ENHANCED EXTRACTION OF IMPURITIES

FROM MIXTURE COMPRISING NITRILES

FIELD OF THE INVENTION

[0001] The invention relates to recovery of catalyst and ligand from a hydrocyanation reaction product mixture comprising organic dinitri!es using liquid-liquid extraction.

BACKGROUND OF THE INVENTION

[0002] It is well known in the art that complexes of nickel with phosphorous-containing ligands are useful as catalysts in hydrocyanation reactions. Such nickel complexes using monodentate phosphites are known to catalyze hydrocyanation of butadiene to produce a mixture of pentenenitriies. These catalysts are a!so useful in the subsequent hydrocyanation of pentenenitriies to produce adiponitriie, an important intermediate in the production of nylon, it is further known that bidentate phosphite, phosphinite and phosphonite ligands can be used to form nickel-based catalysts to perform such hydrocyanation reactions.

[0003] U.S. Patent No. 3,773,809 describes a process for the recovery of Ni complexes of organic phosphites from a product fluid containing organic nitriles produced by hydrocyanating an ethylenicalfy unsaturated organic mononitrile such as 3-pentenenitrile through extraction of the product fluid with a paraffin or cycioparaffin hydrocarbon solvent. Similarly, U.S. Patent No. 6,936,171 to Jackson and McKinney discioses a process for recovering diphosphite-containing compounds from streams containing dinitrtles.

[0004] U.S. Patent No. 4,339,395 describes the formation of an interfacia! rag layer during extended periods of continuous extraction of certain phosphite ligands. The '395 patent notes that the interfacial rag hinders, if not halts, the phase separation. Because the process is operated continuously, the rag must be removed continuously from the interface as it accumulates to avoid interrupting operation. To solve this problem for the disclosed

components, the '395 patent discioses the addition of minor amounts of substantially water-free ammonia.

[0005] U.S. Patent No. 7,935,229 describes a process for extractively removing

heterogeneously dissolved catalyst from a reaction effluent of a hydrocycanation of unsaturated mononitriles to dinitriies with a hydrocarbon. The catalyst comprises a !igand which may be a monophosphite, a diphosphite, a monophosphonite or a diphosphonite. Ammonia or an amine may be added to a mixture of liquid phases before phase separation takes place. [0006] A mixing section of a liquid-liquid extractor forms an intimate mixture of unseparated light and heavy phase. This intimate mixture comprises an emulsion phase. The emulsion phase may or may not comprise particulate solid material. This emulsion phase separates into a light phase and a heavy phase in a settling section. Accordingiy, a settling section will contain at least some emulsion phase located between the upper light phase and the lower heavy phase. This emulsion phase tends to reduce in size over time. However, in some instances settling takes longer than desired or the emulsion phase never fully separates into a light phase and a heavy phase.

[0007] Addition of Lewis base, such as water, ammonia or amine, to the feed to a liquid- liquid extractor may result in enhanced settling of the emulsion phase. For example, this addition may result in the reduction of the size of the emulsion phase in the settling section, wherein the size of the emulsion phase is based upon the size of the emulsion phase in the absence of addition of Lewis base. Enhanced settling in the settling section may also be measured as an increased rate of settling, based upon the rate of settling in the absence of addition of Lewis base.

[0008] Another problem, which may be solved by addition of Lewis base, is formation of rag and build-up of a rag layer the settling section. Rag formation is discussed in U.S. Patent No. 4,339,395 and U.S. Patent No. 7,935,229. Rag comprises particulate solid material, and may be considered to be a form of an emulsion phase, which is particularly stable in the sense that it does not dissipate in a practical amount of time for conducting an extraction process. Rag may form in the mixing section or the settling section of an extraction stage. In the settling section, the rag forms a layer between the heavy phase and the light phase. The formation of a rag layer in the settling section inhibits proper settling of the heavy phase and the light phase. The formation of a rag layer may also inhibit the extraction of phosphorus-containing ligand from the heavy phase into the light phase. In a worst case scenario, rag can build up to the extent of completely filling a separation section, necessitating shut down of the extraction process to clean out the settling section. Addition of Lewis base to the mixing section may reduce or eliminate the size of a rag layer or reduce its rate of formation, based upon the size and rate of formation of the rag layer in the absence of addition of Lewis base.

SUMMARY OF THE INVENTION

[0009] There are problems associated with various Lewis bases, when used to in an effort to enhance phase separation. For example, water may cause hydrolysis of water sensitive ligands, such as diphosphate or diphosphonite !igands. Ammonia forms a complex with Lewis acids, which is partially soluble in the raffinate phase of extraction process. This complex has been found to promote the cyclization reaction of adiponitrile to form 2- cyanocyclopentyiidinimine, when the raffinate is subjected to distillation conditions involved in the separation of adiponitrile from the raffinate phase. Other Lewis base additives, such as pyridine, should be avoided for safety reasons. Pyridine is a teratogenic substance.

[0010] In accordance with embodiments described herein, it has been discovered that polyamines are particularly advantageous, when used as Lewis base additives. Under extraction conditions discussed herein, the polyamines tend to form a complex with Lewis acid, which is solid and readily separates into the raffinate phase. Furthermore, this solid precipitate is sufficiently dispersed in the raffinate phase to flow with the raffinate phase throughout the stages of a countercurrent multistage liquid-liquid extraction process. Although this complex does tend to catalyze the formation of 2-cyanocycSopentylidinimine from adiponitrile under certain distillation conditions, it can readily be removed from the raffinate phase from a countercurrent multistage liquid-liquid extraction process, e.g., by filtration, before the raffinate phase is subjected to such distillation conditions. It has further been found that bis- hexamethyiene triamine is a particularly useful Lewis base additive in processes described herein.

[0011] The process of the present invention recovers adiponitrile from a mixture comprising adiponitrile (ADN), 3-pentenenitrile (3PN), a Lewis acid and a catalyst. The process comprises steps (a) to (j).

[0012] In step (a), a countercurrent multistage extraction zone is provided. The extraction zone comprises at least three mixer-settlers connected in series, in particular, the mixer- settlers are fluidly connected.

[0013] In step (b), a mixture comprising ADN, 3PN, Lewis acid and a catalyst is introduced to a first terminal mixer-settler in the series. In step (c), an extraction solvent is introduced into the second terminal mixer-settler in the series.

[00 4] In step (d), a light phase comprising extraction solvent and a heavy phase comprising ADN and 3PN is formed in the settling sections of each of the mixer-settlers. In step (e), the heavy phase is caused to flow progressively from the first terminal mixer-settler through each of the intermediate mixer-settlers connected in series and into the second terminal mixer- settler, in step (f), the light phase is caused to flow progressively from the second terminal mixer-settler through each of the intermediate mixer-settlers connected in series and into the first terminal mixer-settler. [0015] In step (g), the light phase comprising extraction solvent and extracted catalyst is withdrawn from the first terminal mixer-settler. In step (h), the heavy phase comprising ADN and 3PN is withdrawn from the second terminal mixer-settler.

[0016] In step (h), the withdrawn light phase from step (g) is distilled to separate extraction solvent from catalyst. In step (i), the withdrawn heavy phase from step (h) is distilled to separate ADN from 3PN.

[0017] The catalyst comprises zero valent nickel and a phosphorus-containing ligand, such as a bidentate phosphite ligand or a bidentate phosphonite ligand. A polyamine is added to the mixing section of the first terminal mixer-settier to form a precipitate comprising a complex of the Lewis acid with the polyamine. The precipitate is entrained in the flow of heavy phase through the series of mixer-settlers. The precipitate is withdrawn from the second terminal mixer-settler, along with the heavy phase, which comprises ADN and 3PN.

