Open AccessProton exchange between oxymethyl radical and acids and bases: semiempirical quantum-chemical study
Author(s) -
Irina Pustolaikina,
Kamshat Zhambylovna Kutzhanova,
Irina Leonidovna Stadnik,
Alfia Faridovna Kurmanova
Publication year - 2016
Publication title -
habaršy - a̋l-farabi atyndag̣y k̦azak̦ memlekettik ụlttyk̦ universiteti. himiâ seriâsy/chemical bulletin of kazakh national university
Language(s) - English
Resource type - Journals
eISSN - 2312-7554
pISSN - 1563-0331
DOI - 10.15328/cb800
Subject(s) - proton , chemistry , diamagnetism , paramagnetism , hydrogen bond , base (topology) , computational chemistry , hydrogen , quantum chemical , molecule , chemical physics , organic chemistry , quantum mechanics , physics , magnetic field , mathematical analysis , mathematics
The reactions with proton participation are widely represented in the analytical, technological and biological chemistry. Quantum-chemical study of the exchange processes in hydrogen bonding complexes will allow us to achieve progress in the understanding of the elementary act mechanism of proton transfer in hydrogen bonding chain as well as the essence of the acid-base interactions. Oxymethyl radical •CH2ОН is small in size and comfortable as a model particle that well transmits protolytic properties of paramagnetic acids having more complex structure. Quantum-chemical modeling of proton exchange reaction oxymethyl radical ∙CH2OH and its diamagnetic analog CH3OH with amines, carboxylic acids and water was carried out using UAM1 method with the help of Gaussian-2009 program. QST2 method was used for the search of transition state, IRC procedure was applied for the calculation of descents along the reaction coordinate. The difference in the structure of transition states of ∙CH2OH/ CH3OH with bases and acids has been shown. It has been confirmed that in the case of bases, consecutive proton exchange mechanism was fixed, and in the case of complexes with carboxylic acids parallel proton exchange mechanism was fixed. The similarity in the reaction behavior of paramagnetic and diamagnetic systems in the proton exchange has been found. It was suggested that the mechanism of proton exchange reaction is determined by the structure of the hydrogen bonding cyclic complex, which is, in turn, depends from the nature of the acid-base interactions partners.