Thermal rearrangement studies of deuterium labeled dibenzo [a,e] cyclooctatetraenes

Author

Charles W. Wenger, New Jersey Institute of Technology

Document Type

Thesis

Date of Award

5-30-1982

Degree Name

Master of Science in Chemical Engineering - (M.S.)

Department

Chemical Engineering and Chemistry

First Advisor

Howard David Perlmutter

Second Advisor

David S. Kristol

Third Advisor

Richard B. Trattner

Abstract

In an attempt to further substantiate the findings of Stiles and Salisbury on the rearrangement of aryl disubstiuted dibenzo [a, e] cyclooctatetraenes a new pair of derivatives were synthesized. The 5,6 and 5,11 dideuteriodibenzo-[a,e] cyclcoctetetraenes were prepared. The 5,6 derivative was prepared starting with dibenzo [a,e] cyclooctene-5,6-dione. The 5,11 derivative was prepared starting with o-tolualdehyde. In the case of the 5,6 derivative the deuterium was introduced by a LiAlD₄ reduction of the dibenzo [a,e]-cyclooctene-5,6-dione. The 5,11 derivative had been labeled with deuterium in the final step during the Wittig reaction. The use of methanol-d₁ as the solvent in place of methanol facilitated the exchange. These compounds can be distinguished by proton nuclear magnetic resonance spectroscopy. The 5,6 derivative had a n.m.r. spectrum with a sharp singlet in the olefinic region. The 5,11 derivative had a n.m.r. spectrum with an unresolved triplet in the olefinic region. The corresponding 5,6 aryl disubstituted dibenzo [a,e] cycloocta-tetraenes were shown by Stiles and Salisbury to rearrange to the 5,11 isomer. Supporting evidence for a diradical intermediate was developed by use of benzenethiol in trapping experiments. Our thermolysis studies revealed no rearrangement with the deuterium labeled species. The temperature at which our experiments were conducted exceeds other published experimental data with aryl substituents which underwent yield rearrangements. Therefore the lack of stabilization by the deuterium as opposed to the phenyl substituents in this rearrangement lends credence to the diradical intermediates.

Recommended Citation

Wenger, Charles W., "Thermal rearrangement studies of deuterium labeled dibenzo [a,e] cyclooctatetraenes" (1982). Theses. 2030.
https://digitalcommons.njit.edu/theses/2030