[0018] The complex of Lewis acid and polyamine formed in the mixing section of the first terminal mixer-settler may be capable of catalyzing the cyclization reaction of ADN to form 2- cyanocyclopentyiideneimine (CPi). The complex may be removed from the raffinate phase prior to subjecting contents of the raffinate phase to distillation conditions involving

temperatures to promote the catalyzed conversion of ADN to CPI. In particular, the ADN recovery process may comprise additional steps (k) and (I). In step (k), precipitate comprising a complex of the Lewis acid with the polyamine is removed from the heavy phase withdrawn in step (h). Step (I) takes place after (k) and prior to separating dinitriles comprising ADN from compounds having a boiling point higher than the boiling point of ADN. For example, step (I) may take place prior to separating ADN from 3PN.

[0019] The catalyst may comprise a bidentate phosphite ligand or a bidentate phosphonite ligand. The Lewis acid may comprise, for example, ZnCI ₂ or triphenyiborane.

[0020] The extraction solvent feed from the second stage of the countercurrent multistage extraction zone may comprise at least 1000 ppm, for example, from 2000 to 5000 ppm, of phosphorus-containing ligand. The extraction solvent feed from the second stage may comprise at least 10 ppm, for example, from 20 to 200 ppm, of nickel. At least one stage of the extraction may be carried out above 40°C.

[0021] The feed mixture to the countercurrent multistage extraction zone may be an effluent stream from a hydrocyanation process. The hydrocyanation process may include a 3- pentenenitrile hydrocyanation process or a 1 ,3-butadiene hydrocyanation process.

[0022] Examples of polyamines, which may be added to the mixing section of the first terminal mixer-settler, include hexamethylene diamine, bis-hexamethylene triamine and 1 ,2- diaminocyclohexane. For example, bis-hexamethylene triamine may be added to the mixing section of the first terminal mixer-settler.

[0023] When the phosphorus-containing iigand is a diphosphonite-containing ligand, the diphosphonite ligand may have the formula L:

(R ¹ )(R ² -O)P-0-Y-O-P(O-R ³ )(R ⁴ )

L

where R ¹ and R ² are each independently identical or different, separate or bridged organic radicals; R ³ and R ⁴ are each independently identical or different, separate or bridged organic radicals; and Y is a bridging group.

[0024] Examples of phosphonite-containing compounds of formula (L) may be diphosphonite ligands of formula (LI) or (formula LI I):

(ArR) _b (ArR) _b

(RArO - _a P P-{OArR) _a

\ /

LI

Lil wherein:

x=0 to 4;

y=0 to 2;

a and b individually are either 0, 1, or 2, provided a+b=2;

each Ar is individually phenyl or naphthyl, and the two Ar groups that are directly or indirectly (through an oxygen) bonded to the same phosphorus atom may be linked to each other by a linking unit selected from the group consisting of direct bond, alkylidene, secondary or tertiary amine, oxygen, sulfide, sulfone, and

sulfoxide;

each R is individually hydrogen, ethenyl, propenyi, acryloyl, methacryloyi, an organic radical with a terminal ethenyl, propenyi, acryloyl, or methacryloyi group, linear or branched alkyl, cycloalkyl, acetal, ketal, aryl, aikoxy, cycloalkoxy, ary!oxy, formyl, ester, fluorine, chlorine, bromine, perhaloalkyi, hydrocarbylsulfinyl,

hydrocarbylsuifonyi, hydrocarbyicarbonyl or cyclic ether;

each Ar can be further substituted with linear or branched alkyl, cycloalkyl, acetal, ketal, aryl, aikoxy, cycloalkoxy, ary!oxy, formyl, ester, fluorine, chlorine, bromine, perhaloalkyi, hydrocarbylsulfinyl, hydrocarbylsuifonyi, hydrocarbyicarbonyl or cyclic ether;

each R" is individually hydrogen, ethenyl, propenyi, an organic radical with a terminal ethenyl or propenyi group, linear or branched alkyl, cycloalkyl, acetal, ketal, aryl, aikoxy, cycloalkoxy, aryloxy, formyl, ester, fluorine, chlorine, bromine,

perhaloalkyi, hydrocarbylsulfinyl, hydrocarbylsuifonyi, hydrocarbyicarbonyl or cyclic ether.

[0025] Examples of diphosphonite iigands of formula (LI I) include compounds where at least one R represents ethenyl, propenyi, acryloyl, methacryloyi or the organic radical with a terminal ethenyl, propenyi, acryloyl, or methacryloyi group or at ieast one R" represents ethenyl, propenyi, or the organic radical with a terminal ethenyi or propenyi group.

[0026] An example of a diphosphonite !igand of formula (Lll) is a compound of formula (IV):

!V

[0027] Diphosphonite !igands and the synthesis of these diphosphonite ligands are described in U.S. Patent No. 6,924,345 and in U.S. Patent No. 7,935,229.

[0028] When the phosphorus-containing !igand is a diphosphite-containing iigand, the ligand may have the formula of diphosphite-containing ligands described in International Patent Publication No. WO 2013/095853. Particular examples of diphosphite ligands are described hereinafter with reference to ligands of formulae I to XX.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a diagram showing the flow of fluids through a multistage countercurrent liquid-liquid extractor.

[0030] Figure 2 is a diagram showing a mixing section and a settling section of a stage of a multistage countercurrent liquid-liquid extractor.

[0031] Figure 3 is a diagram showing a mixing/settling apparatus (i.e. a mixer-settler) having three chambers in the settling section.

[0032] Figure 4 is a diagram showing a distillation train which may be used to recover adiponitrile from a raffinate stream.

[0033] Figures 5 and 6 are graphs showing the conversion of adiponitrile to 2- cyanocyclopenty!ideneimine (CP!) in the presence of various additives over time.

DETAILED DESCRIPTION OF THE INVENTION

[0034] The processes of the present invention involve methods for recovering phosphorus- containing iigand from a mixture comprising phosphorus-containing ligand and organic dinitriles, using liquid-liquid extraction. [0035] Figure 1 is a diagram of a multistage countercurrent liquid-liquid extractor. Lines in Figure 1 represent flow of materials, rather than any particular type of equipment, such as pipes.

[0036] Three stages are depicted in Figure 1. The first stage is depicted by mixer-settler 1. The second stage is depicted by mixer-settler 2. The final stage is depicted by mixer-settler 3. Gap 30 represents a space where additional stages may be inserted. For example, one or more, for example, from one to four, mixer-settlers may be inserted in gap 30 between mixer- settler 2 and mixer-settier 3.

[0037] In Figure 1, mixer-settler 1 and mixer-settler 3 represent the terminal mixer-settlers of the multistage countercurrent liquid-liquid extractor. According to terminology used herein, mixer-settier 1 represents the first terminal mixer-settler, and mixer-settier 3 represents the second terminal mixer-settler. Any mixer-settler connected in series between the first terminal mixer-settler 1 and the second terminal mixer-settler 3 is referred to as an intermediate mixer- settler.

[0038] In Figure 1, a fresh extraction solvent feed, for example, cyclohexane, is introduced into the multistage countercurrent extractor via line 10. The extraction solvent or light phase exiting from mixer-settier 3 passes through line 12 to the next stage of the multistage extractor. In a multistage countercurrent liquid-liquid extractor having three stages, extraction solvent in line 12 would pass directly into stage 2 via line 14. Extraction solvent from stage 2 passes through line 16 to stage 1. The extraction solvent comprising extracted phosphorus-containing !igand passes out of the stage 1 mixing and settling section through line 18.

