HK1189190A - Extraction solvent control for reducing stable emulsions - Google Patents

Abstract

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

Description

Extraction solvent control for reduced stable emulsion

RELATED APPLICATIONS

This application claims the benefit of provisional application No. 61/578,495 filed on 21/12/2011, which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to the recovery of catalyst and ligand from a hydrocyanation reaction product mixture comprising organic dinitriles using liquid-liquid extraction.

Background

It is well known in the art that complexes of nickel with phosphorous-containing ligands can be used as catalysts in hydrocyanation reactions. It is known to catalyze the hydrocyanation of butadiene using these nickel complexes of monodentate phosphites to produce a mixture of pentenenitriles. These catalysts can also be used in the subsequent hydrocyanation of pentenenitriles to produce adiponitrile, an important intermediate in the production of nylon. It is also known that bidentate phosphite and phosphinite ligands can be used to form nickel-based catalysts to carry out these hydrocyanation reactions.

U.S. Pat. No. 3,773,809 describes a process for the recovery of Ni complexes of organophosphites from organic nitrile-containing product liquors produced by hydrocyanating ethylenically unsaturated organic mononitriles such as 3-pentenenitrile by extraction of the product liquor with an alkane or cycloalkane solvent. Similarly, U.S. Pat. No. 6,936,171 to Jackson and McKinney discloses a process for recovering diphosphite-containing compounds from a stream containing dinitriles.

U.S. Pat. No. 4,339,395 describes the formation of an interfacial rag layer (rag layer) during an extended period of continuous extraction of a particular phosphite ligand. The' 395 patent states: interfacial debris hinders, if not stops, phase separation. Because the process is run continuously, debris must be continuously removed from the interface as it accumulates to avoid interrupting the run. To address this problem with the disclosed components, the' 395 patent discloses the addition of a relatively small amount of ammonia that is substantially free of water.

Summary of The Invention

The process recovers diphosphite-containing compounds from a mixture comprising diphosphite-containing compounds, organic mononitriles and organic dinitriles.

Disclosed is a process for recovering diphosphite-containing compounds from a feed mixture comprising diphosphite-containing compounds, organic mononitriles and organic dinitriles 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 a first stage of a multistage countercurrent liquid-liquid extractor; and

b) contacting the feed mixture with an extraction solvent in a multistage countercurrent liquid-liquid extractor;

wherein a first stage of the multistage countercurrent liquid-liquid extractor comprises a mixing section and a settling section, wherein a light phase is separated from a heavy phase in the settling section, wherein a mixed phase comprising both the heavy phase and the light phase is present between the light phase and the heavy phase in the settling section, wherein the light phase comprises an extraction solvent and extracted diphosphite-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 and treated to recover diphosphite-containing compounds extracted into the light phase, wherein a first portion of the heavy phase is sent to a second stage of the multistage countercurrent liquid-liquid extractor, and wherein a second portion of the heavy phase is withdrawn from the settling section of the first stage of the multistage countercurrent liquid-liquid extractor and recycled to the settling section of the first stage of the multistage countercurrent liquid-liquid extractor.

The mixing sections of the stages of the multistage countercurrent liquid-liquid extractor form a homogeneous mixture of the unseparated light and heavy phases. The homogeneous mixture comprises an emulsion phase. The emulsion phase may or may not include a particulate solid material. The emulsion phase separates into a light phase and a heavy phase in the settling section of the stages including the first stage. Thus, the settling section of a stage will contain at least some emulsion phase between the upper light phase and the lower heavy phase. The emulsion phase tends to reduce in size over time. However, in some cases, settling takes longer than necessary or the emulsion phase never completely separates into a light phase and a heavy phase. This separation problem can be particularly problematic in the first stage of a multistage countercurrent liquid-liquid extractor.

It has been found that the recirculation of the heavy phase in the separation section of the first stage results in an enhanced settling of the emulsion phase. For example, the recirculation may result in a reduction in the size of the emulsion phase in the settling section, wherein the size of the emulsion phase is based on the size of the emulsion phase in the absence of recirculation of the heavy phase. Enhanced settling in the settling section can also be measured as an increased rate of settling, based on the rate of settling in the absence of recycle of the heavy phase.

Another problem that can be solved by recycling of the heavy phase is the formation of debris and the accumulation of debris layers in the settling section. Debris formation is discussed in U.S. patent No. 4,339,395 and U.S. patent No. 7,935,229. The fragments comprise particulate solid matter and may be considered in the form of an emulsion phase, which is particularly stable in the sense that it does not dissipate for a practical amount of time for carrying out the extraction process. Debris can form in the mixing or settling section of an extraction stage, particularly in the first stage of a multistage countercurrent liquid-liquid extractor. In the settling section, the chips form a layer between the heavy and light phases. The formation of rag layers in the settling section inhibits proper settling of the heavy and light phases. The formation of rag layers can also inhibit the extraction of diphosphite-containing compounds from the heavy phase into the light phase. In a worst case scenario, debris can accumulate to the point of completely filling the separation section, forcing the extraction process to shut down to clean the settling section. It has been found that the recirculation of the heavy phase in the settling section can reduce or eliminate the size of the rag layer or reduce the rate of its formation based on the size and rate of formation of the rag layer in the absence of recirculation of the heavy phase.

Thus, the recycling of the heavy phase in the settling section of the first stage of the multistage countercurrent extractor can achieve at least one of the following results: (a) a reduction in the size of the emulsion phase in the settling section based on the size of the emulsion phase in the absence of recycle of the heavy phase; (b) an increase in the rate of settling in the settling section based on the rate of settling in the absence of recycle of the heavy phase; (c) an increase in the amount of diphosphite-containing compounds in the light phase based on the amount of diphosphite-containing compounds in the light phase in the absence of recycle of the heavy phase; (d) a partial or complete reduction in the size of the rag layer in the settling section based on the size of the rag layer in the settling section in the absence of recycle of the light phase; and (e) a reduction in the rate of formation of the rag layer in the settling section based on the rate of formation of the rag layer in the settling section in the absence of recycle of the heavy phase.

The second portion of the heavy phase recycled in the first stage may be recycled to the settling section in the absence of an intermediate step to remove diphosphite-containing compounds from the heavy phase.

The second portion of the heavy phase recycled in the first stage may be recycled to the settling section without passing through another liquid-liquid extraction stage.

