2,4-Dimethylbenzoic acid → 3-bromo-2,4-dimethylbenzoic acid

HRID 1186935Notes

Reaction equation

HRID 1186935 reaction equation
[CH3:1][C:2]1[CH:10]=[C:9]([CH3:11])[CH:8]=[CH:7][C:3]=1[C:4]([OH:6])=[O:5].C1C(=O)N([Br:19])C(=O)C1>C(O)(C(F)(F)F)=O>[Br:19][C:10]1[C:2]([CH3:1])=[C:3]([CH:7]=[CH:8][C:9]=1[CH3:11])[C:4]([OH:6])=[O:5]

Participants

4

Reactant 2

HCID 118972,4-Dimethylbenzoic acidHCID 67184N-bromobutanimide

Product 1

HCID 224422683-bromo-2,4-dimethylbenzoic acid

Reagents, catalysts & solvents 1

HCID 6422Trifluoroacetic acidSolvent

Conditions

Temperature
50 °C

Procedure

2,4-Dimethylbenzoic acid (7.00 g, 46.6 mmol) and NBS (12.4 g, 69.9 mmol) were dissolved in TFA (150 mL). The mixture was then heated at 50° C. for overnight. Analysis by LC as well as TLC (hexanes/EtOAc=1/1) indicated that reaction had gone to completion. The solvent was removed in vacuo and the resulting residue was dissolved in DCM, absorbed onto silica gel, and loaded onto a silica MPLC column for separation. The desired product was separated using the solvent system of hexanes/EtOAc (1/1) to yield 3-bromo-2,4-dimethylbenzoic acid. The undesired isomeric 5-bromo-2,4-dimethylbenzoic acid was also isolated. 1H-NMR (CDCl3, 500 MHz), δ 7.868 (d, J=7.5 Hz, 1H), 7.2 (d, J=7.5 Hz, 1H), 2.793 (s, 3H), 2.526 (s, 3H).

Workup

  1. customThe solvent was removed in vacuo
  2. dissolutionthe resulting residue was dissolved in DCM
  3. customabsorbed onto silica gel
  4. customloaded onto a silica MPLC column for separation
  5. customThe desired product was separated

Sources & evidence

ORD record
ord-244042b7e3fb41eaadc5e3b301df2580
Source dataset
uspto-grants-2014_03
Patent number
US08673920B2

Reaction notes

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