FR3029201A1 - METATHESIS METHOD - Google Patents

Abstract

The present invention relates to a process for metathesis of olefin (s). The method according to the invention comprises contacting at least one fatty acid ester or a fatty acid with a metathesis catalyst, said fatty acid ester or fatty acid comprising at least one unsaturation, in which the ester or the fatty acid is treated with a sorbent before it comes into contact with the metathesis catalyst, the sorbent being maintained in the reaction medium when the ester or fatty acid is brought into contact with the catalyst. metathesis.

Description

The present invention relates to a method for metathesis of olefin (s) and more particularly fatty acid (s) or ester (s) of fatty acid comprising at least one unsaturation. One of the important challenges of today's chemistry is to be more respectful of the environment, be it animal or vegetable. In chemistry, respect for the environment is reflected in particular by a reasoned use of solvents, and in particular polluting solvents, the preferential use of biosourced reagents, such as fatty acids or fatty acid esters derived from vegetable oils, limiting the number of steps in a synthesis, saving energy, for example by limiting the stages of heating, and the limitation of risks. This desire to make chemistry more environmentally friendly has led chemists to rethink strategies for synthesizing chemicals. Metathesis is a carbon-carbon bond formation reaction that in many cases greatly shortens synthetic strategies. In addition, this reaction has the advantage of producing few by-products and hazardous waste. The word metathesis comes from the Greek "meta" (change) and "tera" (place). This reaction, whose mechanism was elucidated by the team of Yves Chauvin in 1971, aims to change the place of the fragments. More particularly, the metathesis of olefin (s) is a chemical reaction that induces a redistribution of the alkylidene moieties by cleavage of a carbon-carbon double bond, for example according to the following scheme: AABB 1 A SeS + S33 B 2 wherein A and B each represent unsubstituted substituents. The metathesis reaction can take place between two different olefins (direction 2 in the diagram above); we will then speak of cross metathesis. Alternatively, the metathesis reaction can take place between two identical olefins (direction 1 in the diagram above); we will then speak of homometathesis. Whatever the metathesis reaction, it requires the presence of a metathesis catalyst, such as transition metal catalysts. Particularly suitable transition metals are ruthenium, tungsten or molybdenum, but also less commonly based on osmium, chromium or rhenium. These catalysts can be removed and / or be in the presence of ionic liquid. Particularly effective catalysts for metathesis are ruthenium catalysts such as those proposed by Grubbs and Hoveyda. These catalysts make it possible not only to obtain excellent conversions, but also have the advantage of being stable in air. However, their costs can be significant. In addition, although few data are available to assess the toxicity of ruthenium, it appears that the latter is at least genotoxic. The EMEA ("European Medicines Agency") has therefore issued a recommendation that the oral limit of exposure to ruthenium be 10 ppm per day (see "Guideline on the speci fi c limits for residues of metal catalyst or metal reagents"). , February 21, 2008). However, the use of a catalyst during a chemical reaction has the consequence that a residual amount of catalyst remains present in the reaction product. The presence of a residual amount of ruthenium can be a source of problems such as the isomerization of olefins during a possible distillation of the reaction product, the decomposition of the product over time or the increase of its toxicity. This last point is a fact that manufacturers must take into account if the product is to be the subject of a pharmaceutical, cosmetic or food application. Decontamination processes exist, but also have a cost, and they use products which are sometimes themselves toxic and / or are not necessarily sufficiently effective to achieve a satisfactory ruthenium content in the reaction product. The objective of the industrialists is therefore to reduce to the minimum the necessary amount of catalyst to make the industrialization of the metathesis process economically acceptable and more respectful of the environment.

One way of reducing the amount of metathesis catalyst is to avoid any loss of efficiency of said catalyst. Indeed, by increasing the efficiency and / or the life of the catalyst, it is possible to use a smaller amount during the reaction. One approach to limit catalyst efficiency losses is to reduce the amount of catalyst poisons in the reaction medium.

