Stereochemistry of anionic oligomerization, 22. Effects of chain length and stereochemistry on the kinetics of addition of 1,1‐diphenylethylene to oligomeric models of living poly(2‐vinylpyridine)lithium

Rate constants and equilibrium constants were determined for the addition of 1,1-diphenylethylene to living trimers of 2-vinylpyridine in THF having either a meso or a racemic diad adjacent to the carbanion center. The racemic isomer was shown to be slightly more reactive (≈40%) compared with the meso isomer and slightly less than the corresponding dimer. The living dimer of 2-vinylpyridine in turn is slightly more reactive than the meso trimer, but is five times less reactive compared to the lithio salt of 2-ethylpyridine. The changes in equilibrium constant were quite dramatic, the constant for lithio-2-ethylpyridine being about 100–200 times larger than for the living oligomers and about 2 600 times larger than that of the living polymer.