Acetic acid compressibility factor

FIGURE 1.3-3 Compressibility factor Z for acetic acid vapor at 40°C, Circles are data curve is computed from chemical theory, assuming dimerization, with K = 380. 

For acetic acid and HF, where tetramers or hexamers are regarded, the equation must be solved numerically, which is, however, pretty easy, as 0 < zi < 1. Having calculated zi, the compressibility factor z can be determined as the ratio between the number of associates and the number of molecules in the vapor phase ... 

In the intramolecular reactions studied by Bruice and Koshland and their co-workers, proximity effects (reduction in kinetic order and elimination of unfavourable ground state conformations) and orientation effects might give rate accelerations of 10 -10 . Hence, these effects can by themselves account for the enhancements seen in most intramolecular reactions. However, a factor of 10 -10 is less than the rate acceleration calculated for many enzyme reactions and certain intramolecular reactions, for example, hydrolysis of benzalde-hyde disalicyl acetal (3 X 10 ) (Anderson and Fife, 1973) and the lactonization reaction of[l] (10 ) where a trimethyl lock has been built into the system. If hydrolysis of tetramethylsuccinanilic acid (Higuchi et al., 1966) represents a steric compression effect (10 rate acceleration), then proximity, orientation, and steric compression... 

---