Reaction #64368

Reaction equation

water

1,4-benzoquinone

2,3-dimethyl-1,3-butadiene

→

title compound

Yield 88.0%

5,8-dihydro-6,7-dimethyl-1,4-naphthoquinone

Yield 88.0%

Solvents

toluene

acetic acid

Conditions

Workup

1. 1
   workup.STIRRINGstirred further for 3 hours at 40° C
2. 2
   OtherThe liquid reaction mixture
3. 3
   Washwas washed with water
4. 4
   Otheran organic layer was dried
5. 5
   Concentrationconcentrated under reduced pressure
6. 6
   workup.ADDITIONConcentrated hydrochloric acid (1 ml) and ethanol (60 ml) were added to the residue
7. 7
   workup.STIRRINGthe mixture was stirred for 1 hour at 40° C
8. 8
   OtherAfter the liquid reaction mixture
9. 9
   Concentrationwas concentrated under reduced pressure
10. 10
    workup.DISSOLUTIONthe residue was dissolved in a liquid mixture of acetonitrile (100 ml) and water (30 ml)
11. 11
    OtherThe liquid reaction mixture
12. 12
    Extractionextraction with toluene (50 ml × 2)
13. 13
    WashThe resulting organic layer was washed with water
14. 14
    Otherdried
15. 15
    Concentrationconcentrated under reduced pressure

Procedure

In toluene (60 ml) and acetic acid (10 ml), were dissolved 14.0 g (0.13 mol) of 1,4-benzoquinone, to which 20.0 g (0.24 mol) of 2,3-dimethyl-1,3-butadiene were added at -10° C. under stirring. Thereafter, the resultant mixture was gradually heated and stirred further for 3 hours at 40° C. The liquid reaction mixture was washed with water, and an organic layer was dried and concentrated under reduced pressure. Concentrated hydrochloric acid (1 ml) and ethanol (60 ml) were added to the residue, and the mixture was stirred for 1 hour at 40° C. After the liquid reaction mixture was concentrated under reduced pressure, the residue was dissolved in a liquid mixture of acetonitrile (100 ml) and water (30 ml). To the solution, were added 20.0 g (0.036 mol) of ceric ammonium nitrate at room temperature to stir the resultant mixture for 1 hour. The liquid reaction mixture was poured into water (200 ml) to make extraction with toluene (50 ml × 2). The resulting organic layer was washed with water, dried and concentrated under reduced pressure to obtain 21.5 g of a crude product of the title compound (yield: 88%).

Source