Alcohols, acidity correlation energy

A complementary paper was reported soon after by Adam, Bach and coworkers where eight transition structures for the epoxidation of the chiral allylic alcohol (Z)-3-methyl-3-penten-2-ol with peroxyformic acid were computed by the B3LYP density functional method with 6-31G(d) and 6-31G(d,p) basis sets. The four lowest-energy transition structures and their respective prereaction clusters were fuUy re-optimized by employing 6-31H-G(d,p) and correlation-consistent polarized valence triple- cc-pZTV basis sets. 

More recent measurements related to carbocation stabilities in strongly acidic media have involved rates of reaction rather than equilibria.52,54,72 75 Application of the X0 function to the correlation of reaction rates as well as equilibria mirrors the use of structure-based free energy relationships. Of interest is the access this gives to rate constants for (a) protonation of weakly basic alkenes and (b) acid-catalyzed ionization of alcohols to relatively unstable... 

The acid-base properties of zeolites or oxides are often studied by measuring the selectivities to the different products in the decomposition of alcohols and particularly isopropanol. The rate of propene formation can very often be correlated to the number of acidic sites determined by ammonia adsorption. A relationship has been found between the strength of the acid sites of bulk oxides, as determined by ammonia adsorption microcalorimetry [95], and the activation energy of dehydration, while the activation energy of dehydrogenation was independent of the strength of the sites [149]. 

Linear free-energy relationships in the chromic acid oxidation of alicylic alcohols have been subjected to a detailed scrutiny using pairs of epimers, including a variety of alkylcyclohexanols and some pentanols. The correlation proposed by Sicher (1962) required modification thus = O.S RT ln kjkj), where and... 

Radical-solvent complexes are more difficult to detect spectroscopically however, they do provide a plausible explanation for many of the solvent effects observed in free-radical homopolymerization—particularly those involving unstable radical intermediates (such as vinyl acetate) where complexation can lead to stabilization. For instance, Kamachi (50) observed that the homopropagation rate of vinyl acetate in a variety of aromatic solvents was correlated with the calculated delocalization stabilization energy for complexes between the radical and solvent. If such solvent effects are detected in the homopolymerization of one or both of the comonomers, then they are likely to be present in the copolymerization systems as well. Indeed, radical-complex models have been invoked to explain solvent effects in the copolymerization of vinyl acetate with acrylic acid (51). Radical-solvent complexes are probably not restricted merely to systems with highly unstable propagating radicals. In fact, radical-solvent complexes have even been proposed to explain the effects of some solvents (such as benzyl alcohol, A7 / 7 -dimethyl for-mamide, and acetonitrile) on the homo- and/or copolymerizations of styrene and methyl methacrylate (52-54). Certainly, radical-solvent complexes should be considered in systems where there is a demonstrable solvent effect in the copolymerizations and/or in the respective homopolymerizations. 

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