EP1003697A1

EP1003697A1 - Method for oxidising substituted hydrocarbon derivatives

Info

Publication number: EP1003697A1
Application number: EP98941513A
Authority: EP
Inventors: Michel Gubelmann-Bonneau; Claire Poix-Davaine; Hervé Ponceblanc
Original assignee: Rhodia Chimie SAS
Current assignee: Rhodia Chimie SAS
Priority date: 1997-08-01
Filing date: 1998-07-31
Publication date: 2000-05-31
Also published as: FR2766818B1; ZA986754B; JP2001512089A; WO1999006338A1; AU8986498A; FR2766818A1

Abstract

The invention concerns a method for controlled oxidation of a substituted hydrocarbon substrate, consisting in contacting said substituted hydrocarbon substrate with a source of oxygen in the presence of at least a catalyst selected among those whereof the active phase is obtained from a heteropolyacid of formula (I): Hf[CcDdEeOx] in which: C represents Mo and/or W; D represents phosphorus, arsenic, antimony, silicon, germanium and/or boron; E represents an element selected among vanadium optionally in combination with at least a metal of columns VA, VIIA, VIII or chromium; x being the oxygen number required to observe valences; A represents at least a monovalent cation; B represents VO?2+, VO3+¿, an ion of an alkaline-earth metal or of one metal of columns VIIA, VIII, IB, IVB and VB of the periodic table of elements; f = a + αb with α being the ion B charge, i.e. equal to 2, 3 or 4; c varies between 5 and 20 inclusively; d varies between 1 and 5 inclusively; e varies between 1 and 9 inclusively; and said substrate has a chain > CH- bearing an electroattractive group (or atom). The invention is applicable to organic synthesis.

Description

PROCESS FOR THE OXIDATION OF SUBSTITUTED HYDROCARBON DERIVATIVES

The present invention relates to a controlled oxidation process of electron-depleted substrates, in the presence of a catalyst whose active phase is obtained from heteropolyacid (s). It relates more particularly to the gentle oxidation of a substrate having a methylene carrying at least one function or of an electron-withdrawing group.

The present invention further relates to a composition obtained from certain specific heteropolyacids and titanium dioxide as a support, as well as a catalyst comprising said composition as active phase. By convention, the term heteropolyacid will be used in this text.

(or HPA) to designate the compound corresponding to the Keggin structure, both heteropolyacids and polyoxometallates.

In this area, with regard to the nature of Keggin's structure, we can refer to two articles published in "the catalyst review newsletter"; the one published in October 1993 about the "solid acid '93 meeting, Houston Texas" on page 9 and the one in volume 4 N ° 7, page 12.

Obtaining a carbon-oxygen bond, in particular a simple one, from a link> CH- (in general, methyl) of which at least one of the bonds is linked to an electron-withdrawing group, by gentle oxidation of said link presents the advantage of using a raw material whose cost is very competitive compared to those used in existing technologies. However, to the knowledge of the Applicant, no process of this type has been described to date.

Such a process would be of particular interest for the synthesis of carbon derivatives which are also both oxygenated and halogenated and above all fluorinated. As an example of a problem to be solved, we can cite the cases where the electron-withdrawing group or groups are chosen from fluorine atoms and radicals whose carbon of attachment (that is to say linked to said> CH-) is mono- , advantageously di-fluorinated. As the electron-withdrawing group, special mention should be made of perfluoroalkyls and in particular trifluoromethyl. This is why one of the aims of the present invention is to provide a controlled oxidation process which makes it possible to treat substrates depleted in electron.

Another object of the present invention is to provide a process of the above type which allows the formation of carbon oxygen bond (s).

Another object of the present invention is to provide a process of the above type which allows the formation of ether, ester and / or acid function (s).

Another object of the present invention is to provide a process of the above type which allows the formation of ether, ester and / or acid function (s) from a methylated perfluoroalkane, and in particular from trifluoro-1, 1, 1 ethane. .

These aims and others which will appear subsequently are achieved by means of a process of gentle oxidation of substituted hydrocarbon substrate (s) in which they are used. contact the said (s) substrate (s) hydrocarbon (s) substituted (s) with an oxygen source in the presence of at least one catalyst chosen from those whose active phase is obtained from a heteropolyacid of formula (I): HftC _Q DdEgOx] in which:

- C represents Mo and / or W;

- D represents phosphorus, arsenic, antimony, silicon, germanium and / or boron; - E represents an element chosen from vanadium optionally in combination with at least one metal from columns VA, VIIA, VIII or chromium; said acid can be partially or even completely neutralized by a cationic entity of formula (II) [A _a E substituting for H _f : x being the number of oxygen necessary for the respect of the highest valences of C, D and E ;

- A represents at least one monovalent cation chosen from hydrogen, an alkali metal, or even an ammonium or phosphonium ion;

