The Lydersen method is a group contribution method for the estimation of critical properties temperature (T<sub>c</sub>), pressure (P<sub>c</sub>) and volume (V<sub>c</sub>). The method is named after Aksel Lydersen who published it in 1955. The Lydersen method is the prototype for and ancestor of many new models like Joback, Klincewicz, Ambrose, Gani-Constantinou and others.
The Lydersen method is based in case of the critical temperature on the Guldberg rule which establishes a relation between the normal boiling point and the critical temperature.
Guldberg has found that a rough estimate of the normal boiling point T<sub>b</sub>, when expressed in kelvins (i.e., as an absolute temperature), is approximately two-thirds of the critical temperature T<sub>c</sub>. Lydersen uses this basic idea but calculates more accurate values.
M is the molar mass and G<sub>i</sub> are the group contributions (different for all three properties) for functional groups of a molecule.
Acetone is fragmented in two different groups, one carbonyl group and two methyl groups. For the critical volume the following calculation results:
V<sub>c</sub> = 40 + 60.0 + 2 * 55.0 = 210 cm<sup>3</sup>
In the literature (such as in the Dortmund Data Bank) the values 215.90 cm<sup>3</sup>, 230.5 cm<sup>3</sup> and 209.0 cm<sup>3</sup> are published.