A catalyst poison is a substance that blocks or inhibits the catalyzed reaction, most often by binding to the catalyst, more strongly than the reactant whose reaction is to be catalyzed. In the case of olefin metathesis catalysts, the poisons prevent the olefin from binding to the catalyst. In order to increase the performance of the catalysts and the conversion rates, a strategy therefore consists in attempting to reduce the amount of catalyst poisons. In the case of fatty acids and esters of fatty acids, the main poisons are products resulting from oxidative degradation (primary and secondary oxidation products), such as peroxides, hydroperoxides and aldehydes. Other impurities present in the fatty acids which are likely to impair the effectiveness of the catalyst are glycerol, water, alcohols, ketones, nitriles, terminal conjugated polyolefins, metal residues and colored impurities. indane, pyrene, phenanthrene, naphthalene and alkylbenzene.

Treatment methods have been described, in particular to reduce the amount of peroxides. WO2009 / 020665 discloses a method of metathesis of a starting material, said starting material being a natural oil or a derivative, wherein the starting material undergoes heat treatment at a temperature above 100 ° C, prior to the introduction of the metathesis catalyst, the heat treatment having the objective of reducing the catalyst poisons. By way of example, the natural oil derivative may be a fatty acid or a fatty acid alkyl ester derived from natural oil. To further reduce the amount of catalyst poison, the starting material can also be treated with adsorbents. There is therefore still a need for a method for metathesis of fatty acid (s) or ester (s) of fatty acid to obtain an optimized conversion. The work of the inventors has made it possible to demonstrate that, in the context of a method for metathesis of fatty acid (s) or ester (s) of fatty acid comprising at least one unsaturation, a particular treatment of said one or more acid (s) or ester (s) significantly increased the conversion of the metathesis reaction.

The present invention thus relates to a metathesis process comprising bringing at least one fatty acid or fatty acid ester into contact with a metathesis catalyst, said fatty acid or fatty acid ester comprising at least one unsaturation, in which the fatty acid or the ester is treated with a sorbent before it is brought into contact with the metathesis catalyst, the sorbent being maintained in the reaction medium when the fatty acid or the ester is brought into contact with the metathesis catalyst. Surprisingly, the maintenance in the reaction medium of the sorbent in the process according to the invention does not lead to poisoning of the catalyst by the sorbent, but has the advantage of improving the conversion rate of the fatty acid or of the fatty acid ester having at least one unsaturation. In particular, the process according to the invention avoids any step of separating the sorbent from the fatty acid and / or from the acid ester comprising an unsaturation, such as a liquid-solid separation operation by filtration, decantation or centrifugation. Throughout the present application, by fatty acid and / or fatty acid ester having an unsaturation, a fatty acid having an unsaturation and / or a fatty acid ester having an unsaturation is targeted. By "sorbent" is meant an adsorbent and / or an absorbent.

Preferably, the sorbent is chosen from silicas, metal oxides (such as aluminum oxide, magnesium oxide, calcium oxide, sodium oxide, potassium oxide, iron oxide and / or titanium oxide), aluminosilicates, titanosilicates, active carbons, molecular sieves (such as microporous coals, zeolites, aluminosilicates, etc.) or mixtures thereof. Indeed, each sorbent can be used alone or mixed with one or more other sorbents selected from the list above. In the process according to the invention, the sorbent is advantageously dried at a temperature of at least 60 ° C., preferably at least 80 ° C., prior to the treatment of the fatty acid and / or the acid ester. with at least one unsaturation.

Advantageously, the drying time is at least 30 minutes, preferably at least 1 hour. The metathesis method according to the invention relates to fatty acids and / or fatty acid esters comprising at least one unsaturation. Preferably, in the metathesis process according to the invention, the fatty acid or the fatty acid ester comprising at least one unsaturation has the following formula (I): ## STR2 ## in which: n is an integer between 1 and 21, R 1 is a hydrogen atom in the case of a fatty acid or a straight or branched alkyl chain of 1 to 10 carbon atoms in the case of a fatty acid ester, R2 is a hydrogen atom or a linear or branched, alkyl or alkenyl chain of 1 to 20 carbon atoms, optionally substituted with one or more hydroxyl groups, carboxyl and / or ester (s).

