# US 4,392,978 A · Selective aromatic nitration

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- Number: US 4,392,978 A
- Document ID: US4392978A
- Status: Granted
- Kind: A
- Application number: 06/107,235
- Filed: 1979-12-26
- Granted: 1983-07-12
- Earliest claimed: 1979-12-26
- Assignees: Allied Corporation
- Inventors: Ronald L. Elsenbaumer; Edel Wasserman
- Web page: https://patentgrep.com/patent/US4392978A

## CPC

- C07C 201/08: by substitution of hydrogen atoms by nitro groups
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

A method and reagent for the selective nitration of aromatic hydrocarbons which comprises contacting a complex of at least a catalytic amount of a polyether with a nitronium containing substance, e.g., NO.sub.2 BF.sub.4 with an aromatic hydrocarbon, e.g., toluene with at least one replaceable hydrogen. Nitration of toluene with these complexes at ambient temperature resulted in a reduction in meta substitution. In competitive studies, soluble crown ether complexes of NO.sub.2 BF.sub.4 in CH.sub.2 Cl.sub.2 nitrated toluene 45-59 times faster than they nitrated benzene.

## Claims

### Claim 1

A reagent for selective aromatic nitration which comprises a complex of a nitronium containing substance and at least a catalytic amount of a macrocyclic polyether in the presence of a solvent selected from the group consisting of CH.sub.2 Cl.sub.2, CHCl.sub.3, SO.sub.2, CH.sub.3 NO.sub.2, CH.sub.3 CN, (CH.sub.2).sub.4 SO.sub.2, CS.sub.2 and polyhaloalkanes having 1 to 8 carbons.

### Claim 2 (depends on 1)

A reagent as described in claim 1 wherein the nitronium containing substance is selected from a group consisting of NO.sub.2 BF.sub.4, NO.sub.2 PF.sub.6, NO.sub.2 SbF.sub.6, NO.sub.2 SF.sub.6, NO.sub.2 CF.sub.3 SO.sub.3, NO.sub.2 SnF.sub.6 and NO.sub.2 AsF.sub.6.

### Claim 3 (depends on 1)

A reagent as described in claim 1 wherein the macrocyclic polyether is selected from the group consisting of dicyclohexano-18-crown-6 and crown ethers having from 4 to 10 -O-M units wherein M for a particular macrocyclic polyether is ##STR8## wherein each R.sub.n is independently selected from the group consisting of hydrogen or an alkyl group consisting of 1 to 4 carbons or wherein at least one M is (b) and the remaining are (a).

### Claim 4 (depends on 3)

A reagent as described in claim 3 wherein the macrocyclic polyether is at least one of the members of the group selected from 12-crown-4, 15-crown-5, 18-crown-6 and meso- and d,l-dicyclohexano-18-crown-6.

### Claim 5 (depends on 3)

A reagent as described in claim 3 wherein the macrocyclic ether is 18-crown-6.

### Claim 6 (depends on 5)

A reagent is described in claim 5 wherein the crown ether and the nitronium substance are in a molar ratio of about 1 to 1.

### Claim 7 (depends on 3)

A reagent as described in claim 3 wherein the macrocyclic ether is 15-crown-5.

### Claim 8 (depends on 7)

A reagent as described in claim 7 wherein the crown ether and the nitronium containing substance are in a molar ratio of about 1.7 to 1.

### Claim 9 (depends on 3)

A reagent as described in claim 3 wherein the macrocyclic ether is 12-crown-4.

### Claim 10 (depends on 9)

A reagent as described in claim 9 wherein the crown ether and the nitronium containing substance are in a molar ratio of about 3.0 to 1.