Positive poles, nitration

The combined inductive and field effects of these poles do not produce strong discrimination between the m- and /i-positions in nitration m p for. NMe3+, and smaller for the protonated poles). This situation is in marked contrast to that produced by, say, the nitro group ( 9.1.3), and suggests that the —M effect is more discriminating between m- and -positions than is the — I effect. 

Hammett s equation, and substituent effects, 137-43 heteromolecules, 130 Holleman s product rule, 3 hyperconjugation, in nitration of alkyl-benzenes, 165-7 in nitration of positive poles, 169... 

Nitration by nitric acid in sulphuric acid has also been by Modro and Ridd52 in a kinetic study of the mechanism by which the substituent effects of positive poles are transmitted in electrophilic substitution. The rate coefficients for nitration of the compounds Pl CHi NMej (n = 0-3) given in Table 10 show that insertion of methylene groups causes a substantial decrease in deactivation by the NMej group as expected. Since analysis of this effect is complicated by the superimposed activation by the introduced alkyl group, the reactivities of the... 

Argentic peroxide is obtained by electrolysing a solution of argentic nitrate, when it is deposited upon the positive pole. 

Page ioi. A solution of acetate of lead submitted to the action of the voltaic current, yields lead at the negative pole, and brown peroxide of lead at the positive pole. A solution of nitrate of silver, under the same circumstances, yields silver at the negative pole, and peroxide of silver at the positive pole. 

Again consider the silver nitrate concentration cell in which q > q The positive pole of the cell is the electrode in contact with the solution q That is, current tends to flow inside the cell in the direction indicated, since the purpose of the flow of current is to equalise the concentrations cx and q, and this is evidently effected by silver dissolving off at the left-hand electrode and depositing on the nght Suppose the single P D s as indicated are eh es, and e3, the total e m f being E—... 

Before leaving this subject, some other theories of the decomposition of salt solutions by an electric current may be mentioned. Riffault and Chompre supposed that two simultaneous currents caused decompositions throughout their whole course, producing separation of the elements there and not only at the poles. The negative current carried acids etc. to the positive pole, and the positive current carried bases to the negative pole. The currents were supposed to be more powerful nearer their respective poles, and the positive current superior in power to the negative current, nitrate of soda being decomposed by the former but not by the latter. 

If this electrostatic treatment of the substituent effect of poles is sound, the effect of a pole upon the Gibbs function of activation at a particular position should be inversely proportional to the effective dielectric constant, and the longer the methylene chain the more closely should the effective dielectric constant approach the dielectric constant of the medium. Surprisingly, competitive nitrations of phenpropyl trimethyl ammonium perchlorate and benzene in acetic anhydride and tri-fluoroacetic acid showed the relative rate not to decrease markedly with the dielectric constant of the solvent. It was suggested that the expected decrease in reactivity of the cation was obscured by the faster nitration of ion pairs. 

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