Methanol → 2,4-Dibromo-3-methylthiophene

HRID 2372661Notes

Reaction equation

HRID 2372661 reaction equation
CO.[CH3:3][C:4]1[C:8]([Br:9])=[C:7]([Br:10])[S:6][C:5]=1[Br:11]>[Cl-].C[N+](CCCCCCCC)(CCCCCCCC)CCCCCCCC.[Cl-].[Zn+2].[Cl-].C(Cl)Cl>[Br:11][C:5]1[S:6][CH:7]=[C:8]([Br:9])[C:4]=1[CH3:3].[Br:10][C:7]1[S:6][CH:5]=[C:4]([CH3:3])[C:8]=1[Br:9]

Participants

7

Reactant 2

HCID 887MethanolHCID 30178012,3,5-Tribromo-4-methylthiophene

Product 2

HCID 144308112,3-Dibromo-4-methylthiopheneYield 3%HCID 148351682,4-Dibromo-3-methylthiopheneYield 73.4%

Reagents, catalysts & solvents 3

HCID 21218Trioctylmethylammonium chlorideCatalystHCID 3007855ZincchlorideCatalystHCID 6344DichloromethaneSolvent

Procedure

A catholyte of 300 ml of methanol, 100 ml of methylene chloride, 15 g of zinc chloride, 0.5 g of methyltrioctylammonium chloride and 31 g of 3-methyl-2,4,5-tribromothiophene were electrolysed in electrolysis cell 1 at a current density of 50 mA/cm2 at the start and 25 mA/cm2 at the end of the batch, a voltage of 4 or 3 V, a temperature of 34° to 24° C. and pH of -0.8. The current consumption was 14.8 Ah. After addition of 500 ml of water to the catholyte and working up as described in Example 1, 17.4 g of 2,4-dibromo-3-methylthiophene (yield: 73.4%), 0.71 g of 2,3-dibromo-4-methylthiophene (yield: 3%) and 2.92 g of 4-bromo-3-methylthiophene (yield: 17.8%) were obtained.

Workup

  1. customa temperature of 34° to 24° C. and pH of -0.8
  2. customThe current consumption
  3. additionAfter addition of 500 ml of water to the catholyte

Sources & evidence

ORD record
ord-7e19d5c448e445e9b8cd7894c89058c7
Source dataset
uspto-grants-1992_03
Patent number
US05100520

Reaction notes

Loading…