The extraction solvent feed from the second stage of the multistage countercurrent liquid-liquid extractor to the first stage of the multistage countercurrent liquid-liquid extractor may comprise at least 1000ppm, for example 2000 to 5000ppm diphosphite-containing compounds. The extraction solvent feed from the second stage may comprise at least 10ppm, for example 20 to 200ppm, of nickel.

The Raffinate Recycle Ratio (RRR) may be from 0.1 to 0.9, for example, from 0.2 to 0.8, wherein RRR is defined by a ratio of X to Y, wherein X is the mass per unit time of the second portion of the heavy phase recycled to the settling section of the first stage of the multistage countercurrent liquid-liquid extractor, and wherein Y is the mass per unit time of the entire heavy phase withdrawn from the settling section of the first stage of the multistage countercurrent liquid-liquid extractor.

The diphosphite-containing compound can be a Ni complex having a diphosphite ligand selected from the group consisting of:

(R¹O)₂P(OZO)P(OR¹)₂，

I

and is

Wherein in I, II and III, R¹Being unsubstituted or substituted by one or more C₁To C₁₂Alkyl or C₁To C₁₂Alkoxy-substituted phenyl; or unsubstituted or substituted by one or more C₁To C₁₂Alkyl or C₁To C₁₂Alkoxy-substituted naphthyl; and wherein Z and Z¹Independently selected from the group consisting of structural formulas IV, V, VI, VII, and VIII:

and wherein

R²、R³、R⁴、R⁵、R⁶、R⁷、R⁸And R⁹Independently selected from H, C₁To C₁₂Alkyl, and C₁To C₁₂Alkoxy groups;

x is O, S or CH (R)¹⁰)；

R¹⁰Is H or C₁To C₁₂An alkyl group;

and wherein

R¹¹And R¹²Independently selected from H, C₁To C₁₂Alkyl, and C₁To C₁₂Alkoxy and C0₂R¹³A group of components selected from the group consisting of,

R¹³is C₁To C₁₂Alkyl, or unsubstituted or substituted by C₁To C₄Alkyl substituted C₆To C₁₀An aryl group;

y is O, S or CH (R)¹⁴)；

R¹⁴Is H or C₁To C₁₂An alkyl group;

wherein

R¹⁵Is selected from H, C₁To C₁₂Alkyl, and C₁To C₁₂Alkoxy and CO₂R¹⁶A group of components selected from the group consisting of,

R¹⁶is C₁To C₁₂Alkyl, unsubstituted or substituted by C₁To C₄Alkyl substituted C₆To C₁₀Aryl radicals，

And wherein

For structural formulae I to VIII, C₁To C₁₂Alkyl and C₁To C₁₂The alkoxy group may be linear or branched.

At least one stage of the extraction may be carried out at a temperature above 40 ℃.

At least one stage of the extraction may contain a lewis base.

If at least one stage of the extraction contains a Lewis base, the Lewis base may be a monodentate triarylphosphite in which the aryl groups are unsubstituted or substituted with alkyl groups having from 1 to 12 carbon atoms, and in which the aryl groups may be linked to one another.

The lewis base may optionally be selected from the group consisting of:

a) anhydrous ammonia, pyridine, alkylamines, dialkylamines, trialkylamines, wherein the alkyl group has 1 to 12 carbon atoms; and

b) a polyamine.

If the lewis base is a polyamine, the polyamine may include at least one selected from the group consisting of: hexamethylenediamine, and dimers and trimers of hexamethylenediamine, for example, bis-hexamethylenetriamine.

The Lewis base may optionally include a basic ion exchange resin, for example, AmberlystAnd (3) resin.

One example of a suitable cyclic alkane extraction solvent is cyclohexane.

At least a portion of the process may be carried out in an extraction column or a mixer-settler.

The feed mixture may be an effluent stream from the following process: hydrocyanation processes, for example, processes for hydrocyanating 3-pentenenitrile, processes for the monohydrocyanation of 1, 3-butadiene to pentenenitrile or processes for the double hydrocyanation of 1, 3-butadiene to adiponitrile.

The first stage of the multistage countercurrent liquid-liquid extractor can occur in an extraction column. The entire column can be considered to be a settling section comprising a mixing section between the heavy phase collection section and the light phase collection section. The heavy phase may be recycled to the mixing section of the extraction column.

The first stage of the multistage countercurrent liquid-liquid extractor may occur in a mixer-settler. The mixer settler may comprise a settling section separate from the mixing section. The recycled heavy stream may be recycled upstream of the point of withdrawal of said recycled heavy stream.

Brief Description of Drawings

Fig. 1 is a diagram showing the flow of fluids through a multistage countercurrent liquid-liquid extractor.

Fig. 2 is a diagram showing the recycle of the heavy phase in the settling section of one stage of a multistage countercurrent liquid-liquid extractor.

Fig. 3 is a diagram showing the recycle of the heavy phase in the settling section of the extraction column.

Figure 4 is a diagram showing the recirculation of the heavy phase in the settling section of a mixing/settling device having three chambers in the settling section.

Figure 5 is a graph showing the level of debris in the settler during catalyst extraction in continuous operation.

Detailed Description

The process of the present invention includes a process for recovering diphosphite-containing compounds from a mixture comprising diphosphite-containing compounds and organic dinitriles using liquid-liquid extraction.

Fig. 1 is a diagram of a multistage countercurrent liquid-liquid extractor. The lines in fig. 1 represent the flow of matter, rather than any particular type of instrument, such as a pipe. Similarly, the blocks in this figure represent stages or stages for mixing and settling, rather than any particular type of instrument.

Three stages are depicted in fig. 1. The first stage is depicted by mixing and settling section 1. The second stage is depicted by mixing and settling section 2. The final stage is depicted by mixing and settling section 3. The void 30 represents a space in which additional stages may be inserted. For example, one or more, such as one to four, mixing and settling sections may be inserted in the interspace 30 between the mixing and settling section 2 and the mixing and settling section 3.

In fig. 1, a fresh extraction solvent feed, such as cyclohexane, is introduced into a multistage countercurrent extractor via line 10. The extraction solvent or light phase from the mixer-settler section 3 is passed via line 12 to the next stage of the multistage extractor. In a multistage countercurrent liquid-liquid extractor with three stages, the extraction solvent in line 12 will pass directly into stage 2 via line 14. The extraction solvent from stage 2 enters stage 1 via line 16. The extraction solvent containing the extracted diphosphite-containing compounds exits the stage 1 mixing and settling section via line 18.

