Hydrocyanation process with reduced yield losses

1. A hydrocyanation process to produce adiponitrile and other dinitriles having six carbon atoms, the process comprising:

a) forming a reaction mixture in the presence of at least one Lewis acid, said reaction mixture comprising ethylenically unsaturated nitriles having five carbon atoms, hydrogen cyanide, and a catalyst precursor composition, by continuously feeding the ethylenically unsaturated nitriles, the hydrogen cyanide, and the catalyst precursor composition;

b) controlling X and Z,

wherein X is the overall feed molar ratio of 2-pentenenitriles to all unsaturated nitriles; and

Z is the overall feed molar ratio of hydrogen cyanide to all unsaturated nitriles; by selecting

a value for X in the range of about 0.001 to about 0.5; and

a value for Z in the range of about 0.5 to about 0.99;

such that the value of quotient Q, wherein

Q

=

X

⁢

[

(

moles

⁢

⁢

3

⁢

PN

+

4

⁢

PN

⁢

⁢

in

⁢

⁢

the

⁢

⁢

feed

)

/

⁢

⁢

moles

⁢

⁢

all

⁢

⁢

unsaturated

⁢

⁢

nitriles

⁢

⁢

in

⁢

⁢

the

⁢

⁢

feed

)

-

Z

]

⁢

is in the range from about 0.2 to about 10, wherein 3PN is 3-pentenenitriles and 4PN is 4-pentenenitrile; and

c) withdrawing a reaction product mixture comprising adiponitrile;

wherein the ratio of the concentration of 2-pentenenitriles to the concentration of 3-pentenenitriles in the reaction mixture is in the range from about 0.2/1 to about 10/1;

wherein the catalyst precursor composition comprises a zero-valent nickel and at least one bidentate phosphite ligand; and

wherein the bidentate phosphite ligand is selected from a member of the group represented by Formulas I and II, in which all like reference characters have the same meaning, except as further explicitly limited:

wherein

each R 1 is independently selected from the group consisting of methyl, ethyl, and primary hydrocarbyl of 3 to 6 carbon atoms;

each R 2 is independently selected from the group consisting of primary and secondary hydrocarbyl of 1 to 6 carbon atoms; and

each R 11 , R 12 , R 13 , R 21 , R 22 , and R 23 is independently selected from the group consisting of H, aryl, and a primary, secondary, or tertiary hydrocarbyl of 1 to 6 carbon atoms.

2. The process of claim 1 ,

wherein the selected value for X is in the range from about 0.01 to about 0.25 and the selected value for Z is in the range from about 0.70 to about 0.99; and wherein the value of Q is in the range from about 1 to about 5; and

wherein the ratio of the concentration of 2-pentenenitriles to the concentration of 3-pentenenitriles in the reaction mixture is in the range from about 1/1 to about 5/1.

3. The process of claim 2 wherein at least one bidentate phosphite ligand is selected from a member of the group consisting of:

the compound represented by Formula I where

each R 1 =methyl, each R 2 =iso-propyl,

each R 11 ═H, each R 12 ═H, each R 13 ═H,

each R 21 ═H, each R 22 =methyl, and each R 23 =methyl;

the compound represented by Formula I where

each R 1 =methyl, each R 2 =iso-propyl,

each R 11 ═H, each R 12 =methyl, each R 13 ═H,

each R 21 ═H, each R 22 =methyl, and each R 23 =methyl;

the compound represented by Formula I where

each R 1 =methyl, each R 2 =iso-propyl,

each R 11 ═H, each R 12 ═H, each R 13 =methyl

each R 21 ═H, each R 22 =methyl, and each R 23 =methyl;

the compound represented by Formula II where

each R 1 =methyl, each R 2 =iso-propyl,

each R 11 ═H, each R 12 ═H, and each R 13 ═H;

the compound represented by Formula II where

each R 1 =methyl, each R 2 =iso-propyl,

each R 11 ═H, each R 12 =methyl, and each R 13 ═H;

the compound represented by Formula II where

each R 1 =methyl, each R 2 =iso-propyl,

each R 11 ═H, each R 12 ═H, and each R 13 =methyl;

the compound represented by Formula I where each R 1 =methyl, each R 2 =methyl,

each R 11 ═H, each R 12 H, each R 13 ═H,

each R 21 ═H, each R 22 =methyl, and each R 23 =methyl;

