Polarisation and chemical reactivity in aromatic substances: The influence of the sulphonyl dipole on the course followed by substitution displacement and migration reactions with amines phenols and aminophenols.

The electronic interpretation of organic chemical reactions is based on a consideration of the properties of compounds containing the real poles associated with salt formation and ionisation. Modern views of valency have indicated that finite charges are present on the nitrogen atom of a nitro-compound and on the sulphur atom in a sulphone. Moreover the charge present on the sulphur atom should be twice that present on the nitrogen atom. A study has been made of the sulphonyl derivatives of some amines, phenols and aminophenols in order to obtain evidence for and determine the special properties associated with a positively charged sulphur atom. The work is presented in four main sections, the first dealing with the preparation, the second the scission and the third the substitution of sulphonainilides and phenylsulphonates. The fourth section deals with the migration of acyl radicals in o-aminophenols. It is found that amines may he divided into three groups according to the nature of their reaction with a molecular amount of p-toluenesulphonyl chloride. Most give a quantitative yield of the sulphonanilide but some fail to react at all whilst others give the disul- of chelate rings, emphasise a certain similarity between tbe nitro-group and halogen atoms in respect of inductive displacements and show that effects can be transmitted through the -SO2- group. Further light is thrown on the mechanism of conversion of nitrophenols into nitrochlorobenzenes under the action of p-toluenesul-phonyl chloride. The work with nitroaminophenols provides additional examples of the effects observed with phenols and amines alone, and discloses the existence of a new class of compound-the anhydro-p-toluenesulphonamidopyridinium hydroxides. The section on the scission of sulphonanilides and phenylsulphonates deals in particular with the use of piperidine. The exceptional behaviour of 2:4-dinitrophonyl-p-toluonesulphonate, which undergoes scission in two distinct ways, is discussed in some detail. Substitution experiments have boon made in the benzene, diphenyl and naphthalene series and the orienting effects of the -NHSO2, NMe. SO2, -N(SO2)2 and -O. SO2 groups determined. The experiments on diphenyl have involved the development of improved methods of preparation of the initial materials and the description of over one hundred of the common compounds such as bromo-4-hydroxy-diphenyls, nitro-4-methoxydiphenyls, and nitro-2 and 4-aminodiphonyIs. With naphthalene sufficient experiments have been made to show that the fusion of two Kekule rings does not lead to a full interpretation of substitution such as bromo-4-hydroxydiphenyls, nitro-4-methoxydiphenyls, and nitro-2 and 4-aminodiphenyls. With naphthalene sufficient experiments have been made to show that the fusion of two Kekule rings does not lead to a full interpretation of substitution results with this hydrocarbon. The o/p ratio of these substitutions is discussed. The experiments which Raiford has made on the migration of acyl radicals in o-aminophenols have thrown little light on the mechanism of these changes. introduction of the use of sulphonyl derivatives has revealed (1) the tendency towards benzoxazole formation in o-amino-phenols (2) the dependence of the migration on some property of the acyl group absent from the arylsulphonyl group. A theory of these changes is advanced which has led to the detection of acyl migrations in diacyl-o-aminophenols and the correction of several of Raiford's results. Little doubt can be entertained that the sulphur semipolar double bond is a stable entity although the magnitude of the charge present on the sulphur atom is smaller than might be anticipated. Electronic principles provide a uniform basis for the interpretation of the diverse types of reaction recorded in this thesis