Integrated exploration of intermolecular interactions in 3-methyl-1-butanol and C5-C8 1-alkanol mixtures via density functional theory and experimental approaches

Abstract

The investigation provides a study on the thermophysical properties of 3-methyl-1-butanol with medium-chain alcohols (1-pentanol to 1-octanol) within the temperatures 293.15 K to 333.15 K. Findings indicate positive excess molar volumes that escalate with the lengthening of the carbon chain in the alcohols. Viscosity measurements demonstrate negative deviations from ideality, which are accentuated with longer alkyl chains. The analysis suggests that intermolecular forces between 3-methyl-1-butanol and alcohols are weak. Furthermore, the study uses the Cubic Plus Association (CPA) model to establish a relationship between the densities of the mixtures, demonstrating a close match with data obtained through experimentation. The CPA model deviates by a maximum of 0.53 % and indicates the model's reliability in portraying real-world data. Furthermore, this study entails a density functional theory (DFT) investigation of hydrogen bonding among 3-methyl-1-buthanol + 1-alkanol. The analysis encompasses properties including interaction energies, geometrical parameters, nuclear magnetic resonance (NMR) analyses, atoms in molecules analysis (AIM), natural bond orbital analysis (NBO), and excess volume. Our calculations reveal the strongest hydrogen bonding occurs in mixtures of 3-methyl-1-butanol and 1-pentanol, while the weakest interactions form in mixtures of 3-methyl-1-butanol and 1-octanol. Notably, calculated data on hydrogen bonding between 3-methyl-1-buthanol and 1-alkanols align with experimental findings, underscoring the agreement between computational and empirical approaches.