EP0479463A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Process for the production of carboxylic acid anhydrides
Assignee: BP Chemicals Ltd
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Filing: 1991-09-23
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Granted: —
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Expires: 2011-09-23
Abstract
Abstract The solubility and stability of rhodium catalysts in rhodium-catalysed carbonylation of alkyl esters or alkyl ethers under substantially anhydrous conditions to produce carboxylic acid anhydrides is improved by the use of co-promoters selected from the group: 1,3-dialkyl-4-methylimidazolium iodide; 1,3-dialkyl-4-ethylimidazolium iodide; 1,3-dialkyl-4-n-propylimidazolium iodide; 1,3-dialkyl-4-isopropylimidazolium iodide; 1,3-dialkyl-4-n-butylimidazolium iodide 1,3-dialkyl-4-sec-butylimidazolium iodide 1,3-dialkyl-4-tert-butylimidazolium iodide; 1,3-dialkyl-2,4,5-trimethylimidazolium iodide and mixtures thereof where the alkyl groups are independently C₁ to C₂₀ alkyl.
Inventors
- 👤 Robert George Beevor
- 👤 Neil Angus Greener
- 👤 David Jeffrey Gulliver
- 👤 Robert Michael Sorrell
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 19:11
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/09; C07C51/54; C07C51/56
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
85 words
A process for the production of a carboxylic acid anhydride comprising reacting in a reaction zone under substantially anhydrous conditions, carbon monoxide with a carboxylic acid ester or an alkyl ether in the presence of a rhodium catalyst, an iodide promoter and a co-promoter characterised in that the co-promoter is selected from the group consisting of: 1,3-dialkyl-4-methylimidazolium iodide; 1,3-dialkyl-4-ethylimidazolium iodide; 1,3-dialkyl-4-n-propylimidazolium iodide; 1,3-dialkyl-4-isopropylimidazolium iodide; 1,3-dialkyl-4-n-butylimidazolium iodide; 1,3-dialkyl-4-sec-butylimidazolium iodide; 1,3-dialkyl-4-tert-butylimidazolium iodide; 1,3-dialkyl-2,4,5-trimethylimidazolium iodide and mixtures thereof where the alkyl groups are independently C₁ to C₂₀ alkyl.
Claim 2
Dependent Claim
20 words
A process as claimed in claim 1 characterised in that the alkyl groups of the co-promoter are methyl or ethyl.
Claim 3
Dependent Claim
24 words
A process as claimed in claim 1 characterised in that the copromoter is selected from the group consisting of: 1,3,4-trimethylimidazolium iodide; and 1,2,3,4,5-pentamethylimidazolium iodide;
Claim 4
Dependent Claim
29 words
A process as claimed in any one of the preceeding claims characterised in that the co-promoter is prepared in situ by quaternising a corresponding imidazole with an alkyl iodide.
Claim 5
Dependent Claim
27 words
A process as claimed in claim 4 characterised in that the corresponding imidazole is prepared in situ by alkylating a less substituted imidazole by an alkyl iodide.
Claim 6
Dependent Claim
54 words
A process as claimed in any one of the preceeding claims characterised in that the process is operated continuously with removal of reaction medium from the reaction zone and with separation from the reaction medium of the carboxylic acid anhydride product prior to recycle of the rhodium catalyst and promoters to the reaction zone.
Claim 7
Dependent Claim
28 words
A process as claimed in any one of the preceeding claims characterised in that the carboxylic acid ester or alkyl ether has from 2 to 6 carbon atoms.
Claim 8
Dependent Claim
20 words
A process as claimed in claim 7 characterised in that the carboxylic acid ester is methyl acetate or ethyl acetate.
Claim 9
Dependent Claim
40 words
A process as claimed in any one of the preceeding claims characterised in that a controlled amount of alkanol and/or water is introduced to the reaction zone with the carboxylic acid ester and/or alkyl ether feedstock to coproduce carboxylic acid.
Claim 10
Dependent Claim
33 words
A process as claimed in claim 9 characterised in that a controlled amount of methanol and/or water is introduced to the reaction zone with methyl acetate to coproduce acetic acid with acetic anhydride.
Claim 11
Dependent Claim
31 words
A process as claimed in any one of the preceeding claims characterised in that the co-promoter is present in a molar ratio to the rhodium catalyst of from 0.5:1 to 10⁵:1.
References Cited (Backward Citations)
No citation records indexed.
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