Rhone-Poulenc Chimie

Alain Nonn

Jean-Roger Desmurs

Jean R Desmurs

A process for the bromination of biphenyl, particularly for the preparation of 4-bromobiphenyl or of 4,4'-dibromobiphenyl. The process comprises reacting biphenyl with BrCl. The BrCl may be formed in situ in the reaction medium or may be formed before reaction with biphenyl.

Process for bromination of biphenyl with BRCL

A process for the purification of dihydroxybiphenyls, preferably 4,4'-dihydroxybiphenyl, by acylation of the preparation medium of the dihydroxybiphenyl and selective precipitation of the biphenyl diester (diacetylbiphenyl), followed by conversion of the biphenyl diester to dihydroxybiphenyl.

Process for the purification of dihydroxybiphenyls

4,4'-Dibromobiphenyl is selectively produced in high yields by actively brominating biphenyl in a reaction medium containing at least one strong acid having a pKa of at most 4, e.g., a carboxylic or sulfonic acid, and, optionally, a reaction solvent.

Preparation of 4,4'-dibromobiphenyl

4-Bromobiphenyl is selectively produced in high yields, and in high conversions, by monobrominating biphenyl in a solvent reaction medium containing at least one organosulfur compound, amide, nitrile or acid having a pKa of at least 3.

Preparation of 4-bromobiphenyl

The preparation of 4,4'-dibromobiphenyl. A biphenyl is reacted with bromine in a solvent in the presence of a catalytic system based on at least one component selected from the group consisting of Lewis acids and iodine.

Process for the preparation of 4,4'-dibromobiphenyl in a solvent medium

A process for preparing hydroxybiphenyls. A bromobiphenyl is contacted with a base in aqueous liquid phase at a temperature less than or equal to 230.degree. C. in the presence of a copper-based catalyst. The hydroxyl ion concentration of base ranges from 0.1 to about 1.6 molar equivalents per liter. At temperatures less than 215.degree. C., a cocatalyst is preferably added.

Process for the preparation of hydroxybiphenyls

A process for the production of a hydroxybiphenyl by the hydrolysis of a bromobiphenyl, at a temperature below 300.degree. C., in the presence of both a copper-based catalyst and a separate cocatalyst selected from amongst halides, phosphates, nitrates, alcoholates, silicates, alcohols, carboxylic acids, sulfonic acids, organic sulfur-containing compounds, carbon monoxide, quinolines, tertiary amines, ammoniums, phosphines, phosphoniums, cyanides and palladium.

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Sainte Foy Les Lyon, France

Alain Nonn