Theoretical Investigation into Thermodynamics and Kinetics of Tautomerization of 2-Aminopropenal

Sari

Compound 2-aminopropenal is one of the simplest molecules that has 2 functional groups that allows for tautomerization reaction. The tautomerization reaction is while quite well known, the kinetics and thermodynamics of this specific molecule is quite interesting because it can be used as model compound for more complex reaction. The calculation of the process was performed using AM1 method employing Orca 4.2.1 software. CI-NEB-TS search algorithm was used to compute the minimum energy pathway. Calculation results show that the keto form is more stable that that of enol form, with transition state (TS) form having the higher energy. The N-O distance decrease as the reaction happen, reached a minimum at TS, and increase as the product started to form, indicating that the proton transfer process was closer to a hand-off than a simple transfer. HOMO moiety as well as partial charges support this conclusion by showing that proton at TS form had a very low electron density due to the proximity of both O and N thus depleting H atom of its electron.