Resorcinol → 4,6-Dibromobenzene-1,3-diol

HRID 1481837Notes

Reaction equation

HRID 1481837 reaction equation
[C:1]1([CH:8]=[CH:7][CH:6]=[C:4]([OH:5])[CH:3]=1)[OH:2].[Br-:9].[Br-:10].[Br-].[NH+]1C=CC=CC=1.[NH+]1C=CC=CC=1.[NH+]1C=CC=CC=1>ClCCl.CO>[Br:9][C:6]1[CH:7]=[C:8]([Br:10])[C:1]([OH:2])=[CH:3][C:4]=1[OH:5]

Participants

5

Reactant 2

HCID 5054ResorcinolHCID 21124087Pyridiniumtribromide

Product 1

HCID 2541394,6-Dibromobenzene-1,3-diolYield 90%

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 6344DichloromethaneSolvent

Procedure

This synthesis was adapted from Shoji Kajigaeshi, Takaaki Kakinami, Tsuyoshi Okamoto, Hiroko Nakamura, Masahiro Fujikawa, Bulletin of the Chemical Society of Japan, 1987, volume 60, pages 4187-4189. To a solution of resorcinol (5.00 grams, 45.4 millimoles, 1.0 equivalent), dissolved in 100 milliliters dichloromethane and 40 milliliters methanol, pyridinium tribromide (29.0 grams, 90.8 millimoles, 2.0 equivalent) was added in small portions over the course of 60-70 minutes. The reaction was stirred at room temperature overnight. The solvent was removed on the rotary evaporator, and the residue taken up in chloroform (1×50 milliliters) and reconcentrated. Addition of ethyl acetate resulted in precipitation of side product. The ethyl acetate phase was separated by decanting, and the precipitate was further washed several times (4×150 milliliters 1:1 ether/ethyl acetate, 1×150 milliliters ethyl acetate, solvent separated by decanting). The combined decanted solvents were concentrated, followed by purification via automated flash chromatography (methanol in chloroform, 0-15%). The product was obtained in the form of an off-white solid (10.9 grams, 40.7 millimoles, 90%). m.p.: 66.4° C.; 1H-NMR (400 MHz, CDCl3) δ 7.53 (s, 1H), 6.74 (s, 1H), 5.46 (s, 2H); 13C NMR (101 MHz, THF-d8) δ 155.60, 136.10, 105.13, 100.74, 67.57; FTIR: 569, 594, 659, 742, 837, 868, 993, 1053, 1138, 1193, 1282, 1326, 1440, 1462, 1494, 1577, 1598, 1711, 2918, 3089, 3379, 3451, 3504 cm−1; UV/Vis: 223, 236, 296 nm; ESI/MS/MS of m/z=267: 267 [M79Br/81Br-H]−, 188 [M81Br-HBr)]−, 186 [M79Br-HBr)]−, 160 [M81Br-HBr—CO)]−, 158 [M79Br-HBr—CO)]−, 81 [81Br]−, 79 [79Br]−; HRMS (ESI−): 374.95735 calc. for C6H3Br2O2− [M-H]−: 264.8505, found 264.8510.

Workup

  1. customThe solvent was removed on the rotary evaporator
  2. additionAddition of ethyl acetate
  3. customresulted in precipitation of side product
  4. customThe ethyl acetate phase was separated
  5. customby decanting
  6. customseveral times (4×150 milliliters 1:1 ether/ethyl acetate, 1×150 milliliters ethyl acetate, solvent separated by decanting)
  7. customThe combined decanted solvents
  8. concentrationwere concentrated
  9. customfollowed by purification

Sources & evidence

ORD record
ord-7e62b630371e493fb44eb6c138bb0a13
Source dataset
uspto-grants-2016_08
Patent number
US09410016B2

Reaction notes

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