Alkyl aromatic aldehydes

Details Alkyl aromatic aldehydes Alkyl aromatic aldehydes

2001-08-20

2003-05-13

Richter, Johann (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Carboxylic acids and salts thereof

C562S406000, C562S409000, C562S413000, C562S480000, C568S425000

Reexamination Certificate

active

06562996

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to compositions of alkyl aromatic aldehydes from a process for making alkyl aromatic aldehydes from the carbonylation of alkyl aromatic compounds.
BACKGROUND OF THE INVENTION
Carbonylation of an alkyl aromatic compound to form an alkyl aromatic aldehyde can be carried out by a reaction generally referred to as the Gatterman Koch reaction. Published in 1897, Gatterman and Koch described the direct carbonylation of various aromatic compounds by the use of carbon monoxide (CO) and hydrogen chloride in the presence of aluminum chloride and cuprous chloride (Gatterman, L. and Koch, J. A.,
Chem. Ber.,
30, 1622 (1897)). The reaction was subsequently expanded to include other Lewis acids. A review of such reactions is set forth in Olah, G. A., “
Friedel
-
Crafts and Related Reactions
”, Wiley-Interscience, N.Y., Vol. 1153 (1964).
Catalysts used in a Gatterman-Koch carbonylation reaction are typically complexed with the resulting aromatic aldehyde product. To free the desired aldehyde from the acid catalyst, water is added and the resulting organic and aqueous phases separated. For example, water can be added to a tolualdehyde-AlCl
3
complex to obtain the aldehyde product in a complex-free form. However, this separation procedure chemically alters and destroys the utility of the catalyst. This aqueous separation method, which leads to a one time use of catalyst, renders this process commercially unattractive as catalyst regeneration and recycle would be prohibitively expensive.
U.S. Pat. No. 2,485,237, describes replacing the hydrogen chloride and aluminum chloride catalyst with a hydrogen fluoride:boron trifluoride (HF:BF
3
) catalyst. An improved method of recovering the fluorides is described is U.S. Pat. No. 3,284,508.
A method to recycle the HF:BF
3
was proposed by Olah, G. A. et al.,
J. Am. Chem. Soc.,
98:1, 296 (1976). The carbonylation reaction is carried out at low temperatures, typically from 0° C. to 20° C, with excess HF. The lower boiling catalyst is separated from the aldehyde-catalyst complex by a distillation technique, condensed and returned to the carbonylation reactor. While this method is useful, it is generally desirable to have a method that avoids the use of HF, a material which requires special containment and handling facilities.
U.S. Pat. No. 3,948,998 describes a two-step process for making tolualdehyde. First, a toluene-HF—BF
3
complex is formed and reacted with CO to form tolualdehyde. Second, additional CO and optionally additional toluene is added to the reaction medium. Other catalysts that have been used in a Gatterman-Koch type carbonylation include combinations of Lewis and strong Bronsted acids, e.g., SbF
5
—HF, described in U.S. Pat. No. 4,218,403. The use of Bronsted acids alone, such as fluorosulfonic acid or trifluomethane sulfonic acid, were also reported to be effective catalysts. See for example Olah, G. A. Laali, K., and Farooq, O.,
J. Org. Chem.,
50, 1483 (1985).
However, the catalysts used in Gatterman-Koch carbonylation are typically complexed with the aldehyde product. Thus a stoichiometric amount of catalyst is “consumed” in the reaction. Further, in order to obtain the aldehyde product in a complex-free form, a separation step is needed. For instance, water can be added to a tolualdehyde-AlCl
3
complex to obtain the aldehyde product in a complex-free-form. However, this step chemically alters and destroys the utility of the catalyst. Such a separation, which leads to a one time use of the catalyst renders this process commercially unattractive as catalyst regeneration and recycle would be prohibitively expensive.
SUMMARY OF THE INVENTION
