# US 4,394,309 A · Process for the preparation of N,N-dimethyl-N-(2-bromo-4-methylphenyl)-triazene

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- Number: US 4,394,309 A
- Document ID: US4394309A
- Status: Granted
- Kind: A
- Application number: 06/249,247
- Filed: 1981-03-30
- Granted: 1983-07-19
- Earliest claimed: 1980-04-12
- Assignees: Bayer Aktiengesellschaft
- Inventors: Claus Stolzer
- Web page: https://patentgrep.com/patent/US4394309A

## CPC

- C07C 17/093: by replacement by halogens
- C07C 231/12: by reactions not involving the formation of carboxamide groups
- C07C 241/00: Preparation of compounds containing chains of nitrogen atoms singly-bound to each other, e.g. hydrazines, triazanes
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

A process for the preparation of N,N-dimethyl-N'-(2-bromo-4-methyl-phenyl)-triazene of the formula ##STR1## comprising (a) reacting N-acetyl-p-toluidine of the formula ##STR2## with bromine at a temperature between about 0.degree. and 100.degree. C., to give the intermediate product of the formula ##STR3## (b) reacting the intermediate product with hydrochloric acid by either (i) adding a dilute solution of aqueous hydrochloric acid to the intermediate product in its reaction solution and heating the mixture to a temperature between about 50.degree. and 120.degree. C., or (ii) precipitating the intermediate product from its reaction solution by mixing with water and filtering off, and without purification or drying heating the precipitate with dilute aqueous hydrochloric acid to a temperature between about 50.degree. and 120.degree. C., thereby to form a solution of 2-bromo-4-methylaniline hydrochloride, (c) reacting the resulting aqueous solution with an alkali metal nitrite at a temperature between about -20.degree. and +30.degree. C., and (d) reacting the product with dimethylamine at a temperature between about 0.degree. and 50.degree. C.

## Claims

### Claim 1

A process for the preparation of N,N-dimethyl-N'-(2-bromo-4-methyl-phenyl)-triazene of the formula ##STR9## consisting essentially of (a) reacting N-acetyl-p-toluidine of the formula ##STR10## with bromine at a temperature between about 0.degree. and 100.degree. C., to give the intermediate product of the formula ##STR11## (b) reacting the intermediate product with hydrochloric acid by either (i) adding a dilute solution of aqueous hydrochloric acid to the intermediate product in its reaction solution and heating the mixture to a temperature between about 50.degree. and 120.degree. C., or
(ii) precipitating the intermediate product from its reaction solution by mixing with water and filtering off, and without purification or drying heating the precipitate with dilute aqueous hydrochloric acid to a temperature between about 50.degree. and 120.degree. C., thereby to form a solution of 2-bromo-4-methylaniline hydrochloride,
(c) reacting the resulting aqueous solution with an alkali metal nitrite at a temperature between about -20.degree. and +30.degree. C., and
(d) reacting the product with dimethylamine at a temperature between about 0.degree. and 50.degree. C.

### Claim 2 (depends on 1)

A process according to claim 1, in which step (a) is carried out in the presence of an acid acceptor.

### Claim 3 (depends on 1)

A process according to claim 1, in which step (a) is carried out in the presence of a diluent.

### Claim 4 (depends on 3)

A process according to claim 3, in which the diluent is acetic acid or an acetic acid/water mixture.

### Claim 5 (depends on 1)

A process according to claim 1, in which the reaction solution of the intermediate of step (a) is treated with a reducing agent prior to step (b).

### Claim 6 (depends on 1)

A process according to claim 1, in which step (a) is carried out at a temperature between about 10.degree. and 80.degree. C.

### Claim 7 (depends on 1)

A process according to claim 1, in which, per mole of N-acetyl-p-toluidine, between about 1.05 and 1.3 moles of bromine are employed in step (a), and in step (b) between about 2.5 and 4 moles of hydrochloric acid containing hydrogen chloride, between about 0.95 and 1.1 moles of alkali metal nitrite and between about 1.5 and 2 moles of dimethylamine.

### Claim 8 (depends on 1)

A process according to claim 1, in which the reaction with dimethylamine is carried out in the presence of an acid binding agent.

### Claim 9 (depends on 7)

A process according to claim 7, in which step (a) is carried out at a temperature between about 10.degree. and 80.degree. C. in the presence of an acid acceptor and acetic acid or an acetic acid/water mixture as a diluent, the reaction solution of the intermediate of step (a) is treated with a reducing agent prior to step (b), and the reaction with dimethylamine is carried out in the presence of an acid binding agent.