A study of the kinetic isotope effects of elimination reactions involving isotopically engendered chirality: An ab initio study of the E2 elimination reaction

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6619442

Braden, M L

A new method of determining kinetic isotope effects (KIE) has been developed based upon optical rotation of isotopically engendered chiral compounds. This method can not only measure primary (1{degree}) KIE but also secondary (2{degree}) KIE which are not possible by mass spectral techniques. The mechanisms of the Hoffman, Cope, and E2 elimination reactions were studied using the optical rotation method to determine the 1{degree} and 2{degree} KIE. The syn 1{degree} KIE of (1S,2S)-N-n-butyl-N,N-dimethylcyclooctyl ammonium iodide-2d{sub 1} by a Hoffmann elimination (syn 1{degree} k{sub H}/k{sub D} = 1.40) or E2 elimination (syn 1{degree} d{sub H}/k{sub D} = 3.28) were measured for the formation of E-cyclooctene via a early transition state. Primary and secondary KIE provided evidence for a late transition state for the Cope elimination of syn (2R,3R)-3-amino-N,N,6,6-tetramethylbicyclo (3.1.1)heptane-N-oxide-2d{sub 1} (syn 1{degree} k{sub H}/k{sub D} = 2.22) and the anti-(2S,3R)-3-amino-N,N,6,6-tetramethylbicyclo (3.1.1) heptane-N-oxide-2d{sub 1} (2{degree} k{sub H}/k{sub D}) = 1.061. The mechanism of the E2 elimination of the corresponding bicyclic ammonium iodides and the bicyclic chlorides and bromides were also studied using 1{degree} and 2{degree} KIE determined by the optical rotation method. A study of the anionic oxy-Cope rearrangement using divinyl carbonols revealed that a chair transition state is more favorable that an boat revealed that a chair transition state is more favorable than a boat transition state. A theoretical study of the anti E2 elimination of HF from ethyl fluoride with hydride and cyanide anion and HCl from ethyl chloride with hydride ion provided evidence that the four electron three molecular orbital interactions are involved. These interactions help contribute to phase cancellation in the molecular orbitals leading to the transition state.

• Research Organization: Wayne State Univ., Detroit, MI (USA)
• OSTI ID: 6619442
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
ALKANES
ALKENES
CHEMICAL PREPARATION
CYCLOALKENES
DEUTERIUM
ELEMENTS
FLUORINE COMPOUNDS
HALOGEN COMPOUNDS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROGEN
HYDROGEN ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
NONMETALS
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
STABLE ISOTOPES
SYNTHESIS
TRACER TECHNIQUES