β-nitrostyrene as a novel spectroscopic probe for measuring nucleophilicity.

A new probe for measuring nucleophilicity was introduced. The kinetics of various species with β-nitrostyrene (NS) as an electrophile was studied in methanol at room temperature. All measurements were performed by scanning the UV absorptions of NS as a probe scale. The novelty of probe, and method solve the difficulties in measuring the nucleophilicity and show interesting findings for primary, secondary amines, thiols, and salts. The results are helpful to find the reaction rates, mechanisms, and pathways based on the nature of the nucleophiles. The solvents parameters, including hydrogen bond donor/acceptor, polarizability and dipole moments of the solvents were considered in the analysis of the measurements. This work shows that nucleophilicity is mainly influenced by the type of nucleophiles.