Mechanistic and synthetic studies of deuterium-labeled vinylcyclopropanes, cyclopropylallenes, and spiropentanes

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

OSTI ID:5600403

Olson, L P

A number of hydrocarbons were prepared and pyrolyzed in the gas phase to study stereochemistry and kinetic isotope effects in the isomerizations. Heating 1-(Z-1[prime]-tert-butyl-2[prime]-deuteriovinyl)-trans-2-trans-3-dideuteriocyclopropane to 290.0[degrees]C leads to the [l brace]1,3[r brace] sigmatropic rearrangement product 1-tert-butyl-3,4,5-trideuteriocyclopentene. Accompanying this rearrangement is a geometric isomerization of the ring deuteriums which occurs in a random fashion and is four times more rapid than rearrangement. The [l brace]1,3[r brace] shift occurs 75--100% via the Woodward-Hoffmann [open quotes]allowed[close quotes] suprafacial-inversion pathway, suggesting a concerted mechanism for rearrangement. At 311.6[degrees]C, there is a normal kinetic isotope effect (KIE) of 1.14 upon the [l brace]1,3[r brace] shift of 1[prime]-tert-butyl-2[prime],2[prime]-dideuteriovinylcyclopropane relative to its nondeuterated analogue. At 311.5[degrees]C, there is a normal KIE of 1.15 upon the [l brace]1,3[r brace] shift of 1-cyclopropyl-3,3-dideuterioallene relative to its nondeuterated analogue. trans-1,2-Bis(2[prime],2[prime]-dideuteriovinyl)-cyclopropane and its nondeuterated analogue were pyrolyzed over temperatures from 100 to 191[degrees]C. A normal KIE was observed upon the [l brace]3,3[r brace] shift to 1,4-cycloheptadiene. This KIE is relevant to understanding the mechanism of some [l brace]1,3[r brace] shifts, [l brace]3,3[r brace] shifts, and Diels-Alder reactions. The magnitude of the KIE was found to vary with temperature. trans-1,2-Diallenylcyclopropane rearranges at 196.4[degrees]C to give primarily the [l brace]3,3[r brace] shift product 3,4-dimethylene-1,5-cycloheptadiene. Study of the geometric isomerization of parent spiropentane will require analysis by polarimetry and infrared spectrometry, but in the case of phenylspiropentane, NMR may be used. Synthetic approaches to suitably deuterium-labeled spiropentanes were established.

• Research Organization: Indiana Univ., Bloomington, IN (United States)
• OSTI ID: 5600403
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALKANES
ALKENES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CYCLOALKANES
CYCLOALKENES
DECOMPOSITION
DEUTERIUM
DIELS-ALDER REACTION
EXTRAPOLATION
FRACTIONATION
HYDROCARBONS
HYDROGEN ISOTOPES
ISOMERIZATION
ISOTOPE EFFECTS
ISOTOPES
LABELLING
LIGHT NUCLEI
NUCLEI
NUMERICAL SOLUTION
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PYROLYSIS
SEPARATION PROCESSES
STABLE ISOTOPES
STEREOCHEMISTRY
SYNTHESIS
THERMOCHEMICAL PROCESSES