A feed comprising diphosphite-containing compounds is fed via line 20 to the stage 1 mixer and settler. The feed also comprises: a mixture comprising organic mononitriles and dinitriles immiscible with the extraction solvent. In stage 1, a portion of the diphosphite-containing compounds is extracted into the extraction solvent, which exits stage 1 via line 18. Immiscible dinitrile and mononitrile mixtures or heavy phases are removed from stage 1 mixing and settling section through line 22 and sent to stage 2 mixing and settling section. A portion of the diphosphite-containing compounds is extracted into the light phase in stage 2 mixing and settling section. The heavy phase leaves the stage 2 mixing and settling section via line 24. Similarly, if additional stages are present in the void 30 shown in fig. 1, extraction of diphosphite-containing compounds will occur in such intermediate stages in a manner similar to that which occurs in stage 2.

After the heavy phase passes through the first stage and any intermediate stages, it passes through the final mixing and settling section 3. In particular, the heavy phase is introduced into the mixing and settling section 3 through line 26. After passing through the final mixing and settling section 3, the heavy phase exits via line 28.

The two-stage multistage countercurrent liquid-liquid extractor is represented in fig. 1 by mixing and settling sections 1 and 2; lines 14, 16 and 18 show the direction of extraction solvent flow; and lines 20, 22 and 24 show the direction of heavy phase flow. In a two-stage multistage countercurrent liquid-liquid extractor, a mixing and settling section 3; lines 10, 12, 26 and 28; and the void 30 is omitted. In the two-stage countercurrent liquid-liquid extractor, the extraction solvent containing the extracted diphosphite-containing compounds exits the extractor through line 18 and the extracted heavy phase, raffinate, exits the extractor through line 24.

Thus, it can be seen that a multistage countercurrent liquid-liquid extractor comprises two or more stages with countercurrent flow of extraction solvent and heavy phase.

Figure 2 is a schematic representation of one type of mixing and settling section, also referred to herein as a mixer-settler. A mixer-settler of this type may be used in any of the stages shown in fig. 1. The mixer-settler comprises a mixing section 40 and a settling section 50. The mixing section 40 and the settling section 50 are separate. The entire effluent from the mixing section 40 flows into the settling section 50. The fluid from the mixing section 40 flows through the settling section 50 in a horizontal manner, although there is no restriction on the movement of fluid vertically through the settling section 50.

The extraction solvent is introduced into mixing section 40 via line 42. A feed comprising diphosphite-containing compounds is introduced into mixing section 40 via line 44. Alternatively, the contents of lines 42 and 44 may be combined upstream of mixing section 40 and introduced into mixing section 40 through a single inlet. The two feeds are mixed in the mixing section 40 to provide a mixed phase comprising an emulsion phase, represented in figure 2 by the shaded area 46.

Line 48 represents the flow of mixed phase 46 from mixing section 40 into settling section 50. As depicted in fig. 2, there are three phases in the settling section 50, including a heavy phase 52, a mixed phase 54, and a light phase 56. Due to the extraction of diphosphite-containing compounds into light phase 56, heavy phase 52 is depleted of diphosphite-containing compounds, provided it has a lower concentration of diphosphite-containing compounds than the concentration of diphosphite-containing compounds in feed 44. Accordingly, light phase 56 is enriched in diphosphite-containing compounds due to the extraction of diphosphite-containing compounds into light phase 56, provided that it has a higher concentration of diphosphite-containing compounds than the concentration of diphosphite-containing compounds in extraction solvent feed 42. The heavy phase 52 exits the settling section 50 via line 58. At least a portion of the light phase 56 is removed from the settling section 50 via line 60, and optionally another portion of the light phase 56 may be removed from the settling section 50 and recycled to the mixing section 40 or to the settling section 50 via a line not shown in fig. 2.

Although not shown in fig. 2, which schematically illustrates the flow of fluid, it should be understood that each of the mixing section 40 and settling section 50 may include one or more stages, sub-sections, compartments or chambers. For example, settling section 50 can include more than one chamber between the point at which mixed phase 46 is introduced via line 48 and the point at which the light and heavy phases are withdrawn via lines 58, 60, and 62. The horizontal extension between the point of introduction of the mixed phase 46 through line 48 and the point of withdrawal of the light and heavy phases through lines 58, 60 and 62 facilitates the settling of the light and heavy phases 56 and 52. The size of the mixed phase 54 may become progressively smaller as the fluid settles and flows through the chamber. For example, the last chamber from which the fluid is removed may contain little or no mixed phase 54. It should also be understood that the mixing section 40 may include one or more types of mixing devices, such as impellers, not shown in fig. 2.

Figure 3 provides a representation of another type of apparatus for use as a mixing and settling section. An apparatus 70 of the type shown in fig. 3 is referred to herein as an extraction column. The extraction column 70 includes a mixing section 72, a heavy phase collection section 74 and a light phase collection section 76. The entire column 70 can be considered to be a settling section with a mixing section between the harvesting section 74 and the harvesting section 76. In the extraction column 70, the mixing section 72 is part of the settling section. Extraction solvent is introduced into column 70 via line 80. The heavier phase comprising diphosphite-containing compounds is introduced into column 70 via line 90. As the light phase passes upward through the column and the heavy phase passes downward through the column, a mixture of the two phases is formed in the mixing section 72. The mixture is shown in figure 3 as shaded mixed phase 84. The mixed phase 84 may comprise an emulsion phase. The point of introduction of the heavy phase via line 90 should be sufficiently higher than the point of introduction of the light phase to allow for adequate mixing of the two phases in the mixing section, resulting in extraction of diphosphite-containing compounds into the light phase. Intimate mixing of the light and heavy phases in the mixing section 72 may be facilitated by mechanical or static mixing devices not shown in fig. 3. For example, the mixing section 72 may include baffles or perforated plates not shown in FIG. 3.

The heavy phase 82 is deposited into the collection section 74 and exits the column 70 through line 96. The light phase 86 is deposited in the collection section 76 and exits the column via line 92. The heavy phase 82 settles to the collection section 74 and exits the column 70 through line 96. A portion of this heavy phase is withdrawn as a side stream via line 94 and passed into mixing section 72 as recycle to column 70. Alternatively, line 94 may be taken directly from the harvesting section 74, instead of being taken as a side stream from line 96. In another alternative embodiment, line 94 may flow directly into line 80 or column 72 at a point near the interface of mixed phase 84 and heavy phase 82.

