# US 8,772,527 B2 · Process for isomerization of cis-2-pentenenitrile to 3-pentenenitriles

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- Number: US 8,772,527 B2
- Document ID: US8772527B2
- Status: Granted
- Kind: B2
- Application number: 13/867,671
- Filed: 2013-04-22
- Published: 2013-10-31
- Granted: 2014-07-08
- Earliest claimed: 2012-04-27
- Assignees: BASF SE
- Applicants: BASF SE
- Inventors: Rolf-Hartmuth Fischer; Alfred Oftring; Robert Baumann; Hermann Luyken
- Web page: https://patentgrep.com/patent/US8772527B2

## CPC

- C07C 253/30: by reactions not involving the formation of cyano groups
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

The present invention relates to an improved process for batchwise or continuous isomerization of cis-2-pentenenitrile to 3-pentenenitriles in the presence of 1,4-diazabicyclo[2.2.2]octane as catalyst.

## Claims

### Claim 1

A process for batchwise or continuous isomerization of cis-2-pentenenitrile to 3-pentenenitriles, which comprises isomerizing cis-2-pentenenitrile with 1,4-diazabicyclo[2.2.2]octane.

### Claim 2 (depends on 1)

The process according to claim 1, wherein cis-2-pentenenitrile is isomerized at temperatures of 80 to 200° C. and a pressure of 0.01 to 50 bar.

### Claim 3 (depends on 1)

The process according to claim 1, wherein the isomerization of cis-2-pentenenitrile to 3-pentenenitriles is performed in a reaction column.

### Claim 4 (depends on 1)

The process according to claim 1, wherein
a) 3-pentenenitriles or a mixture comprising 3-pentenenitriles is/are hydrocyanated to adiponitrile in the presence of nickel(0)-phosphorus ligand complexes as catalysts,
b) adiponitrile, 2-methylglutaronitrile and nickel(0)-phosphorus ligand complex are removed from the hydrocyanation output, thereby obtaining an organic phase,
c) the cis-2-pentenenitrile in the thus obtained organic phase comprising unsaturated C5 mononitriles is isomerized to 3-pentenenitriles with the aid of 1,4-diazabicyclo[2.2.2]octane as a catalyst, which has a higher boiling point at standard pressure than cis-2-pentenenitrile,
wherein
d) the organic phase which comprises essentially unsaturated C5 mononitriles and is obtained in c) is supplied to a distillation column K1, cis-2-pentenenitrile and cis- and trans-2-methyl-2-butenenitrile are removed from the distillation column K1 via the top, and 3-pentenenitrile and trans-2-pentenenitrile are removed from the distillation column K1 via the bottom and are recycled into the reaction step for hydrocyanation of 3-pentenenitriles,
e) the top product from the distillation column K1 is fed to a distillation column K2, and trans-2-methyl-2-butenenitrile is removed and discharged as a bottom product of column K2,
f) a top product from column K2 and 1,4-diazabicyclo[2.2.2]octane are supplied to a reactor R1, and the reaction product from the reactor R1 and the 1,4-diazabicyclo[2.2.2]octane are supplied to a distillation column K3, and
g) a top product from distillation column K3 is recycled into the reactor R1 and a substream of the top product comprising cis-2-methyl-2-butenenitrile and cis-2-pentenenitrile is discharged, a mixture of cis-2-pentenenitrile, trans-3-pentenenitrile and trans-2-pentenenitrile from a side draw is recycled into the distillation column K1, and 1,4-diazobicyclo[2.2.2]octane and optionally high boilers are discharged as the bottom product.

### Claim 5 (depends on 4)

The process for continuous isomerization of cis-2-pentenenitrile to 3-pentenenitriles according to claim 4, wherein the unsaturated C5 mononitriles comprise one or more of cis-3-pentenenitriles and trans-3-pentenenitriles, 4-pentene-nitrile, trans-2-pentenenitrile, cis-2-methyl-2-butenenitrile, trans-2-methyl-2-butenenitrile, or 2-methyl-3-butenenitrile.

### Claim 6 (depends on 4)

The process for continuous isomerization of cis-2-pentenenitrile to 3-pentenenitriles according to claim 4, wherein the isomerization of cis-2-pentenenitriles is performed in a reaction column.