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Arene bromomethylation; Bis(4-(bromomethyl)phenyl)methane

SyntheticPage 423
DOI: 10.1039/SP423
Submitted Jun 01, 2010, published Jun 01, 2010
Suzanne Elizabeth Howson (s.e.howson@warwick.ac.uk)
A contribution from Scott group, Warwick University


			Reaction Scheme: Arene bromomethylation

Chemicals Used

Diphenylmethane
HBr (48% aq.)
Acetic Acid (glacial)
1,3,5-Trioxane
Tetradecyltrimethylammonium Bromide

Procedure

Diphenylmethane (5.00 g, 29.72 mmol, 1.0 eq.) was added to a solution of 48% aq. HBr (80 ml) and glacial acetic acid (21 ml). 1,3,5-trioxane (5.35 g, 59.44 mmol, 2.0 eq.) was then added to the mixture, followed by tetradecyltrimethylammonium bromide (0.16 g, 0.48 mmol, 0.016 eq.). The reaction was stirred at reflux (125°C) overnight (16 h). After this time the solution was cooled to ambient temperature, then to 0°C in an ice-water bath. The dark yellow solid was filtered off and washed with several portions of water. The solid was then dissolved in DCM (150 ml), washed with water (100 ml) before drying the DCM layer over Na2SO4. This was filtered and the solvent removed in vacuo leaving a light yellow solid, which was recrystallised from hot DCM leaving the pure product as a white solid. Yield = 2.63 g, 7.43 mmol, 25%.

Author's Comments

Reaction also successfully carried out replacing diphenylmethane with bibenzyl.

Data

1H NMR (400 MHz, 298 K, CDCl3) 7.32 (4H, d, 3JHH = 8 Hz, Ph), 7.15 (4H, d, 3JHH = 8 Hz, Ph), 4.48 (4H, s, CH2Br), 3.96 (2H, s, CH2).


13C{1H} NMR (100 MHz, 298 K, CDCl3) 141.1 (Ph), 135.7 (Ph), 129.3 (Ph), 129.2 (Ph), 41.3 (CH2), 33.4 (CH2Br).


Lead Reference

R. H. Mitchell and V. S. Iyer, Synlett, 1989, 55-57 (General procedure for bromomethylation in the para position on a phenyl ring)

Supplementary Information

1H NMR (1H NMR 429.jcamp)
13C NMR (13C NMR 429.jcamp)

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Keywords: addition, alkyl/alkenyl/aryl halides, aromatics/arenes, bromomethylation

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