[0039] A feed comprising phosphorus-containing ligand is fed into the stage 1 mixer-settler via line 20. The feed further comprises a mixture comprising organic mononitriles and dinitriles, which is immiscible with the extraction solvent. The feed further comprises a Lewis acid. In stage 1 , a portion of the phosphorus-containing ligand is extracted into the extraction solvent which exits stage 1 via line 18. The immiscible dinitrile and mononitri!e mixture or the heavy phase is removed from the stage 1 mixer-settler by line 22 and is passed into the stage 2 mixer- settler. A portion of the phosphorus-containing ligand is extracted into the light phase in the stage 2 mixer-settler. The heavy phase exits the stage 2 mixer-settler by Sine 24. Similarly, if there are additional stages in gap 30 shown in Figure 1 , extraction of phosphorus-containing ligand will take place in such intermediate stages in a similar manner to that taking place in stage 2.

[0040] After the heavy phase passes through the first stage and any intermediate stages, it passes through the final stage mixer-settier 3. In particular, the heavy phase is introduced into mixer-settler 3 through line 26. After passing through the final stage mixer-settler 3, the heavy phase exits via line 28.

[0041] Thus, it can be seen that the multistage countercurrent liquid-liquid extractor comprises three or more stages with countercurrent flow of extraction solvent and heavy phase. In view of the direction of flow of light and heavy phase through the stages of extraction, it will be appreciated that the concentration of so!ute, e.g., phosphorus-containing !igand, is highest in both the light and heavy phases of the first stage and iowest in the light and heavy phases of the final stage.

[0042] Figure 2 is a diagrammatic representation of one type a mixer-settler. This mixer- settler may be used in any of the stages shown in Figure 1. This mixer-settler comprises a mixing section 40 and a settling section 50. The mixing section 40 and the settling section 50 are separate. All of the effluent from the mixing section 40 flows into the settling section 50. Fluid from the mixing section 40 flows through the settling section 50 in a horizontal manner, although there is also no restriction of movement of fluids vertically throughout the settling section 50.

[0043] An extraction solvent is introduced into the mixing section 40 by line 42. A feed comprising phosphorus-containing ligand is introduced into the mixing section 40 by line 44. Alternatively, the contents of lines 42 and 44 may be combined upstream of the mixing section 40 and introduced into mixing section 40 through a single inlet. These two feeds are mixed in the mixing section 40 to provide a mixed phase comprising an emulsion phase represented in Figure 2 by shaded area 46.

[0044] Line 48 represents the flow of mixed phase 46 from the mixing section 40 into the settling section 50. As depicted in Figure 2, there are three phases in the settling section 50, including a heavy phase 52, a mixed phase 54, and a light phase 56. The heavy phase 52 is depleted in phosphorus-containing ligand, insofar as it has a Sower concentration of

phosphorus-containing ligand as compared with the concentration of phosphorus-containing ligand in feed 44, due to the extraction of phosphorus-containing ligand into the light phase 56. Correspondingly, the light phase 56 is enriched in phosphorus-containing ligand, insofar as it has a higher concentration of phosphorus-containing ligand as compared with the concentration of phosphorus-containing ligand in extraction solvent feed 42, due to the extraction of phosphorus-containing ligand into the light phase 56. At least a portion of the heavy phase 52 exits the settling section 50 via line 60. At least a portion of the light phase 56 is removed from the settling section 50 via line 58. [0045] Although not shown in Figure 2, which is diagrammatically shows the flow of fluids, it will be understood that each of the mixing section 40 and the settling section 50 may comprise one or more stages, subsections, compartments or chambers. For example, settling section 50 may include more than one chamber between the point of introduction of the mixed phase 46 through line 48 and the point of withdrawa! of light phase and heavy phase through !ines 58 and 60. Horizontal extension between the point of introduction of the mixed phase 46 through line 48 and the point of withdrawa! of light and heavy phases through lines 58 and 60 promotes settling of the light and heavy phases 56 and 52. The size of the mixed phase 54 may become progressively smaller as fluids settle and flow through the chamber. For example, the final chamber from where fluids are removed may include little or no mixed phase 54. it will further be understood that mixing section 40 may include one or more types of mixing apparatus, such as an impeller, not shown in Figure 2.

[0046] Figure 3 provides a representation of a mixer-settler 100 having a multistage settling section. Mixer-settler 100 has a mixing section 110 and a settling section 112. In mixer-settler 100, the mixing section 110 is separate from the settling section 112. The settling section has three compartments, represented in Figure 3 as sections 114, 116, and 18. These sections are separated by coalescence plates 120. The coalescence plates 120 may be designed to provide flow of separated light and heavy phases between chambers, while restricting the flow of emulsion phase between chambers. A feed comprising a phosphorus-containing ligand is passed into the 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 shaft 136 to provide for mechanical mixing of fluids. Mixing of the feeds provides a mixed phase comprising an emulsion phase represented in Figure 3 by shading 140.

[0047] The mixed phase 140 flows into the settling section 112 as an overflow from the mixing section 110. This mixed phase 140 is prevented from flowing directly into the light phase 144 by baffle plate 142. As settling occurs in settling section 112, the volume of the mixed phase 140 decreases, the volume of the light phase 144 increases, and the volume of the heavy phase 146 increases. Heavy phase 146 is removed from settling section 12, in particular from chamber 118, via line 152 and light phase 144 is removed from settling section 12, in particular, from chamber 118, via line 150.

[0048] It is desirable for both a mononitrile and a dinitrile to be present in the countercurrent contactor. For a discussion of the role of monodentate and bidentate ligand in extraction of hydrocyanation reactor effluent streams, see U.S. Patent No. 3,773,809 to Walter and U.S. Patent 6,936,1 1 to Jackson and McKinney. [0049] For the process disclosed herein, suitable molar ratios of mononitrile to dinitrile components include 0.01 to 2.5, for example, 0.01 to 1.5, for example 0.65 to 1.5.

[0050] Maximum temperature is limited by the volatility of the hydrocarbon solvent utilized, but recovery generally improves as the temperature is increased. Examples of suitable operating ranges are 40°C to 100°C and 50°C to 80°C.

[0051] The controlled addition of monophosphate iigands may enhance settling. Examples of monophosphite Iigands that may be useful as additives include those disclosed in Drinkard et al U.S. Patent 3,496,215, U.S. Patent 3,496,217, U.S. Patent 3,496,218, U.S. Patent 5,543,536, and published PCT Application WO 01/36429 (BASF).

[0052] As described herein, the addition of polyamine to a mixture comprising phosphorus- containing iigand, organic mononitn!es and organic dinitriles enhances settling, especially when the mixture comprises a Lewis acid, such as ZnCi ₂ . Polyamines are organic compounds having two or more amino groups. These amino groups may be primary, secondary or tertiary amino groups. The polyamines may be aliphatic or cycloaliphatic compounds having from 1 to 15 carbon atoms. Examples of polyamines include polymethy!ene diamines having from 2 to 10 carbon atoms, dimers of such poiymethylene diamines, and trimers of such po!ymethylene diamines. Particular examples of such polyamines include hexamethyiene diamine, a dimer of hexamethylene diamine and a trimer of hexamethyiene diamine. Bis-hexamethyiene triamine (BHMT) is a dimer of hexamethyiene diamine (HMD). Another example of a polyamine is a diaminocyclohexane, such as 1 ,2-diaminocyc!ohexane. The addition of polyamine tends to reduce or eliminate any inhibiting effect of Lewis acid on catalyst and Iigand recovery.