In particular, when R 1 is a hydrogen atom and R 2 is a linear or branched alkyl or alkenyl chain of 1 to 20 carbon atoms, substituted by a carboxyl group, the fatty acid of formula (I) is a diacid . On the other hand, when R 1 is a linear or branched alkyl chain of 1 to 10 carbon atoms and R 2 is a linear or branched alkyl or alkenyl chain of 1 to 20 carbon atoms, substituted by an ester group, the ester of formula (I) is a diester and the ester group is preferably a -COORi group, with R1 as indicated above. Throughout this application, the ranges of values are included limits.

More preferably, the fatty acid or the fatty acid ester is of formula (I) in which: n is an integer between 1 and 21, R1 is a hydrogen atom in the case of a fatty acid or an alkyl chain, linear or branched, of 1 to 10 carbon atoms in the case of a fatty acid ester, R2 is a hydrogen atom or a linear or branched alkyl chain, from 1 to 20 carbon atoms. carbon, optionally substituted with one or more hydroxyl groups.

More preferably still, the fatty acid or the fatty acid ester is of formula (I) in which: n is an integer between 5 and 13, R1 is a hydrogen atom in the case of an acid fatty acid or an alkyl chain, linear or branched, of 1 to 10 carbon atoms in the case of a fatty acid ester, R2 is a linear or branched alkyl chain of 2 to 10 carbon atoms, optionally substituted by a hydroxyl group. Even more preferentially, the fatty acid or the fatty acid ester is of formula (I) in which: n is an integer between 7 and 11, R1 is a hydrogen atom in the case of an acid fatty acid or a linear alkyl chain of 1 to 10 carbon atoms in the case of a fatty acid ester, R2 is a linear alkyl chain of 4 to 8 carbon atoms. Preferably, in the case of a fatty acid ester, R 1 is an alkyl chain of 1 to 5 carbon atoms, more preferably a methyl or an ethyl. In particular, the fatty acid or fatty acid of the fatty acid ester is preferably a monounsaturated fatty acid and may be myristoleic acid (cis-9-tetradecenoic acid) or palmitoleic acid (cis-9-hexadecenoic acid) , oleic (cis-9-octadecenoic), elaidic (trans-9-octadecenoic), ricinoleic (12-hydroxy-9-cis-octadecenoic), gadoleic (cis-9-eicosenoic) and / or erucic (cis-13-docosenoic) ). Preferably, the fatty acid is oleic acid and the fatty acid ester, an alkyl oleate, preferably methyl oleate. Alternatively, the fatty acid or fatty acid of the fatty acid ester may be polyunsaturated, such as linoleic acid ((9Z, 122) -octadeca-9,12-dienoic acid) or its isomers, the γ-linolenic acid (6Z 9Z 12Z-octadeca-6,9,12-trienoic) and / or α-linolenic acid (9Z-12Z-15Z-octadeca-9,12,15-trienoic).

According to a preferred embodiment, the metathesis process according to the invention is carried out on a product to be treated, comprising at least one fatty acid or a fatty acid ester, comprising an unsaturation. The product to be treated may comprise a single type of fatty acid or fatty acid ester, comprising at least one unsaturation, or a mixture of different fatty acids and / or fatty acid esters, of which at least one has at least one unsaturation. Indeed, the fatty acids and / or fatty acid esters used in the process according to the invention are advantageously of natural origin, that is to say derived from a plant, an animal or an algae. More particularly, the fatty acids and / or fatty acid esters used may be derived from rapeseed oil, sunflower oil, soybean oil, oleic sunflower oil, castor oil, safflower oil, coconut oil, palm oil, tallow oil, bacon, olive, cotton, flax, corn, Chinese wood, peanut, calendula, grape seed. Therefore, the product to be treated may be: a hydrolysed vegetable oil, such as a hydrolysed oleaginous oil, or hydrolysed triglycerides; alkyl esters of a vegetable oil, such as an oleaginous oil, or alkyl esters of triglycerides, for example obtained by transesterification of the vegetable oil or triglycerides. Hydrolyzed vegetable oil, hydrolysed triglycerides, vegetable oil alkyl esters and / or triglyceride alkyl esters may optionally have been purified, such as distillation, in order to enrich the product to be treated with certain fatty acids and / or or fatty acid esters having at least one unsaturation. Impurities may therefore be present in the product to be treated. These can be various depending on the origin of the oil or triglycerides and more or less numerous, depending on the degree of purification.

