Reaktion #586395

Reaktionsgleichung

Potassium carbonate

ethylene diamine

ethyl 2-bromoisobutyrate

→

3,3-dimethylpiperazin-2-one

Lösungsmittel

toluene

toluene

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThe suspension is heated
2. 2
   Temperaturto reflux over night
3. 3
   Filtrationfiltered
4. 4
   WaschenThe filter cake is washed with toluene (500 ml)
5. 5
   TemperaturThe combined filtrates (volume 4.01) are heated on a water bath
6. 6
   workup.DISTILLATIONdistilled at 0.3 atm.
7. 7
   workup.DISTILLATIONfirst 1200 ml distillate is collected at 35° C. (the temperature in the mixture
8. 8
   Sonstigeis 75° C.
9. 9
   workup.ADDITIONMore toluene is added (600 ml)
10. 10
    workup.DISTILLATIONanother 1200 ml distillate is collected at 76° C. (the temperature in the mixture
11. 11
    Sonstigeis 80° C.
12. 12
    workup.ADDITIONToluene (750 ml) is added again
13. 13
    workup.DISTILLATION1100 ml of distillate is collected at 66° C. (temperature in the mixture 71° C.)
14. 14
    Sonstigewhereby the product precipitates
15. 15
    SonstigeThe product is isolated by filtration
16. 16
    Waschenwashed with toluene
17. 17
    Sonstigedried over night in a vacuum oven at 50° C

Vorschrift

Potassium carbonate (390 grams) and ethylene diamine (1001 grams) are stirred with toluene (1.501). A solution of ethyl 2-bromoisobutyrate (500 grams) in toluene (750 ml) is added. The suspension is heated to reflux over night, and filtered. The filter cake is washed with toluene (500 ml). The combined filtrates (volume 4.01) are heated on a water bath and distilled at 0.3 atm. using a Claisen apparatus; first 1200 ml distillate is collected at 35° C. (the temperature in the mixture is 75° C.). More toluene is added (600 ml), and another 1200 ml distillate is collected at 76° C. (the temperature in the mixture is 80° C.). Toluene (750 ml) is added again, and 1100 ml of distillate is collected at 66° C. (temperature in the mixture 71° C.). The mixture is stirred on an ice bath and inoculated, whereby the product precipitates. The product is isolated by filtration, washed with toluene, and dried over night in a vacuum oven at 50° C. Yield 171 g (52%) of 3,3-dimethylpiperazin-2-one. NMR consistent with structure.

Quelle