- B represents V0 ²⁺ , V0 ³⁺ , an ion of an alkaline earth metal or of a metal of columns VII A, VIII, IB, IV B and VB of the periodic table of the elements;

- f = a + αb with α being the charge of the ion B, ie equal to 2.3 or 4;

- c varies between 5 and 20-e inclusive;

- d varies between 1 and 5 inclusive;

- e varies between 1 and 9 inclusive; and that said substrate has a link (> CH-), advantageously methylene (CH2), carrying at least one electron-withdrawing group (or atom). f / d is, on the one hand, at least equal to 1 and, on the other hand, at most equal to 12, advantageously to 8, preferably to 6. In general, f / d is an integer. X is equal to (f + cγ + dδ + eε) / 2 where the Greek letters represent the highest valence of the elements represented by the corresponding Latin capital letters.

The concept of electron-withdrawing device is well known to those skilled in the art; one can thus refer to the third edition of the March "advanced organic chemistry" published by John WILEY & sons (pages 237, following and passim).

Thus, the radicals, the atoms or the groups having a Hammett constant σ _p greater than zero are considered to be electron-withdrawing agents (cf., for example, table on page 244). According to the present invention, it is preferred that the σ _p is at least equal to 0.1; advantageously 0.2, preferably 0.3. The preferred electron-withdrawing character is the inducing effect, so we recommend that the above values be reached by the single inducing effect (component σ of σ p [see page 247 of the March]); in this case, the preferred values are that σ \ is at least equal to 0.1; advantageously 0.3, preferably 0.4. With the exception of fluorinated groups, electron-withdrawing groups (GEA) having a strong electron-withdrawing component by mesomeric effect such as nitro (which is not easy to use because it is dangerous) or sulfonyl groups are not preferred.

Here and for the entire description, the information relating to the table of the periodic classification of the elements refers to that which appeared in the supplement to the bulletin of the Société Chimique de France (n ° 1 - January 1966).

The invention also relates to a composition obtained from titanium dioxide as a support and a heteropolyacid of formula (I).

In the following, the terms titanium dioxide and titanium oxide have the same meaning.

Thus, the process according to the invention consists in using a catalyst whose active phase is obtained from a heteropolyacid of formula (I) mentioned above.

More particularly, element B is chosen from the ions V0 ²⁺ , V0 ³⁺ , Cu ⁺ , Fe ³⁺ , Co ²⁺ , Ag ⁺ , Ni ²⁺ , Mn ²⁺ , Mg ²⁺ , Bi ⁺ . Sn ⁺ . Sn ⁴⁺ .

Advantageously, the element B is chosen from the ions V0 ²⁺ , V0 ³⁺ , preferably the ion VO ++.

As regards the element E different from vanadium, this is more particularly chosen from chromium, manganese, iron, cobalt, nickel.

According to a preferred variant of the invention, the heteropolyacid used in the preparation of the active phase corresponds to formula (I) in which D is phosphorus, E vanadium, d is 1, C is between 1 and 3, and the sum of c + e is 12.

According to a particular embodiment, the catalyst used has an active phase comprising, in addition, a support. As a suitable support for carrying out this particular embodiment, mention may, for example, be made of titanium, silicon, zirconium, cerium, tin, alumina, silica-alumina, these compounds which can be used alone or as a mixture .

Preferably, the support is chosen from titanium or zirconium bioxides, the first being preferred.

According to a variant of this embodiment, the active phase of the catalyst has an atomic ratio, (C + E) / metallic element of the support, of between 0.1 and 30%. By metallic element of the support is meant titanium, zirconium, cerium, etc. Preferably, the above atomic ratio is between 5 and 20%.

In the case where the active phase comprises a support, the distribution between the two constituents of the active phase is such that the heteropolyacid of formula (I) is more particularly dispersed on the surface of said support.

According to a first embodiment, the catalyst is used in mass form, that is to say a catalyst comprising only the active phase obtained from the heteropolyacid and, where appropriate, from the support.

According to a second embodiment, the catalyst is used in dilute form, that is to say that the abovementioned active phase is mixed with an inert.

In the latter case, the active phase can be either deposited thereon, coated or even mixed therewith.

As materials capable of being used as inert, there may be mentioned: sintered clay, magnesia, magnesium silicate, diatomaceous earth.

These types of inert materials can be used in porous form or not.

Preferably, the inert used is in non-porous form. If necessary, it can be glazed to make it so.

Ceramic materials, such as cordierite, mullite, porcelain, silicon and boron nitrides, silicon carbide, can also be used as inert.

The catalyst used in the process according to the invention, diluted or not, is in the form of particles or of monolith.

If the catalyst consists of particles, the particle size of these depends on the mode of use of the catalyst. It can therefore vary within wide limits, such as in particular being between a few micrometers and a ten millimeters. More particularly, and by way of indication, a catalyst used in a fixed bed has a particle size distribution generally between 0.5 and 6 mm. The particle size of the particles of a catalyst used in a fluidized or moving bed is usually between 5 and 700 microns, and preferably between 5 and 200 microns for 80% of the particles.