[0053] The reaction product of Lewis acid with polyamine becomes entrained in the raffinate phase as it moves through the multistage countercurrent liquid-liquid extractor. In particular, this product may forms a precipitate in the raffinate phase in the form of a complex of Lewis acid with polyamine. it will be understood that the polyamine is a Lewis base. This precipitate exists as a dispersion of fine particles distributed throughout the raffinate phase. This precipitate may be removed by conventional techniques, such as filtration, centrifugation or distillation accompanied by removal of bottoms containing the precipitate, after the raffinate is removed from the last stage (i.e. the second terminal mixer-settler) of the multistage

countercurrent liquid-liquid extractor.

[0054] The phosphorus-containing Iigand extracted by the processes described herein may comprise bidentate phosphorus-containing Iigands. These extracted Iigands comprise free Iigands (e.g., those which are not complexed to nickel) and those which are complexed to nickel. Accordingly, it will be understood that extraction processes described herein are useful

I I for recovering phosphorus-containing ligand which are metal/ligand complexes, such as a complex of zero valent nickel with at least one ligand comprising a bidentate-phosphorus containing ligand.

Phosphorus-Containing Ligands

[0055] The catalysts used in the process of the invention comprise a zero-valent nickel and at least one phosphorus-containing (P-containing) ligand. The P-containing ligand may be selected from the group consisting of a phosphite, a phosphonite, a phosphinite, a phosphine, and a mixed P-containing ligand or a combination of such members.

[0056] The P-containing ligands chemically bound to nickel as complexes comprising zero- valent nickel, and the free P-containing ligands not bonded to said complexes, may be monodentate or multidentate, for example bidentate or tridentate. The term "bidentate" is well known in the art and means both phosphorus atoms of the ligand may be bonded to a single metal atom. The term "tridentate" means the three phosphorus atoms on the ligand may be bonded to a single metal atom. The terms "bidentate" and "tridentate" are also known in the art as chelate ligands.

[0057] As used herein, the term "mixed P-containing ligand" means a multidentate P- containing ligand comprising at least one combination selected from the group consisting of a phosphite-phosphonite, a phosphite-phosphinite, a phosphite-phosphine, a phosphonite- phosphinite, a phosphonite-phosphine, and a phosphinite-phosphine or a combination of such members.

Diphosphite Ligands

[0058] Examples of bidentate phosphite ligands useful in the invention include those having the following structural formulae:

(RO) ₂ P(OZO)P(OR ¹ ) ₂ ,

II

IN wherein in I , il and ill, R is phenyl, unsubstituted or substituted with one or more Ci to C _t2 alky! or C to C ₁₂ alkoxy groups; or naphthyi, unsubstituted or substituted with one or more C to C ₂ alkyl or C to C ₁₂ alkoxy groups; and Z and Z ¹ are independently selected from the group consisting of structural formulae IV, V, VI, VII, and Vill:

IV V

and wherein

R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , and R ⁹ are independently selected from the group consisting of H, Ci to C ₂ alkyl, and Ci to C ₁₂ alkoxy;

X is O, S, or CH(R ¹⁰ );

R ¹⁰ is H or d to C ₁₂ alkyl;

VI Vil

and wherein

R ¹ and R ² are independently selected from the group consisting of H, Ci to C½ alkyl, and C-i to C ₂ alkoxy; and C0 ₂ R R is C-i to C ₂ alkyi or C ₆ to C ₀ ary!, unsubstituted or substituted, with Ci to C ₄ aikyl;

Y is O, S, or CH(R ¹⁴ );

R ¹⁴ is H or C-i to C ₁₂ alkyi;

VIII

wherein

R ¹⁵ is selected from the group consisting of H, C-i to C ₁₂ alkyi, and Ci to C ₁₂ aikoxy and C0 ₂ R ¹⁶ ;

R ¹⁶ is 0] to C ₁₂ alkyi or C ₆ to C ₁₀ aryl, unsubstituted or substituted with to C ₄ alkyi.

[0059] In the structural formulae I through Vil!, the to C ₁₂ aikyl, and C-i to C ₂ aikoxy groups may be straight chain or branched.

[0060] Another example of a formula of a bidentate phosphite Iigand that is useful in the present process is that having the Formula X, shown below

[0061] Further examples of bidentate phosphite ligands that are useful in the present process inciude those having the Formulae XI to XIV, shown below wherein for each formula, R ¹⁷ is selected from the group consisting of methyl, ethyl or iso-propyl, and R ¹⁸ and R ¹⁹ are independently selected from H or methy!:

XIV

[0062] Additionai examples of bidentate phosphite ligands that are useful in the present process include a ligand selected from a member of the group represented by Formulae XV and XVI, in which all like reference characters have the same meaning, except as further explicitly limited:

Formula XV Formula XVI wherein

R ⁴ and R ⁴⁵ are independently selected from the group consisting of Ci to C ₅ hydrocarbyl, and each of R ⁴² , R ⁴³ , R ⁴⁴ , R ⁴⁶ , R ⁴⁷ and R ⁴⁸ is independently selected from the group consisting of H and to C ₄ hydrocarbyl.

[0063] For example, the bidentate phosphite ligand can be selected from a member of the group represented by Formula XV and Formula XV! , wherein R ⁴ is methyl, ethyi, isopropyl or cyclopenty!;

R ⁴² is H or methy!;

R ⁴³ is H or a C-i to C ₄ hydrocarbyl;

R ⁴⁴ is H or methyl;

R ⁴⁵ is methy!, ethyl or isopropyl; and

R ⁴⁶ , R ⁴⁷ and R ⁴⁸ are independently selected from the group consisting of H and to C ₄ hydrocarbyl.

[0064] As additional examples, the bidentate phosphite ligand can be selected from a member of the group represented by Formula XV, wherein

R ⁴ , R ⁴⁴ , and R ⁴⁵ are methyl;

R ⁴² , R ⁴⁶ , R ⁴⁷ and R ⁴⁸ are H; and

R ⁴³ is a d to C ₄ hydrocarbyl;

or

R ⁴¹ is isopropyl;

R ⁴² is H;

R ⁴³ is a C-i to C ₄ hydrocarbyl;

R ⁴⁴ is H or methyl;

R ⁴⁵ is methyl or ethyl;

R ⁴⁶ and R ⁴⁸ are H or methyl; and

R ⁴⁷ is H, methyl or tertiary-butyl;

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

R ⁴¹ is isopropyl or cyclopentyl;

R ⁴⁵ is methyl or isopropyl; and

R ⁴⁶ , R ⁴⁷ , and R ⁴⁸ are H.

[0065] As yet another example, the bidentate phosphite ligand may be represented by Formula XV, wherein R ⁴¹ is isopropyl; R ⁴² , R ⁴⁶ , and R ⁴⁸ are H; and R ⁴³ , R ⁴⁴ , R ⁴⁵ , and R ⁴⁷ are methyl.

[0066] It will be recognized that Formulae X to XVI are two-dimensional representations of three-dimensional molecules and that rotation about chemical bonds can occur in the molecules to give configurations differing from 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 Formulae X to XVI, respectively, can bring the two phosphorus atoms of each Formula in closer proximity to one another and can allow the phosphite ligand to bind to nickei in a bidentate fashion. The term "bidentate" is well known in the art and means both phosphorus atoms of the !igand are bonded to a single nicke! atom.

[0067] Further examples of bidentate phosphite ligands that are useful in the present process include those having the formula XX to Llll, shown below wherein R ¹⁷ is selected from the group consisting of methyl, ethyl or isopropyl, and R ⁱ⁸ and R ¹⁹ are independently selected from H or methyl:

XX

[0068] Further examples of bidentate phosphite ligands that are useful in the present process are described with reference to the formulae formula XXI to Llll in International Patent Publication No. WO 2013/095853.

