Glyoxal And Methylglyoxal Polymerization

Glyoxal and Methylglyoxal are common secondary atmospheric pollutants. They are significant atmospheric aldehyde formed from both aromatic compounds of anthropogenic and isoprene of natural source .The chemical reaction of them is related to Secondary Organic Aerosol (SOA). The organic of SOA effects the physical and chemical changes of aerosol particles, thus impacts atmosphere and climate. Therefore, we need to be further gone into the reaction pathway of SOA formation and polymerization of organic aldehydes. This thesis will have its focus on the organic compounds glyoxal and methylglyoxal in aqueous solution polymerization.It is completely proved that the main products of the chemical reaction of glyoxal aqueous solution are glyoxal monohydrate, dehydrate and five-ring structure of glyoxal dimer by the means of 1H NMR, 1H-1H COSY and ATR-FTIR combined with the quantum chemical calculation results of Gibbs free energy of various compounds in glyoxal aqueous solution, which confirms the mechanism of polymerization in glyoxal aqueous solution.The thesis discusses the polymerization of methylglyoxal by using regular and two-dimensional NMR spectroscopy of 1H NMR,13C NMR,HMBC and HSQC, identifying 1H and 13C atoms NMR signals, testing methylglyoxal through ATR-FTIR method. Applying Density Functional Theory (DFT/B3LYP) method based on 6-311+G (d,p) basis set to optimize geometrical structures of methylglyoxal, methylglyoxal hydrate, and methylglyoxal dimer. Then, calculating 1H and 13C atoms NMR chemical shift of methylglyoxal and aqueous solution compounds with GIAO method. The theoretical results closely tally with the experimental results, which helps to identify 1H and 13C atoms chemical shift of methylglyoxal compounds. Finally, it is showed that the main polymer of methylglyoxal aqueous solution is the five-ring dimer of dihydrate condensation.