Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-01-19
2001-02-06
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S323000, C568S326000, C568S328000, C556S064000
Reexamination Certificate
active
06184418
ABSTRACT:
This invention relates to a method for acylating an aromatic compound. More precisely, the invention refers to a method for acylating an activated or deactivated aromatic compound.
This invention is particularly interesting in the case of the acylation of a deactivated aromatic compound.
The invention is suitable for the preparation of aromatic ketones.
The invention also relates to the preparation of the catalyst and of new bismuth compounds.
In the following presentation of the invention, by “aromatic compound” we understand the conventional notion of aromaticity as defined in the literature, in particular by Jerry MARCH in Advanced Organic Chemistry, 4
th
Edition, John Wiley and Sons, 1992, p 40 and following.
By “deactivated aromatic compound”, we define an aromatic compound without substitutent, such as benzene for example, or an aromatic compound that contains one or several substitutents that deactivate the aromatic nucleus, such as electroattractive groups.
By “activated aromatic compound”, we mean an aromatic compound consisting of one or more substitutents that activate the aromatic nucleus such as electron donor groups.
The notions of electron donor and electroattractive groups are defined in literature. One may refer, among others, to Jerry MARCH in Advanced Organic Chemistry, 4
th
Edition, John Wiley and Sons, 1992, chapter 9, pp. 273-292.
A standard method for the preparation of aromatic ketones consists of performing an acylation reaction of the Freidel-Crafts sort.
A reaction of the aromatic compound and an acylation agent is performed in the presence of a catalyst, usually aluminum chloride.
An example of this type of method is shown in the works of C. Kuroda et al [Sci. Papers Inst. Phys. Chem. Res. 18, pp 51-60 (1932)] that have described the preparation of methoxyacetophenones, by reaction of an aromatic compound that carries from 1 to 3 methoxy groups, with acetyl chloride in the presence of aluminum chloride.
However, the use of aluminum chloride presents many inconveniences. Aluminum chloride is a corrosive and irritant product. Furthermore, it is necessary to use a large quantity of aluminum chloride, at least as much as the stoichiometry on account of the complexation of the ketone formed. Consequently, aluminum chloride is not a true catalyst.
At the end of the reaction, it is necessary to eliminate the aluminum chloride from the reaction solution by performing a basic or acid hydrolysis.
This hydrolysis involves adding water to the reaction solution, which appreciably complicates the implementation of the process since the metal cation, more specifically the aluminum cation, then forms aluminum polyoxo- and/or polyhydroxo-complexes of a milky consistency in the presence of water which are later difficult to separate. This results in the need to perform a long and costly treatment that consists, after the hydrolysis, of an extraction of the organic phase, a separation of the aqueous and organic phases, possibly even a drying of the latter. The separation of the aluminum chloride is therefore long and costly.
Besides, there is also the problem of saline aqueous runoffs that must later be neutralized, requiring an additional operation.
Furthermore, the aluminum chloride cannot be recycled because of the hydrolysis.
To avoid this inconvenience, Atsushi Kawada et al [J. Chem. Soc. Chem. Commun. Pp 1157-1158 (1993) and Synlett pp 545-546 (1994)] have proposed to perform the acylation reaction of an aromatic compound using an acetic anhydride in the presence of a catalytic quantity of trifluoromethanesulfonate of lanthanide, in particular ytterbium or scandium triflate.
The inconvenience of these catalysts is that they only allow the acylation of activated aromatic compounds, such as anisole.
These last references, as many catalysts described in prior art, do not address in a general way the acylation problems of aromatic substrates that are both activated as well as deactivated, and in conditions that are easy to implement.
This invention reaches this objective and gives a procedure to avoid the afore-mentioned inconveniences.
There is now, and this is what this invention pertains to, a method that will allow for the acylation of an aromatic compound that consists in making the said aromatic compound react with an acylation agent, in the presence of a catalyst characterized by the fact that the acylation reaction is performed in the presence of an effective quantity of at least one bismuth salt of triflic acid.
In this text, by “triflic acid” we mean the trifluoromethanesulfonic acid CF
3
SO
3
H.
As mentioned below, the invention calls for the use of tris-trifluoromethanesulfonate of bismuth as a catalyst as well as catalysts containing less than three trifluoromethanesulfonic anions for one bismuth cation.
Another element of the invention is the preparation process of the catalyst for the invention.
Lastly, another element of the invention relates to new bismuth compounds
More precisely, this invention relates to the acylation method of an aromatic compound that fits the general formula (I):
In which:
A symbolizes the remainder of a cycle forming all or a part of a carbocyclic or heterocyclic system that is either aromatic, monocyclic, or polycyclic: said cyclic remainder may carry a radical R representing a hydrogen atom or one or several identical or different substitutents,
n represents the number of substitutents on the cycle.
The invention applies in particular to aromatic compounds that match the formula (I) in which A is the remainder of a cyclic compound, having preferably at least 4 atoms in the cycle, possibly substituted, and representing at least one of the following cycles:
A monocyclic or polycyclic aromatic carbocycle
A monocyclic or polycyclic aromatic heterocycle containing at least one of the heteroatoms O, N and S.
More specifically, without however limiting the extent of the invention, the possibly substituted remainder A represents the remainder:
1) of a monocyclic or polycyclic aromatic carbocyclic compound, by “polycyclic carbocyclic compound” we mean:
a compound consisting of at least 2 aromatic carbocycles that between them form ortho- or ortho- and peri-condensed systems,
a compound consisting of at least 2 carbocycles of which only one is aromatic and that between them form ortho- or ortho- and peri-condensed systems
2) of a monocyclic or polycyclic aromatic heterocyclic compound, by “aromatic heterocyclic compound” we mean:
a compound consisting of at least 2 heterocycles containing at least one heteroatom in each cycle of which at least one of the two cycles is aromatic and that between them form ortho- or ortho- and peri-condensed systems
a compound consisting of at least one hydrocarbonic cycle and at least one heterocycle of which at least one of the cycles is aromatic and that between them form ortho- or ortho- and peri-condensed systems.
3) of a compound composed of a chain of cycles, such as those defined in paragraphs 1 and/or 2 linked together:
by a valencial link,
by an alkylene or alkylidene radical with 1 to 4 carbon atoms, preferably a methylene or isopropylidene radical,
by one of the following groups
In these formulas, Ro represents a hydrogen atom or an alkyl radical with 1 to 4 carbon atoms, a cyclohexyl or phenyl radical.
As examples of cycles 1 to 3, let us cite:
1) Benzene, toluene, xylene, naphthalene, anthracene,
2) Furan, pyrrole, thiophene, isoxasole, furazan, isothiazole, imidazole, pyrazole, pyridine, pyridazine, pyrimidine, quinoline, naphtyridine, benzofuran, indole
3) Biphenyl, 1,1′-methylenebiphenyl, 1,1′-isopopylidenebiphenyl, 1,1′-oxybiphenyl, 1,1′-iminobiphenyl
In the method of the invention, we preferably use a formula (I) aromatic compound in which A represents a benzene nucleus.
The formula (I) aromatic compound can carry one or several substitutents.
The number of substitutents present on the cycle depends on the carbon condensation of the cycle and on whether or not unsaturations are present on the cycle.
The maximum number of substitutents t
Desmurs Jean-Roger
Dubac Jacques
Gaspard Hafida
Labrouillere Mireille
Laporterie Andre
Burns Doane Swecker & Mathis L.L.P.
Padmanabhan Sreeni
Rhodia Chimie
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