Linear free energy relationship heterocycles

So-called aryl values have been introduced by Imoto et ai. - for the piu pose of systematizing the reactivities of different aromatic systems by means of the linear free-energy relationship, which however, could not be applied to the decomposition rates of heterocyclic acyl azides in toluene. ... 

Applications of Linear Free Energy Relationships to Polycyclic Arenes and to Heterocyclic Compounds , M. Charton, in Recent Advances in Correlation Analysis in Chemistry , ed. N. B. Chapman and J. Shorter, Plenum, New York, 1978, pp. 175-268. Applications of the Hammett Equation to Heterocyclic Compounds P. Tomasik and C. D. 

The reason for writing this article is that important progress in the quantitative analysis of steric effects in heteroaromatics has been made recently by linear free energy relationships (LFER), geometrical, and theoretical methods. Also, heterocycles have been used to propose and exemplify new concepts and new parameters in physical organic chemistry. 

Evaluation of steric effects can also be made by separating electronic from steric effects with the help of linear free energy relationship and appropriate parameters. Applications of the Hammett equation to heterocycles have been reviewed (64AHC(3)209 76AHC(20)1) and the influence of substituent effects on the basicity and N-alkylation of pyridines, which have been by far the most widely studied, shows the difficulties in this approach. Jaffe and Jones (64AHC(3)209) reported a good correlation between pKA of 3- and 4-substituted pyridines and Hammett a parameters ([Pg.179]

Molecular connectivity is a simple and useful method for quantitating the structure of heterocycles. Molecular connectivity for 56 A -bridged compounds was calculated and correlated with the octanol-water partition coefficient. Steric effects caused deviations from the LEER (Linear Free Energy Relationship) <83MI 9l8-0l>,... 

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