Hydrogenation of liquid carboxylated nitrile rubber (L-XNBR) was carri
ed out using homogeneous palladium and rhodium catalysts. It was obser
ved that the six-membered cyclic palladate complex of 2-benzoylpyridin
e, 1, reduces the carbon-carbon double bonds without affecting the nit
rile and carboxyl functionality. The intrinsic viscosity of the polyme
rs remains unchanged during hydrogenation. The glass transition temper
ature is marginally lowered for the hydrogenated products. A great ext
ent of decarboxylation was obtained for samples hydrogenated in presen
ce of the rhodium complex, 2.