Reaktion #5118

Reaktionsgleichung

diethyl malonate

sodium

3,4-dimethylbenzyl chloride

→

3-(3,4-dimethylphenyl)propanoic acid

Ausbeute 55.0%

Lösungsmittel

ethanol

ethyl ether

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGThis reaction mixture was stirred for 1 hour at room temperature
2. 2
   Temperaturheated at the boiling temperature for 4 hours
3. 3
   Einengenconcentrated under reduced pressure
4. 4
   Sonstigeto produce residues, which
5. 5
   WaschenThis ethereal solution was washed with water
6. 6
   SonstigeTo the residues obtained
7. 7
   Einengenafter a further concentration of the organic phase
8. 8
   workup.ADDITIONwere added 500 ml of water and 170 g of KOH
9. 9
   Temperaturand this mixture was heated at the boiling temperature for 24 hours
10. 10
    EinengenThis mixture was concentrated under reduced pressure until about a half of the amount
11. 11
    workup.ADDITION200 ml of sulfuric acid was then slowly added
12. 12
    TemperaturThe resultant solution was heated at the boiling temperature for 24 hours
13. 13
    Extraktionextracted twice with 300 ml of ethyl ether
14. 14
    Sonstigeevaporated under reduced pressure
15. 15
    Sonstigeto obtain solids, which
16. 16
    Sonstigewere recrystallized

Vorschrift

To a solution of 70.0 ml of diethyl malonate dissolved in 400 ml of dry ethanol was added 10.0 g of metalic sodium. The reaction mixture was stirred for 30 minutes and cooled to 0° C; and 66.5 g of 3,4-dimethylbenzyl chloride was added thereto. This reaction mixture was stirred for 1 hour at room temperature, heated at the boiling temperature for 4 hours and concentrated under reduced pressure to produce residues, which were dissolved in ethyl ether. This ethereal solution was washed with water. To the residues obtained after a further concentration of the organic phase were added 500 ml of water and 170 g of KOH; and this mixture was heated at the boiling temperature for 24 hours. This mixture was concentrated under reduced pressure until about a half of the amount remained, and 200 ml of sulfuric acid was then slowly added thereto. The resultant solution was heated at the boiling temperature for 24 hours, extracted twice with 300 ml of ethyl ether and evaporated under reduced pressure to obtain solids, which were recrystallized from boiling hexane to provide 42.1 g of 3-(3,4-dimethylphenyl)propanoic acid as a white solid (yield 55%), having the characteristics of: m.p. 82° C.; NMR(CDCl3, 300 MHz) δ2.22(s, 3H, CH3), 2.24(s, 3H, CH3), 2.66(t, J=8 Hz, 2H, ArCH2), 2.89(t, J=8 Hz, 2H, CH2CO), 6.93~7.70(m, 3H, ArH).

Quelle