A mathematical model for the estimation of critical constant(Z c)of organic compounds has been proposed as follows:Z c=a 0+a 1x 1+a 2x 2+a 3x2 1+a 4x2 2x 1=T K 1 bM K 2A K 3d K 4,x 1=T K 5 bM K 6A K 7d K 8in which, T b: normal boiling point, M: molecular weight, N: atomic number of molecular; and a 0,a 1,a 2,a 3,a 4, K 1,K 2,K 3,K 4,K 5,K 6,K 7,K 8 are parameters which are various with the kinds of organic compounds. The validity of these models has been tested extensively with the experimental data of 190 organic compounds. The calculation A.D.(%) of Z c are 2 63, which is obviously lower than those estimated by Wang’s, Joback’s and MXXC’s methods, respectively.
