Theoretical investigation of the hydrogen bonding aniline derivatives with alcohols

Alcohols belong to the class of fluid systems whose intermolecular interactions are dominated by hydrogen bonding leading to chainlike and ring like association of the molecules in the liquid state. This association is broken when the liquid alcohol is mixed with inert liquids such as hydrocarbons resulting in endothermic heat effects upon mixing. The statistical mechanical treatment of such systems is complicated since not only the strength and structure of hydrogen bonding alcohol clusters has to be known, but also non-associative intermolecular interactions and the flexibility of the molecules have to be taken into account. In those systems the number of hydrogen bindings of alcohols broken upon mixing are more or less compensated by the formation of new hydrogen bodings of the cross type O H· · ·N and the resulting heat effect can be endothermic or exothermic depending on the strength of the cross hydrogen bonding in comparison with the strength of the H-bonding caused by self association of the alcohol molecules. In this work we used the ab initio methods for study of binary systems of aniline derivatives such as 2,3 dimethyl-aniline 2,4dimethyl-aniline 2,5 dimethyl-aniline 2,6dimethyl-aniline 3,4 dimethyl-aniline 3,5 dimethyl-aniline with Methanol , Ethanol, Propanol, Butanol, and Pantanol at the gas phase. The results show that the length of hydrogen bonding and thermodynamic parameters and gap of virtual and occupied orbital are changed with number of carbon in alcohol and position of methyl in the aniline ring.