An MO theoretical study on approximate potential energies of proton migration and fragmentation in protonated n-propanolamine and n-butanolamine.

Abstract

Potential energies of proton migration and the H2, H2O, and NH3 elimination reactions in the protonated n-propanolamine were determined by MINDO/3. The elimination reactions in the protonated n-butanolamine were also examined and discussed in an attempt to explain the difference of the ratio of loss of water to loss of ammonia between these alcoholamines. Proton migration between carbon atoms in the protonated alkyl group was found to involve a low activation energy less than 84 kJ/mol but unlikely to take place because of other channels. Elimination of H2 was shown to take place from the C-protonated MH+ ion. There were several reaction paths for water and ammonia losses from the MH+ ion and the paths with hydrogen rearrangements were more likely to occur than the simple cyclization mechanism with the neighboring assistance of the hetero atom of the other end.