FT-IR and FT-Raman spectral investigations, HOMO-LUMO and first-hyperpolarizability analyses of 2,4-dimethoxybenzontrile by ab initio and density functional method

Benzonitrile is a phenyl cyanide compound which is derived mainly from benzoic acid reaction with lead thiocynate by heating. Benzonitrile is used as a solvent and chemical intermediate for synthesis of pharmaceuticals, dye stuffs and rubber chemicals through the reaction of alkylation, condensation, hydrolysis, halogenations or nitration. Many derivatives of benzonitrile are used in medicine as urinary antiseptic in the form of a salt and in vapour form for disinfecting bronchial tubes. The detailed HF/B3LYP comparative studies on the complete FT-IR and FT-Raman spectra of 2,4- dimethoxybenzonitrile (24DMBN) has been reported. In the present investigation, molecular geometry, optimized parameters and vibrational frequencies are computed and the performance of the computational methods for HF and B3LYP at 6-311++G(d,p) basis set are compared. Frontier molecular orbital analysis, and NLO properties and other molecular properties of 24DMBN are also studied. The vibrational assignments have been performed based on total energy distribution (TED).