Patent Application
20130274484
The invention relates to new aromatic compounds bearing at least a phosphonate or phosphinate group on the aromatic ring.
The invention also relates to a process for their preparation.
Some molecules, oligomers or polymers containing both aromatic rings and phosphonic or phosphinic moities are of particular interest for various applications. The presence of these groups can confer some unique properties such as surface modification, flame retardancy, corrosion protection or ion exchange. Such molecules or materials could present some interest in application such as OPV (Organo PhotoVoltaic), fuel cells with proton exchange resins or intrinsic flame retardancy.
The problem is that typically the molecules or materials bearing both an aromatic ring and a phosphonate or phosphinate functionality can be prepared by phosphonation reaction involving aggressive reagents such as PCl3. These reagents can alter the integrity of the material and are typically difficult to scale up. Alternatively, phosphites can be used to phosphonate aromatic ring but it involves a multi-step reaction route that is not practical or cost effective. Phosphonation using trialkylphosphites can be carried out under UV conditions [Bull. Chem. Soc. Jpn., 63, 938-940, (1990)]. However, the reaction is not selective and generates mixtures.
Alternatively, dialkylphosphites can be used to phosphonate rings even within a polymer matrix. The reaction is a 3 step process that involves a bromation, a phosphonation reaction and finally a deprotection reaction of the phosphonate [Macromol. Chem. Phys. (2003), 204, 61-67].
Alternatively, PCl3 can be used to create P—C bond onto an aromatic ring with a catalytic amount of Lewis acid (U.S. Pat. No. 5,698,736) but it requires elevated temperatures. The aryl dichlorophosphine thus formed is very sensitive and must be hydrolysed to obtain the phosphonic acid functions.
The objective of the present invention is to provide a process which makes it possible to overcome the above mentioned disadvantages.
A subject of the invention is a process for preparing aromatic compounds bearing at least a phosphonate or phosphinate group on the aromatic ring.
Another subject of the invention is the new obtained aromatic compounds.
There has now been found, and it is this which constitutes the subject matter of the present invention, a process for the preparation of a aromatic compound bearing a phosphonate or phosphinate group on the aromatic ring from an aromatic compound, characterized in that an aromatic compound with the formula (III):
wherein:
wherein:
The present invention aims to provide new aromatic compounds bearing at least a phosphonate or phosphinate group with the formula (IV):
wherein:
R1, R2, R3, R4, R5 and R6 have the meanings given above.
In the context of the invention, “alkyl” is understood to mean a linear or branched hydrocarbon chain having from 1 to 24 carbon atoms and preferably from 1 or 2 to 10 carbon atoms.
“Alkenyl” is understood to mean a linear or branched hydrocarbon group having from 1 to 24 carbon atoms and preferably from 2 to 15 carbon atoms and comprising one or more double bonds, preferably 1 to 2 double bonds.
“Cycloalkyl” is understood to mean a cyclic hydrocarbon group comprising from 3 to 8 carbon atoms, preferably a cyclopentyl or cyclohexyl group.
“Aryl” is understood to mean an aromatic mono- or polycyclic group, preferably a mono- or bicyclic group, comprising from 6 to 24 carbon atoms, preferably 6 to 12 carbon atoms, and more preferably phenyl or naphthyl.
“Arylalkyl” is understood to mean a linear or branched hydrocarbon group carrying an aromatic monocyclic ring and comprising from 7 to 24 carbon atoms, preferably 7 to 12 carbon atoms, and more preferably phenyl or naphthyl, and more preferably benzyl.
“Heterocycloalkyl” is understood to mean a cycloalkyle in which one or two carbon atoms are replaced by heteroatom such as oxygen, nitrogen, sulfur, comprising from 3 to 24 atoms and preferably from 3 to 18 atoms and more preferably 5 or 6 atoms.
The reagents which are particularly well suited to the implementation of the invention correspond to the formula (I) or (II) in which R1 and R2 represent hydrogen or methyl.
More preferably, R1 represents methyl and R2 represents hydrogen.
In formulae (I) or (II), R3 represents a linear or branched alkyl group having from 1 to 6 carbon atoms, preferably methyl, ethyl, n-propyl, isopropyl group or an electron-donating group which is more particularly:
R3 is not limited to the electron-donating groups mentioned above which constitute examples only.
Preferred compounds have formula (I) or (II) in which R3 represents a C1-C3 alkyl group, a methoxy or ethoxy group, an amino group, a dimethyl or diethylamino group.
R3 is more preferably a methyl group.
As regards the definition of the other symbols R4, R5 and R6 involved in the formula (I) or (II), they represent a linear or branched alkyl group having from 1 to 6 carbon atoms, preferably methyl or ethyl group or metals selected from the group consisting of alkali metal or alkaline earth metal.
