4, 4 -Dihydroxybiphenyl

063 mole) of boron tribromide (Notes 1, 2) in 40 ml. of methylene chloride (Notes 3, 4) is added carefully to the stirred solution through the condenser. When the addition is complete, a calcium chloride tube is fitted to the top of the air condenser in order to protect the reaction mixture from moisture. As the solution of boron tribromide is added, a white precipitate is formed. The reaction mixture is allowed to attain room temperature overnight with stirring, when a clear, brownish yellow solution is obtained. The reaction mixture is then hydrolyzed 

Boron tribromide of 99.9% purity, from Koch-Light Laboratories Ltd., Colnbrook, Bucks, England, was used. 

Boron tribromide is a heavy, colorless liquid d = 2.6) when pure but begins to decompose on exposure to light, liberating free bromine. It fumes vigorously in air, being rapidly hydrolyzed to boric acid, with the evolution of considerable heat. 

Demethylation reactions proceed equally well using dry M-pentane or dry methylene chloride as the solvent for both the ether and the boron tribromide methylene chloride, having by far the more powerful solvent action, is to be preferred. 

When making up the solution of boron tribromide in methylene chloride, it has been found best to stand the vessel containing the solvent in an acetone-dry ice bath at —80° and to add the required amount (it is difficult to measure accurately) to the methylene chloride as rapidly as possible. 

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The above preparation of 3,3 -dihydroxybiphenyl is a good example of the utility of boron tribromide for the cleavage of... 

Dimethoxybiphenyl has been prepared by methylating 3,3 -dihydroxybiphenyl with methyl iodide 3 or dimethyl sulfate 4 and by deaminating tetrazotized o-dianisidine with alcohol.8,8,7 The present procedure is a slight modification of Mai s directions. 

SEE FORMULA NEXT COLUMN N 23.52% orn ndls, mp expl violently on heating was prepd by diazotization of 4,4 -diamino-3,3 dihydroxybiphenyl or its disulfate in acid soln with NaN02... 

Certain primary aromatic amines that are available as a consequence of their use in the manufacture of dyes serve as convenient starting points in the preparation of organic compounds. Their range of utility is increased by the deamination reaction. The syntheses of 2,2 -dinitro-5,5 -dicarboxybiphenyl from o-tolidine38 and of 3,3 -dihydroxybiphenyl from o-dianisidine 80 are examples. 

Monomers with phenyl substituents based on 4,4 -dihydroxybiphenyl, 4-hy-droxy-4 -carboxybiphenyl, and 2,6 functionalized naphthalene have been synthesized and incorporated in various LC copolyester systems. Bhowmik et al. used 3-phenyl-4,4 -dihydroxybiphenyl and 3,3 -dihydroxybiphenyl as comonomers to modify, for example, poly-(p-hydroxybenzoic acid) and poly-(6-hydroxy-2-naphthoic ac-... 

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