Molecular connectivity and steric parameters.

The possible relationship between molecular connectivity indexes, mchi, and Es, a thermodynamically derived parameter used to estimate steric effects in organic reactions and sometimes used in biological structure-activity relationships, was investigated. The extended chi terms, 2chi, 3chi, and 4chi, were correlated significantly to Es (r = 0.961). Aralkyl esters deviated from the correlations, possibly due to intramolecular interactions.