• S D Pradhan

      Articles written in Journal of Chemical Sciences

    • Volume change on mixing : Binary mixtures of methanol with isomeric butylamines

      S D Pradhan

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      The volume change on mixing (VE) of binary systems of methanol (1) +n-butylamine, isobutylamine, sec. butylamine and tert. butylamine (2) were determined at 25‡ C by density method. All the four systems showed a large negative volume change on mixing and the maxima were observed nearly at 0.5 mole fraction. This was attributed to the possibility of 1 : 1 type of complex formation between amine and methanol. TheVE was found to depend on the structure of butylamine and the magnitude ofVE increased as tert.-BuNH2 > sec.-BuNH2 > iso-BuNH2 >n-BuNH2 This particular trend is attributed to increase in the number of amine-alcohol species formed on the mixing and the geometric fitting of methanol in the liquid structure of the butylamine.

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

      S D Pradhan H B Mathur

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      Heats of mixing of the binary mixtures ofn-, sec-, iso- andt-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 ordert-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.

    • Excess volumes of isomeric butanols with di-n-butyl ether

      K R Patil Gopal Pathak S D Pradhan

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      The excess volumes of four isomeric butanols with di-n-butyl ether were determined at 30°C. The isomeric effect was distinctly observed in the excess volume profiles. 1-Butanol and 2-methyl-l-propanol systems exhibited negative excess volumes throughout the concentration range. The 2-butanol system had positive excess volumes up to 0.9 mol fraction of alcohol after which it became negative, while the 2-methyl-2-propanol system exhibited positive excess volumes throughout the concentration range.

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