If the catalyst consists of particles, all the forms are suitable for the implementation of the invention. Thus, the catalyst can be, for example, in the form of beads or rings. By rings we mean hollow objects whose section is circular, parallelipiped, ellipsoidal among others. One can likewise envisage any other type of complex structure obtained by extrusion of the inert for example (cross, star, etc.).

In a conventional manner, the quantity of inert entering into the composition of the catalyst varies within wide limits depending, most of the time, on the method of shaping of the catalyst.

Thus, the catalysts obtained by coating or depositing the active phase on the inert material have an amount of active phase usually varying between 0.1 and 30% and, preferably between 2 and 20% by total weight of catalyst (active phase + inert). In cases where the catalyst comprises the active phase dispersed in an inert, the amount of active phase is between 1 and 90% by total weight of catalyst.

According to a preferred embodiment of the invention, the active phase of the catalyst coats the inert present. The catalyst can be prepared according to any conventional, simple and reproducible method, which constitutes an additional advantage of the invention.

Heteropolyacids are known compounds and a person skilled in the art can refer to the publications relating to them to prepare them.

As regards more particularly heteropolyacids, that is to say the compounds for which A represents a hydrogen atom, it is possible in particular to implement two types of process.

According to a first method more particularly suitable for the preparation of heteropolyacids in which b is 0 and d is 1, a mixture comprising the constituent elements of the heteropolyacid is refluxed in water for 24 hours, preferably in the form of 'oxides.

Another method of obtaining heteropolyacids of the same type as above and for which the value of c is between 6 and 12, consists in preparing a solution of the constituent elements of HPA, present in the form of alkali or alkaline earth metal salts. This is obtained by dissolving said compounds in water.

Once the solution obtained, it is neutralized by the addition of a mineral acid such as hydrochloric acid in particular. The resulting product is extracted from the medium with ether and then contacted with distilled water to obtain an aqueous solution, from which the heteropolyacid can be crystallized.

At the end of each of these two methods, it is possible to obtain, by evaporation or crystallization, the desired heteropolyacid. This can be used directly as a catalyst in the reaction according to the invention, optionally after having undergone a calcination step which will be described below.

In a usual way, and in the case where the catalyst used comprises a support, the contacting of the heteropolyacid with said support is carried out by means, for example, of a dry impregnation, although d other routes are not excluded a priori. As such, mention may be made of the mixture of the various constituents, heteropolyacid and support in solid form for example.

According to the impregnation method, the support is brought into contact as defined above, with a solution of heteropolyacid in an amount such that the atomic ratio, (C + E) / metallic element of the support, is between 0.1 and 30% and, preferably between 5 and 20%.

The resulting suspension is then dried. This drying step can advantageously be carried out in two stages: the first consisting in evaporating the solvent or dispersant from the mixture, more particularly water, until dry, the second in drying the paste thus obtained.

Generally, the first step is carried out at a temperature varying from 20 to 100 ° C., under vacuum or not, for the time necessary to obtain a paste.

Evaporation is usually carried out with stirring. The paste obtained is then dried, in a second step, under an atmosphere, preferably non-reducing, such as oxygen or air for example, for an average duration of 15 h.

The drying temperature is usually between 100 and 150 ° C. It should be noted that other drying methods can be envisaged, such as for example drying the suspension by atomization in any type of apparatus and under conditions known to those skilled in the art. The dried product is then subjected to a calcination step. This is carried out, in a conventional manner, under a non-reducing atmosphere. Advantageously, air is used, but oxygen could just as easily be used.

The calcination temperature is usually between 200 and 500 ° C.

Generally, the duration of the operation varies between 1 and 24 hours.

Before and / or after the calcination step, the dried product can undergo a deagglomeration step.

In the case where the catalyst used in the process according to the invention comprises an inert, the coating method is preferably used.

Thus, the inert is brought into contact, preferably in the form of rough particles, and the active phase in a high shear mixer (LODIGE type devices) or in a granulation device (drageers, in the form of a drum or plate).

The operation is generally carried out at a temperature varying between 20 and 150 ° C. for the time necessary for coating the inert material with the desired quantity of active phase, more particularly in air, for at least 30 min. The particles thus obtained are usually calcined at a temperature between 300 and 500 ° C.

The duration of the calcination is generally at least 3 h.

Of course, all these methods of preparing the heteropolyacid (HPA), of bringing said HPA into contact with the support and / or the inert, are only given for information and can in no case constitute a list exhaustive.

As mentioned previously, the method according to the invention consists in carrying out a controlled oxidation of a substrate which has a link (> CH-), advantageously methylene (CH2), carrying at least one group (or atom ) electron-withdrawing device with a source of oxygen, in the presence of a catalyst as described above.