the compound represented by Formula I where

each R 1 =methyl, each R 2 =methyl,

each R 11 ═H, each R 12 =methyl, each R 13 ═H,

each R 21 ═H, each R 22 =methyl, and each R 23 methyl;

the compound represented by Formula I where

each R 1 =methyl each R 2 =methyl,

each R 11 ═H, each R 12 ═H, each R 13 =methyl,

each R 21 ═H, each R 22 =methyl, and each R 23 =methyl;

the compound represented by Formula I where

each R 1 =methyl, each R 2 =methyl,

each R 11 ═H, each R 12 ═H, each R 13 ═H,

each R 21 =methyl, each R 22 =methyl, and each R 23 =methyl;

the compound represented by Formula I where

each R 1 =methyl, each R 2 =methyl,

each R 11 ═H, each R 12 =methyl, each R 13 ═H,

each R 21 methyl, each R 22 methyl, and each R 23 =methyl;

the compound represented by Formula I where

each R 1 =methyl, each R 2 =methyl,

each R 11 ═H, each R 12 ═H, each R 13 =methyl,

each R 21 =methyl, each R 22 =methyl, and each R 23 =methyl;

the compound represented by Formula II where

each R 1 =methyl, each R 2 =cyclopentyl,

each R 11 ═H, each R 12 ═H, and each R 13 ═H;

the compound represented by Formula II where

each R 1 =methyl, each R 2 =cyclopentyl,

each R 11 ═H, each R 12 =methyl, and each R 13 ═H;

the compound represented by Formula II where

each R 1 =methyl, each R 2 =cyclopentyl,

each R 11 ═H, each R 12 ═H, and each R 13 =methyl;

the compound represented by Formula I where

each R 1 =ethyl, each R 2 =iso-propyl,

each R 11 ═H, each R 12 ═H, each R 13 ═H

each R 21 ═H, each R 22 =methyl, and each R 23 =methyl; and

the compound represented by Formula I where

each R 1 =methyl, each R 2 =iso-propyl,

each R 11 ═H, each R 12 =tert-butyl, each R 13 ═H

each R 21 ═H, each R 22 =methyl, and each R 23 =methyl.

4. The process of claim 2 wherein at least one bidentate phosphite ligand is selected from a member of the group consisting of:

the compound represented by Formula I where

each R 1 =methyl, each R 2 =iso-propyl,

each R 11 ═H, each R 12 ═H, each R 13 ═H,

each R 21 ═H, each R 22 =methyl, and each R 23 =methyl;

the compound represented by Formula I where

each R 1 =methyl, each R 2 =iso-propyl,

each R 11 ═H, each R 12 =methyl, each R 13 ═H

each R 21 ═H, each R 22 =methyl, and each R 23 =methyl; and

the compound represented by Formula II where

each R 1 =methyl, each R 2 =iso-propyl,

each R 11 ═H, each R 12 ═H, and each R 13 ═H.

5. The process of claim 1 wherein the overall feed molar ratio of 2-pentenenitriles to all unsaturated nitriles is controlled by addition of 2-pentenenitriles produced in an independent process or by direct recycle of the 2-pentenenitriles from the reaction product mixture within the process.

6. The process of claim 1 wherein the Lewis acid promoter comprises at least one compound selected from the group consisting of zinc chloride, iron (II) chloride, manganese (II) chloride, and mixtures thereof.

7. The process of claim 3 wherein the reaction mixture is maintained at a temperature of from about 20° C. to about 90° C.

8. The process of claim 1 wherein the reaction mixture is maintained at a temperature of from about 35° C. to about 70° C.

9. The process of claim 1 wherein the 2-pentenenitriles originate from a pentenenitrile hydrocyanation process.

10. The process of claim 1 wherein the 3-pentenenitriles originate from a 1,3-butadiene hydrocyanation process.

11. The process of claim 1 wherein the catalyst precursor composition further comprises at least one monodentate phosphite ligand.

12. The process according to claim 1 wherein the reaction product mixture has pentenenitrile to dinitrile molar ratio from about 0.01 to about 2.5, and wherein said reaction product mixture is fed to a liquid-liquid extraction process.

13. The process of claim 1 wherein the 2-pentenenitriles originate from distillation of an extract, a raffinate, or extract and raffinate phases of a liquid-liquid extraction process.

14. The process of claim 1 wherein the bidentate phosphite ligand is a ligand of Formula II.