Thermodynamic study of binary mixtures of isomeric butylamines with methanol enthalpy of hydrogen bonded complex

Abstract

Heats of mixing of the binary mixtures of n-, sec-, iso- and t-butylamines with methanol were determined in the entire concentration range. All the four systems showed a strong exothermic behaviour. The exothermic heats of mixing vary in the ordert-BuNH₂ >n-BuNH₂ > sec-BuNH₂ > iso-BuNH₂. The enthalpy of hydrogen bond in the methanol-butylamine complexes was calculated by means of a thermochemical cycle and found to vary in the order t-BuNH₂ >n-BuNH₂ > iso-BuNH₂ > sec-BuNH₂. This order is different than that found for the hydrogen bond due to self-association. The difference has been explained in the light of steric and electromeric effects arising out of the substitution of the methyl groups in the alkyl chain of the butylamine.