Evaluation of an Appropriate Parameter for Steric Effect

Department of Chemistry, Sambalpur University, Buria-768 017

Manuscript received 8 January 1979, accepted 9 January 1980

The observed pKa values of eight sets of substituted organic acids have been fitted to the equation, pKa =\(P_i^o\) + α if _j F_k +β_ir_jRk+ δf(steric), where f _j F_k, r_j R_k and f (steric) refer to field. resonance and steric factors respectively. The values of \(P_i^o\) , α_i, β_i and δ are obtained by multiple regression analysis method. From the values of multiple correlation co-efficient and t-test, it has been concluded that steric density (SD) is also an appropriate parameter for steric effect.