Among alkali metals, sodium or potassium is preferred.
Among alkaline earth metals, calcium is preferred.
Mention may be made, as preferred examples of reagents of formula (I) or (II) capable of being employed in the process of the invention, inter alia, of:
The phosphonate or phosphinate reagent of formula (I) or (II) and the process for their preparation are disclosed in PCT/CN2009/074726 and PCT/CN2009/07473 O.
The aromatic compound involved in the process of the invention corresponds to formula (III).
In the remainder of the description, the term “aromatic” denotes the conventional concept of aromaticity as defined in the literature, in particular by Jerry MARCH, “Advanced Organic Chemistry”, 4th edition, John Wiley & Sons, 1992, pp 40 ff.
The invention is of particular application to aromatic compounds with formula (III) in which A is the residue of a cyclic compound, preferably containing at least 4 carbon atoms in its cycle, preferably 5 or 6, optionally substituted, and representing at least one of the following cycles: a monocyclic or polycyclic aromatic carbocycle, i.e., a compound constituted by at least 2 aromatic carbocycles and between them forming ortho- or ortho- and peri-condensed systems, or a compound constituted by at least 2 carbocycles only one of which is aromatic and between them forming ortho- or ortho- and peri-condensed systems;
The aromatic compound with formula (III) preferably carries at least one electron-donating group when this compound corresponds to formula (III) in which A represents a monocyclic or polycyclic aromatic carbocycle.
More particularly, optionally substituted residue A preferably represents the residue of an aromatic carbocycle such as benzene, an aromatic bicycle containing two aromatic carbocycles such as naphthalene; or a partially aromatic bicycle containing two carbocycles one of which is aromatic, such as tetrahydro-1,2,3,4-naphthalene.
The invention also envisages the fact that A can represent the residue of an aromatic heterocycle such as furan, pyridine or thiophene; an aromatic bicycle comprising an aromatic carbocycle and an aromatic heterocycle such as benzofuran or benzopyridine; a partially aromatic bicycle comprising an aromatic carbocycle and a heterocycle such as methylenedioxybenzene; an aromatic bicycle comprising two aromatic heterocycles such as 1,8-naphthylpyridine; a partially aromatic bicycle comprising a carbocycle and an aromatic heterocycle such as 5,6,7,8-tetrahydroquinoline.
In the process of the invention, an aromatic compound with formula (III) is preferably used in which A represents an aromatic nucleus, preferably a benzene or naphthalene nucleus.
The invention does not exclude the presence of a concatenation of the aromatic groups as defined above bonded together by a valence bond and/or by one of the following groups of the aromatic cycle into by a valence bond or by an alkylene group C1-C6 or by one of the following groups: —O—, —CO—, —COO—, —COO—.
The aromatic compound with formula (III) may carry no substituent particularly when the compound comprises a heterocycle with at least one atom carrying a free electron pair, preferably a nitrogen, oxygen, sulphur.
The aromatic compound with formula (III) preferably carries at least one electron-donating group when this compound only comprises one or several carbocycles.
The aromatic compound with formula (III) may carry one or several substituents
In the present text, the term “several” generally means less than 4 substituents R on the aromatic nucleus. n is preferably 1 or 2.
When there are other substituents than an electron-donating group, the nature of the other substituents is unimportant provided that it does not interfere with the principal reaction.
The aromatic compound with formula (III) carries more preferably an electron-donating group.
In the present text, the term “electron-donating group” means a group as defined by H. C. BROWN in the work by Jerry MARCH, “Advanced Organic Chemistry”, 4th edition, John Wiley & Sons, 1992, Chapter 9, pp. 273-292.
Starting compounds with formula (III) include those with formula (III) where R represents one of the following groups:
Preferred compounds have formula (III) in which R represents a methoxy or an ethoxy group.
R is not limited to the electron-donating groups mentioned above which constitute examples only.
The catalyst used in the process of the invention is a Friedel-Crafts type catalyst.
A first class of catalysts suitable for the invention is constituted by Lewis acids.
Examples of organic salts which can be cited are the acetate, propionate, trifluoroacetate, benzoate, methanesulphonate and trifluoromethanesulphonate of metallic elements or metalloids from groups (IIIa), (IVa), (VIII), (IIb), (IIIb), (IVb), (Vb) and (VIb) of the periodic table.
Regarding inorganic salts, the chloride, bromide, iodide, sulphate, oxide and analogous products of metallic elements or metalloids from groups (IVa), (VIII), (IIb), (IIIb), (IVb), (Vb) and VIb) of the periodic table can be used.
In the present text, reference shall be made to the periodic table published in the Bulletin de la Société Chimique de France, no 1 (1966).
