Rate-Product Correlations for the Solvolysis of 5-Nitro-2-Furoyl Chloride

Abstract

The solvolysis rate constants of 5-nitro-2-furoyl chloride (5-NO2(C4H2O)-2-COCl, 1) in 27 different solvents are well correlated with the extended Grunwald-Winstein equation, using the NT solvent nucleophilicity scale and YCl solvent ionizing scale, with sensitivity values of 1.20 ± 0.05 and 0.37 ± 0.02 for l and m, respectively. The activation enthalpies (ΔH≠) were 5.63 to 13.0 kcal·mol−1 and the activation entropies (ΔS≠) were −25.9 to −43.4 cal·mol−1·K−1, which is consistent with the proposed bimolecular reaction mechanism. The solvent kinetic isotope effect (SKIE, kMeOH/kMeOD) of 2.65 was also in accord with the SN2 mechanism and was possibly assisted using a general-base catalysis. The product selectivity (S) for solvolysis of 1 in alcohol/water mixtures was 1.2 to 11, which is also consistent with the proposed bimolecular reaction mechanism. Key Words: 5-Nitro-2-furoyl chloride, Extended grunwald-winstein equation, SN2 mechanism, Solvent kinet-ic isotope effect, Product selectivit