Extraction of nickel (0) complexes from nitrile mixtures with reduced rag formation

A process for extractively removing homogeneously dissolved catalysts from a reaction effluent of a hydrocyanation of unsaturated mononitriles to dinitriles reaction with a hydrocarbon H, comprising

• a) concentrating the reaction effluent before step b) by distillation at pressures of from 0.1 to 5000 mbar and temperatures of from 10 to 150° C.,
• b) adding a hydrocarbon H to the concentrated reaction effluent to obtain a stream I, and
• c) feeding stream I, without prior separation of liquid phases, into an extraction apparatus and extracting it at a temperature T with the hydrocarbon H to obtain a stream II comprising the hydrocarbon H enriched with the catalyst and a stream III having a low catalyst content,
• further comprising treating the reaction effluent with ammonia or a primary, secondary or tertiary, aromatic or aliphatic amine before step b), or treating stream I with ammonia or the primary, secondary or tertiary, aromatic or aliphatic amine.