4-Methylbenzophenone → 4-(Bromomethyl)benzophenone

HRID 342367

Reaction equation

HRID 342367 reaction equation
[CH3:1][C:2]1[CH:15]=[CH:14][C:5]([C:6]([C:8]2[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=2)=[O:7])=[CH:4][CH:3]=1.[Br:16]Br>C1C=CC=CC=1>[Br:16][CH2:1][C:2]1[CH:15]=[CH:14][C:5]([C:6]([C:8]2[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=2)=[O:7])=[CH:4][CH:3]=1

Participants

4

Reactant 2

HCID 86524-Methylbenzophenone2×HCID 24408Bromine

Product 1

HCID 1229514-(Bromomethyl)benzophenoneYield 60%

Reagents, catalysts & solvents 1

HCID 241BenzeneSolvent2×

Procedure

4-Methylbenzophenone, 750 g (3.82 moles), was added to a 5 liter Morton flask equipped with an overhead stirrer and dissolved in 2850 ml of benzene. The solution was then heated to reflux, followed by the dropwise addition of 610 g (3.82 moles) of bromine in 330 ml of benzene. The addition rate was approximately 1.5 ml/min and the flask was illuminated with a 90 watt (90 joule/sec) halogen spotlight to initiate the reaction . A timer was used with the lamp to provide a 10% duty cycle (on 5 seconds, off 40 seconds), followed in one hour by a 20% duty cycle (on 10 seconds, off 40 seconds). At the end of the addition, the product was analyzed by gas chromatography and was found to contain 71% of the desired Compound VI, 8% of the dibromo product, and 20% unreacted 4-methylbenzophenone. After cooling, the reaction mixture was washed with 10 g of sodium bisulfite in 100 ml of water, followed by washing with 3×200 ml of water. The product was dried over sodium sulfate and recrystallized twice from 1:3 toluene : hexane. After drying under vacuum, 635 g of Compound VI were isolated, providing a yield of 60% and having a melting point of 112°-114° C. Analysis on an NMR spectrometer was consistent with the desired product: 1H NMR (CDCl3) aromatic protons 7.20-7.80 (m, 9 H) and benzylic protons 4.48 (s, 2 H). The final compound was stored for use in the preparation of a photoactivatable chain transfer agent as described in Example 7.

Workup

  1. customequipped with an overhead stirrer
  2. temperatureThe solution was then heated
  3. temperatureto reflux
  4. customthe reaction
  5. customto provide a 10% duty cycle (on 5 seconds, off 40 seconds)
  6. additionAt the end of the addition
  7. temperatureAfter cooling
  8. washthe reaction mixture was washed with 10 g of sodium bisulfite in 100 ml of water
  9. washby washing with 3×200 ml of water
  10. dry with materialThe product was dried over sodium sulfate
  11. customrecrystallized twice from 1:3 toluene
  12. customAfter drying under vacuum

Sources & evidence

ORD record
ord-e654ab9206c647e1989d502f0fecb3ea
Source dataset
uspto-grants-1999_01
Patent number
US05858653

Linked notes

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