Kinetically Investigated Common Ligand Effects in Phosphoryl Transfer Process of Pyridinolysis of Isothiocyanophosphates in Acetonitrile

초록

The mechanistic interpretation mostly depends on the kinetic investigations, which are largely important for the interpreting characteristics of the organo-phosphorus compounds. By analyzing Hammett and Br?nsted plots the organo-phosphorus compounds are appearing as an interesting recently in the field of physical organic chemistry specially by clarification of mechanistic criteria using cross-interaction constants and its effect in the biochemical activities in life. In the incessant of the progress of the search, we have investigated the kinetics and concern physical factors of the pyridinolysis of RR′ isothiocyanophosphates in acetonitrile at 55.0oC where R and R′ are MeO, EtO, PhO and their combinations. A biphasic Hammett plot indicates the mechanistic alteration during the course of reaction. The deuterium kinetic isotope effects, respective activation parameters and obtained selectivity parameters were found in support of the proposed mechanistic behavior of the present system. Where we especially endeavor to introduce the frontal and backward attack of nucleophiles through the usual phenomena of nucleophilic substitution reactions and which are generally observed for the phosphate, phosphonate and phosphinic systems.