Organic compounds -- part of the class 532-570 series – Organic compounds – Sulfur containing
Reexamination Certificate
2000-07-13
2002-09-24
Vollano, Jean F. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Sulfur containing
C568S034000
Reexamination Certificate
active
06455738
ABSTRACT:
A subject-matter of the present invention is a novel catalytic composition and its use as Lewis acid, in particular in reacting an acid anhydride or halide with an aromatic derivative, for example an acylation. This use is particularly advantageous in sulfonation processes, sometimes denoted by sulfonylation processes, is which consists in grafting an —SO
2
-Grp radical. This process is targeted in particular at a process for the sulfonation of an aromatic compound. More specifically, the invention relates to a process for the sulfonation of an activated or deactivated aromatic compound. Grp means here the organic part of the sulfonyl radical; it represents a carbonaceous group, in particular a fluorocarbonaceous group, advantageously a hydrocarbonaceous group, that is to say comprising hydrogen and carbon, chosen more particularly from aryls or alkyls.
In the account which follows of the present invention, the term “aromatic compound” is understood to mean the conventional notion of aromaticity as defined in the literature, particularly by Jerry March, Advanced Organic Chemistry, 4th edition, John Wiley and Sons, 1992, pp. 40 et seq.
The term “deactivated aromatic compound” defines a substituent-free aromatic compound, such as, for example, benzene, or an aromatic compound comprising one or more substituents which deactivate the aromatic nucleus, such as electron-withdrawing groups.
The term “activated aromatic compound” denotes an aromatic compound comprising one or more substituents which activate the aromatic nucleus, such as electron-donating groups.
The notions of electron-withdrawing groups and electron-donating groups are defined in the literature. Reference may be made, inter alia, to the work by Jerry March, Advanced Organic Chemistry, 4th edition, John Wiley and Sons, 1992, Chapter 9, pp. 273-292.
A conventional process for the preparation of of aromatic sulfones consists in carrying out a sulfonation reaction of Friedel-Crafts type.
The aromatic compound and an aryl sulfonating agent are reacted in the presence of a catalyst, which is generally aluminum chloride.
However, the use of aluminum chloride exhibits numerous disadvantages. Aluminum chloride is a corrosive and irritating product. Furthermore, it is necessary to employ a large amount of aluminum chloride at least equal to stoichiometry, as a result of the complexing of the sulfone formed. Consequently, aluminum chloride is thus not a true catalyst. In addition, at the end of the reaction, it is necessary to remove the aluminum chloride from the reaction mixture by carrying out an acidic or basic hydrolysis.
This hydrolysis technique involves the addition of water to the reaction mixture, which significantly complicates the implementation of the process as the metal cation, and more particularly the aluminum cation, then forms, in the presence of water, polyoxy- and/or polyhydroxo-aluminum complexes with a milky consistency which are difficult to separate subsequently. This results in the need to carry out a lengthy and expensive treatment comprising, after the hydrolysis, extraction of the organic phase, separation of the aqueous and organic phases, indeed drying of the latter. The separation of the aluminum chloride is thus lengthy and expensive. Furthermore, the problem is posed of the saline aqueous effluents which subsequently have to be neutralized, which requires an additional operation. Furthermore, the aluminum chloride cannot be recycled because of its hydrolysis.
The use of bismuth tritriflates [(TfO)
3
Bi; TfO meaning: CF
3
SO
2
—] as Lewis acid has also been provided but these compounds are both very expensive, in particular because of the cost of the triflic anion, and very difficult to manufacture. The patent application filed on behalf of the Applicant Company, published under No. EPA 0 877 726, illustrates these difficulties.
One of the aims of the present invention is to provide a substitute for the best Lewis acid which exhibits less perfluoroalkanesulfonate anion, in particular triflate anion, than tritriflates.
Another aim of the present invention is the sulfonation of both activated and deactivated aromatic substrates under easily employed conditions.
The present invention achieves these objectives and provides a process which makes it possible to overcome the abovementioned disadvantages.
A process for the sulfonation of an aromatic compound has now been found, and it is this which constitutes the subject-matter of the present invention, which consists in reacting said aromatic compound with an aryl sulfonating agent in the presence of a catalyst, characterized in that the sulfonation reaction is carried out in the presence of a catalytically effective amount of a mixture of bismuth trihalide and of perfluoroalkanesulfonic acid.
During the use of the catalyst of the present invention, it may happen that the halide ion is partially displaced by the sulfonic acid and escapes in the form of hydrohalic acid. This displacement only affects at most two thirds of the halides bonded to the bismuth, generally at most ⅓, and a small fraction of ⅓. This is because the displacement of the second and third halides from the bismuth halide is increasingly difficult as the replacement proceeds. A limitation on the amount of perfluoroalkanesulfonic acid with respect to the bismuth is for this reason desirable. This ratio will be specified subsequently. It is certainly preferable to prevent the triperfluorosulfonate from being formed but this restriction and not really one as generally only mono- and diexchanged derivatives are formed.
Although it is preferable to obtain the catalytic mixture by mixing perfluoroalkanesulfonic acid and bismuth halide, said catalytic mixture can be prepared by any mixings, in particular at the time of use, of halide ion, of bismuth cation and of triflate ion in appropriate ratios.
In the present text, the term “perfluoroalkanesulfonic acid” is understood to mean the compounds of formula R
f
SO
3
H. Any R
f
group which comprises a perfluoromethylene (—CF
2
—), preferably a perfluoroethylene (—CF
2
—CF
2
—), carrying the sulfonic group is regarded as an R
f
group.
More generally, the catalytic mixture according to the present invention is targeted at reactions catalyzed by Lewis acids in which conventional Lewis acids are replaced by the mixture according to the present invention.
In the present text, the term “triflic acid” is understood to mean trifluoromethanesulfonic acid CF
3
SO
3
H.
The present invention is targeted essentially at the bismuth trihalide and perfluoroalkanesulfonic acid mixtures in which the molar ratio is less than the stoichiometry resulting in the complete exchange of the halide by the sulfonic functional group. More specifically, the ratio of the sulfonic functional groups, expressed in equivalents, to the bismuth salts, expressed in moles, is advantageously at most equal to 2, preferably at most equal to 1.5, more preferably at most equal to 1.
More specifically, a subject-matter of the present invention is a process for the sulfonation of an aromatic compound corresponding to the general formula (I):
in which:
A symbolizes the residue of a ring forming all or part of a monocyclic or polycyclic, aromatic, carbocyclic or heterocyclic system, it being possible for said cyclic residue to carry a radical R representing a hydrogen atom or one or more identical or different substituents,
n represents the number of substituents on the ring.
The invention applies in particular to the aromatic compounds corresponding to the formula (I) in which A is the residue of a cyclic compound preferably having at least 4 atoms in the optionally substituted ring and representing at least one of the following rings:
a monocyclic or polycyclic aromatic carbocycle,
a monocyclic or polycyclic aromatic heterocycle comprising at least one of the heteroatoms O, N and S.
To be more specific, without for all that limiting the scope of the invention, the optionally substituted residue A represents the residue:
1)—of a monocyclic or polycyclic aromatic
Dubac Jacques
Le Roux Christophe
Repichet Sigrid
Rhodia Chimie
Vollano Jean F.
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