Elucidation of hydrogen bond strength of benzylalcohol with alkyl Acetoacetates: The confirmation study by excess thermodynamic Properties, FTIR and DFT analysis

Abstract

In this study, density of pure liquids and their binary mixtures of benzylalcohol (BA) with methyl acetoacetate (MAA), ethyl acetoacetate (EAA) and allyl acetoacetate (AAA) were measured experimentally at T=(298.15–313.15) K and P = 0.1 MPa by using Rudolph Research Analytical digital densitometer. Experimental data was correlate by applying Jouyban–Acree theoretical equation. Furthermore, the speed of sound of all studied pure and their binary solutions were measured at T= (298.15 and 308.15) K at atmospheric pressure at 2 MHz. The experimental density and speed of sound data further were used to calculate the excess molar volume (VmE), isentropic compressibility (κs), excess isentropic compressibility (κsE) and excess speed of sound (uE) at all compositions and temperature ranges. The calculated VmE, κsE, uE and experimental speed of sound were compared with theoretical models such as Redlich-Kister, Hwang, CFT and FLT equations. The obtained data were analyzed in terms of intermolecular interactions such as hydrogen bond formation between two atoms of benzylalcohol and acetoacetates. Among all the three systems, BA + MAA showed highest negative excess molar volume magnitude due to the change of molecular geometry through the keto-enol tautomerism. The negative magnitude of VmE data confirms the formation of H-bond between the –OH---O- groups of component molecules. Similarly, BA + EAA system showed highest negative magnitude of κSE owing to the more compressible than resultant ideal solutions. The deviation in κSE magnitude in binary systems due to the geometrical fitting and specific interactions in atoms of the benzylalcohol and acetoacetates. Furthermore, the existence of hydrogen bond and its strength in binary mixtures were confirmed by experimental FTIR spectroscopy and theoretical density functional theory (DFT) calculations.