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Lattice‐fluid equation of state with hydrogen‐bond cooperativity
Author(s) -
Muthukumaran Poongunran,
Brinkley Ray L.,
Gupta Ram B.
Publication year - 2002
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690480221
Subject(s) - cooperativity , hydrogen bond , chemistry , thermodynamics , molecule , bond strength , ab initio quantum chemistry methods , bond order , computational chemistry , crystallography , bond length , organic chemistry , biochemistry , physics , adhesive , layer (electronics)
Hydrogen bonding plays an important role in thermodynamic properties of polar fluids. Existing equations of state that include h‐bonding cannot accurately predict the phase behavior for polar fluids. In the theories for h‐bond‐chain forming molecules, h‐bonding strength is considered a constant at a given temperature and pressure. Infrared spectroscopy and ab initio calculations show that the h‐bonding strength depends on whether or not the molecule was previously h‐bonded at other sites. When an h‐bond is formed between an already hydrogen‐bonded species and a free species, the second h‐bond has different energetic characteristics from the primary h‐bond. In the case of l‐alkanol self‐h‐bonding, the equilibrium constant for the second h‐bond is ten times that for the primary h‐bond. This phenomenon called h‐bond cooperativity was incorporated in a lattice‐fluid‐hydrogen‐bonding equation of state. Calculations for pure l‐alkanols, show that the theory can be improved significantly by the incorporation of h‐bond cooperativity. Agreement with the phase behavior and spectroscopic h‐bonding data improves using cooperativity, without any additional adjustable parameters. Heat of mixing calculations agree well with the experimental data.