Process for preparing 2-bromo-4,4'-dialkylbiphenyl

Abstract

Process for preparing 2-bromo-4,4′-dialkylbiphenyl, wherein 4,4′-dialkylbiphenyl is, in the presence of catalytic amounts of iodine and, if appropriate, in a halogenated hydrocarbon as solvent, reacted with bromine.

Description

EXAMPLE 1

1 g of 4,4′-di-tert-butylbiphenyl were dissolved in 10 g of dichloromethane, and 30 mg of iodine were added. The mixture was then cooled to 5° C. Over a period of 1 h, 650 mg of bromine were added. The mixture was then stirred at room temperature for 1 h. For work-up, 3 ml of a 10% strength solution of NaHSO₃ were added, the phases were separated and the organic phase was washed until neutral, dried and concentrated using a rotary evaporator. This gave 1.28 g of 2-bromo-4,4′-di-tert-butylbiphenyl (98.6% of theory).

Claims

1. Process for preparing 2-bromo-4,4′-dialkylbiphenyl, wherein 4,4′-dialkylbiphenyl is, in the presence of catalytic amounts of iodine and, if appropriate, in a halogenated hydrocarbon as solvent, reacted with bromine.

2. Process according to claim 1, wherein the 2-bromo-4,4′-dialkylbiphenyl is 2-bromo-4,4′-di-tert-butylbiphenyl.

3. Process according to claim 1 or 2, wherein the iodine is employed in an amount of from 0.1-10 mol %, based on the 4,4′-dialkylbiphenyl.

4. Process according to any of the preceding claims, wherein the halogenated hydrocarbon is methylene chloride.

5. Process according to any of the preceding claims, wherein the reaction is carried out at a temperature in the range of 0-40° C.

6. Process according to any of the preceding claims, wherein the reaction time is between one and 10 h.