Reaktion #71006

Reaktionsgleichung

but-3-en-2-one

but-3-en-2-one

2,4-dimethyl-1,3-pentadiene

Dichloromethane

THF

→

1-(2,2,4-trimethyl-cyclohex-3-enyl)-ethanone

Lösungsmittel

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturIn a 500 ml sulfonation flask with cooling funnel
2. 2
   TemperaturWhite fumes and increase of temperature to 20° C.
3. 3
   Sonstigewas decreased to 15° C.
4. 4
   SonstigeExothermic reaction
5. 5
   workup.STIRRINGThe reaction mixture was stirred for 8 hours at 25° C. and for 10 hours at 45° C
6. 6
   workup.ADDITIONwas added dropwise (22 ml; 0.26 mol) (10 min)
7. 7
   workup.STIRRINGthe mixture was stirred for additional 48 hours at 25° C
8. 8
   workup.STIRRINGwas stirred for 5 min
9. 9
   Filtrationfiltered over celite
10. 10
    SonstigeThe red solution obtained
11. 11
    Extraktionextracted with dichloromethane (4×300 ml)
12. 12
    WaschenCombined organic layers were washed with brine (500 ml) and water (500 ml)
13. 13
    Trocknendried over sodium sulfate
14. 14
    Filtrationfiltered over silica
15. 15
    SonstigeThe solvent was removed in vacuo

Vorschrift

In a 500 ml sulfonation flask with cooling funnel, dropping funnel and mechanical stirring under air (*) at 5° C. was added but-3-en-2-one (43 ml; 0.52 mol) then THF (4.2 ml; 52 mmol) followed by a careful portionwise addition of aluminum chloride (3.5 g; 26 mmol). White fumes and increase of temperature to 20° C. were observed. The mixture turned red. The temperature was decreased to 15° C. and 2,4-dimethyl-1,3-pentadiene (68 ml; 0.52 mol) was added dropwise (90 min). Exothermic reaction was observed. The reaction mixture was stirred for 8 hours at 25° C. and for 10 hours at 45° C. As the diene was still detected but-3-en-2-one was added dropwise (22 ml; 0.26 mol) (10 min) and the mixture was stirred for additional 48 hours at 25° C. Dichloromethane (200 ml) was added to the mixture which was stirred for 5 min and filtered over celite. The red solution obtained was poured into cold water (1 l) and extracted with dichloromethane (4×300 ml). Combined organic layers were washed with brine (500 ml) and water (500 ml), dried over sodium sulfate and filtered over silica. The solvent was removed in vacuo to afford 84 g (97% of theory) of 1-(2,2,4-trimethyl-cyclohex-3-enyl)-ethanone as a clear red oil.

Quelle