The theory of thermodynamic similarity is used to substantiate the lim
its of applicability of Trouton's rule, Quantitative criteria are esta
blished, ensuring reliable prognosis of the enthalpy of vaporization a
t boiling point (Delta H-b) by Trouton's rule. Using the data obtained
as a basis, a technique is proposed for evaluating the validity of pu
blished Delta H-b values.