The product to be treated is therefore preferably a fatty acid or a fatty acid ester, comprising at least one unsaturation, or a mixture of fatty acids and / or fatty acid esters, at least one of which contains at least one unsaturation, in all its degrees of purity and more particularly, a fatty acid or a fatty acid ester of formula (I) or a mixture of fatty acid (s) and / or acid ester (s) wherein at least one is of formula (I) in all its degrees of purity. Preferably, the degree of purity of the product to be treated is at least 50%, preferably at least 60%, more preferably at least 70%, more preferably at least 80%. For example, for the fatty acid, oleic acid Nouracid HE 1885, sold by Oleon, Ertvelde, Belgium, used in Examples 2 and 8, has a degree of purity of 85%. This oleic acid is obtained by hydrolysis of a high oleic acid oil in the presence of water.

Similarly, for the fatty acid ester, Radia® 7072, marketed by Oleon, Ertvelde, Belgium, used in Example 1 is obtained by transesterification of a high oleic acid oil in the presence of methanol. Radia® 7072 is therefore methyl oleate with a degree of purity of 85%.

Advantageously, the treatment with the sorbent is carried out with a quantity of sorbent of between 0.01 and 10% by weight relative to the total weight of the product to be treated. Preferably, the amount of sorbent is between 0.05 and 5%, more preferably between 0.1 and 3.5%. More preferably still, the treatment with the sorbent is carried out with a quantity of sorbent of between 0.1 and 1.0%, for example at a quantity of approximately 0.9%, plus or minus 0.1%, by weight. , on the weight of the product to be treated. Alternatively, the treatment with the sorbent is carried out with an amount of sorbent of about 3%, plus or minus 0.1%, by weight, on the weight of the product to be treated. Alternatively, the amount of sorbent to be introduced for the treatment can be evaluated on the total weight of fatty acid (s) and / or ester (s) of fatty acid comprising at least one unsaturation. In this case, the amount of sorbent is between 0.02 and 20% by weight, preferably between 0.01 and 10% by weight, more preferably between 0.2 and 5% by weight relative to the total weight of acid. (s) Fat having at least one unsaturation. The temperature at which the treatment with the sorbent is carried out is preferably between 20 and 80 ° C. In addition, the treatment is carried out for at least one hour.

More preferably, the temperature is between 40 and 60 ° C. More preferably still, the treatment is carried out at a temperature of about 50 ° C. In addition, the treatment with the sorbent is preferably carried out for at least one hour and a half, more preferably still, for two hours. Alternatively, in the case where the reaction of the process according to the invention is a homometathesis of a fatty acid, the treatment with the sorbent can be carried out for at least six hours, preferably for fifteen hours. The metathesis catalyst in the process according to the invention is preferably a ruthenium catalyst, and preferably a catalyst having the following formula (II): in which: R 3 is an alkyl chain of 1 to 5 carbon atoms, optionally branched R4 is a hydrogen atom, an alkyl chain of 1 to 3 carbon atoms or an alkyl ether with an alkyl chain of 1 to 10 carbon atoms, and R5 is a hydrogen atom or a group -N H- Wherein R 6 is an optionally branched oxyalkyl chain of 1 to 15 carbon atoms or an alkyl chain of 1 to 5 carbon atoms, optionally substituted with halogen atoms. In formula (II), it should be noted that the bond between the diamino group and the ruthenium has a double bond character.

Preferably, the catalyst has the formula (II) above in which: R 3 is an optionally branched alkyl chain of 1 to 5 carbon atoms, R 4 is a hydrogen atom or an alkyl chain of 1 to 3 carbon atoms and R5 is a hydrogen atom or a group -N H-00-R6, wherein R6 is an optionally branched oxyalkyl chain of 1 to 15 carbon atoms or an alkyl chain of 1 to 5 carbon atoms, optionally substituted by halogen atoms. More preferably still, the catalyst has the formula (II) above in which: R 3 is an alkyl chain of 1 to 3 carbon atoms, optionally branched, more preferably a methyl or an isopropyl, R 4 is a hydrogen atom or a methyl, and R5 is a hydrogen atom or a group -N H-00-R6, wherein R6 is an oxyalkyl chain of 1 to 5 branched carbon atoms, oxyalkyl chain of 7 to 12 unbranched carbon atoms or trifluoromethyl.

