Abstract: Iron nitrosyl carbonyl is prepared by electrochemically reducing either an iron nitrosyl halide or a mixture of iron chloride and a source of NO in the presence of CO. Constant current or constant potential is used to effect the reduction.

Abstract: Catalysts suitable for the dimerization of a diolefin, e.g. butadiene to 4-vinylcyclohexene, are prepared by reacting (1) iron chloride and sodium nitrite or alternatively (2) iron nitrosyl chloride with (3) carbon monoxide in an organic solvent in the presence of iron. The catalyst solution is preferably filtered prior to use. While the reaction employing iron chloride and sodium nitrile is preferred, the catalyst produced by either method contains a minimum of reducing agent and by-products. It can be isolated and stored in the absence of diolefin monomer and carbon monoxide while retaining its stability and activity.

Abstract: Iron nitrosyl carbonyl catalyst is prepared by dissolving impure iron nitrosyl carbonyl in a solvent solution, then adding sufficient miscible non-solvent to the solution to result in separation of the mixture into an upper layer and a lower layer containing iron nitrosyl carbonyl. Preferably, the solvent is used in preparation of the iron nitrosyl carbonyl, and the solution is, therefore, the product of the preparation. The miscible non-solvent is added to the product solution to effect separation of layers for isolation of purified iron nitrosyl carbonyl product.

Abstract: Catalysts suitable for the dimerization of a diolefin, e.g. butadiene to 4-vinylcyclohexene, are prepared by reacting (1) iron chloride and sodium nitrite or alternatively (2) iron nitrosyl chloride with (3) carbon monoxide in an organic solvent in the presence of a readily oxidizable metal, e.g. tin. The catalyst solution is filtered prior to use to remove particulate matter such as unreacted tin.While the reaction employing iron chloride and sodium nitrite is preferred, the catalyst produced by either method contains a minimum of reducing agent and by-products. It can be isolated and stored in the absence of the butadiene monomer while retaining its stability and activity.