Inhibiting CPI formation from adiponitrile

• US 10,640,459 B2
• Filed: 08/31/2016
• Issued: 05/05/2020
• Est. Priority Date: 09/03/2015
• Status: Active Grant

• Current Assignee: INV Nylon Chemicals Americas LLC
• Original Assignee: Invista North America Sarl (Invista)
• Inventors: Tenn, III, William J.
• Primary Examiner(s): McCaig, Brian A
• Application Number:
  US15/755,235
• Publication Number:
  US 20180244607A1
• Time in Patent Office: 1,343 Days
• CPC Class Codes: B01D 3/143 by two or more of a fractionation, separation or rectification step
• CPC Class Codes: B01D 3/34 with one or more auxiliary substances
• CPC Class Codes: C07C 253/34 Separation; Purification
• CPC Class Codes: C07C 255/04 containing two cyano groups bound to the carbon skeleton

Abstract

Disclosed is a method for inhibiting the formation of by-products from dinitriles, such as the formation of cyclopentylideneimine (CPI) from Adiponitrile (ADN), comprising adding an effective amount of a Brønsted acid to the ADN. Also disclosed is a method of refining a dinitrile compound by distillation the method comprising the steps of: (a) supplying (i) a feedstream comprising the dinitrile compound and (ii) a Brønsted acid to a distillation apparatus; and (b) withdrawing from the distillation apparatus an overhead distillate stream comprising the dinitrile compound.

Claims

1. A method of refining a dinitrile compound by distillation, the method comprising:

(a) supplying (i) a feedstream comprising the dinitrile compound, wherein the dinitrile compound is adiponitrile and wherein the feedstream comprises a Lewis acid that is ZnX₂, BX₃, or AlX₃, wherein X represents a halogen, trifluoromethanesulfonate, methanesulfonate, or toluenesulfonate, and (ii) a Brø

nsted acid to a distillation apparatus, wherein

the Brø

nsted acid is supplied to the distillation apparatus in an amount of from 5 to 5,000 ppm by weight, based on the total weight of the dinitrile-containing feedstream and the Brø

nsted acid,

the amount of the Brø

nsted acid supplied to the distillation apparatus is effective to inhibit the formation of 2-cyanocyclopentlideneimine (CPI) from the dinitrile compound in the distillation apparatus, and

the Brø

nsted acid does not degrade in the distillation apparatus; and

(b) withdrawing from the distillation apparatus an overhead distillate stream comprising the dinitrile compound and withdrawing the Brø

nsted acid from the distillation apparatus in a bottoms stream comprising the Brø

nsted acid.

2. A method according to claim 1, wherein the amount of Lewis acid present in the dinitrile-containing feedstream is in the range of from 50 to 10,000 ppm by weight based on the total weight of the dinitrile-containing feedstream.

3. A method according to claim 1, wherein the feedstream to the distillation apparatus in (a) comprises a reaction effluent from a process for the production of dinitriles via the hydrocyanation of unsaturated mononitriles.

4. A method according to claim 3, wherein the feedstream to the distillation apparatus in (a) comprises a reaction effluent from a process for the production of ADN via the hydrocyanation of 3PN.

5. A method according to claim 4 wherein the reaction effluent comprises a nickel (0) catalyst stabilized with phosphorus-containing ligands and/or excess phosphorus-containing ligands.

6. A method according to claim 1, wherein the Brø

nsted acid is selected from phosphoric acids, sulfuric acid, C₄ to C₁₂ alkanesulfonic acids and C₇ to C₁₈ alkylbenzenesulfonic acids.

7. A method according to claim 6, wherein the Brø

nsted acid is selected from phosphoric acid, polyphosphoric acid, pyrophosphoric acid, octanesulfonic acid, decanesulfonic acid, dodecanesulfonic acid, 4-toluenesulfonic acid, 4-ethylbenzenesulfonic acid, 4-butylbenzenesulfonic acid and 4-dodecylbenzenesulfonic acid.

8. A method according to claim 1, wherein the distillation apparatus is operated with a bottoms temperature in the range of from 150 to 200°

C.

9. A method according to claim 1, wherein the distillation apparatus comprises a plurality of distillation columns and wherein the Brø

nsted acid is supplied to at least one of the distillation columns.

10. A method for inhibiting the formation of by-products from a dinitrile compound, the method comprising adding from 5 to 5,000 ppm by weight of a Brø

nsted acid to a composition comprising the dinitrile compound, based on the total weight of the dinitrile-containing composition and the Brø

nsted acid, wherein the dinitrile compound is adiponitrile, the composition comprises a Lewis acid that is ZnX₂, BX₃, or AlX₃, wherein X represents a halogen, trifluoromethanesulfonate, methanesulfonate, or toluenesulfonate, the amount of the Brø

nsted acid supplied to the composition is effective to inhibit the formation of 2-cyanocyclopentylideneimine (CPI) from the dinitrile compound, and wherein the Brø

nsted acid has lower volatility than the dinitrile compound and the Brø

nsted acid does not degrade in the composition.

11. A method according to claim 10, for inhibiting the formation of CPI from ADN.

12. A method according to claim 10, comprising refining the dinitrile compound by distillation, wherein (i) a feedstream comprising the dinitrile compound and (ii) the Brø

nsted acid are supplied to a distillation apparatus;

an overhead distillate stream comprising the dinitrile compound is withdrawn from the distillation apparatus; and

the Brø

nsted acid is withdrawn from the distillation apparatus in a bottoms stream comprising the Brø

nsted acid;

wherein the amount of the Brø

nsted acid supplied to the distillation apparatus is effective to inhibit the formation of 2-cyanocyclopentylideneimine (CPI) from the dinitrile compound in the distillation apparatus.

13. A method according to claim 10, wherein the method comprises adding 5 to 800 ppm by weight of the Brø

nsted acid to the composition comprising the dinitrile compound based on the total weight of the composition comprising the dinitrile compound and the Brø

nsted acid.