Handbook of Solvents - George Wypych - ChemTech - Ventech!

9.4 Mixed solvent influence on the chemical equilibrium 553
confirmed by equality of the constants of spin - spin interaction 2 I( 1 H- 199 Hg) for different
organic compounds in these solvents. This was also confirmed 61 for participants of the equilibrium
[9.111].
Systems with one associated participant of equilibrium
Methanolysis of triphenylchloromethane may serve as an example of such reaction:
Ph 3CCl + CH 3OH ↔ Ph 3COCH 3 + HCl [9.112]
This process has been studied in benzene, 1,2-dichloroethane, chloroform,
trifluoromethylbenzene and in mixed solvents hexane - nitrobenzene, toluene -
nitromethane, toluene - acetonitrile.
Low constant of the ion associate formation process of triphenylchloromethane, high
constant of the ion association process, and low constant of the heteromolecular association
process of HCl (HCl solutions in listed solvents obey the Henry’s Law) show that only
methanol is an associative participant of the equilibrium.
Systems with two associated participants of equilibrium
These systems have been studied be means of reaction of acidic exchange between acids
and anhydrides with different acidic groups:
CH 2ClCOOH +(CH 3CO) 2O ↔ CH 2ClCOOCOCH 3 + CH 3COOH [9.113a]
CH 3COOH +(CH 2ClCO) 2O ↔ CH 2ClCOOCOCH 3 + CH 2ClCOOH [9.113b]
in binary mixed solvents formed from tetrachloromethane with chlorobenzene,
trifluoromethylbenzene and nitrobenzene.
The system trifluoroacetic acid and methanol, undergoing esterification reaction:
CF 3COOH + CH 3OH ↔ CF 3COOCH 3 + H 2O [9.114]
also belongs to the group.
The equilibrium process has been studied in binary mixed solvents such as hexane-chloroform,
hexane-chlorobenzene, chloroform-chlorobenzene. Also, re-esterification
CH 3COOC 3H 7 +CX 3COOH ↔ CX 3COOC 3H 7 +CH 3COOH [9.115]
(where X is F or Cl) has been studied for the full concentration range of propyl acetate -
trifluoro- and trichloroacetic acids. 62
Etherification process of ethanol by caproic or lactic acids has been studied by these
authors. 63 The reaction of acetal formation was studied 64
RCHO + R’OH ↔ RCH(OR’) 2 + H 2O [9.116]
in systems of isoamyl alcohol-benzaldehyde (a) and ethanol - butyric aldehyde (b).
The relationship between the maximum output of the reaction of exchange interaction
and associative state of equilibrium [9.110] participants follows the
Gibbs-Dugem-Margulis equation: