Selective Hydrogenation of 1,3‐Butadiene and 1‐Butyne over a Rh/Chitosan Catalyst Investigated by using Parahydrogen‐Induced Polarization

Hydrogenation of 1,3‐butadiene and 1‐butyne over the Rh/chitosan catalyst in gaseous and liquid phases was investigated by using the NMR and parahydrogen‐induced polarization technique. The Rh/chitosan system was a very selective catalyst for the partial hydrogenation of 1,3‐butadiene and 1‐butyne to 1‐ and 2‐butenes. The catalyst demonstrated high activity in the hydrogenation of 1‐butyne after its activation in the hydrogenation of 1,3‐butadiene. Therefore, the Rh/chitosan catalyst was used for the catalytic removal of 1,3‐butadiene and 1‐butyne from gaseous butene streams. Moreover, the syn ‐ and anti ‐addition of the hydrogen molecule to substrates proceeded in a pairwise manner in the gas phase heterogeneous hydrogenation as was demonstrated by parahydrogen‐induced polarization. However, in the liquid phase hydrogenation of 1‐butyne, both hydrogen atoms from the same hydrogen molecule were added to 1‐butyne only through the syn ‐addition route.