Polar Substituent Effects in the Solvolysis of Primary and Tertiary Alkyl Halides. Polar Effect IX

Article abstract of DOI:10.1002/hlca.19800630804

When the Hammett-Taft equation log (k/k₀) = ρ^q <*> ?^q_i is applied to the solvolysis of the 3-substituted propyl bromides 6a-6i in ethanol/water 4:1 (v/v) log k correlates linearly with ?^q_I except in cases where R exerts an anchimetric effect.The reaction constant ρ^q for 6 is -0.12 and is typical for a nucleophilic solvent assisted k_s process at a primary C-atom.The tertiary halides 1 and 3, however, which reacty with little or no nucleophilic solvent assistance, i.e. by k_c processes, lead to larger ρ^q values of -0.71 and -1.14, respectively.The reacton constant ρ^q is therefore a sensitive gauge for charge development in the transition state for solvolysis of satured compounds.