Redistribution, viii

However, the spatial inhomogeneity in the distribution of reagents is not the only reason why the radiolysis of substances in the condensed state is different from that of gases. As we have already mentioned in Section VIII, as we pass from the gaseous state to the condensed one, at the primary stage of radiolysis we already observe a redistribution of yields of primary active particles (resulting in the increase of the yield of ionized states). Also different are the subsequent relaxation processes, as well as the processes of decay of excited and ionized states.354 Another specific feature of processes in a condensed medium is the cage effect, which slows down the decay of a molecule into radicals.355 Finally, the formation of solvated electrons is also a characteristic feature of radiation-chemical processes in liquids.356... 

This sequence explains Price s observations adequately and seems to be required in this particular case. The oxidative elimination of halide ion from salts of phenols does not always follow this course, however. In the peroxide-initiated condensation of the sodium salt of 2,6-dichloro-4-bromophenol (Reaction 23) molecular weight continues to increase with reaction time after the maximum polymer yield is obtained (Figure 5) (8). Furthermore, Hamilton and Blanchard (15) have shown that the dimer of 2,6-dimethyl-4-bromophenol (VIII, n = 2) is polymerized rapidly by the same initiators which are effective with the monomer. Obviously, polymer growth does not occur solely by addition of monomer units in either Reaction 22 or 23 some process leading to polymer—polymer coupling must also be possible. Hamilton and Blanchard explained the formation of polymer from dimer by redistribution between polymeric radicals to form monomer radicals, which then coupled with polymer, as in Reaction 11. Redistribution has indeed been shown to occur under... 

It is apparent from the examples in this section that the lability of the groups on silicon is greatly dependent on the catalyst. With conventional acid or base catalysts, SiO— is classed as a labile ligand, SiH as semi-labile, and Si—R (R = alkyl or aryl) as nonlabile (/). However, with low-valent complexes of the group VIII metals, SiH is the most labile ligand, and SiO— and Si—R appear to have comparable reactivities. Hence, these two sets of catalysts types are complementary in their capacity to redistribute ligands on silicon. 

In a similar calculation, Bednarek and Rossler also had to use an xinusual potential in order to get good agreement between experiment and theory for the LA and TA phonon assisted absorption. In their case, the form factor was cut off at q = 5 and approached zero for small values of q. They felt that their potential simulated nonlocal and charge redistribution effects. The results of their calculations are also listed in Tables VII and VIII. 

VIII. Redistribution Reactions of Metal Alkyls and Metal Halides. . . 107... 

The available heats of redistribution, all of which are exothermic (some substantially so), are presented in Table VIII. 

Polymer II (a sample with [n] 0.35 dl/g) was used as a phenol for copolymerization with 2,6-dimethylphenol. The physical properties of the product (intrinsic viscosities as high as 0.68 dl/g no fractionation of VIII during methylene chloride complex-ation l no long range nmr effects) suggested a block copolymer structure for the product. Since it is likely that polymer II did not redistribute under the mild conditions of polymerization (Table I shows little equilibration with monomer even at 80 ), polymer II was functioning as a monofunctional consonant which did not readily co-equilibrate with the oth r oligomers. Polymer II can be viewed as a chain stopper for reaction (4) and the product can be represented by structure XIII. Colorless, hazy... 

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