Relationships between some properties of pure homologous organic liquids

The vapor pressures of eleven primary straight chain alkyl chlorides and eleven primary straight chain alcohols between C3 and C16 were determined within a range of 5 to 760 mm Hg. These data were obtained by determining the boiling points of the pure materials at various pressures by using differential thermal analysis. The boiling points were determined with a precision of -.1 degree Centigrade at a 95 per cent C.I. The Antoine equation was used to analytically describe the data. The constants for this equation were determined by a multiple linear regression technique for each individual compound. The heats of vaporization were generated for each compound from the experimental vapor pressure data by the Haggen-macher and Fishtine method. A correlation was developed, based on a hole model for a liquid, which relates vapor pressures between 5 and 760 mm Hg with corresponding liquid densities and the number of carbon atoms in a molecular chain for an homologous series. The correlation constants were determined from a multiple linear regression analysis by the use of available literature density data. Any missing density data were then predicted from the knowledge of experimental vapor pressure data. The maximum error in correlating the available density data was 2.7 per cent. A relationship was also developed which relates vapor pressures between 5 and 760 mm Hg, internal heats of vaporization and the number of carbon atoms in a molecular chain for an homologous series. The maximum error in correlating the internal heat of vaporization data was 8.2 per cent. This relationship was also used to determine energies of vaporization which can be ascribed to different functional groups independently of the remaining molecule. Both of the above correlations were applied to the straight chain homologous series consisting of the n-alkanes, n-alkenes, n-alkyl chlorides, and the n-alkanols