Sulfuric Acid → Dibenzoylmethane

HRID 2188353Notes

Reaction equation

HRID 2188353 reaction equation
[CH:1]([OH:14])([C:8]1C=CC=CC=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[OH-].[K+].C1(C(C)C)C=CC=CC=1.[C:26]([O:34]C)(=O)[C:27]1[CH:32]=[CH:31][CH:30]=[CH:29][CH:28]=1.C(C1C=CC=CC=1)(=O)C.S(=O)(=O)(O)O>>[C:1]([CH2:8][C:26](=[O:34])[C:27]1[CH:28]=[CH:29][CH:30]=[CH:31][CH:32]=1)(=[O:14])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1

Participants

7

Reactant 6

HCID 1118Sulfuric AcidHCID 7037BenzhydrolHCID 7150Methyl BenzoateHCID 7406CumeneHCID 7410AcetophenoneHCID 14797Potassium Hydroxide

Product 1

HCID 8433DibenzoylmethaneYield 95%

Procedure

Benzhydrol (189.77 g; 1.03 mol), potassium hydroxide (84.3%; 66.56 g; 1.0 mol) and cumene (375 mL) were placed into a four-necked, round bottom, one liter flask equipped with a stirrer, a thermometer, and an Oldershaw column with a Dean-Stark trap and a condenser. The mixture was heated to boiling with stirring under a blanket of nitrogen and the water was azeotroped out (temperature of reflux 148-150° C). When no more water was collected (27 mL, yield=95%, about 2 hours) the mixture was cooled down to and kept at 90° C. The fractionation column and trap were replaced with a reflux condenser, while maintaining the nitrogen stream. Methyl benzoate (181.5 g; 1.33 mol) was added at once, and slow addition (12 minutes) of acetophenone (80.10 g; 0.667 mol) by means of a syringe pump was begun. After 60 minutes from the beginning of the addition of the ketone, the mixture was allowed to cool to room temperature, whereupon it was acidified with 10% sulfuric acid. The cumene layer was washed with a saturated solution of sodium bicarbonate in water and then with water. The organic layer was then concentrated under vacuum in a rotary evaporator. The residue was crystallized from 90% isopropanol, affording DBM (112.13 g, 75% yield) having a purity of 98% (GC).

Workup

  1. customequipped with a stirrer
  2. temperatureThe mixture was heated
  3. customthe water was azeotroped out (temperature of reflux 148-150° C)
  4. customWhen no more water was collected (27 mL, yield=95%, about 2 hours) the mixture
  5. temperaturewas cooled down to and
  6. customkept at 90° C
  7. customThe fractionation column and trap were replaced with a reflux condenser
  8. temperaturewhile maintaining the nitrogen stream
  9. washThe cumene layer was washed with a saturated solution of sodium bicarbonate in water
  10. concentrationThe organic layer was then concentrated under vacuum in a rotary evaporator
  11. customThe residue was crystallized from 90% isopropanol
  12. customaffording DBM (112.13 g, 75% yield)

Sources & evidence

ORD record
ord-2b22aa3133a14b469b85a40a1cc05cf6
Source dataset
uspto-grants-2002_06
Patent number
US06410795B1

Reaction notes

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