Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
2001-03-19
2002-08-20
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C562S414000, C562S494000, C568S438000, C568S810000, C568S815000
Reexamination Certificate
active
06437176
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns an efficient method for preparing aromatic carboxylic acids, aromatic aldehydes, and aromatic alcohols, wherein the aromatic carboxylic acids, aromatic aldehydes, and aromatic alcohols are compounds represented by following formulae (II), (III), and (IV);
(wherein n represents any of integer 1 to 5; and substituent R represents an alkyl group, an aryl group, an aralkyl group, halogen atom, haloalkyl group, OR
1
, SR
1
, SOR
1
, SO
2
R
2
, NO
2
, NR
1
R
2
, CH
2
OR
1
, CH(OR
1
)(OR
2
), C(OR
1
)(OR
2
)(OR
3
), COR
1
, or COCOR
1
(wherein each of R
1
, R
2
, and R
3
is selected from an alkyl group, an aryl group, and hydrogen atom); and when n takes 2 or more, R may be the same or different)
The aromatic carboxylic acids, aromatic aldehydes, and aromatic alcohols are all regarded as industrially important raw materials for pharmaceutical and agricultural products, and polymer products.
2. Prior Art
A reaction for producing the aromatic carboxylic acids from aromatic compounds having methyl group, such as chlorotoluene, nitrotoluene, and the like, by oxidation, such as air oxidation, is well known technique. Further, it is also well known that in said reaction an industrially important byproduct, such as aromatic aldehyde, aromatic alcohol, and etc., is produced.
In the oxidizing reaction, to effectively produce the aimed aromatic carboxylic acid by suppressing forming various intermediate oxidizing products, several approaches have been tried so far. For instances, a method for producing p-toluic acid by oxidation with a gas containing oxygen, in the presence of specific shaped catalyst of cobalt oxide (British Patent 1,005,315), a method for producing benzoic acid derivatives by liquid phase oxidation of toluene derivatives with a gas containing oxygen in the presence of phase transfer catalyst composed of quaternary onium salt and transition metal salt, and together with a small amount of polar solvent, which is capable of dissolving said catalyst (Jp-A-1-2287054, “JP-A” used herein means unexamined Japanese Patent Publication), and the like, may be exemplified.
On the other hand, it is well known that aromatic carboxylic acid may be obtained by distilling, sedimenting with acid, or crystallizing reacting solution, or that aromatic aldehyde and aromatic alcohol may also be obtained by directly distilling the reacting solution, or by extracting effective component from the reacting solution using extracting solution, followed by rectifying thereof. (JP-B-48-23430, “JP-B” used herein means examined Japanese Patent Publication, JP-A-53-82734, JP-A-54-79244, JP-B-62-2576, JP-B-62-30974, JP-B-62-30975, JP-A-2-73038, JP-B-4-3370, JP-B-7-116096, and International Patent Publication 95-20560, and etc.)
Of the aromatic carboxylic acids, p-toluic acid may be produced by oxidizing p-xylene. As the byproduct of the reaction, p-methylbenzyl alcohol, p-tolualdehyde, p-hydroxymethylbenzoic acid, 4-carboxybenzaldehyde, terephthalic acid and the like, may be formed.
For purifying p-toluic acid produced, a physical process, such as distillation, extraction, and recrystallization, which are conventionally used, has not been applied, due to sublimable property of p-toluic acid, or readily soluble property in various solvents.
As a purifying process for p-toluic acid, a process has been known, which comprises treating at high temperature crude p-toluic acid solution in organic solvent, which is capable of selectively reacting in forming salt of the byproducts, and removing the salt, thus produced, in water extraction, and cooling the same (JP-A-54-79244). Subsequently, a washing of crystal with n-hexane is carried out to further improve purity of the p-toluic acid.
