Phenylbiphenyls

A limitation of both methods is that the second component must be liquid at the temperature of-the reaction, which is 5-10° for the diazohydroxide reaction and room temperature or slightly higher for the nitrosoacetylamine reaction. Experiments with solid reactants in solution have not been very successful, because of the difficulty of finding a suitable solvent. The solvent should be neutral and immiscible with water, have a high solvent action and reasonably low boiling point, and be inert to the free radicals which result from the diazo compound. The last qualification is the most difficult one to satisfy. Of the solvents which have been tried, carbon tetrachloride and chloroform appear to be the most suitable.18 From diazotized aniline and biphenyl in these solvents, some p-terphenyl is obtained, and from diazotized p-nitroaniline and biphenyl a small amount of 4-nitro-4 -phenylbiphenyl is formed. In these reactions an appreciable amount of tfie aryl halide (chlorobenzene and p-nitrochlorobenzene) is produced as a by-product. In general, the yields of products obtained by coupling with reactants in solution are extremely low. 

SYNS p-DIPHENYLBENZENE 1,4-DIPHENYL-BENZENE 4-PHENYLBIPHENYL 4-PHENYLDI-PHENYL SANTOWAX p-TRIPHENYL... 

Synonyms/Trade Names Hydrogenated diphenylbenzenes, Hydrogenated phenylbiphenyls, I Hydrogenated triphenyls [Note Complex mixture of terphenyl isomers that are partially hydrogenated.] ... 

Synonyms/Trade Names o-Diphenylbenzene 1,2-Diphenylbenzene 2-Phenylbiphenyl 1,2-Terphenyl ortho-Terphenyl o-Triphenyl ... 

Synonyms/Trade Names p-Diphenylbenzene 1,4-Diphenylbenzene 4-Phenylbiphenyl 1,4-Terphenyl para-Terphenyl p-Triphenyl ... 

In the following, examples of /I-carbon elimination when A = O are shown. The reaction is observed in the Pd-catalyzed reaction of fert-alcohols. Conversion of tert-alcohols to ketones occurs via their Pd-alkoxides 49 and the reaction can be understood by elimination of j6-carbon. Fission of a carbon-carbon bond occurs. It should be noted that jS-carbon elimination can be regarded as a reverse process of nucleophilic attack to the carbonyl group by R-Pd-X (see Chapter 3.7.2). As an example, Pd-catalyzed reaction of a,Q -dimethylarylmethanol 50 with bromobenzene is explained by elimination of jS-carbon of the arylpal-ladium alkoxide 51 to generate the diarylpalladium intermediate 52. Its reductive elimination affords 2-phenylbiphenyl (53) and acetone [41]. Similarly, Pd(II)-promoted reaction of the cyclobutanol 54 to give the unsaturated ketone 56 can be understood by elimination of j6-carbon from 55 and subsequent jS-H elimination [42],... 

J.-l. Jin and S.-M. Huh, Wholly aromatic polyesters derived from 6-hydroxy-5-phenyl-2-naphthoic acid and 4 -hydroxy-3 -phenylbiphenyl-4-carboxylic add, Macromol. Symp., 96, 125 (1995). 

Diazotization in tetrahydrofuran. Tetrahydrofuran is recommended as a solvent for diazotization where a) the amine forms salts (including the diazonium salts) of low solubility in dil. mineral acids, and which on account of low solubility in acetic acid cannot be used satisfactorily in the procedure of Hodgson and Mahadevan (s. Synth. Meth. A, 287) and b) where the subsequent reaction for which the diazonium salt soln. is to be used, is fast relative to the deamination. For slow reactions such as arylation of arenes via diazonium acetate, the presence of the ether can be of disadvantage, because of competition from it for the free radicals, in addition to the deamination Reaction.—E Aq. HCl added to a soln. of 2-amino-4 -phenylbiphenyl in tetrahydrofuran, treated with aq. NaNOg at 5-10°, stirred 20 min., treated with Kl-soln., heated and stirred for 2hrs. 2-iodo-4 -phenylbiphenyl. Y 88%. F. e. s. J. A. Cade and A. Pilbeam, Chem. Ind. 1959, 1578. 

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