Selective hydrogenation of nitrile-butadiene rubber catalyzed by thermoregulated phase transfer phosphine rhodium complex

Hydrogenation of polymer having C=C double bond can be carried out with the metal-organic complex as catalyst, which has the property of themoregulated phase transfer. In this study, a new complex RhCl[PPh[(OCH₂CH ₂)_5âcirc6CH₃]₂]₃ (Rh/AEOPP) was synthesized with a good yield, which was further used as catalyst to selectively hydrogenated nitrile-butadiene rubber (HNBR). This is the first time that Rh/AEOPP complex was synthesized and applied in nitrile-butadiene rubber (NBR) hydrogenation. The result shows that hydrogenation degree of product (HNBR) can be extended to 90%, when the condition is [Cat] = 3% (based the weight of NBR), L₂: Cat (Weight Ratio) = 2, [NBR] = 5% (based on the weight of xylene solution), P (H₂) = 1.5 MPa, T = 155°C, and t = 8 h. Also, by adjusting temperature, the catalyst could be easily separated from products with 89% catalyst complex recovery. In addition, ¹H-NMR and infrared (IR) spectra showed that C=C double bonds in NBR was successfully hydrogenated without causing reduction of the CN group.