CAGE analysis

The analysis of recent measurements of the density dependence of has shown, however, that considering only the variation of solvent structure in the vicinity of the atom pair as a fiinction of density is entirely sufficient to understand tire observed changes in with pressure and also with size of the solvent molecules [38]. Assuming that iodine atoms colliding with a solvent molecule of the first solvation shell under an angle a less than (the value of is solvent dependent and has to be found by simulations) are reflected back onto each other in the solvent cage, is given by... 

Analysis This cage-like structure contains 6, 5 and 4-membered rings we are most interested in the 4, and can disconnect this in two ways ... 

As we have seen in Section I.B x-ray analysis of both hydroqui-none clathrates and hydrates has revealed that all cavities are approximately spherical and that their walls consist of a relatively large number of atoms. It is therefore plausible to suppose that the field of force acting on a solute molecule in its cage has a spherical symmetry, and, in addition to the aforementioned assumptions (a)-(d), to make the two further assumptions ... 

Three types of model study have been performed. The first approach has been to decompose a mixture of two initiators (/.< . one to generate radical A, the other to generate radical B). With this method experimental difficulties arise because the two types of radical may not be generated at the same rate and because homotermination products from cage recombination complicate analysis. 

A second approach has been to use an unsymmetrical initiator which allows the two radicals of interest to be generated simultaneously in equimolar amounts.175 In this case, analysis of the cage recombination products provides information on cross termination uncomplicated by homotermination. Analysis of products of the encounter reaction can also give information on the relative importance of cross and homotermination. However, copolymerization of unsaturated products can cause severe analytical problems. 

This brief analysis explains why it is very important to know whether the Hubbard relation is reproduced in the liquid cage model. The existence of the Hubbard limit means that orientational relaxation is insensitive to the precise details of the interaction. Below, it is shown that this is the case. 

The second of these steps, the rate of hydrolysis at 12 °C, measured by analysis of the ADP content in fibers rapidly frozen at different times after ATP release from caged-ATP, is 40-60 s (Ferenczi, 1986) which is similar to the rate of active force increase at 20°C once the difference in temperature has been accounted for. This rate is similar to that measured in solution however, and is not rate limiting in solution. Therefore, force generation in the caged-ATP experiments could be limited by hydrolysis, or more likely, by a step following hydrolysis such as Pj release. The idea that release of phosphate is linked to force production in muscle... 

A subsequent detailed analysis of the permanganate oxidation of the tertiary hydrogen atom of 4-phenylvaleric acid in 2.5 M potassium hydroxide solution supports the caged radical mechanism. The reaction order is two overall, A h/ d is ca. 11.5, ring substitution has little elfect on the rate (p 0) and the oxidation proceeds with a net 30-40 % retention of optical configuration. 

Further evidence consistent with the polar radical pair mechanism was provided by a crossover experiment (Scheme 6.26). A 1 1 mixture of labeled 8Z /8 and unlabeled 8Z/8E was heated in xylene at 125 °C for 2h and at 135 °C for 4h to afford hydroxypyrimidinones 3 and 3. Analysis of the products by high resolution mass spectrometry showed no crossover between the labeled and unlabeled fragments. This result reinforces the computational results discussed previously wherein PRP recombines to give product within the solvent cage (Scheme 6.24). 

These spacings correspond to cationized fragments with the general composition [SixOyHz]+. The results of the peak analysis prove that the uppermost monolayer of the surface film consists of totally hydrolyzed polymeric siloxanes. There is evidence that these fragments appear as ring- and cage-like silsesquioxane cations (Fig. 2) ... 

The NaCl -SOD formed during these reactions can be clearly identified by its IR spectrum, perchlorate sodalite collapse at 1050°C. From the thermo gravimetric analysis it is evident that at this temperature the entire amount of NaCl escapes. The degree of the cage filling by salt molecules can be calculated on the basis of both the oxygen and the NaCl loss. 

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