As the reaction is advantageously carried out with the substrate in the gas phase, it is desirable, in order to obtain significant productivity, that the substrate have a saturated vapor pressure of at least 1 kiloPascal at the temperature at which the oxidation is carried out, advantageously 5 , preferably 10 kiloPascals. It is preferable that these values are reached from 200 ° C (3 significant figures), advantageously from 180 ° C.

It is desirable that said methylene link carries a hydrogen and therefore forms a methyl. It is desirable that said electron-withdrawing group (or atom) be difficult to oxidize, that is to say that when the open bond is replaced by a fluorine the compound thus constructed is not considered to be flammable within the meaning of the European directives on transport. on the day of filing of this request.

Advantageously, the said electron-withdrawing group (s) [or atom (s)] have at least one halogen atom, advantageously fluorine.

The results, as has been said in the introduction, are of particular interest when the bond between said group and said link> CH- is carried by a carbon carrying at least two halogen atoms, advantageously at least one , preferably at least two are fluors.

Said electron-withdrawing group is advantageously chosen from highly halogen groups, that is to say groups whose ΣHydrogen / ∑Halogen ratio is at most equal to 1, advantageously 2/3, preferably 1/2. In particular, mention may be made of the trihaiogenomethyl, pentahaloethyl, dihalogenomethyl, tetrahaloethyl, penta- or hexa-halo-propyl hex, hepta- or octa-halobutyl radicals.

Unless it is desired to carry out the oxidation at two locations on the substrate, said electron-withdrawing group is advantageously chosen from perhalogenated groups, preferably from perfluorinated groups Rf.

It is desirable that said halogens are advantageously at least for half of the fluorines, preferably said group is chosen from Rf groups such as trifluoromethyl or pentafluoroethyl, or highly fluorinated groups such as, for example, difluoromethyl, tetrafluoroethyl, penta- or hexa- hepta- or octa-fluorobutyl fluoropropyls. As indicated above, it is preferable that the halogens are arranged so that there are at least two halogen atoms on the vicinal carbon of the link to be oxidized.

As appears from the above, said link (to be oxidized)> CH-, can carry an alkyl radical, a second electron-withdrawing group (or even a third) or, preferably, a hydrogen (thus forming a methylene stricto sensu).

[in the present description ALCO-y / e is taken in its etymological sense of hydrocarbon residue of an ALCO-O / after ignorance of the alcohol (or ol) function]; A second electron-withdrawing group can be connected to the first electron-withdrawing group to form a cycle.

Said link> CH- can carry an acrylic group. Said link> CH- may advantageously be a methylene group (CH2), preferably carrying a hydrogen to form a methyl radical. Preferred substrates can be written as follows:

GEA-CH (R ₁ ) (R ₂ ) where (GEA) represents an electron-withdrawing group (including atom), advantageously by inducing effect (see above); where Rj represents either a hydrogen or an electron-withdrawing group (including atom); where R2 represents either a hydrogen or even an alkyl group (but this is not preferred).

Among the atoms forming an electron-withdrawing group, halogens, advantageously light (Cl and F), preferably fluorine, are preferred. However, the more complex electron-withdrawing groups are preferred, linked to the carbon to be oxidized (> CH-) by a carbon-carbon bond. It is desirable that one, preferably both of R ^ and R2 are

Hydrogen.

GEA can carry another oxidizable site so that oligomeric ethers or esters can be made, or rather when the shortest distance between the two sites is suitable (two, three or four links [advantageously perhalogenated, preferably perfluorinated], not including the methylene oxidation sites), an ether or even ester cycle.

It is also possible to submit two substrates simultaneously, in particular to form asymmetric ethers. To do this, the optimum molar ratio between the two substrates must be determined on a case-by-case basis. The substrates are limited in molecular mass by the volatility constraint.

It can be indicated that these compounds generally have at most about 20 carbon atoms, advantageously at most 15 carbon atoms, preferably at most 10 carbon atoms, more preferably at most 8 carbon atoms. In the present description the term "approximately" is used to highlight the fact that the values which follow it correspond to mathematical rounding and in particular that when the digit (s) furthest to the right of a number are zeros, these zeros are position zeros and not significant digits, unless of course specified otherwise. Returning to the composition of the catalyst, it should be recalled that, according to an advantageous variant of the present invention, the reaction is advantageously carried out in the presence of a catalyst whose active phase is obtained from a heteropolyacid of formula (I ) in which D is phosphorus, E le vanadium, e is between 1 and 3 inclusive, d is 1, the sum of c + e is equal to 12 and x = 40. The reaction is advantageously carried out in the presence of a catalyst whose active phase is deposited on a support. In particular, the reaction is carried out in the presence of a catalyst the said active phase of which is deposited on a support and that the support is chosen from titanium, silicon, zirconium, cerium and tin bioxides. alumina, silica-alumina, or mixtures thereof.

