Reactive species in the gas phase: A variable temperature flowing afterglow study on the formation, reactivity, and stability of carbanions and radicals anions

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7070001

Chou, P K

The chemistry of a number of gas phase carbanions has been investigated utilizing a variable temperature flowing afterglow device. Bicyclobutane is sufficiently acidic to be deprotonated. It has a gas phase acidity of 398 [+-] 2 kcal/mol and an electron binding energy of 17.8 [+-] 7.6 kcal/mol. The conjugate base of tricyclo[4.1.0.0[sup 2,7]]heptane displayed identical thermodynamic and reactive properties relative to the bicyclobutyl anion. Bridgehead formyl- and cyano-substitution provides significant stabilization. Elevated temperature fluorodesilylation has been developed as technique by which basic carbanions can be conveniently produced. (E)-1-propenyl and (Z)-1-propeny anions are able to be generated stereospecifically by this method. This is the first demonstrated example of stereospecific carbanion syntheses in the gas phase. Reaction of O[sup [minus]] with bicyclobutane produces the radical anion of bicyclobutene. Utilizing values for proton affinity and electron binding energy allowed for the determination of thermodynamic quantities including the first experimental heat of formation of bicyclobutene. The unimolecular rearrangements of mono- and disubstituted byclopropyl anions were demonstrated to occur. Phenylcyclopropyl anion isomerizes at [approximately]200[degrees]C to the 2-phenylallyl anion. Higher temperatures ([approximately]260[degrees]C) are required to induce the rearrangement of formylcyclopropyl anion to the 2-formylallyl anion. Cyanocyclopropyl anion does not rearrange at temperatures up to [approximately]370[degrees]C. The conjugate base of dimethylcyclopropane-1,2-dicarboxylate rearranges to its corresponding allylic isomer at [approximately]75[degrees]C. Utilizing the Arrhenius equation, the activation energies for the processes were estimated for phenylcyclopropyl anion, formylcyclopropyl anion, cyanocyclopropyl anion, and the conjugate base of 1,2-dimethylcyclopropane-1,2-dicarboxylate.

• Research Organization: Minnesota Univ., Crookston, MN (United States)
• OSTI ID: 7070001
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACTIVATION ENERGY
ALKANES
ANIONS
CARBANIONS
CHARGED PARTICLES
CHEMICAL PROPERTIES
CHEMICAL REACTIONS
CYCLOALKANES
ENERGY
FLUIDS
GASES
HYDROCARBONS
IONS
ISOMERIZATION
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
STEREOCHEMISTRY
THERMODYNAMIC PROPERTIES