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ISRN Physical Chemistry
Volume 2013 (2013), Article ID 804576, 9 pages
Research Article

Extension of LIR Equation of State to Alkylamines Using Group Contribution Method

School of Chemistry, Shahrood University of Technology, P.O. Box 3619995161, Shahrood, Iran

Received 31 December 2012; Accepted 3 February 2013

Academic Editors: Y. Kimura and H. Reis

Copyright © 2013 Zahra Kalantar et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In this work, the modified linear isotherm regularity (LIR) equation of state parameter table is extended in order to represent volumetric behaviour of primary alkylamines. In addition, the isothermal compressibility and thermal expansion coefficient of these compounds have been predicted. To do so, we consider each of primary alkylamine as a hypothetical mixture of methyl, methylene and a primary amine functional group, in which the interaction potential of each pair is assumed to be the average effective pair potential. Then, the LIR equation of state has been extended to such a hypothetical mixture. Furthermore, three basic compounds, namely, propane, -butane, and cyclohexane are used to obtain the contribution of methyl and methylene groups in the EOS parameters, and also other appropriate compounds are used to obtain the contribution of the primary amine functional groups, such as 1-pentylamine for the contribution of −CH2NH2 and 2-aminopentane for the contribution of groups. The calculated EOS parameters along with the modified EOS are then used to calculate the density and its derivatives for alkylamines at different pressures and temperatures. The obtained results for different properties are compared with the experimental values.