The steric effect of alkyl groups is characterized by the Steric Vertex Topological Index (SVTI). SVTI is equal to the sum of the distances not greater than three between the attachment site and the carbon atoms of the alkly group. The correlations presented, either with reaction rates of acid-catalyzed esterification of carboxylic acids or with various steric parameters, i.e. Es, E\u27s, v, and E, indicated that SVTI can serve as a useful steric parameter in reactivity studies
