Solvolysis of cyclopentyl p-bromobenzenesulfonate in aqueous hexafluoroisopropyl alcohol. Deuterium rate effects, stereochemistry of substitution and elimination, and reaction mechanism
In 90% hexafluoroisopropyl alcohol--10% water cyclopentyl p-bromobenzenesulfonate solvolyzes at 25/sup 0/C with a half-life of 26 min. The yield of cyclopentene is 80% and syn elimination is favored over anti by a factor of about 4. The ..cap alpha..-d rate effect is large (1.23), indicating that the intimate ion pair is reversibly formed and that nucleophilic attack to give cyclopentanol is not rate determining or partially rate determining. The cis-..beta..-d rate effect (1.35) is larger than the trans-..beta..-d effect (1.22). The ..beta..-d/sub 4/ rate effect (2.86) is large and greater than the square of the product of the cis-..beta..-d and the trans-..beta..-d rate effects (2.71). It is concluded that the reaction mechanism involves reversible formation of the intimate ion pair which further reacts mainly by two irreversible, competitive processes: (1) removal of the cis-..beta.. proton by the leaving group to give cyclopentene and (2) conversion to the solvent-separated ion pair. The solvent-separated ion pair gives cyclopentanol and possibly some additional cyclopentene. These results are briefly compared with results published earlier for the solvolysis of cyclopentyl p-bromobenzenesulfonate in ethanol--water, dioxane--water, and trifluoroethanol--water solvents. 7 tables.
- Research Organization:
- Indiana Univ., Bloomington
- OSTI ID:
- 6389666
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 100:26; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
ALCOHOLS
ALKENES
AQUEOUS SOLUTIONS
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
CYCLOALKENES
DECOMPOSITION
DEUTERIUM
DEUTERIUM COMPOUNDS
DIOXANE
DISPERSIONS
ESTERS
ETHANOL
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
HYDROXY COMPOUNDS
ION PAIRS
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
MEDIUM TEMPERATURE
MIXED SOLVENTS
MIXTURES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
REACTION KINETICS
SOLUTIONS
SOLVENTS
SOLVOLYSIS
STABLE ISOTOPES
STEREOCHEMISTRY
SULFONIC ACID ESTERS
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
YIELDS