Methanol → 3,4-Dibromo-2-methylthiophene

HRID 2372660Notes

Reaction equation

HRID 2372660 reaction equation
CO.[Sn](Cl)Cl.[CH3:6][C:7]1[S:8][C:9]([Br:14])=[C:10]([Br:13])[C:11]=1[Br:12].BrC1SC(C)=CC=1Br>[Cl-].C[N+](C)(C)C.C(Cl)Cl>[Br:12][C:11]1[C:10]([Br:13])=[CH:9][S:8][C:7]=1[CH3:6].[Br:14][C:9]1[S:8][C:7]([CH3:6])=[C:11]([Br:12])[CH:10]=1

Participants

8

Reactant 4

HCID 887MethanolHCID 24479Stannous ChlorideHCID 148351692,3,4-Tribromo-5-methylthiopheneHCID 1483517030319-03-0

Product 2

HCID 1223733,5-Dibromo-2-methylthiopheneYield 2.7%HCID 128752643,4-Dibromo-2-methylthiopheneYield 166.5%

Reagents, catalysts & solvents 2

HCID 6379Tetramethylammonium chlorideCatalystHCID 6344DichloromethaneSolvent

Procedure

A catholyte of 400 ml of methanol, 200 ml of methylene chloride, 1 g of tin(II) chloride, 5 g of tetramethylammonium chloride and 20.4 g of 2-methyl-3,4,5-tribromothiophene were electrolysed in the electrolysis cell 1 at a current density of 25 mA/cm2, a voltage of 3.8 to 2.9 V and a temperature of 30° C. The current consumption was 8.4 Ah. After addition of 500 ml of water to the catholyte, phase separation and removal of the methylene chloride by distillation, 12.98 g of 3,4-dibromo-2-methylthiophene (yield: 83.1%), 0.45 g of a mixture of 2,3-dibromo-5-methylthiophene and 2,4-dibromo-5-methylthiophene (yield: 2.7%) and 0.071 g of unreacted 2-methyl-3,4,5-tribromothiophene were obtained.

Workup

  1. customa temperature of 30° C
  2. customThe current consumption
  3. additionAfter addition of 500 ml of water
  4. customto the catholyte, phase separation and removal of the methylene chloride

Sources & evidence

ORD record
ord-252a49edb92644e6875cbff279b66f92
Source dataset
uspto-grants-1992_03
Patent number
US05100520

Reaction notes

Loading…