Ionization energies and entroples of cycloalkanes. Kinetics of free energy controlled charge-transfer reactions

Journal Article · Thu Sep 02 04:00:00 EDT 1982 · J. Phys. Chem.; (United States)

OSTI ID:6388792

Sleck, L W; Mautner, M

Enathalpies and entropies of ionization (..delta..H/sup 0//sub ion/ and ..delta..S/sup 0//sub ion/) of alkylcyclohexanes, as well as cycloheptane, cyclooctane, and trans-Decalin, have been determined by charge-transfer equilibrium measurements. Values of ..delta..H/sub ion/, in units of kcal mol/sup -1/ (or eV), range from 229.6 (9.96) for cycloheptane to 210.7 (9.14) for trans-Decalin. A major effect of alkyl substitution is observed following substitution at a site ..cap alpha.. to a tertiary hydrogen atom (as from methylcyclohexane to 1,2-dimethylcyclohexane), or following replacement of a tertiary hydrogen atom (as from methylcyclohexane to 1,1-dimethylcyclohexane). In both cases, ..delta..H/sup 0//sub ion/ decreases by ca. 5 kcal mol/sup -1/. Entropies of ionization are near zero for alkylcyclohexanes but range up to 5 cal deg/sup -1/mol/sup -1/ for nonsubstituted cycloalkanes (cyclooctane). The sum of the reaction efficiencies (r = k/k/sub collision/) of the forward and reverse processes of charge-transfer is near unity.

• Research Organization: National Bureau of Standards, Washington, DC
• OSTI ID: 6388792
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 86:18; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ALKANES
CHEMICAL REACTION KINETICS
CYCLOALKANES
DATA
ENTHALPY
ENTROPY
EQUILIBRIUM
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
IONIZATION
KINETICS
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOTOIONIZATION
PHYSICAL PROPERTIES
REACTION KINETICS
THERMODYNAMIC PROPERTIES