Solvent polarity and hydrogen bond effects on nucleophilic substitution reaction of 2‐bromo‐5‐nitrothiophene with piperidine

The reaction kinetics of 2‐bromo‐5‐nitro thiophene with piperidine was studied in a solvent with a mixture of propan‐2‐ol with methanol and n ‐hexane at 25°C. The measured rate coefficients of the reaction demonstrated dramatic variations in propan‐2‐ol– n ‐hexane mixtures and mild variations in propan‐2‐ol–methanol system. The second‐order rate coefficients of the reaction, k A , decreased sharply with n ‐hexane content. The multiparameter correlation of log k A versus molecular‐microscopic solvent parameters shows interesting results in these solutions. Linear free energy relationship investigations confirm that polarity has a major effect on the reaction rate and hydrogen bond ability of the media has a slight effect on the reaction rate. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 185–190, 2011