According to a particularly advantageous implementation of the present invention, the reaction is carried out with a gas mixture comprising 0.1 to 99.9% by mole of substrate, and more particularly between 0.1 and 3% or between 10 and 99% by mole of substrate and is preferably used as a source of oxygen in the air, oxygen or nitrous oxide.

Furthermore, the reaction is carried out with a gas mixture comprising 0.1 to 99.9% by mole of oxygen and, more particularly, comprising between 1 and 90% or between 97 and 99.9% by mole of oxygen.

Advantageously, a gas mixture having a substrate / oxygen molar ratio of less than 20 and, more particularly, between 0.01 and 0.2 or between 0.6 and 18 is used.

According to an advantageous variant of the present invention, the reaction is carried out in the presence of a diluent chosen from water, or inert gases, or recycled gases from the reaction, alone or as a mixture and, more particularly, a gaseous mixture comprising 0.1 to 70 mol% of water and preferably comprising 1 to 20 mol% of water.

According to a particularly advantageous implementation of the present invention, the heteropolyacid of formula (I) corresponds to the crude formula (III):

H ₃ ΨΔ ₁₂ O40 with:

Ψ representing the following atoms or entities P, As, Sb, HSi, HGe, H ₂ B; Δ representing the following atoms or entities W, Mo, HV and their mixtures.

In other words, Ψ represents a pentavalent entity (including an atom) chosen from P, As, Sb, HSi, HGe, H ₂ B, or even the mixtures they form with one another, advantageously among the phosphorus atoms and arsenic, preferably Ψ represents phosphorus. Δ represents a hexavalent entity (including an atom) chosen from W, Mo, HV and their mixtures. When Δ represents a mixture, it is recommended that the atomic ratio (W + Mo) / (W + Mo + V) be at least equal to 1/3, advantageously 1/2, preferably 2/3.

The values of Ψ bring together the same elements as D but provide a more restrictive relationship between the choice of these elements and the number of hydrogen (s) in HPA.

The values of Δ bring together elements common to C and E but provide a more restrictive relationship between the number of vanadium V and the number of hydrogen (s) in HPA; this explains that the replacement of a molybdenum or a hexavalent tungsten by a vanadium V must be compensated by the contribution of an external valence [in formula I this compensation is brought by the metals of E (except V) in inverse reason for their valence (for example, only one third in mole of trivalent is added per vanadium V introduced) and by H, while in formula III compensation is carried out at the rate of hydrogen by Vanadium V since a hydrogen brings only one valence].

It is desirable that the heteropolyacid of formula (III) have a so-called Keggin structure.

According to the present invention the role of delta (Δ) is important for the level of oxidation obtained (see below).

Thus, the heteropolyacid of formula (III) can be such that Δ is a mixture of at least two atoms or entities.

According to one option, the heteropolyacid of formula (III) is such that Δ has an atomic ratio W / Mo at least equal to 1/2, advantageously to 1, preferably to 2.

According to a variant, the heteropolyacid of formula (III) is such that Δ has an atomic ratio V / (W + Mo + V) at least equal to 1/12, advantageously 1/6, preferably 1/4.

More precisely if it is desired that the substrate be oxidized to carboxylic acid (essentially in the case where said link> CH- is methyl) and it will be preferred that the heteropolyacid of formula (III) and the cationic entity of formula (II) are such that the atomic ratio between all the hydrogens present and Ψ is at least equal to 3, advantageously to 4, preferably to 5.

If it is desired that the substrate be oxidized in the medium state II (for example into an ester or a ketone), it will be preferred that the heteropolyacid of formula (III) and the cationic entity of formula (II) are such that the atomic ratio between all the hydrogens present and Ψ is at least equal to 2 and at most equal to 3.

he If it is desired that the substrate be oxidized to ether, it will be preferred that the heteropolyacid of formula (III) and the cationic entity of formula (II) are such that the atomic ratio between all of the hydrogens present (c (i.e. including those provided by the entity (HV) in Δ and by the entities HSi, HGe, H2B in Ψ) and Ψ is at most equal to 3, advantageously to 2, preferably to 1. It it is also preferable that the cationic entity [AaBb] at least partially replacing the hydrogen comprises vanadium IV (VO ++).

Thus the present invention also relates to a composition which comprises a support phase chosen from titanium and zirconium bioxides and their mixture and at least one heteropolyacid phase of formula (III) in which Δ has an atomic ratio W / Mo at least equal to 1/12, preferably at

1/4, preferably 1/3.

Also targeted is a composition where the heteropolyacid of formula (III) and the cationic entity of formula (II) are such that the atomic ratio between the totality of the hydrogens present and au is at most equal to 3, advantageously to 2, of preferably 1.

Also targeted is a composition where the heteropolyacid of formula (III) and the cationic entity of formula (II) are such that the atomic ratio between the totality of the hydrogens present and Ψ is at least equal to 3, advantageously to 4, of preferably 5.

