Hydrogen transfer correlation

The transformation of a cyclopentanol/cyclohexanone mixture allows us to estimate simultaneously the acidity and the basicity of catalysts. Two reactions take place the hydrogen transfer (HT) on basic sites and the alcohol dehydration (DEH) on acid sites. This reaction was carried out at two temperatures over four aluminas. Theta alumina seems to be the most basic of the aluminas tested. Correlation between model reaction and IR study were also discussed. 

Figure 4. Correlation between infrared data and model reaction, (a) Basicity Hydrogen transfer activity versus surface area of 1230 cm 1 band of adsorbed C02 species after RT evacuation, (b) Acidity Dehydration activity versus quantity of Bronsted acid sites able to retain DMP at 150°C.

The results report in Figure 4a show that there is no linear correlation between the basic activity and the carbon dioxide retained at RT. In the case of eta and gamma, some basic sites were detected by C02 adsorption but could not be active in hydrogen transfer at 250°C. 

Ab initio electron correlated calculations of the equilibrium geometries, dipole moments, and static dipole polarizabilities were reported for oxadiazoles <1996JPC8752>. The various measures of delocalization in the five-membered heteroaromatic compounds were obtained from MO calculations at the HF/6-31G level and the application of natural bond orbital analysis and natural resonance theory. The hydrogen transfer and aromatic energies of these compounds were also calculated. These were compared to the relative ranking of aromaticity reported by J. P. Bean from a principal component analysis of other measures of aromaticity <1998JOC2497>. 

Ionic dissociation of carbon-carbon a-bonds in hydrocarbons and the formation of authentic hydrocarbon salts, 30, 173 Ionization potentials, 4, 31 Ion-pairing effects in carbanion reactions, 15, 153 Ions, organic, charge density-NMR chemical shift correlations, 11, 125 Isomerization, permutational, of pentavalent phosphorus compounds, 9, 25 Isotope effects and quantum tunneling in enzyme-catalyzed hydrogen transfer. 

Figure 6.2. Empirical correlation between Rao, hydrogen transfer distance (curve 1), and the barrier height (curve 2) in the OH O fragment.

In contrast, because of similar electronegativities, the transition state for hydrogen transfer from benzene thiol to a perfluoro-n-alkyl radical should have little polar character. In confirming the important role of polar effects in these hydrogen transfer processes, a good Hammett correlation was observed for the reduction of n- c7f15i by a series of arene thiols [141,143]. 

H. Yamataka, S. Nagase, J. Org. Chem. 53, 3232 (1988). Ah Initio Calculations of Hydrogen Transfers. A Computational Test of Variations in the Transition-State Structure and the Coefficient of Rate-Equilibrium Correlation. 

Obara et al. (95) co-carbonized a petroleum pitch which gave a coke of mosaic size of optical texture with the strong Lewis acid catalyst, aluminium chloride,which promoted the size of the optical texture and extents of hydrogen transfer to added anthracene. A correlation was established between size of optical texture of the resultant cokes and extents of formation of 9,10-dihydroanthracene plus evolved hydrogen gas. 

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