The salts used in the process of the invention are more particularly those from elements from group (IIa) of the periodic table, preferably scandium, yttrium and the lanthanides; from group (IVa), preferably titanium, zirconium; from group (VIII), preferably iron; from group (IIb), preferably zinc; from group (IIIb), preferably boron, aluminium, gallium, indium; from group (IVb), preferably tin; from group (Vb), preferably bismuth; from group (VIb), preferably tellurium.
Of the inorganic salts, metallic halides can be cited, preferably zirconium chloride, ferric chloride, zinc chloride, aluminium chloride, aluminium bromide, gallium chloride, indium chloride, stannic chloride, bismuth chloride, boron trifluoride; ferrous oxide, ferric oxide, and gallium oxide.
The present invention includes the case where the halide can be generated in situ using a known method.
Preferred examples of catalysts which can be cited are aluminium chloride and zinc chloride.
Regarding organic salts, rare earth and/or bismuth salts of trifluoromethanesulphonic acid (commonly known as triflic acid) are preferably used.
The term “rare earth” means lanthanides with an atomic number or 57 to 71, also yttrium and scandium.
The process of the invention more particularly envisages using the following rare earths: lanthanum, ytterbium, lutetium and/or scandium.
Rare earth triflates are known products. They are generally obtained by reacting a rare earth oxide with trifluoromethanesulphonic acid.
Bismuth salts of triflic acid can also be used in the process of the invention.
A further class of catalysts which is suitable for the invention is constituted by Brönsted acids, in particular sulphuric acid, hydrofluoric acid, hydrochloric acid, phosphoric acids and polyphosphoric acids, sulphonic acids and in particular trifluoromethanesulphonic acid, perfluorosulphonic acid and fluorosulphonic acid.
Preferred example of catalysts is sulphuric acid.
In the process of the invention, a solid catalyst as defined above is used which may also be supported. To this end, the support can be selected from metal oxides such as aluminium oxides, silicon and/or zirconium oxides, clays, more particularly kaolin, talc or montmorillonite, or from charcoal, possibly activated by a known treatment with nitric acid, acetylene black or resins.
The support can be in any form, for example a powder, beads, granules, extrudates . . . .
In the catalyst, the amount of active phase represents 5% to 100% of the weight of the catalyst.
In accordance with the process of the invention, the reaction between the aromatic compound and the phosphonate or phosphinate reagent is carried out in the liquid phase, in the presence or absence of an organic solvent; one of the reactants can be used as the reaction solvent.
In a preferred variation of the process of the invention, the reaction is carried out in an organic solvent.
A number of factors govern the choice of solvent.
It must be inert under the conditions of the invention, and must have a boiling point which is higher than the reaction temperature.
Preferably, an aprotic, low polarity organic solvent is used.
Examples of solvents which are suitable for the present invention which can in particular be cited are aliphatic or aromatic hydrocarbons, which may or may not be halogenated.
Examples of aliphatic hydrocarbons which can in particular be cited are paraffins such as hexane, heptane or cyclohexane and aromatic hydrocarbons, in particular aromatic hydrocarbons such as benzene, toluene, xylenes, cumene, and petroleum cuts constituted by a mixture of alkylbenzenes.
Regarding aliphatic or aromatic halogenated hydrocarbons, the following can in particular be cited: perchlorinated hydrocarbons such as tetrachloromethane; partially chlorinated hydrocarbons such as dichloromethane, chloroform, 1,2-dichloroethane and trichloroethylene; and halogenated aromatic hydrocarbons such as monochlorobenzene, dichlorobenzenes and mixtures thereof.
It is also possible to use mixture of organic solvents.
The present reaction is carried out using the reactants in the proportions mentioned below.
The ratio between the number of moles of aromatic compound and the number of moles of phosphonate or phosphinate reagent can vary as the substrate may act as the reaction solvent. Thus, the ratio can be from 0.1 to 10, preferably from 1 to 2.
The quantity of catalyst used is determined such that the ratio between the number of moles of catalyst and the number of moles of phosphonate or phosphinate reagent is preferably in the range 0.001 to 1.0, more preferably in the range 0.02 to 0.2.
Regarding the quantity of organic solvent used, it is generally selected such that the ratio between the number of moles of organic solvent and the number of moles of aromatic compound is preferably in the range 0 to 100, more preferably in the range 10 to 20.
The temperature at which the reaction is carried out depends on the reactivity of the starting substrate.
It is in the range 60° C. to 120° C., preferably in the range 80° C. to 100° C.
In general, the reaction is carried out at atmospheric pressure and the mixture is heated under reflux of reactants or of the solvent.
From a practical viewpoint, there are no restrictions on how the reactants are processed. They can be introduced in any order.
After bringing the reactants into contact, the reaction mixture is brought to the desired temperature.
