# US 5,334,724 A · Preparation of substituted 2-chloropyridines

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- Number: US 5,334,724 A
- Document ID: US5334724A
- Status: Granted
- Kind: A
- Application number: 07/905,080
- Filed: 1992-06-24
- Granted: 1994-08-02
- Earliest claimed: 1990-01-18
- Assignees: Bayer Aktiengesellschaft
- Inventors: Dieter Kaufmann; Klaus Jelich; Rudolf Braden; Winfried Rosen
- Web page: https://patentgrep.com/patent/US5334724A

## CPC

- C07D 213/61: Halogen atoms or nitro radicals
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)

## Abstract

A process for the preparation of a substituted 2-chloropyridine derivatives of the formula ##STR1## in which R.sup.1, R.sup.2, R.sup.3 and R.sup.4 represent hydrogen or various other radicals, which comprises reacting a pyridine-1-oxide of the formula ##STR2## with an aromatic carbonyl chloride in the presence of an inert organic solvent and in the presence of an acid acceptor at a temperature between about -20.degree. C. and 200.degree. C.

## Claims

### Claim 1

A process for the preparation of a substituted 2-chloropyridine of the formula ##STR10## in which R.sup.1 represents hydrogen, fluorine, chlorine, cyano, COOCH.sub.3, COOC.sub.2 H.sub.5, CON(CH.sub.3).sub.2 or CON(C.sub.2 H.sub.5).sub.2,
R.sup.2 represents hydrogen, fluorine, chlorine, CH.sub.3, C.sub.2 H.sub.5, CH.sub.2 Cl, CH.sub.2 CN, CH.sub.2 --OCH.sub.3, CH.sub.2 --OC.sub.2 H.sub.5, CH.sub.2 --N(i--C.sub.3 H.sub.7).sub.2, CH.sub.2 --N(i--C.sub.4 --H.sub.9).sub.2, ##STR11## or in which R.sup.1 and R.sup.2 together represent the divalent group --CH.dbd.CH--CH.dbd.CH--,
R.sup.3 represents hydrogen, chlorine, COOCH.sub.3, COOC.sub.2 H.sub.5, CON(CH.sub.3).sub.2 or CON(C.sub.2 H.sub.5).sub.2, and
R.sup.4 represents hydrogen, fluorine, chlorine or cyano, or in which R.sup.3 and R.sup.4 together represent the divalent group --CH.dbd.CH--CH.dbd.CH--, which comprises reacting a pyridine-1-oxide of the formula ##STR12## with an aromatic carbonyl chloride in the presence of an inert organic solvent and in the presence of an organic acid acceptor at a temperature between about -20.degree. C. and 200.degree. C., provided that only one of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 can represent cyano or carbalkoxy at one time.

### Claim 2 (depends on 1)

A process according to claim 1, wherein the aromatic carbonyl chloride is selected from the group consisting of benzoyl chloride, monochlorobenzoyl chloride, dichlorobenzoyl chloride, monomethylbenzoyl chloride, monochloromethylbenzoyl chloride, dimethylbenzoyl chloride, monomethoxybenzoyl chloride, dimethylbenzoyl chloride, monomethoxybenzoyl chloride, mononitrobenzoyl chloride, phthaloyl chloride, dichlorophthalide, monochlorophthaloyl chloride, dichlorophthaloyl chloride, mononitrophthaloyl chloride and naphthalenecarbonyl chloride.

### Claim 3 (depends on 1)

A process according to claim 1, wherein the acid acceptor is a basic organic nitrogen compound selected from the group consisting of a trialkylamine, dialkylcycloalkylamine and dialkylaralkylamine.

### Claim 4 (depends on 1)

A process according to claim 1, wherein the acid acceptor is triethylamine.

### Claim 5 (depends on 1)

A process according to claim 1, wherein the reaction is effected in the presence of an activator.

### Claim 6 (depends on 5)

A process according to claim 5, wherein the activator is a formamide.

### Claim 7 (depends on 1)

A process according to claim 1, wherein during the reaction there is added phosgene or thionyl chloride and the reaction is effected at the temperature from about 70.degree. to 160.degree. C.

### Claim 8 (depends on 1)

A process according to claim 1, wherein the inert solvent is methylene chloride, ethylene chloride, 1,1,2-trichloroethane, 1,2-dichloropropane, 1,2,3-trichloropropane, chloroform or chlorobenzene.

### Claim 9 (depends on 1)

A process according to claim 1, wherein the reaction is carried out at a temperature between about 0.degree. and 160.degree. C.

### Claim 10 (depends on 1)

A process according to claim 1, wherein about 1 to 10 moles of the aromatic carbonyl chloride are added dropwise to a solution of 1 mole of the substituted pyridine-1-oxide and of 1 to 10 moles of an amine as the acid acceptor.

### Claim 11 (depends on 10)

A process according to claim 10, including adding a formamide and 2 to 5 moles of phosgene or dropwise adding chloride.

### Claim 12 (depends on 1)

A process according to claim 1, wherein the reaction mixture formed is subjected to steam distillation.

### Claim 13 (depends on 1)

A process according to claim 1, in which R.sup.2 is methyl and R.sup.1, R.sup.3 and R.sup.4 are hydrogen the process comprising reacting 3-methyl-pyridine-1-oxide with a benzoyl chloride or phthaloyl chloride in methylene chloride, ethylene chloride, 1,2-dichloropropane, 1,2,3-trichloropropane or chlorobenzene with the addition of triethylamine as acid acceptor.