[0069] Additional suitable bidentate phosphites are of the type disclosed in U.S. Patent 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 phosphinites are of the type disclosed in U.S. Patent Nos. 5,523,453 and 5,693,843, the disclosures of which are incorporated herein by reference. Diphosphonite Ligands

[0070] The diphosphonite-containing iigand may be a diphosphonite ligand of formula (L):

(R ¹ )(R ² -0)P-0-Y ^™ 0-P(0-R ³ )(R ⁴ )

L

where R ¹ and R ² are each independently identical or different, separate or bridged organic radicais; R ³ and R ⁴ are each independently identical or different, separate or bridged organic radicais; and Y is a bridging group.

[0071] The R ¹ and R ² radicals may each independently be identical or different organic radicals. Exampies of R ¹ and R ² radicals are aryl radicals, preferably those having from 6 to 10 carbon atoms, which may be unsubstituted or mono- or polysubstituted, in particular by C C ₄ - alkyi, halogen, such as fluorine, chlorine, bromine, halogenated alkyl, such as trifluoromethyl, aryi, such as phenyl, or unsubstituted aryl groups.

[0072] The R ³ and R ⁴ radicals may each independently be identical or different organic radicals. Examples of R ³ and R ⁴ radicals are aryl radicals, preferably those having from 6 to 10 carbon atoms, which may be unsubstituted or mono- or polysubstituted, in particular by CrC - a!kyl, halogen, such as fluorine, chlorine, bromine, ha!ogenated alkyl, such as trifluoromethyi, aryl, such as phenyi, or unsubstituted aryl groups.

[0073] The R ¹ and R ² radicals may each be separate or bridged. The R ³ and R ⁴ radicais may also each be separate or bridged. The R ¹ , R ² , R ³ and R ⁴ radicals may each be separate, two may be bridged and two separate, or all four may be bridged.

[0074] Exampies of phosphonite-containing !igands of formula (L) may be diphosphonite iigands of formula (LI) or (formula Lll):

(RArO^ _a P P-fOArR) .

\ / (ArR) _b (ArR) _b

(RAiO ^P P 0ArR) _a

\

Lll wherein:

x=0 to 4;

y=0 to 2;

a and b individually are either 0, 1 , or 2, provided a+b=2;

each Ar is individually phenyl or naphthyl, and the two Ar groups that are directly or indirectly (through an oxygen) bonded to the same phosphorus atom may be linked to each other by a linking unit selected from the group consisting of direct bond, alkylidene, secondary or tertiary amine, oxygen, sulfide, sulfone, and sulfoxide;

each R is individually hydrogen, ethenyi, propenyl, acryloyl, methacryloyi, an organic radicai with a terminal ethenyi, propenyl, acryloyl, or methacryloyi group, linear or branched alkyl, cycloa!kyl, acetal, ketai, aryl, aikoxy, cycloa!koxy, aryloxy, formy!, ester, fluorine, chlorine, bromine, perhaloalkyi, hydrocarbylsuifinyl, hydrocarbylsuifonyl, hydrocarby!carbonyi or cyclic ether;

each Ar can be further substituted with linear or branched alkyl, cycloalkyi, acetal, ketal, aryl, aikoxy, cycloalkoxy, aryloxy, formyl, ester, fluorine, chlorine, bromine, perhaloalkyi, hydrocarbylsuifinyl, hydrocarbylsuifonyl, hydrocarbylcarbony! or cyclic ether;

each R" is individually hydrogen, ethenyi, propenyl, an organic radical with a terminal ethenyi or propenyl group, linear or branched alkyl, cycloalkyi, acetal, ketai, aryl, aikoxy, cycloalkoxy, aryloxy, formyl, ester, fluorine, chlorine, bromine, perhaloa!kyl, hydrocarbylsulfinyl, hydrocarbylsulfonyi, hydrocarbyicarbonyi or cyclic ether.

[0075] At least one R in formula (LI) or formula (LII) may represent ethenyl, propeny!, acryloy!, methacryloyi or the organic radical with a terminal ethenyl, propenyi, acryloyi, or methacryloyl group and/or at least one R" may represent ethenyl, propenyl, or the organic radical with a terminal ethenyl or propenyl group.

[0076] An example of a diphosphonite ligand of formula (LII) is a compound of formula (Llli):

[0077] Diphosphonite ligands and the synthesis of these diphosphonite ligands are described in U.S. Patent No. 6,924,345 and in U.S. Patent No. 7,935,229.

Extraction Solvent

[0078] Suitable hydrocarbon extraction solvents include paraffins and cycioparaffins (aliphatic and aiicyclic hydrocarbons) having a boiling point in the range of about 30 °C to about 135 °C, including n-pentane, n-hexane, n-heptane and n-octane, as well as the corresponding branched chain paraffinic hydrocarbons having a boiling point within the range specified.

Useful aiicyclic hydrocarbons include cyclopentane, cyclohexane and cycioheptane, as well as alkyi substituted aiicyclic hydrocarbons having a boiling point within the specified range.

Mixtures of hydrocarbons may also be used, such as, for example, mixtures of the

hydrocarbons noted above or commercial heptane which contains a number of hydrocarbons in addition to n-heptane. Cyclohexane is the preferred extraction solvent.

Recovery of Products

[0079] 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, which may accumulate in the heavier phase. These solids may contain valuable components which may also be recovered, e.g., by the process set forth in U.S. Patent No. 4,082,811.

[0080] The solids in the heavier phase, also referred to herein as the raffinate phase, comprise a compiex of Lewis acid and po!yamine in the form of dispersion of fine particles. The raffinate phase may also comprise extraction solvent, such as cyclohexane, pentenenitriles, which comprise 3-pentenenitriie, compounds with a higher boiling point than adiponitrile and compounds with a boiling point greater than the boiling point of pentenenitriles and less than the boiling point of adiponitrile. The complex of Lewis acid and polyamine may be removed from the raffinate phase prior to removing extraction solvent, and especially before removing pentenenitriles from the raffinate phase.

[0081] The complex of Lewis acid and polyamine may be removed by any customary solids removal process. Examples of such processes include filtration, crossfiow filtration, centrifugation, sedimentation, classification and decantation. Common apparatus for such solids removal include filters, centrifuges and decanters.

[0082] it has been found that the complex of Lewis acid and polyamine may catalyze the unwanted cyciization reaction of adiponitrile to form 2-cyanocyciopenty!ideneimine (CPi), especially when the raffinate phase is heated to temperatures used in the K' ₃ column, discussed hereinafter, which is used to separate dinitriles, which comprise adiponitrile, from compounds having a boiling point higher than adiponitrile.

[0083] Figure 4 shows a distillation train, which may be used as an adiponitrile purification section. Figure 4 of the present application corresponds to Figure 3 of United States Patent Application Publication No. 2013/021 1126. Line 600 transports a raffinate stream from an extraction zone into distillation column ΚΊ, where extraction solvent is separated from higher boiling components of the raffinate stream. In particular, extraction solvent, such as

cyclohexane, is withdrawn from distillation column through line 625, and higher boiling components of the raffinate stream are withdrawn from distillation column ΚΊ through line 620.

