Finitely limited group contribution correlations for boiling temperatures

Group contribution correlations are presented for the boiling temperatures at (101.33 and 1.33) kPa and for critical temperature applicable to a broad range of organic compounds. The group contributions are based on UNIFAC groups to facilitate simultaneous group identification for estimation of activity coefficients. These correlations recognize a finite limit in boiling temperature and critical temperature as infinite molar mass is approached. The existence of this limit is suggested by: extrapolation of the experimentally measured boiling temperatures, by critical behavior polymer solutions, by engineering equations of state, and by molecular simulation results. The availability of two vapor pressures enables straightforward application of the Clausius–Clapeyron equation to estimate boiling temperatures at other points. In the presented approach, there are three parameters for the boiling temperature correlations and one parameter for the critical temperature plus 72 functional groups. The parameters are regressed through a database consisting of 336 hydrocarbons and 642 non-hydrocarbons. The database consists of various chemical families including aliphatics, olefinics, naphthenics, aromatics, alcohols, amines, nitriles, thiols, sulfides, aldehydes, ketones, esters, ethers, halocarbons, silicones, and acids. The average absolute percent deviations (AAD%) between the correlated and experimental temperatures are calculated in comparison with the Joback–Reid and Gani approaches. For the enthalpy of vaporization at T = 298 K, the Joback model makes calculations possible at 1.33 kPa by assuming that Hvap   is constant over this range. Also, Kolska and Gani have reported a correlation for heat of vaporization at the normal boiling point which is used in this study. We obtain (3.5, 4.7, and 4.1) AAD% in temperature for the present work using the Joback–Reid and Gani methods, respectively. Additionally, the accuracy of the present work is evaluated by calculating the vapor pressures from the DIPPR correlation at the predicted temperatures of each model. We obtained (33, 104, and 48) AAD% in pressure for the present work by means of the Joback–Reid, and Gani methods. The critical temperature correlation results in a 2.6 AAD% in critical temperature. Asher and Pankow have reported a UNIFAC-PL∘ method to predict the vapor pressure of oxygen-containing compounds to model the behavior of organic aerosols over the temperature range of (290 to 320) K. The Asher et al. model is compared to this approach for 66 volatile species. For the vapor pressure at the 1.33 kPa boiling temperature, we obtain 37 AAD% for the present work and 95 AAD% using the Asher–Pankow method.