Modification of Polybutadiene: Chelation-Assisted Hydroacylation of α,ω-Diol with a Rhodium(I) Catalyst

Abstract

Chemical modification of polybutadiene was achieved by intermolecular hydroacylation of α,ω-diol with the vinyl group of polybutadiene using a rhodium(I) complex.

C-H activation - homogeneous catalysis - transition metals - polymers - rhodium

References and Notes

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<A NAME="RU05609ST-9">9</A>

The amount of hydroacylation of the vinyl groups was calculated by the following equation: incorporation rate (%) = e/(b+d+e) × 100, where ‘a’ is the internal olefin, ‘b’ is the unreacted terminal olefin, ‘c’ is the hydrogenated internal olefin, ‘d’ is the hydrogenated terminal olefin and ‘e’ is the hydroacylated vinyl group. a = (A-B/2)/T, b = B/T, c = C/T, d = 2/3D/T, e = E/T, where A is the area of the 5.3-5.6 ppm internal and vinylic -CH, B is the area of the 4.9-5.0 ppm integral (vinylic CH₂), D is the area of the 0.8-0.9 ppm integral (hydrogenated terminal olefin), E is the area of the 2.3-2.6 ppm integral (α-CH₂ to CO), and C = 55/45 (B+2/3D+E)-A+B/2. T = (A-B/2)+C+B+2/3D+E (T is the sum of the area of unreacted internal olefin, hydrogenated internal olefin, unreacted terminal olefin, hydrogenated terminal olefin, and hydroacylated vinyl group).

<A NAME="RU05609ST-10">10</A>

Monitoring the ratio of the integration of -CH₂OH and

a-CH₂ in the reaction of 1b with 7a revealed that the integration of the a-CH₂ group of -CH₂OH decreased as the amount of 7a used decreased. With less than 200 mol% of 7a, based on the amount of vinyl group in polybutadiene, less than a 1:4 ratio was determined, suggesting that some alcohol groups in 8a may further react with the other vinyl groups to afford intermolecular dicarbonyl polymers.