[0084] The solvent-depleted stream in line 620 is then passed into distillation column K' _2l where pentenenitrile is separated from higher boiling components remaining in the raffinate stream. In particular, pentenenitrile, such as 3PN and any 2M3BN present, is withdrawn from distillation column K' ₂ through line 650, and higher boiling components of the raffinate stream are withdrawn from distillation column K' ₂ through line 630. [0085] The pentenenitrile-dep!eted stream in Sine 630 is then passed into distillation column K' ₃ , where dinitriles are separated from higher boiling components remaining in the raffinate stream, in particular, dinitriles, such as ADN and MGN, are withdrawn from distillation column K' ₃ through line 635, and higher boiling components of the raffinate stream are withdrawn from distillation column K' ₃ through line 640. These higher boiling components in line 640 may comprise, for example, catalyst degradation products.

[0086] The dinitrile-enriched stream in line 635 is then passed into distillation column K' ₄ , where adiponitrile is separated from lower boiiing dinitriles, such as MGN. In particular, MGN is withdrawn from distillation column K' ₄ through line 670, and a purified adiponitrile stream is withdrawn from distillation column K' ₄ through line 660.

[0087] Although not shown in Figure 4, a complex of Lewis acid and Lewis base in the form of a dispersed solid precipitate may be removed, e.g., by filtration, from the raffinate before the stream is introduced into distillation column K\. According to another embodiment, this complex may be removed from the stream in line 620 before this stream enters distillation column K' ₂ . According to another embodiment, this complex may be removed from the stream in line 630 before this stream enters distillation column K' ₃ .

EXAMPLES

[0088] In the following examples, vaiues for extraction coefficient are the ratio of weight fraction of catalyst in the extract phase (hydrocarbon phase) versus the weight fraction of catalyst in the raffinate phase (organonitriie phase). An increase in extraction coefficient results in greater efficiency in recovering catalyst. As used herein, the terms, light phase, extract phase and hydrocarbon phase, are synonymous. Also, as used herein, the terms, heavy phase, organonitriie phase and raffinate phase, are synonymous.

[0089] Analyses of the extract and the raffinate streams of the catalyst extraction were conducted on an Agilent 1 00 series HPLC and via I CP. The HPLC was used to determine the extraction efficiency of the process.

[0090] in the Examples which follow, a diphosphite ligand is present. However, it is believed that the results of these Examples would be essentially the same if a different phosphorus-containing ligand, such as a diphosphonite ligand, was substituted for the diphosphite ligand. Example 1

[0091] To a 50 mL, jacketed, glass laboratory extractor, equipped with a magnetic stirbar, digital stir-plate, and maintained at 65°C, was charged 10 grams of the product of a

pentenenitrile-hydrocyanation reaction, and 10 grams of the extract from the second stage of a mixer-settler cascade, operated in counter-current flow. This extract from the second stage comprised approximateiy 50 ppm nickel and 3100 ppm diphosphite ligand. The hexamethylene diamine concentration in the system was 0 ppm.

[0092] The reactor product was approximately:

85% by weight C ₆ dinitriles

1 % by weight C ₅ mononitriles

1 % by weight catalyst components

200 ppm by weight active nickel

230 ppm by weight zinc.

[0093] The laboratory reactor was then mixed at 500 rotations-per-minute, for 10 minutes, and then allowed to settle for 1 minute. After settling for 1 minute, a stable emulsion was present throughout the extract phase. Samples were obtained of the extract and raffinate phases of the extractor and analyzed to determine the extent of catalyst extraction. The ratio of active nickel present in the extract phase vs. the raffinate phase was found to be 5. The concentration of zinc in the raffinate was found to be 230 ppm.

Example 2

[0094] Example 1 was repeated except that hexamethylene diamine (HMD) was added to the system. In particular, a sufficient amount of HMD was added so that the molar ratio of Zn/HMD was 2 in the system.

Example 3

[0095] Example 1 was repeated except that hexamethylene diamine (HMD) was added to the system. In particular, a sufficient amount of HMD was added so that the molar ratio of Zn/HMD was 6 in the system. Example 4

[0096] Example 1 was repeated except that hexamethylene diamine (HMD) was added to the system. In particular, a sufficient amount of HMD was added so that the molar ratio of Zn/HMD was 2.4 in the system.

Example 5

[0097] Example 1 was repeated except that hexamethylene diamine (HMD) was added to the system. In particular, a sufficient amount of HMD was added so that the molar ratio of Zn/HMD was 1.2 in the system.

Example 6

[0098] Example 1 was repeated except that bis-hexamethyiene triamine (BHMT) was added to the system. In particular, a sufficient amount of BHMT was added so that the molar ratio of Zn/BMHT was 5.9 in the system.

Example 7

[0099] Example 1 was repeated except that bis-hexamethyiene triamine (BHMT) was added to the system. In particular, a sufficient amount of BHMT was added so that the molar ratio of Zn/BMHT was 2.9 in the system.

Example 8

[00100] Example 1 was repeated except that bis-hexamethyiene triamine (BHMT) was added to the system. In particular, a sufficient amount of BHMT was added so that the molar ratio of Zn/BMHT was .2 in the system.

Example 9

[00101] Example 1 was repeated except that bis-hexamethyiene triamine (BHMT) was added to the system. In particular, a sufficient amount of BHMT was added so that the molar ratio of Zn/BMHT was 12 in the system.

Example 10

[00102] Example 1 was repeated except that 1 ,2-diaminocyclohexane (DCH) was added to the system. In particular, a sufficient amount of DCH was added so that the mo!ar ratio of Zn/DCH was 1.6 in the system. Example 11

[00103] Example 1 was repeated except that 1 ,2-diaminocyclohexane (DCH) was added to the system. In particular, a sufficient amount of DCH was added so that the molar ratio of Zn/DCH was 2 in the system.

Example 12

[00104] Example 1 was repeated except that 1,2-diaminocyciohexane (DCH) was added to the system. In particular, a sufficient amount of DCH was added so that the molar ratio of Zn/DCH was 4 in the system.

Example 13

[00105] Example 1 was repeated except that 1 ,2-diaminocyclohexane (DCH) was added to the system. In particular, a sufficient amount of DCH was added so that the molar ratio of Zn/DCH was 8 in the system.

Example 14

[00106] Example 1 was repeated except that triethyiamine (TEA) was added to the system. In particular, a sufficient amount of TEA was added so that the molar ratio of Zn TEA was 1 in the system.

Example 15

[00107] Example 1 was repeated except that octylamine was added to the system. In particular, a sufficient amount of TEA was added so that the molar ratio of Zn/octylamine was 1.3 in the system.

Comparative Example 16

[00108] Example 1 was repeated except that polyethyleneg!ycol (PEG-600) was added to the system. In particular, a sufficient amount of PEG-600 was added so that the molar ratio of Zn/PEG-600 was 1.5 in the system. Comparative Exampie 17

[00109] Example 1 was repeated except that adipamide was added to the system. In particular, a sufficient amount of adipamide was added so that the molar ratio of Zn/ adipamide was 2.3 in the system.

Comparative Exampie 18

[00110] Exampie 1 was repeated except that triphenyl phosphine (Ph ₃ P) was added to the system. In particular, a sufficient amount of Ph ₃ P was added so that the moiar ratio of Zn/Ph ₃ P was 1 in the system.

Exampie 19

[00111] Exampie 1 was repeated except that calcium hydroxide (Ca(OH) ₂ ) was added to the system, in particular, a sufficient amount of Ca(OH) ₂ was added so that the moiar ratio of Zn/Ca{OH) ₂ was 0.3 in the system.

[001 2] Results of Examples 1-19 are summarized in Tabie 1.

