Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-11-22
2002-02-19
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S322000, C568S323000, C204S157600, C204S157930
Reexamination Certificate
active
06348631
ABSTRACT:
The present invention relates to a process for the acylation or sulphonylation of an aromatic compound.
To be more exact, the invention relates to a process for the acylation or sulphonylation of an activated or deactivated aromatic compound.
It is of particular interest in the case where the acylation or sulphonylation of a deactivated aromatic compound is desired.
The invention is applied to the preparation of aromatic ketones or sulphones.
In the following description of the present invention, “aromatic compound” is understood as meaning the conventional concept of aromaticity as defined in literature, in particular by Jerry MARCH, Advanced Organic Chemistry, 4
th
edition, John Wiley and Sons, 1992, pp. 40 et seq. “Deactivated aromatic compound” is defined as an aromatic compound without a substituent, such as, for example, benzene, or an aromatic compound containing one or more substituents which deactivate the aromatic nucleus, such as electron-withdrawing groups. “Activated aromatic compound” describes an aromatic compound which contains one or more substituents which activate the aromatic nucleus, such as electron-donating groups.
The concepts of electron-withdrawing groups and electron-donating groups are defined in literature. Reference may be made, inter alia, to the work by Jerry MARCH—Advanced Organic Chemistry, 4
th
edition, John Wiley and Sons, 1992, chapter 9, pp. 273-292.
A conventional process for the preparation of aromatic ketones comprises reacting an aromatic compound and an acylating agent by an acylation reaction of the Friedel-Crafts type.
It is thus known to carry out said reaction in the presence of catalysts such as: FeCl
3
, Fe, ZnCl
2
, l
2
[D. E. PEARSON, C. A. BUEHLER, Synthesis, 1972, p.533]; metallic trifluoromethanesulphonates [A. KAWADA et al., J. Chem. Soc. Chem. Commun. pp. 1157-1158 (1993) and Synlett pp. 545-546 (1994)]; bismuth halides or precursors [EP-A-698 593].
The reactions described are limited to activated aromatic compounds, such as anisole, and most often require very long reaction times.
In the case of deactivated aromatic substrates, such as benzene or the halogenobenzenes, these catalysts are not satisfactory.
However, FeCl
3
has been described for carrying out the benzoylation of benzene (FR-A-2 534 905 and FR-A-2 534 906), but the experimental conditions are then restricting. The reaction is carried out in an autoclave in the presence of 8% FeCl
3
: the yield is only 56% after heating at 145° for 2 h.
D. E. PEARSON et al. [op. cit.] report some exceptional results of acylation of aromatic compounds in the absence of catalysts by a simple thermal effect, but the reaction times are very long and the yields remain low, in particular in the case of deactivated aromatic compounds.
These last references, like the number of catalysts described in the prior art, do not relate in a general manner to the problem of the acylation of both activated and deactivated aromatic substrates under conditions which are easily implemented.
The present invention achieves this objective and provides a process which allows the above-mentioned disadvantages to be prevented.
A process for the acylation or sulphonylation of an aromatic compound has now been found, which is the object of the present invention, which comprises reacting said aromatic compound with an acylating or sulphonylating agent in the presence of a Friedel-Crafts catalyst, characterised in that the acylation or sulphonylation reaction is carried out in a liquid phase under microwave irradiation.
According to the process of the invention, the preparation of an aromatic ketone or aromatic sulphone is carried out by the Friedel-Crafts reaction under microwave radiation under conditions which are greatly improved with respect to those which have been known.
It is possible to carry out the acylation or sulphonylation of activated, non-activated or deactivated aromatic compounds in an open reactor.
The reaction times are very short, and are distinctly lower than the reaction times used under a simple thermal effect in the presence of the same catalysts, and with reaction yields which are often higher.
A considerably reduced consumption of electrical energy comparied with the use of an electric resistance furnace, both in the power required (60 to 300 watt instead of several kilowatt) and in the very much shorter reaction times, is also noted.
To be more exact, the present invention relates to a process for the acylation or sulphonylation of an aromatic compound corresponding to the general formula (I):
in which:
A symbolizes the residue of a ring which forms 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 is applied, in particular, to aromatic compounds corresponding to the formula (I) in which A is the residue of an optionally substituted cyclic compound preferably having at least 4 atoms in the ring, representing at least one of the following rings:
a monocyclic or polycyclic, aromatic carbocyclic ring,
a monocyclic or polycyclic, aromatic heterocyclic ring containing at least one of the heteroatoms O, N and S.
It may be said, but without limiting the scope of the invention, that the optionally substituted residue A represents the residue:
1. —of a monocyclic or polycyclic, aromatic carbocyclic compound.
“Polycyclic carbocyclic compound” is understood as meaning:
a compound made up of at least 2 aromatic carbocyclic rings which form with one another ortho- or ortho- and pericondensed systems,
a compound made up of at least 2 carbocyclic rings, only one of which is aromatic and which form with one another ortho- or ortho- and pericondensed systems.
2. —of a monocyclic or polycyclic, aromatic heterocyclic compound.
“Polycyclic heterocyclic compound” is defined as:
a compound made up of at least 2 heterocyclic rings containing at least one heteroatom in each ring, at least one of which two rings is aromatic and which form with one another ortho- or ortho- and pericondensed systems,
a compound made up of at least one hydrocarbon ring and at least one heterocyclic ring, at least one of which rings is aromatic and which form with one another ortho- or ortho- and pericondensed systems.
3. —of a compound made up of a chain of rings, as defined in paragraphs 1 and/or 2, bonded to one another:
by a valency bond,
by an alkylene or alkylidene radical having 1 to 4 carbon atoms, preferably a methylene or isopropylidene radical,
by one of the following groups:
—O—, —CO—, —COO—, —OCOO—
—S—, —SO—, —SO
2
—,
In these formulae, R
o
represents a hydrogen atom or an alkyl radical having 1 to 4 carbon atoms, a cyclohexyl or phenyl radical.
More particularly, the residue A which is optionally substituted represents the residue:
of an aromatic, carbocyclic, monocyclic compound, such as benzene, toluene, isobutylbenzene, anisole, thioanisole, phenetole or veratrole, guaiacol, guetol, mono- and dichlorobenzenes, fluorobenzene, iodobenzene,
of an aromatic, condensed, polycyclic compound, such as naphthalene, 2-methoxynaphthalene, 3-methoxynaphthalene,
of an aromatic, carbocyclic, non-condensed polycyclic compound, such as phenoxybenzene,
of a partially aromatic, carbocyclic, condensed, polycyclic compound, such as tetrahydronaphthalene, 1,2-methylene dioxybenzene,
of a partially aromatic, carbocyclic, non-condensed, polycyclic compound, such as cyclohexylbenzene,
of an aromatic, heterocyclic, monocyclic compound, such as pyridine, furane, thiophene,
of a partially heterocyclic, aromatic, condensed, polycyclic compound, such as quinoline, indole or benzofurane,
a partially heterocyclic, aromatic, non-condensed polycyclic compound, such as phenylpyridines, naphthylpyridines,
of a partially heterocyclic, partially aromatic, condensed, polycyclic compound, such as tetrahydroquinoline,
of a partially heterocyclic, partially
Desmurs Jean-Roger
Dubac Jacques
Laporte Christian
Laporterie Andre
Marquie Julien
Burns Doane Swecker & Mathis L.L.P.
Padmanabhan Sreeni
Rhodia Chimie
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