According to an advantageous variant of the present invention, the heteropolyacid of formula (III) and the cationic entity of formula (II) are such that the atomic ratio between all the hydrogens present and Ψ is at least equal to 2 and at most equal to 3. Advantageously, the heteropolyacid of formula (III) has a so-called Keggin structure.

Preferably, the heteropolyacid of formula (III) is such that Δ is a mixture of at least two atoms or entities.

It is interesting that the heteropolyacid has a formula (III) such that Δ corresponds to an atomic ratio W / Mo at least equal to 1/2, advantageously to 1, preferably to 2.

It may also be advantageous for the heteropolyacid to have a formula (III) such that Δ corresponds to an atomic ratio V / (W + Mo + V) at least equal to 1/12, advantageously 1/6, preferably 1 / 4.

The following nonlimiting examples illustrate the invention. Overview

Main reactions observed:

CF ₃ CH ₃ + 3/2 O ₂ → CF ₃ CO ₂ H + H ₂ O 2CF ₃ CH ₃ + O ₂ → (CF ₃ CH ₂ ) O + H ₂ O 2CF ₃ CH ₃ + 2 O ₂ → CF ₃ CO ₂ CH ₂ CF ₃ + 2H ₂ O

Minor reactions deemed to be parasitic:

CF ₃ CH ₃ + 3/2 O ₂ → CO ₂ + CF ₃ H + H ₂ O CF ₃ CH ₃ + 1 O ₂ → CO ₂ + CF ₃ H + H ₂ O

1. General operating procedure Schematic diagram

Oxygen'

Trifluoroethane Hot box

Nitrogen

Helium

Online GIC Analysis

Catalysts

We carried out a blank test, ie a test of the Ti0 ₂ support at 250 ° C for seven hours.

It turns out that this solid is weakly active (3 <TTF143a <4%) and preferentially leads to combustion (Sel. CO _x = 95%).

Three families of catalysts can be identified:

tee in

Operating conditions

Mass of the sample: 1 gram of powdered catalyst,

(diluted to 3 ml in silicon carbide),

Pressure: 1 bar (i.e. 10 ⁵ Pa) absolute, Reagents: F143a / 0 ₂ / H ₂ 0 / inert = 15.6 / 15.6 / 7.8 / 61% inert inert: He: 55.9 and N ₂ : 5.1% mol,

Temperature: between 175 and 250 ° C.

- T Temperature

- opt. Optimal

Conversion rate

Salt. Selectivity expressed in molar% COx C0 ₂ + CO Ether (CF ₃ CH ₂ ) ₂ 0 TFA Trifluoroacetic acid

The typical test takes place over two days and has two parts.

1.1 Variable temperature test

There is an analysis of the gaseous effluents in temperature stages of 25 ° C between 175 and 250 ° C, that is to say four analyzes separated by an hour and a half each.

The results are analyzed and the optimum temperature is determined, the operating point of the second part.

Selective catalysts in TFA (trifluoroacetic acid)

Selective TFA and ester catalysts (CF-, CO ₉ CH ₉ CFι)

Selective ether catalysts ((CF ^ CHo) _? O)

* can also be considered as a = 1 A = H

1.2 Optimal temperature test

This is the temperature at which the best compromise is obtained between the overall conversion rate of R143a (CF3-CH3) and the total selectivity to controlled oxidation products (excluding combustion: C0 ₂ and CO). This temperature is either 225 ° C or 250 ° C.

From this temperature kept constant, we perform an analysis per hour, in order to follow the evolution of performance as a function of time. The study time varied from 5:30 to 46:00, depending on:

- the stability of the observed values,

- the possible decrease in the transformation rate of the initial F143a. Selective catalysts in TFA

Selective catalysts in TFA and ester (CF.COOCHPCF

*Salt. ester = 65.2% Selective ether catalysts

2. Preparation and characteristics of the catalysts

The HPAs were dry impregnated on the Ti0 ₂ support according to the procedure described above.

The Ti0 ₂ support has a specific area of 86 m ² / kg and a pore volume with water of 0.94 ml / g.

The impregnation was carried out on 10 g of support and calculated in order to obtain a theoretical monolayer of HPA thereon such that: sum of metals / Ti = 0.167 in atom. The mass of HPA was dissolved in 9.4 ml of water deionized at 40 ° C. Then, the support was impregnated with the clear solution and at room temperature. In some cases, two successive impregnations were necessary, separated by drying at 120 ° C in order to dissolve the necessary mass of HPA. The solids were dried at 110 ° C and tested as such. The table below summarizes the preparations made.