An aromatic aldehyde composition containing isomeric mixtures of dimethylbenzaldehydes prepared from contacting a mixed xylene feedstock with a carbonylation catalyst using a Gatterman-Koch type reaction. The aromatic aldehyde composition contains from about 80% to about 96% by weight, preferably from about 90% to about 96% by weight, 2,4-dimethylbenzylaldehyde, from about 2% to about 15% by weight, preferably from about 2% to about 6% by weight, 3,4-dimethylbenzylaldehyde, less than about 3% by weight 2,5 -dimethylbenzylaldehyde, and less than about 3% by weight 4-ethyllbenzylaldehyde. This aromatic aldehyde composition can then be oxidized using known methods to form an aromatic acid composition containing about 80% to about 98% by weight trimellitic acid and about 2% to about 10% by weight terephthalic acid.
The carbonylation catalyst used in the Gatterman-Koch type reaction is selected from perfluoroalkyl sulfonic acids with about 2 to about 18 carbon atoms, perfluoroether sulfonic acids with about 2 to about 18 carbon atoms, GaBr
3
, GaCl
3
, AlBr
3
, AlCl
13
, AlI
3
, TaF
5
, NbF
5
, or NbBr
5
. Preferably, the carbonylation catalyst is selected from perfluorohexane sulfonic acid, perfluorooctane sulfonic acid, and perfluoroethoxyethane sulfonic acid.
The invention is further directed to a composition of isomeric mixtures of tolualdehydes prepared from contacting a toluene feedstock with a carbonylation catalyst using a Gatterman-Koch type reaction. The composition contains about 85% to about 97% by weight para-tolualdehyde, about 2% to about 10% by weight ortho-tolualdehyde, and about 2% by weight or less, preferably about 1% by weight or less, more preferably about 0.5% by weight or less, meta-tolualdehyde. This aromatic aldehyde composition can then be oxidized using known methods to form an aromatic acid composition containing about 80% to about 98% by weight terephthalic acid, about 2% to about 10% by weight phthalic acid, and less than about 3% by weight isophthalic acid.
DETAILED DESCRIPTION OF THE INVENTION
This invention is directed to compositional mixtures of alkyl aromatic aldehydes. The alkyl aromatic aldehyde compositions of the invention are produced from contacting an alkyl aromatic feed with a carbonylation catalyst. The alkyl aromatic aldehyde compositions can contain two or more of the following alkyl aromatic compounds: ortho-tolualdehyde, meta-tolualdehyde, para-tolualdehyde, 2,4-dimethylbenzaldehyde (2,4-DMB), 3,4-dimethylbenzaldehyde (3,4-DMB), 2,5-dimethylbenzaldehyde (2,5-DMB), 2,4,5,-trimethylbenzaldehyde, 4-ethylbenzaldehyde, 4-propylbenzaldehyde, and 4-isopropylbenzaldehyde. The tolualdehyde compositions are formed if toluene is used as the aromatic aldehyde feedstock. The dimethylbenzaldehydes and the higher 4-alkylbenzaldehydes are formed if a feedstock containing primarily mixed xylenes is used as a feedstock.
The alkyl aromatic aldehyde compositions can also contain a mixture of alkyl-substituted benzaldehydes, wherein the alkyl groups include, but are not limited to, are selected from methyl, ethyl, propyl, isopropyl, or butyl. These alkyl benzaldehyde compositions result from the reaction of an alkyl aromatic feedstock, containing at least three alkyl aromatic compounds, with carbon monoxide in the presence of a high boiling point carbonylation catalyst. The alkyl aromatic feedstocks that can be used to provide the alkyl-substituted benzaldehyde compositions include, but are not limited to, at least three of the following compounds selected from 1-methyl-3-propylbenzene, 1-methyl-2-propylbenzene, 1,4-diethylbenzene, 1-methyl-4-propylbenzene, butylbenzene, 2-ethyl-1,4 -dimethylbenzene, 4-ethyl-1,2-dimethylbenzene, 1-ethyl-2,4-dimethylbenzene, 1,2,4,5-tetramethylbenzene, and 1,2,3,5-tetramethylbenzene.
These alkyl aromatic feedstocks can be defined by an average boiling point of the alkyl aromatic feedstock. The average boiling point is defined by the summation of the wt % of each alkyl aromatic compound in the mixture multiplied by its respective boiling point. In one embodiment, the average boiling point of the alkyl aromatic feedstock is from about 140° C. to about 170° C., preferably from about 140° C. to about 160° C.
The alkyl aromatic aldehyde compositions can also contain a mixture of alkyl-substituted napthylaldehydes. These napthylaldehyde compositions result from the reaction of an alkyl-substituted

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