Primary production distribution

It has also been shown that the selectivity features of para-selective catalysts can be readily understood from an interplay of catalytic reaction with mass transfer. This interaction is described by classical diffusion-reaction equations. Two catalyst properties, diffusion time and intrinsic activity, are sufficient to characterize the shape selectivity of a catalyst, both its primary product distribution and products at higher degrees of conversion. In the correlative model, the diffusion time used is that for o-xylene adsorption at... 

It is interesting to note that the cis-trans ratios obtained by Ghorbel and coworkers (312) on 1-butene isomerization were mostly unaffected by the chemisorption of the different poisons and corresponded to the thermodynamically determined ratio. The same result was obtained by Knozinger and Aounallah (377), when 1-butene was isomerized in a recirculating reactor at 120°C on tj-A1203 (activated at 500°C) that was partially poisoned by pyridine. In micro-catalytic pulse experiments, on the other hand, one observes kinetically determined primary product distributions with cis-trans ratios of about 2 (370). Different types of active sites appear, therefore, to be involved in the doublebond shift and in the cis-trans isomerization, the latter remaining unaffected by pyridine chemisorption. 

The alternative modes of addition under equations (11) and (12) can be easily distinguished on the basis of the primary product distribution. However, bridged species other than open ions are frequently involved as intermediates and ring opening may occur by direct nucleophilic displacement processes (Poutsma and Ibarbia, 1971). 

Smith, D.F., C.D. Mciver, and T.E. Kleindienst Primary product distribution from the reaction of hydroxyl radicals with toluene at ppb NOX mixing ratios. Journal of Atmospheric Chemistry, 30 (1998) 209-228. 

Temperature Effect on Primary Product Distribution from -Decomposition Reaction of... 

Temperature Effect on the Primary Product Distribution from H-Abstraction Reactions of... 

The detailed analysis of the primary product distribution from 1-methyl-4-propyl-cyclohexane (10 C-atoms) is useful for a better understanding of the relative importance of intermediate species. It can also provide useful information regarding the choice of intermediate lumped components. 

The automatic generation of the primary product distributions is based on the assumption that the propagation reactions of radicals are described with an autonomous system, i.e. H-abstraction, radical addition and termination... 

Diffusion constants in sediments. Table 8-4. . 163 Water volume in various reservoirs. Table 9-3. 178 Primary productivity, distribution in oceans. 

In a second part of the work, a Structure-Activity Relationship has been developed for the addition of OH to (poly)alkenes. It was shown that the total rate constants can be expressed in very good approximation by a sum of partial, site-specific rate constants for addition to a given (double-bonded) carbon atom, the values of these partial rate constants depending solely on the stability-type of the ensuing p-hydroxy radical. The SAR is particularly useful in that it also allows the prediction of the detailed primary product distributions of (poly)alkene + OH reactions. Therefore, the SAR is a powerful tool in the modeling of the tropospheric OH-initiated oxidation of biogenic VOC. 

Finally, it was also aimed to obtain quantitative information on the primary-product distributions of reactions of OH with alkenes and polyalkenes. 

The major value of the new Structure-Activity Relationship presented and developed by us [19] for (poly)alkene + OH reactions resides in its inherent predictive potential regarding the detailed primary-product distributions of such reactions. This is especially useful for quantitative assessments of the various possible OH-initiated degradation pathways of biogenic VOC, of which there is such a diversity and multitude that one can realistically hope to perform detailed experimental studies on only a few of them. 

Another related study encompassed the examination of the reactions of Sc" ", Y" ", and Ln ions with phenol (Carretas et al., 1998). All the ions except Yb" " were observed to react, activating O—H, C—O, and/or C—H bonds, with the formation of RO, ROH, and/or ROC6H4 ions as primary products the reaction sequences were also investigated and displayed results in concurrence with those obtained for aliphatic alcohols. The primary product distributions and reaction efficiencies revealed the existence of important differences in the relative reactivities of the rare earth metal cations, which apparently depend on the electron configurations of the metal ions (as illustrated in Fig. 13), their oxophilicity, and the second ionization energies of the metals. 

ViUanueva, F., I. Barnes, E. Monedero, S. Salgado, M.V. Gomez, and P. Martin (2007), Primary product distribution from the Cl-atom initiated atmospheric degradation of furan Enviromnental implications, Atmos. Environ., 41, 8796-8810. 

---