However, since an oxidizing reaction according to the conventional method is exclusively aimed at efficiently producing aromatic carboxylic acid from the aromatic hydrocarbons, regardless of the fact that some of the intermediates in the oxidation process, for example, aromatic aldehyde, and aromatic alcohol, are useful as a raw material for pharmaceutical or agricultural products, the intermediates are disposed as impurities, and are not efficiently utilized.
On the other hand, an attempt for effectively isolating whole compounds from the reacting solution containing these compounds, cannot be said as being sufficiently conducted. That is, since when an aromatic carboxylic acid is to be produced, all compounds other than the aromatic carboxylic compound, which includes aromatic aldehyde, and aromatic alcohol, are considered as impurities, a purification of the aromatic carboxylic acid must be carried out.
However, the aromatic aldehyde or aromatic alcohol is reacted and decomposed, and is liable to be adversely affected in said purification thereof. The similar phenomenon appears in the process for obtaining aromatic aldehyde and aromatic alcohol. As concrete examples, it is well known that if, generally, an aldehyde and alcohol are heated under acidic condition, an acetal is formed with 1 mole of aldehyde and 2 mole of alcohol. Said reaction is the same phenomenon as those for purifying aromatic aldehyde and aromatic alcohol under distillation. By forming acetal in the distillation, an yield of the aromatic aldehyde and aromatic alcohol may be reduced, resulting in lowering yield, as well as purity. Thus, it is difficult to be capable of effectively obtaining all three kinds of the compounds according to a combination of simple unit operation.
Besides these, among the aromatic carboxylic acid, p-toluic acid causes significantly large loss of the product in washing operation, due to solubility thereof. In this connection, although p-methylbenzyl alcohol and p-tolualdehyde, which are byproducts, may form p-toluic acid by subsequent oxidation, these byproducts have never been recovered, nor utilized, so far.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for efficiently preparing aromatic carboxylic acid, simultaneously with aromatic aldehyde and aromatic alcohol, which comprises liquid phase oxidizing an aromatic compound represented by formula (I) with a gas containing molecular oxygen, in the presence of catalyst composed of transition metal compound, tertiary amine, and bromide compound.
(wherein n represents any of integer 1 to 5; and substituent R represents an alkyl group, an aryl group, an aralkyl group, halogen atom, haloalkyl group, OR SR
1
, SOR
1
, SO
2
R
2
, NO
2
, NR
1
R
2
, CH
2
OR
1
, CH(OR
1
)(OR
2
)C(OR
1
)(OR
2
)(OR
3
), COR
1
, or COCOR
1
(wherein each of R
1
, R
2
, and R
3
is selected from an alkyl group, an aryl group, and hydrogen atom); and when n takes 2 or more, R may be the same or different).
Another object of the present invention is to provide a method for efficiently obtaining aromatic aldehyde by acid depositing, or crystal precipitating treatment for reacting solution, which is obtained by the oxidizing the compound represented by formula (I), and simultaneously obtaining aromatic aldehyde and aromatic alcohol from filtrate by treatment, such as distillation.
Still another object of the present invention is to provide a method for attaining preferable result due to a removal of acid, which will become as a catalyst in acetal forming reaction, by adding base into a mixture solution containing aromatic aldehyde and aromatic alcohol to be distilled, in order to suppress producing aromatic aldehyde and aromatic alcohol in distillation step.
Further object of the present invention is to provide a method for efficiently preparing aromatic carboxylic acid of high purity, which comprises purifying crude aromatic hydrocarbons, obtained by oxidizing aromatic hydrocarbons having at least one methyl groups, by washing with raw aromatic hydrocarbons, and simultaneously using in a recycled manner, as a raw material, from which solution and crude aromatic carboxylic acid are removed by washing step.
Still further object of the present invention is to provide a method for preparing by efficient
Kitamura Akira
Matsuoka Shotaro
Suematsu Masaaki
Schnader Harrison Segal & Lewis LLP
Shippen Michael L.
Toray Industries Inc.
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