Reactivities of Metal-Carbenes Toward Alkenes and Alkynes.
Abstract
Stabilized metal-carbenes like the P's in eqs 2 and 3 are very much more reactive toward phenylacetylene than toward cyclopentene (by a factor of 119-170) or cyclooctene (by a factor > 10 to the 4th power). The result is strange but accords with 1 (also a stabilized metal-carbene) reacting much faster with acetylenes than with alkenes. In contrast, unstabilized metal-carbenes like the C's in eqs 4 and 5 are more reactive toward the cycloalkenes (cyclopentene 6-8 fold, cyclooctene ca. > 24 fold) than toward the acetylene. These figures were derived by analyzing the kinetics of eqs 1-5, the simplest theory accounting for why phenylacetylene induces metatheses and why the yields and molecular weights of the polypentenamer formed by combining (phenylmethoxycarbene) pentacarbonyltungsten with phenylacetylene and cyclopentene decrease as the phenylacetylene concentration is increased. Evidence for the theory is found in gel permeation chromatograms of the polymers showing that polyalkenamer and polyacetylene units are linked. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 20, 1980
- Accession Number
- ADA092736
Entities
People
- Edward B. Savage
- Mridula Nair
- Steven J. Lee
- Thomas J. Katz
Organizations
- Columbia University