These catalysts make it possible to obtain very good fatty acid conversion ratios and / or fatty acid esters comprising at least one unsaturation. These catalysts have proved particularly effective for carrying out the metathesis reactions according to the invention (see Example 6). Particularly advantageous examples of catalyst are given in FIGS. 1A and B. These are the catalysts M71-SIPr, M73-SIPr, M73-like (tBu), M73-like (012), available from Omega Cat System , cesson-Sevigne, France and catalysts Hoveyda-Grubbs 2 (HG II) and Hoveyda-Grubbs 2-SIPr (HG II SIPr) marketed by Materia Inc., Pasadena, USA. These catalysts have proved particularly effective for carrying out the metathesis reactions according to the invention (see Example 6).

The catalyst used in the metathesis reaction may be optionally supported. The supports may be varied and may be selected from the group consisting of resins, polymers, PEGs or silica gels having an amino, hydroxy, alkylthio, haloalkyl or carboxylic surface or terminal group. Carbon nanotubes and biopolymers can also be conceivable supports. The catalyst may be added in dissolved form in an organic solvent such as, for example, dichloromethane, in particular degassed and distilled dichloromethane, or in the form of a powder in the initial reaction mixture. The catalyst may be added in dissolved form in an organic solvent such as, for example, dichloromethane, in particular degassed and distilled dichloromethane, or in powder form in the initial reaction medium. The catalyst may be added to the reaction medium either all at once (addition of the catalyst over a period of time of less than 5 min, preferably 30 s), or continuously / several times over a period of time greater than or equal to 5 min. at most the duration of the metathesis reaction. By way of example, for the continuous addition of the catalyst, mention may be made of a time period of 15 minutes, 30 minutes, 1 hour or even 2 hours. This period of time may be even longer in the case of a homometathesis of fatty acid (s), for example over a period of 12h or 24h.

Preferably, the metathesis reaction is carried out at a temperature above 25 ° C and below 100 ° C, preferably at a temperature between 40 and 80 ° C, more preferably still at a temperature between 45 and 65 ° C . The reaction may also be carried out at a pressure of between 1 and 100 bar (s), preferably between 1 and 30 bar (s).

Advantageously, when the unsaturated fatty acid is oleic acid and / or unsaturated fatty acid ester is methyl oleate, the metathesis reaction is carried out at a temperature between 48 to 55 ° C, preferably at a temperature of about 50 ° C, i.e., plus or minus 1 ° C. The metathesis process according to the invention may be carried out in the presence or absence of solvent and / or ionic liquid. Preferably, in the process according to the invention, the metathesis reaction is carried out in the absence of a solvent. Alternatively, the metathesis reaction can be carried out in the presence of solvent and / or ionic liquids. The ionic liquids may be chosen from the group consisting of the liquid salts of general formula Q + in which Q + represents a quaternary ammonium, a quaternary phosphonium, a quaternary guanidinium or a quaternary sulphonium and A- represents an anion capable of forming a liquid salt. below 90 ° C. As far as possible, the presence of air and more particularly of oxygen is avoided during the metathesis reaction. For example, the reaction may be carried out under an inert atmosphere, for example under a nitrogen or argon atmosphere.

More particularly, in the metathesis process according to the invention, the sorbent preferably comprises at least 50% of silica and has a pH of less than 8.

The pH of the sorbent is measured according to the ISO 787-9 standard (see Example 7). By virtue of the selection of sorbents, the process according to the invention makes it possible to obtain the best conversion rates during the metathesis reaction. According to a first embodiment, the product to be treated comprises a fatty acid.

In this first embodiment, the sorbent is chosen so as to have a pH of less than or equal to 7.5 and to comprise at least 50% by weight of TiO 2 and at least 5% by weight of Al 2 O 3, the percentages by weight given on the total weight of sorbent. Preferably, the pH of the sorbent is less than 7, more preferably between 2 and 7.

