DIMERIZATION AND HYDRATION OF GLYOXYLIC ACID: A COMPUTATIONAL STUDY

Abstract

The hydrogen-bonded dimers and 1:1 complexes formed between glyoxylic acid (GA) and H2O have been investigated employing computational techniques like Natural Bond Orbital (NBO) analysis and Atoms in Molecules (AIM) etc. All calculations are carried at B3LYP/6-311++G** level. Seven dimers and four monohydrates are located on the potential energy surface (PES) each for intramolecular hydrogen bonding (IHB) stabilized G3 and non-IHB stabilized rotamer G1. The most stable dimer and hydrate are formed by non-IHB stabilized rotamer G1. In the most stable dimer, two GA units interact in a duo of C=O…H-O hydrogen bonds forming an eight-membered ring structure. In most stable hydrate, H2O acts as a hydrogen bond acceptor and GA acts as an HB donor. The stabilization energies are calculated and the effect of basis set superposition errors (BSSE) is also considered. A good correlation is found between S.E. and the sum of AIM electron densities at bond critical points for both dimers and hydrates. The gas phase hydration and clustering of GA drive new particle formation for atmospheric aerosols, which affect climate, weather, and human health, hence the study has a significant environmental concern.