Table 1

Temp Time

Ex./CEx. (°C) (min) Zn/Additive Additive KLL Zn/Ni

1 65 10 None 5 1.15

2 65 10 12.0 HMD 13 1.09

3 65 10 6.0 HMD 13 1.11

4 65 10 2.4 HMD 23 0.43

5 65 10 1.2 HMD 84 0.12

6 65 10 5.9 BH T 102 0.12

7 65 10 2.9 BHMT 80 0.17

8 65 10 1.2 BHMT 1 12 0.17

9 65 10 12.0 BHMT 18

10 65 10 1.6 DCH 1 19 0.85

1 1 65 10 2 DCH 1 14

12 65 10 4 DCH 27 1.03

13 65 10 8 DCH 8 1.05

14 65 10 1 TEA 20 0.94

15 65 10 1.3 Octyiamine 63 0.96

16 65 10 1.5 PEG-600 5 1.07

17 65 10 2.3 Adipamide 6

18 65 10 1 Ph ₃ P 4 1.15

19 65 10 0.3 Ca(OH) ₂ 14 KLL = amount of cataiyst in the extract / amount of cataiyst in the raffinate;

Zn/Additive = the molar ratio of the zinc-to-additive during extraction;

Zn/Ni = the ratio of the total amount of zinc-to-nickel remaining in both phases after the extraction, as determined by inductively coupled plasma spectrometry (!CP).

[00113] The data summarized in Table 1 represent evaluations of a number of materials as potential additives for improved catalyst extraction. Examples 1-5 show the beneficial effect of hexamethyiene diamine (HMD) on catalyst extraction, as the HMD loading increases

(represented by decreasing Zn/Additive ratio) the catalyst extraction efficiency (represented by KLL) increases. Examples 6-9 show the beneficial effect of bis-hexamethylene triamine (BHMT) on cataiyst extraction. Examples 10-13 show the beneficial effect of ,2- diaminocyciohexane (DCH) on catalyst extraction. Example 15 shows the beneficial effect of adding octylamine on catalyst extraction. Example 19 shows the beneficial effect of calcium hydroxide on catalyst extraction. By way of contrast, Comparative Examples 16-18 show little effect on cataiyst extraction using PEG-600, adipamide, and triphenyl phosphine, respectively.

[00114] The results in Table 1 show that BHMT produced superior results. For example, as compared with HMD, at a Zn/Additive ratio of 1.2, BHMT produced a greater KLL value than HMD. As compared with DCH, BHMT produced a greater KLL value and a smaller Zn/Ni ratio, when used at a Zn/Additive ratio of 5.9, than DCH, when used at a Zn/Additive ratio of 4. As compared with octylamine, BHMT produced a greater KLL value and a smaller Zn/Ni ratio, when used at a Zn/Additive ratio of 1.2, than octylamine, when used at a Zn/Additive ratio of 1.3.

Examples 20-25

[00115] These Examples 20-25 illustrate that effective catalyst recovery occurs for a mononitrile to dinitrile ratio greater than 0.65.

[00116] Five different mixtures comprised of a Ni diphosphite complex, with the diphosphite ligand shown in Structure XX (where R ⁷ is isopropyi, R ¹⁸ is H, and R ¹⁹ is methyl), ZnC! ₂ (equimolar with Ni) and differing in the ratio of mononitrile to dinitrile, were separately liquid- liquid batch extracted with an equal weight of cyane (i.e. cyclohexane). The molar ratio of organic mononitrile to organic dinitrile and the resulting extraction coefficients are shown in the Table 2 below. A compound may be effectively recovered if it has an extraction coefficient of 1 or greater at solvent to feed ratios greater than 1 using a countercurrent multistage extractor. Table 2.

Catalyst and ligand extraction coefficients

for varying ratios of mononitriles-to-dinitriles

Catalyst extraction Ligand extraction

Example mononitri!e/dinitriie coefficient coefficient

20 2.33 1.28 4.09

21 1.85 1.33 8.08

23 1.19 2.02 16.97

24 0.91 2.63 35.99

25 0.57 4.82 49.59

Example 26

[00117] This Example demonstrates the effect of hold-up time on the extractabiiity of the diphosphite ligand catalyst.

[00118] A mixture comprised predominantly of organic dinitriles and a Ni diphosphite complex, the structure of the diphosphite ligand being shown in Structure XX (where R ⁷ is isopropy!, R ¹⁸ is H, and R ⁹ is methyl) and ZnC! ₂ (equimoiar with Ni) was divided into two portions. Both portions are liquid-liquid extracted in a three-stage contactor at 40°C, with an equal weight of cycfohexane. Both portions were sampled with time and the progress of the catalyst recovery into the extract phase is shown in Table 3 as the percent of the final steady state value achieved at a given time.

Table 3

Concentration of Diphosphite ligand with time in the extracting solvent phase.

Example 27

[00119] This Example illustrates the effect of temperature on the extractability of catalyst with first-stage extraction solvent recycle.

[00120] A mixture comprised predominantly of organic dinitriles and a Ni diphosphate complex, the structure of the diphosphite iigand being shown in Structure XXIV (where R ⁷ is methyl, R ¹⁸ is methyl and R ¹⁹ is H) and ZnCI ₂ (equimolar with Ni) was divided into three portions. The portions were batch Iiquid-liquid extracted at 50°C, 65°C and 80°C, respectively, with an equal weight of n-octane and monitored with time. The results are shown in Table 4.

Table 4

Example 28

[00 21] This Example demonstrates the effect of adding water in three-stage extraction with cydohexane recycle in the last stage.

[00122] Fifteen grams of a mixture comprised predominantly of organic dinitriles and a Ni diphosphite complex, the structure of the diphosphite Iigand being shown in Structure XXIV (where R ¹⁷ is methyl, R ¹⁸ is methyl and R ¹⁹ is H) and ZnCI ₂ (equimolar with Ni), was extracted in a three-stage continuous extractor at a temperature of 50°C with an equal weight of

cydohexane for one hour resulting in an catalyst extraction coefficient of 4.3, as measured by the amount of catalyst in the extract of the first stage divided by the amount of catalyst in the feed of the reaction mixture fed to the last stage of the three-stage countercurrent extractor.

[00123] To this mixture, 00 microliters of water was added. After continuing to heat and agitate for another hour, the diphosphite Ni extraction coefficient was measured as 3.4 - a threefold increase. Examples 29 and 30

[00124] These Examples demonstrate the effect of adding hexamethylene diamine (HMD) to the extraction zone.

[00125] Example 1 was repeated except that hexamethylene diamine was added to the product of a pentene-hydrocyanation reaction. To a 50 mL, jacketed, glass laboratory extractor, equipped with a magnetic stirbar, digital stir-plate, and maintained at 65°C, was charged 10 grams of the product of pentene-hydrocyanation reactor product, and 0 grams of the extract from the second stage of a mixer-settler cascade, operated in counter-current flow.

[00 26] The reactor product was approximately:

85% by weight C _B dinitriies

14% by weight C ₅ mononitriles

1% by weight catalyst components

360 ppm by weight active nickel.

[00127] The laboratory reactor was then mixed at 1160 rotations-per-minute, for 20 minutes, and then allowed to settle for 15 minutes. A stable emulsion was present throughout the extract phase in the absence of the addition of HMD. After 15 minutes of settling, essentially no emulsion phase was present when HMD was added. Samples were obtained of the extract and raffinate phases of the extractor and analyzed to determine the extent of catalyst extraction.

