FTIR spectroscopic studies and DFT calculations on the binary solution of methyl acetate with m-xylene

摘要

FTIR spectra have been recorded for pure methyl acetate, pure m-xylene and their equimolar binary solution. Shifts have been observed in all the vibrational modes of methyl acetate, m-xylene in the solution indicating the possibilities for molecular interactions. To get more predse information on the molecular interactions, DFT calculations have been performed. From these calculations it is found that methyl acetate dimers of four different geometries are possible. The most stable among these dimers is the one with C - H center dot center dot center dot O = C interactions stronger than the C - H center dot center dot center dot O - C . If the scenario is opposite in a dimer, the stability becomes the least. These four dimers dissociate in the investigated binary solution and 1:2 (m-xylene:methyl acetate) complexes of five different ge- ometries are formed. In one of the complexes, the homointeractions C - H center dot center dot center dot O = C among the methyl acetate molecules are more stronger than any other interactions and the stability of the complex is the least. In all the other complexes the interactions (methyl acetate)C - H center dot center dot center dot pi (m - xylene) are the strongest. In complexes where the hydrogens attached to ring carbons of m-xylene do not involve in hydrogen bonds with methyl acetate, the stability of the complexes is more. If these hydrogen bonds are formed, the stabilities of those complexes are reduced. (C) 2020 Elsevier B.V. All rights reserved.