Kinetics of the ene reactions of 4-phenyl-1,2,4-triazoline-3,5-dione with -pinene and 2-carene: Temperature, high pressure, and solvent effects

摘要

The data on temperature, solvent, and high hydrostatic pressure influence on the rate of the ene reactions of 4-phenyl-1,2,4-triazoline-3,5-dione (1) with 2-carene (2), and -pinene (4) have been obtained. Ene reactions 1+2 and 1+4 have high heat effects: Hr-n (1+2) -158.4, Hr-n(1+4) -159.2kJ mol(-1), 25 degrees C, 1,2-dichloroethane. The comparison of the activation volume (V(1+2) -29.9 cm(3) mol(-1), toluene; V(1+4) -36.0 cm(3) mol(-1), ethyl acetate) and reaction volume values (Vr-n(1+2) -24.0 cm(3) mol(-1), toluene; Vr-n(1+4) -30.4 cm(3) mol(-1), ethyl acetate) reveals more compact cyclic transition states in comparison with the acyclic reaction products 3 and 5. In the series of nine solvents, the reaction rate of 1+2 increases 260-fold and 1+4 increases 200-fold, respectively, but not due to the solvent polarity.