Volume, enthalpy and entropy of activation of the diels-alder reaction of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate with 1-hexene

Abstract

Pressure and temperature effects on the reaction rate of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate with 1-hexene were investigated. The activation volume (-26.7 cm3 mol1, 298.1 K) is in agreement with the conservation of all four nitrogen atoms in transition state. Densitometry, 1H NMR and calorimetric studies of the reaction indicate nitrogen molecule loss by the intermediate just after its formation. Partial molar volumes in acetone of diene (127.2), 1-hexene (127.6) and the resulting adduct (206.9 cm3 mol-1) were determined.