Patent ID: 7767864

Claim:
A process for the hydroformylation of ethylenically unsaturated compounds, which process comprises reacting said ethylenically unsaturated compound with carbon monoxide and hydrogen, in the presence of a catalyst system, the catalyst system obtainable by combining: a) a Group VIII metal compound; and b) a bidentate compound of general formula (Ia) wherein: R is a bridging group selected from the group consisting of: an alkylene group; and A-Ar—B, in which Ar is an optionally substituted aryl moiety to which A and B are linked on available adjacent carbon atoms, and A and B each independently represent lower alkylene; R 1 to R 12 each independently represent lower alkyl, aryl or Het; Q 1 and Q 2 each independently represent phosphorus, arsenic or antimony, the process characterized in that a chlorine moiety is present in at least said Group VIII metal compound.