Effect of dilution of nonpolar solvents (CCl4 and C6H6) on densities and excess molar volumes of methanol + 1-butanol mixtures over the temperature range 293.15–308.15 K

Abstract

Methanol and 1-butanol have philicity to each other but their binary mixing features were very rarely discussed. Non-linear density-composition plots of methanol + 1-butanol (M-B) binary mixtures indicates non-ideal mixing of the two alcohols. Excess molar volume (VmE) remains positive over the entire composition range. The VmE isotherms in the temperature range from 293.15 K to 308.15 K are measured at 5 K intervals exhibit maxima at xmethanol ~ 0.6, indicating maximum no of H-Bonds among the solvents are formed at this composition. No change in maxima position indicate no significant structural change with temperature. Due to different sizes of alkyl groups “hydrophobic-like” interactions for methanol have been proposed to explain positive VmE. Neat 1-butanol when diluted with CCl4 or C6H6 (nonpolar diluents) exhibits positive VmE is an indication of segregation of its molecules due to their weak mutual interactions. On the other hand, negative VmE for methanol upon adding the diluents suggests oligomer formation in it. Also, the binary mixtures of the alcohol and the diluents addition to neat alcohols results in non-linear density isotherms for methanol and negative VmE while for butanol, linear density isotherms and positive VmE was observed. This behavior should suggest that M-B molecules do not tend to congregate with each other rather methanol-methanol (M-M) association is preferred.