Radicle structure

The formation from neutral substances (triphenylcarbinol) of coloured, salt-like reaction products which are more or less easily decomposed by water is a phenomenon called halochromism . The halo-chromic salts of triphenylcarbinol are regarded as carbonium salts this follows at once from the above discussion. A quinonoid formula, by which various authors explain the colour, seems less probable. Recently the attempt has been made to attribute complex formulae to the carbonium salts (Hantzsch), in accordance with Werner s scheme for ammonium salts. Such formulae express the fact that, in the ion, the charge is not localised at the methane carbon atom, but spread over the field of force of the whole radicle. The simplest carbonium salt of the group, the yellow perchlorate (K. A. Hofmann), would accordingly have the following structural formula ... 

All compounds, therefore, with complex radicle [Co enslt3", in which the two groups II arc in the cis-position, can be resolved into optically active forms. Further, by replacing the two groups in the m-position by a divalent acidic radicle such as carbonato-radicle, a compound is produced which docs not exist in cis- and fraj/.s-forms hut which may he resolved into optical isomers. Thus, carbonato-diethylcnediamino-eobaltie salts arc known in two optically active forms 1 represented by the structural formula ... 

The analyses of H. Davy, and J. L. Gay Lussac and L. J. Thenard show that nitric oxide has the empirical composition NO. This formula agrees with the physical properties of the gas. Oxygen is bivalent, hence the nitrogen in nitric oxide also behaves as a bivalent element 0=N but nitrogen is usually ter-or quinque-valent, so that nitric oxide is usually considered to be an unsaturated compound. No evidence of the existence of 0=N—N=0 has been observed. C. Weltzien considers that the radicle NO is sometimes univalent, and sometimes bivalent. J. C. Thomlinson s calculations of the thermochemical eq. of nitrogen in nitric oxide favoured the assumption that the oxygen is quinquevalent. E. Muller discussed this subject and E. C. Stoner, and C. D. Niven, the electronic structure. 

It is not easy to account for this isomerism according to the ordinary methods of representation of the structure of the platinocyanides. Since samples of anhydrous barium platinocyanide, derived from the isomeric tetrahydrates respectively, are equally fluorescent, it seems fairly certain that any scheme must take into consideration the combined water. Levy therefore suggests that the isomerism of the tetra-hydrate may be accounted for by assuming that two molecules of water are attached to the barium and two to the platinocyanide radicles, since, in the case of the latter radicles, two alternative positions are possible, namely ... 

In an analogous manne three isomerides are, theoretically, possible for potassium ferricyamdc, K3Fe(CN)6, in vhich the central iron atom is trivalent. All of these cyclic schemes are m harmony with the isocyamc structure of ferrous cyanide, They also serve to explain why the potassium ions are ionisable, whereas the iron atom, bound within the centre of the shell, constitutes part of the negative radicle. 

The problem has always attracted intensive study and experiment, but owing to the short period during which this has been prosecuted, as well as the secrecy which has surrounded the results, it is not yet possible to state the general laws with any certainty. However, it will be of interest to give an account of the observations and hypotheses published on the influence of the structure of these substances, and in particular of the introduction of certain atoms or radicles, on the nature of the action exerted. 

The organic compounds having aggressive action usually contain atoms of halogen, sulphur or arsenic or radicles such as —NOg, —CN, etc., in their molecules. It is to these atoms or radicles as well as to the molecular structure that the physio-pathological action is nowadays attributed. 

According to various observations, the aggressive action of a substance depends not only on the presence of particular atoms or radicles in the molecule, but also on the molecular structure, and in particular on... 

At this period much interest was taken in the artificial formation of natural organic substances but at the time I was at the Bo3ral College of Chemistry, although the theory of compound radicles, the doctrine of substitution, Ac. were occupying much attention, very little was known of the internal structure of compounds and the conceptions as to the method by which one compound might be formed from another was necessarily very crude. 

Injection method Most interventionists use this method in which full-strength contrast is slowly injected during slow withdrawal of the needle. As the needle is pulled back, contrast opacifies any structure through which it passes such as radicles of the hepatic veins, the hepatic artery, lymphatics,... 

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