4098
J. Phys. Chem. 1994, 98, 4098-4103
Thermodynamic and N M R Study of the Interactions of Cyclodextrins with Cyclohexane Derivatives Mikhail V. Rekharsky,# Frederick P. Schwarz, Yadu B. Tewari, and Robert N. Goldberg' Biotechnology Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
Minoru Tanaka and Yuko Yamashoji Department of Applied Chemistry, Faculty of Engineering, Osaka University, Yamada-oh, Suita, Osaka 565, Japan Received: November 17, 1993; In Final Form: January 26, 1994'
Equilibrium constants and standard molar enthalpies of reaction have been determined by titration calorimetry for a series of cyclohexane derivatives (cis- 1,2-cyclohexanediol, cis,cis- 1,3,5-cyclohexanetrio1, trans- 1,2cyclohexanediol, cyclohexanol, cyclohexanone, 2-methylcyclohexanone, 2,5-piperazinedione, and 6-valerolactam) with a-cyclodextrin and 8-cyclodextrin. For the reactions involving cyclohexanol, standard molar heat-capacity changes were also determined from calorimetric measurements performed at several temperatures. The equilibrium constants for the reactions of these substances with 8-cyclodextrin are in all cases larger than those for the corresponding reactions with a-cyclodextrin. It was also found that the equilibrium constants for the reactions of these substances with y-cyclodextrin were too small (
