cooled to −10° C. in 200 ml water and methanol each, 400 mmol (57 ml 40% solution) methylglyoxal were added dropwise and subsequently the pH was adjusted to approximately pH 11 with 19 ml 30% NaOH. Heating up to 0° C. was carried out within 2 h and then pH 3 was adjusted with 20% NaOH. The solution was concentrated until dryness under vacuum distillation, the residue was heated to reflux with 50 ml ethanol, after cooling filtering was carried out and the filtrate again concentrated until dryness. 44 g of the solid residue were dissolved in 50 ml water and 15 mmol (4.06 g) FeCl3*6H2O were added, heated up to 50° C. for 30 minutes, concentrated and stored at 5° C. for 4 h. The precipitated solid was filtered off and dried. 3.7 g solid in 50 ml water and 10 ml ethanol were adjusted to pH 11 with 6 ml 1 M NaOH, stirred over night and centrifugalized. The supernatant was decanted, pH 3 was adjusted with 3 ml 1 M HCl and concentrated until dryness. 4.2 g solid were refluxed in 20 ml ethanol, cooled and filtered off. The filtrate was again concentrated until dryness and the obtained 2.8 g solid were suspended with 10 ml water, heated up to 50° C. and left for cooling over night. The suspension was centrifugalized, the supernatant decanted and concentrated until dryness. 2.0 g (3.5% yield) of the title compound were obtained.

1. concentrationThe solution was concentrated until dryness under vacuum distillation
2. temperaturethe residue was heated
3. temperatureto reflux with 50 ml ethanol
4. temperatureafter cooling
5. filtrationfiltering
6. concentrationthe filtrate again concentrated until dryness
7. dissolution44 g of the solid residue were dissolved in 50 ml water
8. temperatureheated up to 50° C. for 30 minutes
9. concentrationconcentrated
10. waitstored at 5° C. for 4 h
11. filtrationThe precipitated solid was filtered off
12. customdried
13. customThe supernatant was decanted
14. concentrationconcentrated until dryness
15. temperature4.2 g solid were refluxed in 20 ml ethanol
16. temperaturecooled
17. filtrationfiltered off
18. concentrationThe filtrate was again concentrated until dryness
19. temperatureheated up to 50° C.
20. waitleft
21. temperaturefor cooling over night
22. customthe supernatant decanted
23. concentrationconcentrated until dryness