Preferably, the sorbent comprises at least 60% by weight of 5iO2; more preferably, the content of 5 02 of the sorbent is between 60 and 85% by weight, the percentages by weight being given on the total weight of sorbent. Furthermore, the sorbent preferably comprises at least 7.5% by weight of Al 2 O 3, and more preferably still, between 8 and 20% by weight, the percentages by weight being given on the total weight of sorbent. Advantageously, at least a portion of the silica 5iO 2 and the alumina A1203 of the sorbent are present in the form of smectite. In addition to silica and alumina (also referred to as "aluminum oxide"), the sorbent may comprise other compounds selected from metal oxides (such as oxides of magnesium, calcium, sodium, potassium, iron and / or titanium), aluminosilicates, titanosilicates, activated carbon and / or molecular sieves (such as microporous coals, zeolites, aluminosilicates, etc.). Advantageously, the sorbent may comprise from 1% to 10%, more preferably from 2% to 8% by weight of Fe 2 O 3, the percentages by weight being given on the total weight of sorbent. The sorbent may also comprise at least 0.5% MgO, preferably from 0.5 to 10% by weight, more preferably from 1 to 7% by weight, the percentages by weight being given on the total weight of sorbent. A preferred sorbent according to the invention has the following composition: at least 50% by weight, preferably 60 to 85% by weight of 5iO 2, at least 5% by weight, preferably at least 7.5% by weight and more preferably from 8 to 20% by weight of Al 2 O 3, optionally from 1 to 10% by weight, preferably from 2 to 8% of Fe 2 O 3, optionally from 0.5 to 10% by weight, preferably from 1 to 7% of MgO, The percentages by weight being given on the total weight of sorbent. A particularly preferred sorbent has a composition falling into all the preferred ranges mentioned above.

Advantageously, the sorbent also has a specific surface area (BET) of between 50 and 500 m 2 / g, preferably between 50 and 300 m 2 / g. According to a preferred embodiment, the sorbent is a soil of discoloration. The term "bleaching earth" (also known as "bleaching earth") refers to a soil whose main purpose is to remove colored pigments and various undesirable compounds contained in an oil. A soil of discoloration mainly involves a physical phenomenon, namely adsorption, even if occasionally, it can lead to chemical modifications. In particular "fading earth", smectite-type clays, such as montmorillonite, bentonite, beidellite, nontronite, saponite, hormite (attapulgite, sepiolite) or their mixtures are targeted. The clay may advantageously be an acid-activated clay. Preferably, the smectite clay is montmorillonite, bentonite and / or attapulgite. The bleaching earth may be used alone or in admixture with at least one other compound selected from the above list, such as, for example, activated charcoal and / or silica, insofar as the pH, 5122 and A1203 content of the sorbent in the process according to the invention are observed. More preferably, the sorbent is selected from the group consisting of Pure Flo® B80, Tonsil® Supreme 112FF, FulcatC) 22B and Tonsil® Supreme 110FF.

Pure Flo® B80 is an attapulgite / bentonite clay from the sedimentary layers of the state of Georgia near Ochlocknee. It is marketed by Oil-Dri, Illinois, USA. Based on our analysis and the information available to us, Pure Flo® B80 has the following characteristics: pH 5i02 content * A1203 content * Fe203 content * MgO content * Specific surface 6.6 between 71 and 75% between 11 and 16% between 3.5 and 7% between 2.5 and 6% between 100 and 150 m 2 / g * The contents are given in% by weight relative to the total weight of sorbent.

Tonsil® Supreme 112FF is a bentonite clay, marketed by Clariant Production, Moosburg, Germany. Based on our analyzes and the information available to us, Tonsil® Supreme 112FF has the following characteristics: pH Content Content Content Content 5i02 * A1203 * F e2 03 * MgO * specific 2.8 70.2% 9.4% 2.8% 2.5% 190 m2 / g * The contents are given in% by weight on the total weight of sorbent.

Fulcat® 22B is a montmorillonite type clay marketed by Rockwood Clay Additives GmbH, Moosburg, Germany. Based on our analysis and the information available to us, Fulcat® 22B has the following characteristics: pH Content Content Content Content Si02 * A1203 * F e2 03 * MgO * specific 2,4 64% 15% 6 % 2.9% 250 m2 / g * The contents are indicated in% by weight on the total weight of sorbent.

