Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
2000-10-31
2004-02-03
Rotman, Alan L. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C562S517000, C562S830000
Reexamination Certificate
active
06686500
ABSTRACT:
The present invention relates to a process for the production of acetic acid and in particular, to a process for the production of acetic acid by carbonylation in the presence of an iridium catalyst and methyl iodide co-catalyst.
Preparation of carboxylic acids by iridium-catalysed carbonylation processes is known and is described, for example in EP-A-0786447, EP-A0643034 and EP-A-0752406.
EP-A-0786447 describes a process for reacting carbon monoxide with a carbonylatable reactant and/or an ester derivative thereof in a liquid reaction composition comprising an iridium carbonylation catalyst, a hydrocarbyl halide, water and carbonylation reaction product, characterised in that the liquid reaction composition comprises water at a concentration of 2 to 8% by weight, hydrocarbyl halide at a concentration in the range 1 to 20% by weight and ester derivative of the carbonylatable reactant at a concentration in the range 1.0 to 60% by weight.
EP-A-0643034 describes a process for the production of acetic acid by carbonylation of methanol or a reactive derivative thereof which process comprises contacting methanol or a reactive derivative thereof with carbon monoxide in a liquid reaction composition in a carbonylation reactor characterised in that the liquid composition comprises (a) acetic acid, (b) an iridium catalyst, (c) methyl iodide, (d) at least a finite quantity of water, (e) methyl acetate and (f) as promoter, at least one of ruthenium and osmium.
EP-A-0752406 describes a process for the production of acetic acid comprising (1) continuously feeding methanol and/or a reactive derivative thereof and carbon monoxide to a carbonylation reactor which contains a liquid reaction composition comprising an iridium carbonylation catalyst, methyl iodide co-catalyst, a finite concentration of water, acetic acid, methyl acetate and at least one promoter; (2) contacting the methanol and/or reactive derivative thereof with the carbon monoxide in the liquid reaction composition to produce acetic acid; and (3) recovering acetic acid from the liquid reaction composition characterised in that there is continuously maintained in the liquid reaction composition throughout the course of the reaction (a) water at a concentration of no greater than 6.5% by weight, (b) methyl acetate at a concentration in the range 1 to 35% by weight and (c) methyl iodide at a concentration in the range 4 to 20% by weight.
The use of polydentate chelating phosphorus or arsenic ligands in carbonylation processes is known, for example from U.S. Pat. No. 4,102,920 and U.S. Pat. No. 4,102,921 which describe respectively, their use in rhodium and iridium catalysed carbonylation processes.
The use of phosphine oxide promoters in rhodium-catalysed carbonylation processes is known from U.S. Pat. No. 5,817,869 and from EP-A-0114703.
Thus, U.S. Pat. No. 5,817,869 relates to process for the production of acetic acid without the use of an alkali metal halide comprising contacting methanol or methyl acetate with carbon monoxide in the presence of a carbonylation system containing about 200 to about 1200 ppm of rhodium-containing component and a liquid reaction medium comprising about 20 to about 80 weight % acetic acid; from about 0.6 to about 36 weight % methyl iodide; from about 0.5 to about 10 weight % methyl acetate, said contacting being in the presence of at least one pentavalent Group VA oxide of the formula R
3
M═O, which is present in a concentration of Group VA oxide to rhodium of greater than about 60:1, and water being added in an amount of from about 4 to about 12 weight %.
EP-A-0114703 relates to a process for the preparation of carboxylic acids and/or esters by reaction of an alcohol with carbon monoxide in the presence of a rhodium compound, an iodide and/or bromide source and a phosphorus, arsenic or antimony-containing compound as promoter, characterised in that the reaction is carried out in the presence of a compound of the formula
wherein X represents phosphorus, arsenic or antimony and Y oxygen, sulphur or selenium and either a and b, independent of one another, are 0 or 1, R
1
represents hydrogen or an unsubstituted or substituted hydrocarbon group and R
2
and R
3
each represent an unsubstituted or substituted hydrocarbon group, or a and b are 0 and R
2
and R
3
together with X form a heterocyclic group and R
1
represents hydrogen or an unsubstituted or substituted hydrocarbon group, or in the presence of a complex of a compound of formula I with a hydrocarbon iodide or bromide, an acyl iodide or bromide or hydrogen iodide or bromide. Examples of compounds of formula I wherein a and b are 0, include triphenylphosphine oxide
According to EP-A-0114703, the quantity of compound of formula I used as promoter in the process may vary within wide limits, for instance between 0.1 and 300 mol per gram atom rhodium. Preference is said to be given to use of 1-200, in particular 10-100 mol per gram atom rhodium. The promoters of EP-A-0114703 are directed towards improving the activity of the rhodium carbonylation catalyst system.
The technical problem to be solved is to provide an improved carbonylation process for the production of acetic acid. It has now been surprisingly found that by using a specified quantity of a monodentate phosphine oxide compound in an iridium-catalysed carbonylation process for the production of acetic acid, the quantities of by-product propionic acid, its precursors and derivatives produced are reduced and hence selectivity to the desired acetic acid is increased.
Thus, according to the present invention, there is provided a process for the production of acetic acid by reacting carbon monoxide with methanol and/or a reactive derivative thereof in a liquid reaction composition comprising an iridium carbonylation catalyst, methyl iodide, methyl acetate, water and acetic acid characterised in that there is also present in the reaction composition a monodentate phosphine oxide compound in an amount of up to and including 200 mol per gram atom of iridium.
The process of the present invention solves the technical problem defined above, by the use of a monodentate phosphine oxide compound in an amount of up to and including 200 mol per gram atom of iridium to reduce the amount of by-product propionic acid, its precursors such as ethyl iodide and ethyl acetate and its derivatives such as methyl propionate and ethyl propionate produced and increase the selectivity of the process to the desired acetic acid.
The monodentate phosphine oxide compound may be represented by the formula
wherein R
1
, R
2
, R
3
are independently an unsubstituted or substituted C
1
to C
10
alkyl group or an unsubstituted or substituted C
5
to C
15
aryl group.
The C
1
to C
10
alkyl group may be straight or branched. Examples of suitable C
1
-C
10
alkyl groups include methyl, ethyl, n-butyl and n-octyl. The C
1
-C
10
alkyl group may be substituted by one or more substituents e.g. 1-4 substituents. Suitable substituents include C
1
to C
10
alkyl groups and C
5
to C
15
aryl groups.
The C
5
-C
15
aryl group may be e.g. phenyl, alpha-naphthyl and beta-naphthyl, preferably phenyl. The C
5
-C
15
group may be substituted with substituents selected from the group consisting of —NO
3
, —OH, —CN, —SO
3
H, —OCH
3
and —CO
2
H.
A preferred monodentate phosphine oxide compound of formula II is triphenylphosphine oxide.
In the process of the present invention if at least one promoter is present in the reaction composition, higher concentrations of the monodentate phosphine oxide compound can be used, which enables the benefits of reduced by-product formation to be achieved at acceptable reaction rates. Suitable promoters are preferably selected from the group consisting of ruthenium, osmium, rhenium, cadmium, mercury, zinc, gallium, indium and tungsten, and are more preferably selected from the group consisting of ruthenium and osmium and most preferably is ruthenium. Preferably, the promoter is present in an effective amount up to the limit of its solubility in the liquid reaction composition and/or any liquid pr
BP Chemicals Limited
Nixon & Vanderhye
Reyes Hector M.
Rotman Alan L.
LandOfFree
Process for the production of acetic acid does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the production of acetic acid, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the production of acetic acid will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3335891