Estimation of Vapor Pressures for Organic Compounds with Corresponding State Group Contribution Method

A new properties estimation method was proposed by combining corresponding state principle with group contribution method through introducing the concept of assumed-critical properties, and then combining it with Riedel equation, a new vapor pressure correlation equation(CSGC-RE) was developed. Contribution values of 87 groups were obtained by correlating 5254 vapor pressure experimental data of 349 organic compounds of 20 type substances including saturated hydrocarbons, unsaturated hydrocarbons, cyclohydrocarbons, aromatics, oxygen compounds, sulfurcompounds, nitrogen compounds, halohydrocarbons, etc. The total average error is 1.35%. Comparing the developed equation with the several usually used equations showed that the new equation(CSGC-PE) has the advantage of both corresponding state method and group contribution method. Predicted results for vapor pressures of 17 compounds in table 5 show that the CSGC-RE equation is superior to those corresponding state equations such as Riedel、Lee-Kesler and Riedel-Plank-Miller equation, etc.