Reactivity of hydrogen-bonded complexes of water, methanol, phenol and methyl amine

Abstract

The donor–acceptor and acid–base properties of organic compounds largely determine the reactivity of organic compounds. Adiabatic ionization potentials, electron affinities, proton affinities, gas-phase basicities, enthalpies and free energies of dissociation of monomers and homoassociates of water, methanol, phenol, and methylamine, as well as mixed hydrogen-bonded complexes of phenol with methanol and methylamine with methanol were calculated using a B3LYP/6-311++(df,p) density functional method. From the calculations it was found that hydrogen-bonded complexes, in comparison with their monomeric forms, have enhanced donor–acceptor and acid–base properties. It has been established in a number of examples that this phenomenon leads to an increased reactivity of hydrogen-bonded complexes compared to their monomers. Hydrogen-bonded complexes can act as effective acid–base catalysts. Cyclic hydrogen-bonded complexes have lower electron donor–acceptor and acid–base properties compared to open-chain ones. Accounting for the participation of hydrogen-bonded associates in reactions where they can form is absolutely necessary for the correct consideration of the kinetic and thermodynamic regularities of chemical reactions.