Reactivity factors influencing

Another consideration of the electronic factors influencing reactivity arises with a DSP treatment of the kinetic data p values are given in... 

Copolymerization of styrene with diolefins provides further support that monomer coordinates with the cationic site prior to addition. Korotkov (218) showed that in homopolymerizations styrene is more reactive than butadiene, but in copolymerization the butadiene reacted first at its homopolymerization rate and when it was exhausted the styrene reacted at its homopolymerization rate. This interesting result has been duplicated by Kuntz (245) and analogous results have been obtained by Spirin and coworkers (237) for the styrene-isoprene system. Presumably, the diene complexes more strongly than styrene with the lithium and excludes styrene from the site. That the complex occurs at a cationic site, rather than at the anion or the metal-carbon bond, is indicated by the fact that dienes form more stable complexes than styrene with Lewis acids (246). It should be emphasized that selective monomer coordination is not the only factor influencing reactivities in copolymerizations. Of greatest importance are the relative reactivities of the different polymer anions. The more resonance-stabilized anion is more readily formed and is less reactive for polymerizing the co-monomer. 

It seems fair to say that at the time of writing the factors influencing reactivity of cyclic ethers and sulphides are still not completely known. We can look for greater insight as more detailed and carefully controlled kinetic studies are made. 

Gas-phase cluster experiments provide a means of studying analogs of potential cataly tically active sites in the absence of factors that often complicate condensed-phase catalysis, thereby deriving knowledge of the basic factors influencing reactivity [2]. 

Most pericyclic reactions, though of course not all, are little influenced by Coulombic forces for example, it is well known that the polarity of the solvent has little effect on the rate of Diels-Alder reactions. We can therefore expect that a major factor influencing reactivity will be the size of the frontier orbital interaction represented by the third term of equation 2-7, p. 27. This is why this chapter is much the largest in this book the most dramatic successes of frontier orbital theory have been the explanations it has given to an amazingly large number of observations in pericyclic chemistry. 

The examples discussed here, illustrate, we hope, some of the diverse factors influencing reactivity of fluorinated—alkenes and -dienes. 

Lehr and McClellan [17] studied a suite of sedimentary phosphate rocks and an igneous phosphate rock concentrate and concluded that carbonate substitution in apatite was the dominant factor influencing reactivity measurements. This study also concluded that reactivity... 

Almarsson O, Bruice TC (1993) Evaluation of the factors influencing reactivity and stereospecificity in NADPH dependent dehydrogenase enzymes. J Am Chem Soc 115 (6) 2125-2138... 

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