# US 4,399,001 A · Separating off organic iodine compounds from acetaldehyde-free carbonylation products of methanol, methyl acetate and dimethyl ether

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- Number: US 4,399,001 A
- Document ID: US4399001A
- Status: Granted
- Kind: A
- Application number: 06/315,726
- Filed: 1981-10-28
- Granted: 1983-08-16
- Earliest claimed: 1980-11-29
- Assignees: BASF SE
- Inventors: Horst Hartmann; Waldhelm Hochstein; Gerd Kaibel; Franz-Josef Mueller
- Web page: https://patentgrep.com/patent/US4399001A

## CPC

- C07C 51/573: Separation; Purification; Stabilisation; Use of additives
- C07C 51/46: by azeotropic distillation
- C07C 67/54: by distillation
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

A process for separating off organic iodine compounds from acetaldehyde-free carbonylation products of methanol, methyl acetate and dimethyl ether by removing the iodine compounds by azeotropic distillation with a hydrocarbon having a boiling point, under atmospheric pressure, of 25-55.degree. C.

## Claims

### Claim 1

A process for separating off organic iodine compounds as an impurity from acetaldehyde-free carbonylation products of methanol, methyl acetate and dimethyl ether, which process comprises:
removing the organic iodine impurity by azeotropic distillation of the acetaldehyde-free carbonylation product with a hydrocarbon having a boiling point, under atmospheric pressure, of 25.degree.-50.degree. C., said distillation being carried out under conditions of temperature and pressure sufficient to obtain substantially all of the organic iodine impurity in the azeotrope distillate fraction and to obtain the remaining carbonylation products in one or more higher boiling fractions.

### Claim 2 (depends on 1)

A process as claimed in claim 1, wherein isopentane is used as the hydrocarbon.

### Claim 3 (depends on 2)

A process as claimed in claim 2, wherein the chief impurity to be removed is methyl iodide.

### Claim 4 (depends on 1)

A process as claimed in claim 1, wherein the azeotropic distillation of the acetaldehyde-free carbonylation product is carried out at a pressure of about 1.5-3 bar.

### Claim 5 (depends on 1)

A process as claimed in claim 1, wherein the hydrocarbon is used in an amount of about 10-200 grams per gram of the organic iodine impurity.

### Claim 6 (depends on 5)

A process as claimed in claim 5, wherein the hydrocarbon is selected from the class consisting of isopentane, n-pentane, cyclopentane and 2,2-dimethylbutane.

### Claim 7 (depends on 5)

A process as claimed in claim 5, wherein the hydrocarbon is isopentane.

### Claim 8 (depends on 1)

A process as claimed in claim 1, wherein the chief impurity to be removed is methyl iodide.