Kinetic Theories for the Study of Reactions Regardless the Presence of Well Defined Saddle Point: Malononitrile Production in Titan’s Atmosphere

Physical-chemistry improvements are achieved by searching for theories to better describe physical systems. The chemical kinetic study is extremely important when it comes to transformation into molecular systems. In this context, this work aims to didactically present two complementary theories, the transition state theory and the capture theory. Both theories have their own specificities and focus on different kind of systems with different properties. Their comprehension allow the analysis of reactions regardless of the existence of a well defined transition state on the proccess. In this work we applied these theories in two sequential reactions that lead to the Malononitrile formation in temperature conditions consistent with those found in Titan atmosphere. The first stepCH2CN + CN + M → NCCH₂NC + M does not present a well defined saddle point in its reactional path, therefore the capture theory was employed, meanwhile the second stepNCCH₂NC → NCCH₂CN presents a well defined saddle point in its reactional path, allowing the use of the transition state theory for its study.

Keywords:
Transition State Theory; Capture Theory; Electronic Structure; Malononitrile