ABSTRACT
This chapter discusses many biphenyl syntheses yield hydroxy- (or alkoxy-) biphenyl derivatives; most of these may be adaptable for the preparation of chlorobiphenylols. It describes the methods for the synthesis of substituted biphenyls which have not been used for the preparation of chlorobiphenyls. Oxidation of aromatic compounds with lead tetraacetate in trifluoroacetic acid gives a number of derivatives including biphenyls, phenols, and aryl-lead compounds. Irradiation of aromatic bromo compounds in benzene gives somewhat lower yields and these starting materials are apparently not useful for the synthesis of amino-and nitrobiphenyls. Biphenyl and methyl biphenyls were prepared by photolysis of N-phenylsulfonyldimethyl sulfoximines in benzene. Reagents which have been used for the oxidative coupling to form biphenyl derivatives include isoamyl nitrite, thallium(III)trifIuoro-acetate and silver carbonate. A large number of biphenyls were prepared by the acid catalyzed reaction of acylquinones with phenols and related compounds. Chloronitrobiphenyls are easily accessible by nitration but are also prepared by Ullmann coupling of halonitrobenzenes.