Table 5

Effect of hexamethylene diamine on catalyst extraction

Examples 31-36

[00128] These Examples demonstrate the beneficial effect of adding hexamethylene diamine (HMD) on the reaction temperature required for catalyst extraction. For Examples 31-33, Example 1 was repeated, but the mixing time was 20 minutes, and the temperature was varied as indicated in Table 6. For Examples 34-36, Example 5 was repeated, and the temperature was varied as indicated in Table 6. Table 6

Effect of hexamethylene diamine on temperature for catalyst extraction.

Example Temp (°C) KLL Zn/HMD

31 65 16.76 No HMD

32 55 13.25 No HMD

33 45 8.06 No HMD

34 65 84.42 1.2

35 55 82.91 1.2

36 45 82.00 1.2

[00129] The data summarized in Table 6 represent evaluations of catalyst extraction performed at varying temperature from 45 to 65 degrees Ceisius, with and without HMD present. Examples 31-33 show that catalyst extraction increases linearly with increasing temperature (represented by KLL). Examples 34-36 show that catalyst extraction does not require increased temperature when HMD is added.

Examples 37-44

[00130] These Examples demonstrate the beneficial effect of adding hexamethyiene diamine (HMD) on the mixing time required for catalyst extraction. For Examples 37-40, Example 31 was repeated, and the mixing time was varied as indicated in Table 7. For Examples 41-44, Example 5 was repeated, and the mixing time was varied as indicated in Table 7.

Table 7

Effect of hexamethylene diamine on mixing time required for catalyst extraction.

Example Mixing Time KLL Zn/HMD

37 20 16.13 No HMD

38 10 14.86 No HMD

39 5 14.49 No HMD

40 1 11.05 No HMD

41 10 84.42 1.2

42 5 114.34 1.2

43 1 98.24 1.2

44 0.5 56.23 1.2

[00131] The data summarized in Tabie 7 represent evaluations of catalyst extraction performed at varying mixing time from 20 minutes to 30 seconds, with and without HMD present. Examples 37-40 show that a decrease in catalyst extraction occurs when the mixing time is decreased to less than 5 minutes. Examples 41-44 show that catalyst extraction does not decrease until the mixing time is decreased to less than 1 minute, when HMD added.

Examples 45-48

[00132] These Examples demonstrate the beneficial effect of adding hexamethylene diamine (HMD) and bis-hexamethylene triamine (BHMT) to the mixing section of a mixer-settler, rather than to the feed line to this mixing section. Results are shown in Table 8.

Table 8

Effect of additive addition point.

Example Addition Additive Mixing KLL Stable

Point Time Emulsion

45 Mixer HMD 20 23 No

46 Mixer BHMT 20 80 No

47 Feed Line HMD N/A 14 Yes

48 Feed Line BHMT N/A 14 Yes

[00133] Examples 45-48 show that addition of the additives HMD or BHMT directly to the mixer system of a catalyst extraction system causes a beneficial increase in catalyst recovery, as indicated by increased KLL.

Examples 49-53

[00134] These Examples demonstrate the ability of complex of zinc chloride (ZnCI ₂ ) and bis- hexamethylene triamine (BHMT) to catalyze the cyclization of adiponitrile (ADN) to 2- cyanocyclopentylideneimine (CP!) under conditions encountered when a raffinate stream is refined to produce purified ADN.

[00135] A simulated raffinate composition which was obtained from the tails stream of a column for removal of pentenenitriles from dinitriles (i.e. column K' ₂ and stream 630 in Figure 4) was used for the following examples. This raffinate had the following composition: 94% adiponitrile, 4% methylglutaronitrile, 0.1 % pentenenitriles, 0.5% ethylsuccinonitri!e, and 271 ppm zinc. To simulate conditions in a distillation column to distill dinitriles the raffinate was heated to 180°C. [00136] Various additives were then added to the heated mixture. The composition of these additives is shown in Table 9.

Table 9

Amount of additive.

Example Additive Amount of BHMT Zn/BHMT

49 BHMT + ZnCi ₂ 1 wt% 1

50 BHMT + ZnCi ₂ 2 wt% 0 5

51 BHMT + ZnCS ₂ 0.5 wt% 2

52 BHMT 2 wt% N/A

53 ZnCi ₂ 0 N/A

[00137] In Table 9, it will be understood that the amount of BHMT is based on the total weight of the raffinate composition before addition of the additive. It will be further understood that the ratio of Zn/BHMT is expressed in terms of equivalents of Zn per mole of BHMT. The amount of ZnCS ₂ added as per Example 53 {EX 53) was 3 wt%, based on the total weight of the raffinate composition before addition of the ZnCI ₂ .

[00138] After the addition of the additive, samples of the mixture were taken at 1 hour, 2 hours, 3 hours and 5 hours. These samples were analyzed, and the concentration of CPI in the samples was determined in terms of CPI (mol/L), i.e. moles of CPI per liter of the mixture.

Results are shown in Figure 5.

[00139] Figure 5 shows that CPI formation was negligible according to Example 52 (EX 52), wherein the additive included BHMT in the absence of ZnCI ₂ . Figure 5 also shows that CPI formation was negligible according to Example 53 (EX 53), wherein the additive included ZnCS ₂ in the absence of BHMT. However, Figure 5 shows that considerable amounts of 2- cyanocyclopentylideneimine (CPI) were formed according to Examples 49-51 (EX 49 to EX 51) in increasing quantities over time when the additive included both BHMT and ZnC! ₂ .

Examples 54-56

[00140] These Examples demonstrate the ability of a complex of zinc chloride (ZnCI ₂ ) and hexamethylene diamine (HMD) to catalyze the cyclization of adiponitrile (ADN) to 2- cyanocyclopentylideneimine (CPI) under conditions encountered when a raffinate stream is refined to produce purified ADN.

[00141] A raffinate material which was obtained from the tails stream of a column for removal of pentenenitriles from dinitriles (i.e. column K' _z and stream 630 in Figure 3) was used for the following examples. This raffinate had the following composition: 94% adiponitrile, 4% methy!g!utaronitrile, 0.1% pentenenitriles, 0.5% ethylsucclnonitrile, and 271 ppm zinc. To simulate conditions in a distillation column to distill dinitriies the raffinate was heated to 180°C.

[00142] Various additives were then added to the heated mixture. The composition of these additives is shown in Table 10.

Table 10

Amount of additive.

Example Additive Amount of HMD Zn/HMD

54 HMD + ZnCI ₂ 0.5 wt% Ϊ

55 ZnCI ₂ o N/A

56 HMD 0.5 wt% N/A

[00143] in Table 10 it will be understood that the amount of HMD is based on the total weight of the raffinate composition before addition of the additive. It will be further understood that the ratio of Zn/HMD is expressed in terms of equivalents of Zn per mole of HMD. The amount of ZnCI ₂ added as per Example 55 (EX 55) was 0.6 wt%, based on the total weight of the raffinate composition before addition of the ZnC! ₂ .

[00144] After the addition of the additive, samples of the mixture were taken at various times including 1 hour, 2 hours, 3 hours, 3.5 hours and 5 hours. These samples were analyzed, and the concentration of CPI in the samples was determined in terms of CPI (mol/L), i.e. moles of CPI per liter of the mixture. Results are shown in Figure 6.

[00145] Figure 6 shows that CP! formation was negligible according to Example 56 (EX 56), wherein the additive included HMD in the absence of ZnCl ₂ . Figure 6 also shows that only small amounts of CPI were formed according to Example 55 (EX 55), wherein the additive included ZnCl ₂ in the absence of HMD. However, Figure 6 shows that considerable amounts of 2-cyanocyclopentylideneimine (CP!) were formed according to Example 54 (EX 54) in increasing quantities over time when the additive included both HMD and ZnCI ₂ , especially when the mixture was heated for 3.5 and 5 hours.