Disclosed herein are methods for recovering phosphorus-containing ligand from mixtures comprising organic mononitriles and organic dinitriles, using liquid-liquid extraction. Also disclosed are treatments to enhance extractability of the phosphorus-containing ligand.

Methods are described herein that involve rotating or gently mixing nickel(II)-containing particles in a reaction vessel while heating the particles and flowing a reducing atmosphere through the reaction vessel for a time sufficient to generate free-flowing nickel metal (Ni(0)) from the nickel(II)-containing particles.

Disclosed herein are methods for recovering phosphorus-containing ligand from mixtures comprising organic mononitriles and organic dinitriles, using liquid-liquid extraction. Also disclosed are treatments to enhance extractability of the phosphorus-containing ligand.

A novel nickel particulate form is provided that efficiently forms a zero-valent nickel complex with a phosphorus-containing ligands in an organic liquid to form a hydrocyanation catalyst. Particles in the nickel particulate form comprise nickel crystallites. For example, the nickel particulate form can have a BET Specific Surface Area of at least about 1 m.sup.2/gm; an average crystallite size less than about 20-25 nm, the nickel particulate form can have at least 10% of the crystallites in the nickel form can have can have a diameter (C10) of less than about 10 nm, and/or there are on average at least about 10.sup.15 surface crystallites per gram nickel. A ratio of BET SSA to C50 for the nickel particulate form can be at least about 0.110.sup.9 m/gm and preferably at least about 0.410.sup.9 m/gm. Methods of preparation and use are also provided.

In the hydrocyanation reaction of butadiene proceeding through pentenenitriles to adiponitrile, catalysis by complexes of zerovalent nickel with bidentate phosphorus-based ligands of the NiL.sub.2A type wherein L.sub.2 is a bidentate ligand and A is an unsaturated compound, can be rate-limited by the solubility of the catalytic complex. The present invention concerns solvent compositions for the nickel-ligand complex comprising mixtures of unsaturated nitriles that provide for increased metal solubility, particularly in the absence of a Lewis acid promoter, resulting in higher hydrocyanation reaction rates in an industrial-scale process for production of important nylon manufacturing intermediates. The mixed nitrile solvent compositions can include mixtures of pentenenitriles and/or methylbutenenitriles. The mixtures of mixed unsaturated nitriles can be, at least in part, from recycle streams from the hydrocyanation reaction for which the nickel-bidentate ligand complexes are used as catalysts.

The invention relates to a process for the purification of a contaminated organophosphorus product which comprises at least one organophosphorus compound and, as contaminant, at least one chlorine compound. It is based on the object of indicating a purification method in which the chlorine content of an organophosphorus product which comprises at least one organophosphorus compound and at least one chlorine compound as contaminant, can be reduced from originally 1000 to 100 000 ppm to a total chlorine content between 10 ppm and 10 000 ppm. This is achieved by a process with the steps: a) provision of the contaminated organophosphorus product; b) complete dissolution of the contaminated organophosphorus product in a solvent to give a contaminated solution; c) separation of the contaminated solution by means of a filter and/or by means of a membrane separation unit to give a purified solution; d) removal of the solvent from the purified solution to give a purified organophosphorus product.

A multidentate phosphite ligand is used in the catalytic synthesis of adiponitrile. The ligand is represented by the following general formula (I). The method of catalytic synthesis of adiponitrile comprises primary hydrocyanation, isomerization, and secondary hydrocyanation reactions, wherein the catalyst adopted each comprises a phosphite ligand-nickel complex composed of a nickel precursor and a multidentate phosphite ligand. The ligand molecule has a higher electron cloud density, and the phosphorus content capable of participating in coordination in the ligand molecule per unit mass is higher, so that the catalytic activity of the catalyst is improved, and the amount of the catalyst is reduced. ##STR00001##

A multidentate phosphite ligand comprising a backbone which comprises a substituted or unsubstituted spirobiindane compound and at least two organophosphite groups chemically bonded to the backbone, wherein the organophosphite groups are alkyl phosphite groups or wherein the organophosphite groups are aryl phosphite groups, wherein the aryl moieties on the aryl phosphite groups are phenyl rings substituted with one or more C.sub.1-C.sub.4 alkyl groups; or which comprises a substituted or unsubstituted spirodifluorene compound and at least two organophosphite groups chemically bonded to the backbone.

A multidentate phosphite ligand comprises an iptycene backbone in which the iptycene is optionally substituted with one or more C1 to C4 alkyl substituents, and at least two aryl phosphite groups chemically bonded to the backbone.

A ligand which contains arsenic and has the formula (I): where n is 2 and the ligand is bidentate; each X is O or NH; and Ar.sup.1 and Ar.sup.2 may be the same or different and each is an aryl group, provided that each Ar.sup.1 group connected to the same As atom may be combined to form a single aryl group.