Article,
Thermodynamic study on aqueous dilute solutions of organic compounds. Part 1.—Cyclic amines
Transactions of the Faraday Society, (1971)
DOI: 10.1039/TF9716701933
Abstract
The enthalpy, entropy and free energy changes have been determined
for the transfer, at 25°C and 1 atm, of cyclic amines of the type
CnH2nNH (n= 4,5,6) and CnH2nNCH3(n= 4,5), from either the ideal gas
state (Xh, X=H,S,G) or the liquid state (Xs, X=H,S,G) to dilute aqueous
solution. Heats of solution of compounds of the type CnH2nNH with
n= 2,3,7 and heats of vaporization (Hv) for all the above compounds
are also reported.In the CnH2nNH series the heat of solution, which
is exothermic, has a maximum at n= 4, whereas Hv values increase
in the homologous series from 8.09 kcal mol–1(n= 2) to 11.04 kcal
mol–1(n= 7). The heats of solution of the N-methyl amines are larger
than those evolved on solution of the corresponding secondary, unsubstituted
amines, while the Hh values are practically equal. On the other hand,
a sensible decrease of Sh is caused by introducing a methyl group
on the nitrogen atom. Possible interpretations of the observed effects
are suggested.
