Reaction #2275680

ord-3b94b3e9be8e4262a89543044da55715

Reaction equation

O
water
O=S(=O)(O)O
sulfuric acid
O=C(O)CC(=O)O
Malonic acid
CC1CCC(C(C)C)C(O)C1
menthol
→
CC1CCC(C(C)C)C(OC(=O)CC(=O)OC2CC(C)CCC2C(C)C)C1
dimenthyl malonate
Yield 76.2%

Reactants

O
water
O=S(=O)(O)O
sulfuric acid
O=C(O)CC(=O)O
Malonic acid
CC1CCC(C(C)C)C(O)C1
menthol

Reagents

None

Solvents

Cc1ccccc1
toluene

Conditions

Detailed conditions
See reaction.notes.procedure_details.

Workup

  1. 1
    Otheris removed by azeotropic distillation
  2. 2
    WashThe organic phase is washed 3 times with water
  3. 3
    Dryingis dried over sodium sulfate
  4. 4
    OtherThe excess menthol is removed by distillation under vacuum (140° C. under 0.6 hPa)
  5. 5
    workup.ADDITIONThe residue is treated with animal charcoal in isopropanol
  6. 6
    Temperatureat reflux
  7. 7
    FiltrationAfter filtering
  8. 8
    Washrinsing

Procedure

Malonic acid (22.2 g, 0.213 mol) and menthol (70 g, 0.448 mol) are brought to reflux for 6 hours in 100 ml of toluene in the presence of 2 ml of concentrated sulfuric acid in a reactor surmounted by a Dean & Stark apparatus. The water formed is removed by azeotropic distillation. The organic phase is washed 3 times with water and is dried over sodium sulfate. The excess menthol is removed by distillation under vacuum (140° C. under 0.6 hPa). The residue is treated with animal charcoal in isopropanol at reflux. After filtering, rinsing and evaporating the solvent, 61.8 g (Yield 76%) of dimenthyl malonate are obtained in the form of a yellow oil which is used as is in the following stage.

Source

DOI: 10.6084/m9.figshare.5104873.v1Patent: US08323624B2uspto-grants-2012_12