Heats of mixing of normal, iso, secondary and tertiary butylamines withn-hexane have been determined at 25°C by means of a twin type calorimeter. All the four systems show an endothermic behaviour throughout the concentration range suggesting significant self association of the four isomeric butylamines. The enthalpy of the hydrogen bonding in butylamines have been found to be 8·4 kJ/mole, 7·5 kJ/mole, 6·6 kJ/mole and 4·9 kJ/mole for n-, iso-, sec- and tert-butylamines respectively. The above order of the energy of self-association has been attributed to steric hindrance to hydrogen bonding as a result of the branching of the alkyl chain.
Volume 134, 2022
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