The nature of the initial, unsupported HPA, in particular the number of molecules of water of hydration was determined by ATD-ATG analysis. The following table shows the mass losses as a function of the temperature

PM: Molar mass in grams eq. : Equivalent No.: Number Tx: Temperature

Claims

1. Process of gentle oxidation: of substituted hydrocarbon substrate (s), characterized in that it comprises bringing said (said) substituted hydrocarbon substrate (s) into contact with an oxygen source in the presence of at least one catalyst chosen from those whose active phase is obtained from a heteropolyacid of formula (I): HffCcDcjEeOx] in which: - C represents Mo and / or W;

- D represents phosphorus, arsenic, antimony, silicon, germanium and / or boron;

- E represents an element chosen from vanadium optionally in combination with at least one metal from columns VA, VIIA, VIII or chromium; said acid being able to be partially or even completely neutralized by a cationic entity of formula (II) [A _a Bk] replacing Hf: x being the number of oxygen necessary for the respect of the highest valences of C, D and E ; - A represents at least one monovalent cation chosen from hydrogen, an alkali metal, or even an ammonium or phosphonium ion;

- B represents V0 ²⁺ , V0 ³⁺ , an ion of an alkaline earth metal or of a metal of columns VII A, VIII, IB, IV B and VB of the periodic table of the elements; - f = a + αb with a being the charge of the ion B, ie equal to 2.3 or 4;

- c varies between 5 and 20-e inclusive;

- d varies between 1 and 5 inclusive;

- e varies between 1 and 9 inclusive; and that said substrate has a methylene group (CH2) carrying an electron-withdrawing group (or atom).

2. Method according to claim 1, characterized in that said electron-withdrawing group (or atom) is difficult to oxidize.

3. Method according to claims 1 and 2, characterized in that the Hammett constant of said electron-withdrawing group (including atom) σ _p is at least equal to 0.1; advantageously 0.2, preferably 0.3.

4. Method according to claims 1 to 3, characterized in that the component σ of σ _{p of} said electron-withdrawing group (or atom) is at least 0.1; advantageously 0.3, preferably 0.4.

5. Method according to claims 1 to 4, characterized in that said electron-withdrawing group (or atom) has at least one halogen atom, advantageously fluorine.

6. Method according to claims 1 to 5, characterized in that the bond between said group and said methylene is carried by a carbon carrying two halogen atoms of which advantageously at least one, preferably two are fluors.

7. Method according to claims 1 to 6, characterized in that said group is an Rf group.

8. Method according to claims 1 to 7, characterized in that said group is chosen from trihalogenomethyl, tetrahalogenoethyl, pentahalogenoethyl groups.

9. Method according to claim 8, characterized in that said halogens are at least half of the fluorines.

10. Method according to claims 1 to 9, characterized in that the said group is chosen from trifluoromethyl, tetrafluoroethyl, pentafluoroethyl groups.

11. Method according to claims 1 to 10, characterized in that said link> CH- carries an alkyl radical, a second electron-withdrawing group or a hydrogen.

12. Method according to claims 1 to 1 1, characterized in that said methylene group (CH2) carries a second electron-withdrawing group connected to the first electron-withdrawing group to form a cycle.

13. Method according to claims 1 to 12, characterized in that said methylene group (CH2) carries an aryl group.

14. Method according to claims 1 to 13, characterized in that said methylene group (CH2) is a methyl radical.

15. Method according to claims 1 to 14, characterized in that the reaction in the presence of a catalyst whose active phase is obtained from a heteropolyacid of formula (I) in which D is phosphorus, E vanadium , e is between 1 and 3 inclusive, d is 1, the sum of c + e is equal to 12 and x = 40.

16. Method according to claims 1 to 15, characterized in that the reaction is carried out in the presence of a catalyst whose said active phase is deposited on a support.

17. Process according to claims 1 to 16, characterized in that the reaction is carried out in the presence of a catalyst, the said active phase of which is deposited on a support and that the support is chosen from titanium, silicon bioxides, zirconium, cerium, and tin, alumina, silica-alumina, or mixtures thereof.

18. Method according to claims 1 to 17, characterized in that the reaction is carried out with a gaseous mixture comprising 0.1 to 99.9% by mole of substrate, and more particularly between 0.1 and 3% or between 10 and 99% by mole of substrate.

19. Method according to claims 1 to 18, characterized in that one uses as the oxygen source air, oxygen or nitrous oxide.

20. Method according to claims 1 to 19, characterized in that the reaction is carried out with a gaseous mixture comprising 0.1 to 99.9% by mole of oxygen, and more particularly comprising between 1 and 90% or between 97 and 99.9% by mole of oxygen.

21. Method according to claims 1 to 20, characterized in that a gas mixture is used having a substrate / oxygen molar ratio of less than 20 and more particularly between 0.01 and 0.2 or between 0.6 and 18.

22. Method according to claims 1 to 21, characterized in that in that the reaction is carried out in the presence of a diluent chosen from water, or inert gases, or recycled gases from the reaction, alone or as a mixture.