The recycle of the heavy phase to the settling section of extractor 70 increases the downward flow of the heavy phase in the settling section. Without wishing to be bound by any theory, it is theorized that this increased downward flow may tend to disrupt the emulsion phase that may otherwise tend to form in the settling section. When present, the emulsion phase may form at the interface of the mixed phase 84 and the heavy phase 82. Thus, the introduction point of the recycled heavy phase, e.g., through line 94 as shown in fig. 3, should be sufficiently above the point at which the emulsion phase will form to allow the heavy phase to flow downward through that point.

Fig. 4 provides an illustration of a mixer-settler 100 with multiple settling stages. The mixer-settler 100 has a mixing section 110 and a settling section 112. In the mixer-settler 100, the mixing section 110 is separated from the settling section 112. The settling section has three compartments, represented in fig. 4 as sections 114, 116 and 118. The segments are separated by a convergence plate 120. The convergence plate 120 may be designed to provide flow of separate light and heavy phases between the chambers while restricting the flow of the emulsion phase between the chambers. The feed comprising diphosphite-containing compounds enters mixing section 110 via line 130. The extraction solvent is introduced into mixing section 110 via line 132. The mixing section 110 includes an impeller 134 mounted on a shaft 136 to provide mechanical mixing of the fluid. The mixing of the feeds provides a mixed phase comprising an emulsion phase, represented in fig. 4 by the shading 140.

The mixed phase 140 flows as an overflow from the mixing section 110 into the settling section 112. The mixed phase 140 is prevented from flowing directly into the light phase 144 by the baffle 142. As settling occurs in settling section 112, mixed phase 140 decreases in volume, light phase 144 increases in volume, and heavy phase 146 increases in volume. The heavy phase 146 is removed from the settling section 112, particularly from chamber 118, via line 152, and the light phase 144 is removed from the settling section 112, particularly from chamber 118, via line 150. A portion of the heavy phase removed via line 152 is withdrawn as a side stream via a line not shown in fig. 4 and introduced back into settling section 112 at a suitable point in section 114. The vertical point at which line 154 is introduced into section 114 can be, for example, at or near the interface of mixed phase 140 and heavy phase 146.

The recycle of the heavy phase 146 into the settling section increases the horizontal flow of the heavy phase 146 relative to the horizontal flow of the mixed phase 140 and the light phase 144 through the settling section 112. Without being bound by any theory, it is speculated that the tendency for emulsion phase stabilization may generally be reduced by an increase in the flow of the heavy phase 146 at the interface between the heavy phase 146 and the mixed phase 140 relative to the flow of the mixed phase 140 and the heavy phase 146. In particular, it is speculated that the increased horizontal flow of the heavy phase 146 may result in mild agitation or shear at the interface of the heavy phase 146 and the mixed phase 140 that may otherwise tend to form a stable emulsion phase. It is also speculated that the downward flow of the heavy phase through the emulsion phase or rag layer may tend to force the emulsion phase or rag layer downward toward or into the heavy phase, thereby tending to disrupt the emulsion phase or rag layer.

It is desirable to maximize the horizontal displacement between the withdrawal point and the re-entry point of the re-circulation stream. For example, in a multi-chamber settling section, the heavy phase 146 may be removed from the chambers, e.g., from the chamber 118 furthest from the point of introduction of the mixed phase 146 from the mixing section 110 into the settling section 112, and the recycled heavy phase 146 may be reintroduced into the settling section 112 at a point near the introduction of the mixed phase 146 from the mixing section 110 into the settling section 112. For example, one point where the recycled heavy phase 146 may be introduced into the settling section 112 is a point upstream of the baffle 142 where the mixed phase 140 overflows from the mixing section 110 into the settling section 112.

It is convenient for both the mononitriles and the dinitriles to be present in a countercurrent contactor. For a discussion of the role of monodentate and bidentate ligands in the extraction of hydrocyanation reactor effluent streams, see U.S. Pat. No. 3,773,809 to Walter and U.S. Pat. No. 6,936,171 to Jackson and McKinney.

For the processes disclosed herein, suitable ratios of mononitrile to dinitrile components include from 0.01 to 2.5, e.g., from 0.01 to 1.5, e.g., from 0.65 to 1.5.

The maximum temperature is limited by the volatility of the hydrocarbon solvent employed, but recovery generally improves with increasing temperature. Examples of suitable operating ranges are 40 ℃ to 100 ℃, and 50 ℃ to 80 ℃.

Controlled addition of monophosphite ligand can enhance settling. Examples of monophosphite ligands that may be used as additives include those disclosed in U.S. Pat. No. 3,496,215 to Drinkard et al, U.S. Pat. No. 3,496,217, U.S. Pat. No. 3,496,218, U.S. Pat. No. 5,543,536, and published PCT application WO 01/36429 (BASF).

The addition of the lewis base compound to the mixture comprising the diphosphite-containing compound, the organic mononitrile, and the organic dinitrile may enhance precipitationEspecially when the mixture contains a Lewis acid, e.g. ZnCl₂Then (c) is performed. The addition may occur before or during the extraction process in a multistage countercurrent extractor. Examples of suitable weak lewis base compounds include water and alcohols. Suitable stronger Lewis base compounds include hexamethylenediamine, dimers and trimers of hexamethylenediamine, ammonia, aryl-or alkylamines, such as pyridine or triethylamine, or basic resins, such as AmberlystA commercially available basic resin manufactured by Rohm and Haas. The addition of lewis base can reduce or eliminate any lewis acid inhibiting effect on catalyst recovery.

Diphosphite-containing compounds extracted by the methods described herein are also referred to herein as bidentate phosphorus-containing ligands. These extracted ligands comprise free ligands (e.g., those not complexed with a metal such as nickel) and those complexed to a metal such as nickel. Thus, it will be appreciated that the extraction processes described herein can be used to recover diphosphite-containing compounds that are metal/ligand complexes, such as complexes of zero-valent nickel with at least one ligand comprising a bidentate phosphorus-containing ligand.

Suitable ligands for extraction are bidentate phosphorous-containing ligands selected from the group consisting of bidentate phosphites and bidentate phosphinites. Preferred ligands are bidentate phosphite ligands.