A further variation of the invention consists of heating one of the reactants (phosphonate or phosphinate reagent or aromatic compound) with the catalyst then introducing the other reactant.
The reaction duration depends on a number of parameters. It is usually 30 minutes to 8 hours.
At the end of the reaction, the aromatic compound bearing at least a phosphonate or phosphinate function is recovered from the organic phase using known techniques, by eliminating the organic solvent by distillation or by crystallisation.
Under acidic conditions the diene function can favor the formation of a carbocation. Such property allows these molecules to be reactive towards aromatic rings under Friedel & Crafts reaction conditions. The overall reaction can create a carbon-carbon bond while the new molecule formed contains a phosphonic or phosphinic functionality. Such method is a very simple and straightforward way to introduce such functionalities onto aromatic rings under mild conditions. Indeed, the reaction can proceed smoothly with catalytic amount of simple acids such as sulfuric acid.
These phosphonating or phosphinating reagents of formula (I) or (II) can be used to prepare new aromatic molecules bearing phosphonic or phosphinic groups that could possess some flame retardant properties.
The same molecules could also be used for surface modification of metallic or glass surface to adjust their wettability and/or improve their paintability. Because of the presence of the aromatic group, these new obtained phosphonate or phosphonate products could find some applications to improve the wettability of electrodes in organic polymers for OPV systems or electronic organic applications.
Thus, another application of the present invention is to introduce a phosphonate or phosphinate group on an aromatic ring which is included into a is polymer.
Indeed, the conditions for introducing the said groups being mild, it is possible to graft the said groups within the final polymer
An example is to prepare proton conducting membranes bearing a phosphonate or phosphinate group.
The following examples, given without implied limitation, illustrate the present invention.
2.1 g (0.015 mol) of 1,4-dimethoxybenzene and 3.4 g (80%, 0.0165 mol) of PoDM are added to 2 ml heptane in a 100 ml reactor.
0.16 ml H2SO4 (98 wt. %) are then added dropwise in 20 min at room temperature and the mixture is heated at 120° C.
The mixture is allowed to react for 3 h reaction and is then cooled down to room temperature.
A 6 M aqueous soda solution is added dropwise until pH=7.
The organic layer (lower layer) is separated and the pH is adjusted at 4 with an aqueous sulphuric acid solution (30 wt. %)
The obtained product precipitates.
3.4 g of that product is recovered by filtration.
The yield is 57%.
The obtained product is analysed by 1H NMR and 31P NMR:
1H NMR (300 MHz, CDCl3, TMS): δ 1.35 (d, J=18.0, 3H), 1.44 (s, 6H), 3.66 ((s, 3H), 3.79 (s, 3H), 6.69-6.91 (m, 4H); 13C NMR (75 MHz, CDCl3, TMS): δ 11.97, 12.11, 28.34, 38.97, 39.25, 55.64, 56.22, 110.46, 113.12, 113.18, 138.23, 151.80, 153.59, 154.40, 154.50;
31P NMR (112 MHz, CDCl3, TMS): δ 25.46. MS (EI) m/z 300 (M+), 268, 219, 203, 187.
2.81 g (95%, 16.5 mmol) of PoDM and 2.77 g (33 mmol) of thiophene are charged into a 50 mL three-necked flask which is equipped with a thermometer, a condenser and a magnetic stirrer.
0.083 g (98%, 0.825 mmol) H2SO4 are then added by dropwise in 5 min at room temperature under nitrogen and then the mixture is heated to reflux for 24 h.
The medium reaction is cooled down to room temperature, diluted with 50 mL of water and is then is extracted with ethyl acetate (30 mL×3).
The organic layer is separated and concentrated to give 1.22 g of a dark red oil.
The obtained yield is 30%.
The obtained product is analysed by 1H NMR and 31P NMR:
1H NMR (300 MHz, DMSO, TMS): δ 1.46 (s, 6H), 1.88 (s, 3H), 6.85 (d, 1H), 6.90 (t, 1H), 7.30 (d, 1H); 31P NMR (112 MHz, DMSO, TMS): δ 15.98.
5.62 g (95%, 33 mmol) of PoDM and 5.54 g (66 mmol) of thiophene are charged into a 50 mL three-necked flask which is equipped with a thermometer, a condenser and a magnetic stirrer.
0.54 g (3.3 mmol) of FeCl3 is added at room temperature under nitrogen and the mixture is then heated to reflux for 24 h.
The medium reaction is cooled down to room temperature, diluted with 100 mL of water and is then is extracted with ethyl acetate (60 mL×3).
The organic layer is separated and concentrated to give 1.63 g of a dark red oil.
The obtained yield is 20%.
The 1H NMR analysis of the obtained product is the same with example 2.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CN10/80263 | 12/24/2010 | WO | 00 | 6/24/2013 |
