Studies in diaryl chemistry

Abstract

An outline is given of the application of electronic theories of organic chemical reactions to the problems of aromatic substitution and previous work on substitution reactions in the diphenyl series is reviewed in the light of such theories. The preparation and nitration of 2-halogeno-4:4'-dimethyldiphenyls are described and the conclusion is drawn that nitration occurs mainly or entirely in position 2' in 2-fluoroditolyl, and in position 2' to the extent of about 60%, in 2-chloro, bromo and iododitolyls, a second mono-nitration product being formed in each case, which it is suggested may be a 6-nitro-2-halogenoditolyl, with possibly a small amount of a third substance which it is suggested may be a 3-nitro-2-halogenoditolyl. Supplementary Work. (I) Attempted asymmetric syntheses of 2:4-dinitro-2'-methyldiphenyl-6-carb-oxylic acid and 2:4:2':4'-tetranitrodiphenyl-6:6'-dicarboxylic acid are described. (II) An investigation of the reactions of 2:4:6-trinitrodiphenyl is described, only indefinite products being obtained. (III) The replacement of the chlorine atoms in 3:3'-dinitro-4:4*-dichloro-diphenyl sulphone is described, crystalline compounds being obtained by the action of (a) hydroxy compounds, (b) aromatic bases and (c) ammonia. Diamines obtained by reduction of these products are also described. (IV) An investigation of the decomposition of diazonium borofluorides in the presence of methyl alcohol is described, the results being similar to those obtained by previous workers using diazonium sulphates. (V) Improved methods are described for the preparation of 2-nitro-2-amino-diphenyl, 2-nitro-2'-aminoditolyl, 3:4-dichlorodiphenyl and 2:5-dichlorodiphenyl. (VI) The preparation of an arsenic acid from 2-aminoditolyl, its conversion into a tricyclic compound and the preparation of a chloroarsine from this are described.