Diphosphite ligands

Examples of bidentate phosphite ligands that may be used in the present invention include those having the following structural formula:

wherein in I, II and III, R¹Being unsubstituted or substituted by one or more C₁To C₁₂Alkyl or C₁To C₁₂Alkoxy-substituted phenyl; or unsubstituted or substituted by one or more C₁To C₁₂Alkyl or C₁To C₁₂Alkoxy-substituted naphthyl; and Z¹Independently selected from the group consisting of structural formulas IV, V, VI, VII, and VIII:

and wherein

R²、R³、R⁴、R⁵、R⁶、R⁷、R⁸And R⁹Independently selected from H, C₁To C₁₂Alkyl, and C₁To C₁₂Alkoxy groups;

x is O, S or CH (R)¹⁰)；

R¹⁰Is H or C₁To C₁₂An alkyl group;

and wherein

R¹¹And R¹²Independently selected from H, C₁To C₁₂Alkyl, and C₁To C₁₂An alkoxy group; and CO₂R¹³A group of components selected from the group consisting of,

R¹³is C₁To C₁₂Alkyl or unsubstituted or substituted by C₁To C₄Alkyl substituted C₆To C₁₀An aryl group;

y is O, S or CH (R)¹⁴)；

R¹⁴Is H or C₁To C₁₂An alkyl group;

wherein

R¹⁵Selected from the group consisting of H, C₁To C₁₂Alkyl, and C₁To C₁₂Alkoxy and CO₂R¹⁶Group consisting of:

R¹⁶is C₁To C₁₂Alkyl or unsubstituted or substituted by C₁To C₄Alkyl substituted C₆To C₁₀And (4) an aryl group.

In the structural formulae I to VIII, C₁To C₁₂Alkyl and C₁To C₁₂The alkoxy group may be linear or branched.

Another example of a bidentate phosphite ligand of formula which may be used in the process of the present invention is one having the formula X shown below:

further examples of bidentate phosphite ligands useful in the process of the present invention include those having the formulae XI to XIV shown below, wherein for each formula, R is¹⁷Selected from the group consisting of methyl, ethyl or isopropyl, and R¹⁸And R¹⁹Independently selected from H or methyl:

further examples of bidentate phosphite ligands useful in the process of the present invention include ligands selected from members of the group represented by formulas XV and XVI, wherein all identical reference symbols have the same meaning, except as further explicitly defined:

wherein

R⁴¹And R⁴⁵Independently selected from C₁To C₅Group consisting of hydrocarbon radicals, and R⁴²、R⁴³、R⁴⁴、R⁴⁶、R⁴⁷And R⁴⁸Each is independently selected from the group consisting of H and C₁To C₄A hydrocarbon group.

For example, the bidentate phosphite ligand may be selected from a member of the group represented by formula XV and formula XVI, wherein

R⁴¹Is methyl, ethyl, isopropyl or cyclopentyl;

R⁴²is H or methyl;

R⁴³is H or C₁To C₄A hydrocarbyl group;

R⁴⁴is H or methyl;

R⁴⁵is methyl, ethyl or isopropyl; and is

R⁴⁶、R⁴⁷And R⁴⁸Independently selected from the group consisting of H and C₁To C₄A hydrocarbon group.

As a further example, the bidentate phosphite ligand may be selected from a member of the group represented by formula XV, wherein

R⁴¹、R⁴⁴And R⁴⁵Is methyl;

R⁴²、R⁴⁶、R⁴⁷and R⁴⁸Is H; and is

R⁴³Is C₁To C₄A hydrocarbyl group;

or

R⁴¹Is isopropyl;

R⁴²is H;

R⁴³is C₁To C₄A hydrocarbyl group;

R⁴⁴is H or methyl;

R⁴⁵is methyl or ethyl;

R⁴⁶and R⁴⁸Is H or methyl; and is

R⁴⁷Is H, methyl or tert-butyl;

or the bidentate phosphite ligand may be selected from a member of the group represented by formula XVI, wherein

R⁴¹Is isopropyl or cyclopentyl;

R⁴⁵is methyl or isopropyl; and is

R⁴⁶、R⁴⁷And R⁴⁸Is H.

As yet another example, bidentate phosphite ligands may be represented by the formula XV, wherein R⁴¹Is isopropyl; r⁴²、R⁴⁶And R⁴⁸Is H; and R is⁴³、R⁴⁴、R⁴⁵And R⁴⁷Is methyl.

It will be recognized that formulae X to XVI are two-dimensional representations of three-dimensional molecules, and that rotation around chemical bonds can occur in the molecule to give structures other than those shown. For example, rotation about the carbon-carbon bond between the 2-and 2' -positions of the biphenyl, octahydrobinaphthyl, and or binaphthyl bridging groups of formulas X through XVI, respectively, can bring the two phosphorus atoms of each formula closer to each other and can allow the phosphite ligand to attach to nickel in a bidentate fashion. The term "bidentate" is well known in the art and means that two phosphorus atoms of a ligand are attached to a single nickel atom.

Additional examples of bidentate phosphite ligands useful in the present thousand processes include those having the formulae XX through LIII shown below, wherein for each formula R is¹⁷Selected from the group consisting of methyl, ethyl or isopropyl, and R¹⁸And R¹⁹Independently selected from H or methyl:

additional suitable bidentate phosphites are those of the type disclosed in U.S. Pat. Nos. 5,512,695, 5,512,696, 5,663,369, 5,688,986, 5,723,641, 5,847,101, 5,959,135, 6,120,700, 6,171,996, 6,171,997, 6,399,534, the disclosures of which are incorporated herein by reference. Suitable bidentate phosphinic acid esters are those of the type disclosed in U.S. Pat. Nos. 5,523,453 and 5,693,843, the disclosures of which are incorporated herein by reference.

Extraction solvent

Suitable hydrocarbon extraction solvents include alkanes and cycloalkanes (aliphatic and alicyclic hydrocarbons) having boiling points in the range of about 30 ℃ to about 135 ℃, including n-pentane, n-hexane, n-heptane, and n-octane, as well as the corresponding branched alkanes having boiling points in the specified range. Useful alicyclic hydrocarbons include cyclopentane, cyclohexane, and cycloheptane, as well as alicyclic hydrocarbons substituted with an alkyl group having a boiling point within the specified range. Mixtures of hydrocarbons may also be used, for example, mixtures of the hydrocarbons given above or commercial heptanes containing several hydrocarbons in addition to n-heptane. Cyclohexane is the preferred extraction solvent.

