The rates of chlorination, by molecular chlorine in acetic acid, of 4-acetamidodiphenyl, 1 : 4-diacetamidobenzene, and 2 : 6-dimethylacetanilide are compared with the corresponding rates of chlorination of 2-methylacetanilide, 4-methylacetanilide, N-methylacetanilide, m-xylene, and benzene. The phenyl and the acetamido-group only slightly deactivate for meta-chlorination. The proportion of 6-chloro-derivative formed in the chlorination of 2-methylacetanilide has been determined by isotopic dilution as 20.0%; that of the 4-chloro-derivative in the chlorination of 2 : 6-dimethylacetanilide is 2.6% ; and that of 3-chloro-derivative in the chlorination of 4-acetamidodiphenyl is 90%. These values, together with the rate-ratios, allow the effect of steric inhibition of tautomeric electron release from the acetamido-group in these compounds to be estimated.

Kinetic study of the indirect oxidation of methylene blue on Pt electrode in presence of several strong electrolytes is undertaken. Different operating conditions that affected the treatment process were studied in order to find the best conditions. The order with respect to methylene blue is zero order in presence of chloride, but it is second order in presence of bromide. The oxidation rate was affected by current density, halide concentration (KCl, KBr), nature of supporting electrolyte and initial pH. However, the initial dye concentration and temperature did not show a significant effect. The oxidation of methylene blue in presence of iodide, fluoride and sulfate is absent, but it is important in presence of chloride and bromide. The product of the indirect oxidation is the chloronated (bromonated) methylene violet bernthsen.

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The products of reaction of biphenyl with chlorine in acetic acid have been examined, particularly by vapour-phase chromatography and isotopic dilution analysis. The 40 : p ratio is 0-3; very little, if any, 3-chlorobiphenyl is produced; and accompanying the substitution is an addition which consumes ca. 14% of the chlorine.THE phenyl group is inductively electron-withdrawing, but can also, when appropriately oriented, withdraw or release electrons conjugatively (-I, &T). Its response to the electronic requirements of a reaction-centre depends on the nature of the reaction, and hence it is sometimes said to have several o-values, some of different sign.2 Conjugative effects of substituents can, in principle, be transmitted through one ring of a biphenyl system to the adjoining ring3 but the quantitative importance of this effect is variable 4s5 and has not been examined very systematically.Theoretical calculations ti which relate reactivities of biphenyl with those of polycyclic aromatic hydrocarbons involve assumptions concerning the magnitude of the energy barrier restricting rotation about the Ar-Ar bond in biphenyl. Current opinions' concerning this quantity include values in the range 0 4 kcal. mole-l, and a considerable effect on reaction velocity and on orientation is to be expected from steric inhibition of conjugation in 2-substituted biaryls.8The rate of molecular chlorination in acetic acid depends much on structural effects, and particularly on conj~gation.~ It seemed useful, therefore, to extend our studies to biphenyl and its derivatives. This paper reports the commencement of such an investigation, including a side-reaction of addition (previously not generally recognised for such compounds in this solvent) whose importance is assessed; the more general considerations will be discussed in other papers. EXPERIMENTALMaterials and Methods.-Some of the materials and methods have been described in previous papers in this series. 2-Chlorobiphenyl, m. p. 33.5" (Iit.,lo 34') was prepared from %aminobiphenyl by the Sandmeyer procedure. The following compounds were prepared from benzene and commercial specimens of the appropriate amines, by the Gomberg reaction: l1 4-chloro-