Tonsil® Supreme 110FF is a bentonite clay, marketed by Clariant Production, Moosburg, Germany. Based on our analysis and the information available to us, Tonsil® Supreme 110FF has the following characteristics: pH Content Content Content Content 5i02 * A1203 * F e2 03 * MgO * specific 3.2 75.5% 12% 2,4% 1,4% 285 m2 / g * The contents are indicated in% by weight on the total weight of sorbent. It should be noted that according to a preferred embodiment of the first embodiment of the process according to the invention, the fatty acid comprising an unsaturation is not subjected to heat treatment. By heat treatment, it is intended a treatment at a temperature greater than or equal to 100 ° C. In contrast, in the process according to the invention, the fatty acid is maintained at a temperature below 100 ° C. Indeed, as can be seen from a comparison of Examples 1 and 3, and contrary to popular belief, the heat treatment not only does not improve the conversion of fatty acids having at least one unsaturation, but still hurts this conversion . Therefore, in the process according to the invention, the fatty acid is preferentially maintained at a temperature below 80 ° C, more preferably at a temperature below 65 ° C. According to a second embodiment, the product to be treated comprises a fatty acid ester. In this second embodiment, the sorbent is selected to have a pH of less than 6.0 and to have at least 65% by weight of 5IO2, the weight percent being given on the total weight of sorbent.

Preferably, the pH of the sorbent is less than 5, more preferably less than 4.5, more preferably between 1.5 and 4. More particularly, the sorbent may be activated with acid. Advantageously, the sorbent also has a specific surface area (BET) of at least 150 m 2 / g, preferably between 170 and 1000 m 2 / g.

According to a first particular embodiment of the second embodiment, the sorbent essentially consists of silica 5iO 2, that is to say that it comprises more than 95%, preferably at least 98%, more preferably more than 99% by weight of silica. Such a sorbent may be synthetic, such as, for example, an amorphous silica hydrogel micronized. Advantageously, the sorbent according to this first particular embodiment of the second embodiment has a specific surface area of at least 500 m 2 / g, preferably from 600 to 1000 m 2 / g. More preferably, the sorbent is Trisyl® 300. Trisyl® 300 is a synthetic micronized silica amorphous hydrogel, sold by W. R. Grace & Co., Columbia, USA. According to our analysis and the information available to us, Trisyl® 300 has the following characteristics: pH Content 5i02 * Specific surface area 2.9> 99% by weight 700 m2 / g * The content is indicated in% by weight on the total weight of dry sorbent. According to a second particular embodiment of the second embodiment, the sorbent comprises from 65 to 95%, preferably from 65 to 80% by weight of silica. In this case, it may advantageously comprise other compounds chosen from metal oxides (such as aluminum oxides, magnesium, calcium, sodium, potassium, iron and / or titanium oxides), aluminosilicates, titanosilicates, activated carbon and / or molecular sieves (such as microporous coals, zeolites, aluminosilicates, etc.).

By way of example, the sorbent may comprise: from 5 to 20% by weight, more preferably from 7 to 15% by weight of alumina A1203, from 1 to 5% by weight, more preferably from 1.5 to 3.5% by weight of Fe 2 O 3, and / or from 0.5 to 5% by weight, more preferably between 0.8 and 3.5% by weight of MgO, the percentages by weight being given on the total weight of sorbent. A preferred sorbent according to this second particular embodiment has the following composition: at least 65% by weight, preferably 65 to 80% by weight of 5iO 2, 5 to 20% by weight, more preferably between 7 and 15% of Al 2 O 3 from 1 to 5% by weight, more preferably from 1.5 to 3.5% by weight of Fe 2 O 3, and from 0.5 to 5% by weight, more preferably from 0.8 to 3.5% by weight, weight of MgO, the percentages by weight being given on the total weight of sorbent. A particularly preferred sorbent has a composition falling into all the preferred ranges mentioned above. Advantageously, the sorbent according to this second particular embodiment has a specific surface area of at least 150 m 2 / g, preferably from 170 to 500 m 2 / g. In the application WO2009 / 020665, the sorbent making it possible to obtain the best conversion is magnesium silicate. Contrary to what could be expected, magnesium silicate does not make it possible to obtain a very good conversion (see Example 2 below). The work of the inventors made it possible to select the sorbents which allowed, after treatment of the fatty acid esters comprising at least one unsaturation by these, to obtain the best conversion. Parameters that have been critical for this selection are pH and silica content. More preferably, the sorbent is selected from the group consisting of Tonsil® Supreme 112FF and Tonsil® Supreme 110FF.

