# US 8,772,477 B2 · Process for preparing lactams

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- Number: US 8,772,477 B2
- Document ID: US8772477B2
- Status: Granted
- Kind: B2
- Application number: 13/260,268
- Filed: 2010-04-27
- Published: 2012-04-19
- Granted: 2014-07-08
- Earliest claimed: 2009-04-27
- Assignees: Rhodia Operations
- Applicants: Philippe Leconte
- Inventors: Philippe Leconte
- Web page: https://patentgrep.com/patent/US8772477B2

## CPC

- C07D 201/08: from carboxylic acids or derivatives thereof, e.g. hydroxy carboxylic acids, lactones or nitriles
- C07D 223/10: attached in position 2
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)

## Abstract

A method for preparing lactams by cyclizing hydrolysis of a corresponding aminonitrile is described. A method for manufacturing a lactam by reacting an aminonitrile with water in the presence of a catalyst involving placing the water and the aminonitrile in contact in vapor phase, passing the mixture of vapors through a bed of catalyst arranged in at least one tube forming a reaction chamber and recovering the lactam at the outlet of the tube is also described.

## Claims

### Claim 1

A process for manufacturing a lactam from a linear or branched aliphatic aminonitrile having from 3 to 12 carbon atoms, the process comprising reacting said aminonitrile with water by forming a mixture of vapors of said aminonitrile and water by bringing into contact, in a vapor phase, water and said aminonitrile, passing said mixture of vapors through a catalyst bed positioned in at least one tube that forms a reactor and recovering the lactam at a tube outlet,
wherein the aminonitrile is aminocapronitrile and the lactam is ε-caprolactam, and
wherein the temperature in the tube is controlled by cooling means to maintain the temperature throughout the length of the tube at a value between 280° C. and 340° C., said cooling means comprising at least two distinct means, a first cooling means which controls the temperature in an upstream part of the tube in order to maintain the temperature at a value below 340° C., and a second cooling means positioned around a downstream part of the tube in order to maintain the temperature of the tube at a value above 280° C. and below 340° C.

### Claim 2 (depends on 1)

The process according to claim 1, wherein the temperature of the means intended to control the temperature in the upstream part of the tube is between 280° C. and 310° C.

### Claim 3 (depends on 1)

The process according to claim 1, wherein the temperature of the means positioned around the downstream part of the tube is between 290° C. and 340° C.

### Claim 4 (depends on 1)

The process according to claim 1, wherein the upstream part of the tube has a length between 0.5 m and 1.5 m, the total length of the tube being between 3.5 m and 7 m.