Extraction solvent control for reducing stable emulsions

A process for recovering diphosphonite-containing compounds from a feed mixture comprising diphosphonite-containing compounds, organic mononitriles, organic dinitriles and a Lewis acid in a multistage countercurrent liquid-liquid extractor with extraction solvent comprising aliphatic hydrocarbon, cycloaliphatic hydrocarbon or a mixture of aliphatic and cycloaliphatic hydrocarbon, said process comprising:

• a) flowing the feed mixture to the first stage of the multistage countercurrent liquid-liquid extractor;
• and
• b) contacting the feed mixture with extraction solvent in the multistage countercurrent liquid-liquid extractor,
• wherein the multistage countercurrent liquid-liquid extractor comprises at least 2 stages, wherein each stage of the multistage countercurrent liquid-liquid extractor comprises a mixing section and a settling section, wherein the mixing section provides a mixed phase comprising a light phase and a heavy phase, wherein a light phase separates from a heavy phase in the settling section, wherein a mixed phase, which comprises both a heavy phase and a light phase, is present in the settling section between the light phase and the heavy phase, wherein the light phase comprises extraction solvent and extracted diphosphonite-containing compounds, wherein the heavy phase comprises organic mononitriles and organic dinitriles, wherein at least a portion of the light phase is withdrawn from the settling section of the first stage and treated to recover diphosphonite-containing compounds extracted into the light phase, wherein at least a portion of the heavy phase from the first stage is passed to the second stage of the multistage countercurrent liquid-liquid extractor, wherein fresh extraction solvent is fed to the final stage, wherein light phase from the second stage is fed to the first stage, and wherein the process further comprises at least one of the following additional steps:
• (i) withdrawing a portion of the heavy phase from the settling section of the first stage of the multistage countercurrent liquid-liquid extractor and recycling the withdrawn heavy phase to the settling section of the first stage of the multistage countercurrent liquid-liquid extractor;
• or
• (ii) withdrawing a portion of the light phase from the settling section of the first stage of the multistage countercurrent liquid-liquid extractor and recycling the withdrawn light phase to the mixing section of the first stage of the multistage countercurrent liquid-liquid extractor.