The lighter (hydrocarbon) phase recovered from the multistage countercurrent liquid-liquid extractor is directed to suitable equipment to recover catalyst, reactants, etc. for recycle to the hydrocyanation, while the heavier (lower) phase containing dinitriles recovered from the multistage countercurrent liquid-liquid extractor is directed to product recovery after removal of any solids that may accumulate in the heavier phase. These solids may contain valuable components that may also be recovered, for example, by the process set forth in U.S. patent No. 4,082,811.

Examples

In the following examples, the value of the extraction coefficient is the ratio of the weight fraction of catalyst in the extract phase (hydrocarbon phase) to the weight fraction of catalyst in the raffinate phase (organonitrile phase). An increase in the extraction factor results in greater efficiency in recovering the catalyst. As used herein, the terms light phase, extract phase, and hydrocarbon phase are synonymous. Also, as used herein, the terms heavy phase, organonitrile phase, and raffinate phase are synonymous.

Example 1

A 50mL jacketed glass laboratory extractor equipped with a magnetic stir bar, digital stir plate and maintained at 65 ℃ was charged with 10 grams of the product of the pentenenitrile-hydrocyanation reaction, and 10 grams of the extract from the second stage of the mixer-settler train operated with countercurrent flow. The extract from the second stage contained approximately 50ppm nickel and 3100ppm diphosphite ligand.

The reactor product was about:

85% by weight of C₆Dinitriles

14% by weight of C₅Mononitriles

1% by weight of catalyst component

360ppm by weight of active nickel.

The laboratory reactor was then mixed for 20 minutes at 1160 rpm and then allowed to settle for 15 minutes. After 15 minutes of settling, a stable emulsion was present throughout the extract phase. Samples were obtained from the extractor extract and raffinate phases and analyzed to determine the extent of catalyst extraction. The proportion of active nickel present in the extract phase versus the raffinate phase was found to be 14.

Example 2

Using the same hydrocyanation reactor product and stage 2 settler extract as in example 1, a 50mL jacketed glass laboratory extractor equipped with a magnetic stir bar, digital stir plate, and maintained at 65 ℃, was charged with 10 grams of the product of the pentene-hydrocyanation reaction, and 10 grams of the extract from the second stage of the mixer-settler train operating in countercurrent flow.

The laboratory reactor was then mixed for 20 minutes at 1160 rpm and then allowed to settle for 15 minutes. After 15 minutes of settling, a stable emulsion was present throughout the extract phase. After this, gentle mixing, approximately 100rpm, was applied, which resulted in unloading of the emulsion. Samples were obtained from the extractor extract and raffinate phases and analyzed to determine the extent of catalyst extraction. The proportion of active nickel present in the extract phase versus the raffinate phase was found to be 16.

Examples 1 and 2 illustrate the beneficial effects of gentle agitation applied to the heavy phase in the settling section of the first stage of a multistage countercurrent liquid-liquid extractor and provide a practical simulation of the effects of heavy phase recycle in continuous operation.

Table 1:

catalyst and ligand extraction factors for various first stage extraction factor recycle ratios.

Examples	RRR	Catalyst and (KLL)	Stable emulsions
				1	0	14	Is that
2	1	16	Whether or not

KLL = amount of catalyst in extract/amount of catalyst in raffinate

Example 3

The three countercurrent liquid-liquid extractors in continuous operation were operated for a duration of 20 days with the same two feed streams as described in example 1. Samples were obtained from the extract and raffinate phases of the settling section of the extractor and analyzed to determine the extent of catalyst extraction. The proportion of active nickel present in the extract phase to the raffinate phase was found to be 5.6 ± 2. The stable emulsion and chips are present throughout the extraction portion of the settling section of the first stage of the extractor. Emulsions and debris are also present to a lesser extent in the settling sections of the second and third stages of the extractor.

Example 4

Example 3 was repeated except that the light phase was recycled from the settling section back to the mixing section of the first stage of the countercurrent liquid-liquid extractor for a duration of 14 days. The benefits of this type of recycling of the light phase are described in the co-pending application labeled (attorney docket PI 2850). This example 4 provides a basic case for demonstrating the improved results as described in example 5 below.

The ratio of active nickel present in the extract phase to the raffinate phase was found to be 8.6 ± 2. Less stable emulsion and debris than in example 3 was present throughout the extract portion of the settling section of the first stage of the extractor.

Example 5

Example 3 was repeated except that both the light and heavy phases were recycled in the first stage of the countercurrent liquid-liquid extractor for a duration of 60 days. The recycle of the light phase from the settler to the mixer occurred in the manner described in example 4. The recycle of the heavy phase from and back to the settler occurs in a manner that provides gentle agitation to the mixed phases in the settler.

The proportion of active nickel present in the extract phase versus the raffinate phase was found to be 10.8 ± 2. Less stable emulsion and debris than in example 4 was present throughout the extract portion of the settling section of the extractor.

The results of examples 3-5 are summarized in Table 2.

Table 2:

catalyst extraction factor for continuous operation using phase recycle.

Examples 3-5 illustrate the beneficial effect of recycling the light phase from the settler back to the mixer, and the heavy phase from the settler and back to the settler while running continuously in the settling section of the first stage of a multistage countercurrent liquid-liquid extractor.

Example 6

In a continuous run as in examples 3-5, the same countercurrent liquid-liquid extractor was used, with an RF probe (Universal III)^TMIntelligent level) to measure the combined level of raffinate and rag layers in the settling section of the extractor. Data from the probe is shown in figure 5. A rapid change of > 2% in less than 2 hours indicates that the rag layer was pushed into the raffinate layer, or that the rag re-formed at the interface. When the raffinate recycle from and back to the settler in the first stage disturbed the interface, the rag layer was pushed into the raffinate layer and the total percent level of raffinate and rag layers in the settler of the first stage decreased rapidly as shown in fig. 5. When the raffinate recycle no longer disturbed the interface, the rag layer was re-formed at the interface, as measured by the% level in the settler for the rapidly increasing raffinate and rag.

