# US 10,870,617 B2 · Method for preparing dialkyl dicarbonates using amine oxides

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- Number: US 10,870,617 B2
- Document ID: US10870617B2
- Status: Granted
- Kind: B2
- Application number: 16/451,532
- Filed: 2019-06-25
- Published: 2020-01-09
- Granted: 2020-12-22
- Earliest claimed: 2018-07-05
- Assignees: LANXESS Deutschland GmbH
- Applicants: LANXESS Deutschland GmbH
- Inventors: Christoph Hofmann
- Web page: https://patentgrep.com/patent/US10870617B2

## CPC

- C07C 68/02: from phosgene or haloformates
- B01J 31/0271: {also containing elements or functional groups covered by B01J31/0201 - B01J31/0231}
- B01J 35/27: in a liquid or molten state
- C07C 69/96: Esters of carbonic or haloformic acids
- B01J 2231/49: Esterification or transesterification
- B01J 2531/002: Materials
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS

## Abstract

The present invention relates to a method for preparing dialkyl dicarbonates from the corresponding alkyl chloroformates using specific amine oxides as catalysts.

## Claims

### Claim 1

A method for preparing dialkyl dicarbonates, comprising reacting an alkyl haloformate with at least one alkali metal hydroxide, alkaline earth metal hydroxide and/or carbonate in the presence of at least one organic solvent immiscible with water and in the presence of a catalyst, wherein the catalyst is at least one compound of the formula (I)
in which
R1 and R2 is straight-chain or branched C1-C6-alkyl,
R3 is straight-chain or branched C10-C22-alkyl,
wherein R1 and R2 may be the same or different.

### Claim 2 (depends on 1)

The method according to claim 1, wherein R3 is selected from the group of straight-chain or branched dodecanyl, undecanyl, tridecanyl, tetradecanyl, pentadecanyl, hexadecanyl, heptadecanyl, octadecanyl, nonadecanyl, eicosanyl, icosanyl, heneicosanyl and dodoconyl.

### Claim 3 (depends on 1)

The method according to claim 1, wherein R3 is selected from the group of straight-chain or branched C10-, C11-, C12-, C13-, C14-, C15-, C16-, C17-, and C18-alkyl.

### Claim 4 (depends on 1)

The method according to claim 1, wherein R1 and R2 are selected from the group of methyl, ethyl, n-propyl, s-propyl, n-butyl, s-butyl, isobutyl and t-butyl and R3 is straight-chain or branched C10-C18-alkyl.

### Claim 5 (depends on 1)

The method according to claim 1, wherein R1 and R2 are methyl and R3 is C10-C16-alkyl.

### Claim 6 (depends on 1)

The method according to claim 1, wherein R1 and R2 are methyl and R3 is selected from the group of dodecanyl, tetradecanyl, and hexadecanyl.

### Claim 7 (depends on 1)

The method according to claim 1, wherein R3 is selected from the group of straight-chain or branched C12-, C14- and C16-alkyl and R1 and R2 are methyl and wherein the content of the compound where R3=C12-alkyl is from 60% by weight to 80% by weight and the content of the compound where R3=C14-alkyl is from 19% by weight to 30% by weight and the content of the compound where R3=C16-alkyl is from 1% by weight to 10% by weight, based on the total weight of the compound of the formula (I).

### Claim 8 (depends on 1)

The method according to claim 1, wherein the dialkyl dicarbonates are of formula (II)
in which
R4 is straight-chain or branched C1-C20-alkyl,
and are formed by reacting alkyl haloformates of formula (III)
in which
Hal is halogen and
R4 is straight-chain or branched C1-C20-alkyl.

### Claim 9 (depends on 8)

The method according to claim 8, wherein R4 is methyl, ethyl, n-propyl, isopropyl, or n-butyl or isobutyl.

### Claim 10 (depends on 1)

The method according to claim 1, wherein the alkali metal hydroxides or alkaline earth metal hydroxides and/or carbonates are in the form of aqueous solutions.

### Claim 11 (depends on 1)

The method according to claim 1, wherein the at least one organic solvent immiscible with water is selected from the group of aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons, dialkyl carbonates, ethers and esters immiscible with water.

### Claim 12 (depends on 1)

The method according to claim 1, wherein the catalyst is present in the amount of 0.1 to 7 mol %, based on the haloformate.

### Claim 13 (depends on 1)

The method according to claim 1, wherein the reaction is carried out at a temperature of 15° C. and 19° C. (at standard pressure).

### Claim 14 (depends on 1)

The method according to claim 1, wherein the reaction is carried out in a continuous mode of operation.

### Claim 15 (depends on 1)

The method according to claim 1, further comprising, after completion of the reaction whereby a reaction mixture is formed, phase separating the dialkyl dicarbonate whereby an organic phase is formed and subsequently performing a multi-stage distillation of the organic phase.