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تسجيل

Hydrogenation

المؤلف:  A. Ravve

المصدر:  Principles of Polymer Chemistry

الجزء والصفحة:  p574-575

2026-02-21

481

Hydrogenation

Atactic 1,4-polybutadiene and syndiotactic 1,2-polybutadiene can be hydrogenated at 100C and 50 bar pressure of hydrogen with a soluble catalyst {[(Ph)₃-P]₃RhCl}. Complete saturation of double bonds results [52]. Butadiene acrylonitrile copolymers can also be hydrogenated quantitatively with this rhodium catalyst under mild conditions [53]. The kinetics are consistent with a mechanism where the active Rh-catalyst interacts with the unsaturation at the polymer in the rate-determining step. The nitrile group, however, appears to also interact with the catalyst and inhibit the rates [53]. Hydrogenation of carbon-to-nitrogen double bonds in polymer backbones and in the pendant groups can be carried out with lithium borohydride [86]:

It was reported [485] that syndiotactic polystyrene can be hydrogenated over Ni/SiO₂ and Pd/BaSO₄ catalysts. The Ni catalyst yields complete hydrogenenation when low molecular weight polymer is used. Hydrogenation of high molecular weight polystyrene, however, is incomplete. On the other hand, the Pd catalyst yields completely hydrogenating material. The hydrogenated syndiotactic polystyrene is a crystalline material with good heat resistance.