As shown in fig. 5, extraction was operated continuously without raffinate recycle for approximately 25 hours, and the level of debris (including the thickness of the debris layer and the thickness of the underlying raffinate layer) was 60% to 70%. After about 25 hours, the recycle of raffinate was started. Figure 5 shows that the level of debris rapidly decreases to below 40% with a corresponding increase in the thickness of the extract layer. After about 1 hour, the recycle of raffinate was interrupted and, as shown in fig. 5, the rag level rapidly increased to at least 60%. However, the rag level did not reach the rag level observed prior to the first recycle of raffinate. After the first recycle of raffinate was interrupted, the extraction operation was continued until the total elapsed time of the experiment reached about 60 hours. At this point, recycle of raffinate is resumed. Figure 5 again shows that the rag level rapidly decreased to below 40% with a corresponding increase in the thickness of the extract layer. The recycle of raffinate was continued until the total elapsed time of the experiment reached about 77 hours. The level of debris remained substantially constant below 40% throughout the period. After a total elapsed time of about 77 hours, the raffinate recirculation was again interrupted and, as shown in fig. 5, the level of debris again increased rapidly, now reaching a level between 50% and 60%. After an elapsed time of about 85 hours, the recycle of raffinate was again resumed. Fig. 5 again shows that the debris level rapidly decreases to below 40%. This level was essentially maintained as the recycle of raffinate continued, up to the end of the experiment at a total elapsed time of 100 hours.

Examples 7 to 11

These examples 7-11 illustrate that effective catalyst recovery occurs for mononitrile to dinitrile ratios greater than 0.65.

From Ni diphosphite complexes, structure XX (wherein R is¹⁷Is isopropyl, R¹⁸Is H, and R¹⁹Is methyl) the diphosphite ligand, ZnCl₂Five different mixtures (equimolar to Ni) with different compositions and ratios of mononitrile to dinitrile were extracted separately in liquid-liquid batch with equal weights of cyane (i.e. cyclohexane). The molar ratio of organic mononitrile to organic dinitrile and the resulting extraction coefficient are given in table 3 below. If a countercurrent multistage extractor is used at a solvent to feed ratio of greater than 1, the compound has an extraction system of greater than 1Then the compound can be efficiently recovered.

Table 3.

Catalyst and ligand extraction coefficients for varying proportions of mononitrile-to-dinitrile

Example 12

This example demonstrates the effect of residence time on the extractability of the diphosphite ligand catalyst.

Will consist essentially of an organic dinitrile and a Ni diphosphite complex (the diphosphite ligand having the structure in Structure XX (wherein R is¹⁷Is isopropyl, R¹⁸Is H, and R¹⁹Is methyl) and ZnCl₂The mixture (equimolar to Ni) was divided into two portions. Both fractions were liquid-liquid extracted with equal weight of cyclohexane at 40 ℃ in a three stage contactor. The two fractions were sampled over time and the progress of catalyst recovery to the extract phase is given in table 4 as a percentage of the final steady state value obtained at a given time.

TABLE 4

The concentration of the diphosphite ligand in the extraction solvent phase over time.

Time in minutes	Steady state concentration at 40%
		2	12
4	19
		8	34
14	52
		30	78
60	100
		91	100

Example 13

This example illustrates the effect of temperature on the extraction capacity of the catalyst in the case of final extraction solvent recycle.

Will consist essentially of an organic dinitrile and a Ni diphosphite complex (the diphosphite ligand having the structure in Structure XXIV (wherein R is¹⁷Is methyl, R¹⁸Is methyl and R¹⁹Is H) and ZnCl₂The mixture (in equimolar amounts with Ni) is divided into three fractions. Each fraction was subjected to batch liquid-liquid extraction with equal weight of n-octane at 50 deg.C, 65 deg.C and 80 deg.C, respectively, and monitored over time. The results are given in table 5.

TABLE 5

Time of day	At 50 ℃ steady state%	At a steady state at 65%	At 80 ℃ steady state%
				2	0.0	0.0	1.8
4	0.0	0.0	1.6
				8	0.0	0.0	3.6
14	0.0	0.0	4.3
				20	0.0	0.0	3.6
30	0.0	0.0	7.6
				60	0.0	1.6	16.3
90	0.7	4.0	48.6

Example 14

This example illustrates the effect of adding water in a three-stage extraction with recycle of cyclohexane in the first stage.

Fifteen grams of a composition consisting essentially of an organic dinitrile and a Ni diphosphite complex (the diphosphite ligand having the structure in Structure XXIV (wherein R is R)¹⁷Is methyl, R¹⁸Is methyl and R¹⁹Is H) and ZnCl₂The mixture (equimolar to Ni) was extracted with an equal weight of cyclohexane in a three-stage continuous extractor at a temperature of 50 c for one hour to give a catalyst extraction factor of 4.3.

To this mixture, 100 microliters of water was added. After continued heating and stirring for another hour, a diphosphite Ni extraction factor of 13.4 was measured, i.e., a three-fold increase.

Examples 15 and 16

These examples illustrate the effect of adding Hexamethylenediamine (HMD) to the extraction zone.

Example 1 was repeated except that hexamethylenediamine was added to the product of the pentene-hydrocyanation reaction. Into a 50mL jacketed glass laboratory extractor equipped with a magnetic stir bar, digital stir plate and maintained at 65 ℃,10 grams of the product of the pentenenitrile-hydrocyanation reaction, and 10 grams of the extract from the second stage of the mixer-settler train operating in countercurrent flow, were charged.

The reactor product was about:

85% by weight of C₆Dinitriles

14% by weight of C₅Mononitriles

1% by weight of catalyst component

360ppm by weight of active nickel.

The laboratory reactor was then mixed for 20 minutes at 1160 rpm and then allowed to settle for 15 minutes. In the absence of HMD addition, a stable emulsion was present throughout the extract phase. After 15 minutes of settling, there was essentially no emulsion phase when HMD was added. Samples were obtained from the extractor extract and raffinate phases and analyzed to determine the extent of catalyst extraction.