23. Method according to claims 1 to 22, characterized in that a gas mixture comprising water is used as diluent.

24. Method according to claims 1 to 23, characterized in that a gas mixture is used comprising 0.1 to 70% by mole of water, and preferably comprising 1 to 20% by mole of water.

25. The method of claims 1 to 24, characterized in that a gas mixture is used comprising an inert gas chosen from rare gases or nitrogen, as diluent.

26. Method according to claims 1 to 25, characterized in that a gas mixture is used comprising 1 to 70 mol% of inert gas and preferably comprising 5 to 20 mol% of said gas.

27. Method according to claims 1 to 26, characterized in that the heteropolyacid of formula (I) corresponds to the crude formula (III):

H ₃ ΨΔ ₁₂ O ₄ o with

Ψ representing the following atoms or entities P, As, Sb, HSi, HGe, H2B; Δ representing the following atoms or entities W, Mo, HV and their mixtures.

28. Method according to claims 1 to 27, characterized in that the heteropolyacid of formula (III) has a so-called Keggin structure.

29. Method according to claims 1 to 28, characterized in that the heteropolyacid of formula (III) is such that Δ is a mixture of at least two atoms or entities.

30. Method according to claims 1 to 29, characterized in that the heteropolyacid of formula (III) is such that Δ has an atomic ratio W / Mo at least equal to 1/2, advantageously to 1, preferably to 2 .

31. Method according to claims 1 to 30, characterized in that the heteropolyacid of formula (III) is such that Δ has an atomic ratio V / (W + Mo + V) at least equal to 1/12, advantageously at 1/6, preferably 1/4.

32. Method according to claims 1 to 31, characterized in that the substrate is oxidized to carboxylic acid and in that the heteropolyacid of formula (III) and the cationic entity of formula (II) is such that the ratio atomic between all the hydrogens present and Ψ is at least equal to 3, advantageously to 4, preferably to 5.

33. Process according to claims 1 to 32, characterized in that the substrate is oxidized to an ester or to a ketone and by the fact that the heteropolyacid of formula (III) and the cationic entity of formula (II) is such that the atomic ratio between all the hydrogens present and Ψ is at least equal to 2 and at most equal to 3.

34. Process according to claims 1 to 33, characterized in that the substrate is oxidized to ether and in that the heteropolyacid of formula (III) and the cationic entity of formula (II) is such that the atomic ratio between all the hydrogens present and Ψ is at most equal to 3, advantageously 2, preferably 1.

35. Composition useful as a catalyst, characterized in that it comprises a support phase chosen from titanium and zirconium bioxides and their mixture, and at least one heteropolyacid phase of formula (III) in which Δ has an atomic ratio W / Mo at least equal to 1/12, advantageous * to 1/4, preferably to 1/3.

36. Composition according to claim 35, characterized in that the heteropolyacid of formula (ill) and the cationic entity of formula (II) are such that the atomic ratio between all of the hydrogens present and Ψ is at most equal to 3, advantageously 2, preferably 1.

37. Composition according to claim 35, characterized in that the heteropolyacid of formula (III) and the cationic entity of formula (II) are such that the atomic ratio between all of the hydrogens present and Ψ is at least equal to 3, advantageously to 4, preferably to 5.

38. Composition according to claim 35, characterized in that the heteropolyacid of formula (III) and the cationic entity of formula (II) are such that the atomic ratio between all of the hydrogens present and Ψ is at least equal to 2 and at most equal to 3.

39. Composition according to claims 35 to 38, characterized in that the heteropolyacid of formula (III) has a so-called Keggin structure.

40. Composition according to claims 35 to 39, characterized in that the heteropolyacid of formula (III) is such that Δ is a mixture of at least two atoms or entities.

41. Composition according to Claims 35 to 40, characterized in that the heteropolyacid of formula (III) is such that Δ has an atomic ratio W / Mo at least equal to 1/2, advantageously to 1, preferably to 2 .

42. Composition according to claims 35 to 41, characterized in that the heteropolyacid of formula (III) is such that Δ has an atomic ratio V / (W + Mo + V) at least equal to 1/12, advantageously at 1/6, preferably 1/4.

43. Oxidation catalyst for a hydrocarbon derivative, characterized in that it comprises, as surface active phase, at least one heteropolyacid of formula (III):

H3ΨΔ12O40 with

Ψ representing the following atoms or entities P, As, Sb, HSi, HGe, H ₂ B;

Δ representing the following atoms or entities W, Mo, HV and their mixtures, said acid possibly being partially or even completely neutralized by a cationic entity of formula (II) [A ^^] replacing the hydrogens of said acid.

44. Oxidation catalyst according to claim 43, characterized in that the said heteropolyacid of formula (III) covers at least 1%, advantageously 5%, preferably 10%, of the surface of the catalyst (BET).

45. Oxidation catalyst according to claims 43 and 44, characterized in that the oxidant is gaseous oxygen.