Complexation in reactions of cycloalkane solvent holes. I. reactions of Cis- and Trans-decalin{lg_bullet}+ with alcohols.
It is shown that solvent holes in cis- and trans-decalin form complexes with aliphatic alcohols that live 1-100 ns, depending on the solute and the solvent temperature. This complexation has near-zero activation energy and occurs with rate constants of (1-1.2) x 10{sup 11} M{sup -1} s{sup -1} in trans-decalin and 3 x 10{sup 10} M{sup -1} s{sup -1} in cis-decalin. The metastable complex decays by proton transfer (for alcohols higher than ethanol); in concentrated solutions a diffusion-controlled reaction of the complex with a second alcohol molecule occurs. While the stability of the complex increases with the carbon number of the alcohol, the standard heat of the complexation decreases in the opposite direction ({Delta}H{sup o} changes from -39 kJ/mol for ethanol to -25 kJ/mol for tert-butanol). The decrease in the standard entropy is small ({Delta}S{sup o}{sub 298} > -80 J mol{sup -1} K{sup -1}), approaching zero for higher alcohols. We argue that this thermochemistry is due to the polaronic nature of the solvent holes.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- SC
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 942773
- Report Number(s):
- ANL/CHM/JA-34521
- Journal Information:
- J. Phys. Chem. B, Journal Name: J. Phys. Chem. B Journal Issue: 15 ; 2000 Vol. 104; ISSN 1089-5647; ISSN JPCBFK
- Country of Publication:
- United States
- Language:
- ENGLISH
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