TABLE 6

Effect of hexamethylenediamine on catalyst extraction

Claims (20)

1. A process for recovering diphosphite-containing compounds from a feed mixture comprising diphosphite-containing compounds, organic mononitriles and organic dinitriles 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 a first stage of the multistage countercurrent liquid-liquid extractor; and

b) contacting the feed mixture with an extraction solvent in the multistage countercurrent liquid-liquid extractor,

wherein a first 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 is separated from a heavy phase in the settling section, wherein a mixed phase comprising a heavy phase, a light phase is present in the settling section between the light phase and the heavy phase, wherein the light phase comprises an extraction solvent and extracted diphosphite-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 and treated to recover diphosphite-containing compounds extracted into the light phase, wherein a first portion of the heavy phase is sent to a second stage of the multistage countercurrent liquid-liquid extractor, and wherein a second portion of the heavy phase is withdrawn from the settling section of the first stage of the multistage countercurrent liquid-liquid extractor and recycled to the settling section of the first stage of the multistage countercurrent liquid-liquid extractor And (4) section.

2. The process of claim 1, wherein the recycle of the heavy phase in the settling section of the first stage of the multistage countercurrent liquid-liquid extractor is sufficient to result in enhanced settling of the light phase and heavy phase in the settling section of the first stage.

3. The process of claim 1, wherein the recycle of the heavy phase in the settling section of the first stage of the multistage countercurrent liquid-liquid extractor is sufficient to achieve at least one of the following results: (a) a reduction in the size of the emulsion phase in the settling section based on the size of the emulsion phase in the absence of recirculation of the heavy phase; (b) an increase in the rate of settling in the settling section based on the rate of settling in the absence of recycle of the heavy phase; (c) an increase in the amount of diphosphite-containing compounds in the light phase based on the amount of diphosphite-containing compounds in the light phase in the absence of recycle of the heavy phase; (d) a reduction in size of a rag layer in the settling section based on the size of the rag layer in the settling section in the absence of recycle of the heavy phase; and (e) a reduction in the rate of rag layer formation in the settling section based on the rate of rag layer formation in the settling section in the absence of recycle of the heavy phase.

4. The process of claim 1, wherein the recycling of the heavy phase in the settling section of the first stage is sufficient to result in: improved extraction of diphosphite-containing compounds based on extraction of diphosphite compounds in the absence of recycle of the heavy phase.

5. The process of claim 1, wherein a Raffinate Recycle Ratio (RRR) is from 0.1 to 0.9, wherein RRR is defined by the ratio of X to Y, wherein X is the mass per unit time of the second portion of the heavy phase recycled to the settling section of the first stage of the multistage countercurrent liquid-liquid extractor, and wherein Y is the mass per unit time of all of the heavy phase withdrawn from the settling section of the first stage of the multistage countercurrent liquid-liquid extractor.

6. The method of claim 1, wherein the RRR is 0.2 to 0.8.

7. The process of claim 1, 2 or 3, wherein the diphosphite-containing compound is a Ni complex having a diphosphite ligand selected from the group consisting of:

wherein in I, II and III, R¹Being unsubstituted or substituted by one or more C₁To C₁₂Alkyl or C₁To C₁₂Alkoxy-substituted phenyl; or unsubstituted or substituted by one or more C₁To C₁₂Alkyl or C₁To C₁₂Alkoxy-substituted naphthyl; and wherein Z and Z¹Independently selected from the group consisting of structural formulas IV, V, VI, VII, and VIII:

and wherein

R²、R³、R⁴、R⁵、R⁶、R⁷、R⁸And R⁹Independently selected from H, C₁To C₁₂Alkyl and C₁To C₁₂Alkoxy groups;

x is O, S or CH (R)¹⁰)；

R¹⁰Is H or C₁To C₁₂An alkyl group;

and wherein

R¹¹And R¹²Independently selected from H, C₁To C₁₂Alkyl and C₁To C₁₂Alkoxy and CO₂R¹³A group of components selected from the group consisting of,

R¹³is C₁To C₁₂Alkyl, or unsubstituted or substituted by C₁To C₄Alkyl substituted C₆To C₁₀An aryl group;

y is O, S or CH (R)¹⁴)；

R¹⁴Is H or C₁To C₁₂An alkyl group;

wherein

R¹⁵Selected from the group consisting of H, C₁To C₁₂Alkyl, and C₁To C₁₂Alkoxy and CO₂R¹⁶A group of components selected from the group consisting of,

R¹⁶is C₁To C₁₂Alkyl, or unsubstituted or substituted by C₁To C₄Alkyl substituted C₆To C₁₀An aryl group, a heteroaryl group,

and wherein

For structural formulas I through VIII, C₁To C₁₂Alkyl and C₁To C₁₂The alkoxy group may be linear or branched.

8. The process of any one of claims 1, 2 or 3, wherein at least one stage of the extraction is performed at above 40 ℃.

9. The process of any one of claims 1, 2 or 3 wherein at least one stage contains a Lewis base.

10. The process of claim 9 wherein the lewis base is a monodentate triarylphosphite wherein the aryl groups are unsubstituted or substituted with alkyl groups having from 1 to 12 carbon atoms, and wherein the aryl groups may be linked to each other.

11. The method of claim 9, wherein the lewis base is selected from the group consisting of:

a) anhydrous ammonia, pyridine, alkylamine, dialkylamine, trialkylamine, wherein the alkyl group has from 1 to 12 carbon atoms; and

b) a polyamine.

12. The method of claim 11, wherein the polyamine comprises at least one selected from the group consisting of hexamethylenediamine, and dimers and trimers of hexamethylenediamine.

13. The method of claim 11, wherein the polyamine comprises a dimer of hexamethylene diamine.

14. The process of claim 9 wherein the lewis base compound isAnd (3) resin.

15. The process of any one of claims 1, 2 or 3, wherein the extraction solvent is cyclohexane.

16. The process of any one of claims 1, 2, or 3, wherein the feed mixture is an effluent stream from a hydrocyanation process.

17. The process of claim 14, wherein the hydrocyanation process comprises a 3-pentenenitrile hydrocyanation process.

18. The process of claim 15, wherein the hydrocyanation process comprises a 1, 3-butadiene hydrocyanation process.

19. The process of any one of claims 1, 2, or 3, wherein the first stage of the multistage countercurrent liquid-liquid extractor occurs in an extraction column, wherein the entire column is a settling section comprising a mixing section between a heavy phase collection section and a light phase collection section, and wherein heavy phase is recycled to the mixing section.

20. The process of any one of claims 1, 2, or 3, wherein the first stage of the multistage countercurrent liquid-liquid extractor occurs in a mixer-settler, wherein the mixer-settler comprises a settling section separate from the mixing section, and wherein a recycled heavy stream is recycled upstream of the point of withdrawal of the recycled heavy stream.