Cyclic and Acyclic N═N Bonds in Reactions with Some Alkenes and Dienes. Issue 8 (16th May 2017) - Kiselev, Vladimir D.
ABSTRACT: The kinetics of the Diels–Alder (DA) reactions of 4‐phenyl‐1, 2, 4‐triazoline‐3, 5‐dione1, trans ‐diethyl azodicarboxylate2, and tetracyanoethene3 with 1, 3‐cyclohexadiene4, cycloheptatriene5, 1, 3‐cycloheptadiene6, cyclooctatetraene7, and 1, 3‐cyclooctadiene8 in a range of temperatures and pressures has been studied. Values of the enthalpy, entropy, and volume of activation, as well as the enthalpy and volume of reaction have been obtained. Observed reaction rates of5+1 and7+1 have been compared with the known rate of norcaradiene17 formation in the equilibrium 5 ⇌ 17, and that of bicyclo[4, 2, 0]‐octa‐2, 4, 7‐triene20 in the equilibrium 7 ⇌ 20 . The kinetic data show that the rate of formation of17 from5 is much greater than the loss rate of dienophile1 in reaction of5+1 . In contrast, the formation rate of tautomer20 is less than the loss rate of dienophile1 in reaction of7+1 . This reflects that the consecutive reaction of5 →17 (+1 ) →15 is possible whereas the consecutive reaction of7 →20 (+1 ) →22 does not occur as the only way.