Migration ability relative

A similar pattern had been observed earlier with p-phenyl-substituted carbocations. Relative migration ability of phenyl and substituted phenyl groups were determined for the first time, not by focusing on carbocations formed via aliphatic series as structural models, but rather by studying 9-ary 1-9,10-dimethylphenanthrenium ions (18, 19). 

Boris Borisovich Polynov (1877-1952) believed that most mobile element is chlorine and proposed to evaluate the relative migration ability of elements relative to chlorine according to equation... 

In 9-X-9,10-dimethylphenanthrenium and l-X-l,2-3-4-5-6-hexamethylbenzenium ions the order of relative migrating ability of para- and meta-substituted phenyl groups has been conserved. The rate coefficients of degenerate rearrangements due to 1,2-shifts of Y-substituted phenyl groups in phenanthrenium ions are well described jjy equation log (ky/ka) = QCf, where q(—50 °C) = —4.5. 

The relative migration ability of CH3, C2H5 and CgHj groups is 1 36 10 (a detailed analysis of rearrangement kinetics and the temperature dependence of rate coefficients see... 

The R groups in ions (US) have the following relative migrating ability... 

In a free radical, there is a third electron in the system. It cannot occupy the same orbital as the other two electrons. It is instead associated with an antibonding level, and therefore leads to a less favorable transition state for migration. The relatively more facile migration of unsaturated groups is associated with the ability of such groups to form bridged intermediates by an addition process. The unpaired electron can then be located in a more stable orbital ... 

Transport numbers are intended to measure the fraction of the total ionic current carried by an ion in an electrolyte as it migrates under the influence of an applied electric field. In essence, transport numbers are an indication of the relative ability of an ion to carry charge. The classical way to measure transport numbers is to pass a current between two electrodes contained in separate compartments of a two-compartment cell These two compartments are separated by a barrier that only allows the passage of ions. After a known amount of charge has passed, the composition and/or mass of the electrolytes in the two compartments are analyzed. Erom these data the fraction of the charge transported by the cation and the anion can be calculated. Transport numbers obtained by this method are measured with respect to an external reference point (i.e., the separator), and, therefore, are often referred to as external transport numbers. Two variations of the above method, the Moving Boundary method [66] and the Eiittorff method [66-69], have been used to measure cation (tR+) and anion (tx ) transport numbers in ionic liquids, and these data are listed in Table 3.6-7. 

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