Tonsil® Supreme 112FF is a bentonite clay, marketed by Clariant Production, Moosburg, Germany. Based on our analyzes and the information available to us, Tonsil® Supreme 112FF has the following characteristics: pH Content Content Content Content 5i02 * A1203 * Fe2 03 * MgO * specific 2.8 70.2% 9.4% 2.8% 2.5% 190 m2 / g * The contents are given in% by weight based on the total weight of dry sorbent. Tonsil® Supreme 110FF is a bentonite clay, marketed by Clariant Production, Moosburg, Germany. Based on our analysis and the information available to us, Tonsil® Supreme 110FF has the following characteristics: pH Content Content Content Content 5i02 * A1203 * Fe2 03 * MgO * specific 3.2 75.5% 12 % 2,4% 1,4% 285 m2 / g * The contents are indicated in% by weight on the total weight of dry sorbent. According to a particularly advantageous embodiment of this second embodiment of the process according to the invention, the fatty acid ester comprising at least one unsaturation is heat-treated before it is brought into contact with the metathesis catalyst. Advantageously, the fatty acid ester is heat-treated at a temperature above 100 ° C, preferably at least 150 ° C for at least one hour. More preferably, the fatty acid ester is heat-treated at a temperature of at least 170 ° C for at least one hour and a half, more preferably at a temperature of at least 180 ° C for two hours.

Advantageously, this heat treatment is carried out under a pressure of less than 50 mbar, more preferably less than 10 mbar, even more preferably less than 1 mbar, still more preferably of 0.1 mbar. A particularly suitable heat treatment is a treatment at a temperature of 180 ° C for two hours at a pressure of 0.1 mbar. In the process according to the invention, the heat treatment can be carried out before or during the treatment of the fatty acid ester with the sorbent. More preferably, the treatment with the sorbent is carried out concomitantly with the heat treatment. By "concomitant" it is meant that at least a portion of the heat treatment and sorbent treatment take place at the same time. Indeed, the two treatments may have different durations and / or be slightly shifted. Indeed, the heat treatment can take place before the treatment with the sorbent and / or during the treatment with the sorbent until the addition of the catalyst. Indeed, the heat treatment must be completed before adding the catalyst and launching the metathesis reaction. The metathesis reaction in the process according to the invention may be a cross-metathesis reaction or a homometathesis reaction. In the case of a cross-metathesis reaction, this can in particular be carried out between a fatty acid or a fatty acid ester, comprising at least one unsaturation, such as those mentioned above, and a hydrocarbon compound chosen from unsaturated hydrocarbons comprising at least one double bond and consisting of a number of carbon atoms ranging from 2 to 10, preferably from 2 to 5. Preferably, this hydrocarbon compound is chosen from the group consisting of ethylene propylene, 1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, 3-pentene, 2-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-butene, cyclopentene and a mixture of these compounds. Ethylene and butene are particularly preferred for carrying out metathesis in the context of the process according to the invention. Advantageously, the metathesis reaction can be carried out in the presence of said hydrocarbon compound in gaseous form and / or at a pressure between atmospheric pressure (under normal conditions of temperature and pressure) and 100 bar. Preferably, the reaction is conducted at a pressure ranging from 2 to 50 bars. Preferably, the hydrocarbon compound is introduced into the reaction medium in the form of gas. This is particularly advantageous because such a procedure makes it possible to eliminate any presence of air and oxygen which could be in contact with the reaction medium.

Alternatively, the metathesis reaction of the process according to the invention is a homometathesis reaction, such as a reaction between two identical fatty acid esters comprising at least one unsaturation such as those mentioned above. The process according to the invention makes it possible to obtain a very good degree of conversion of the fatty acid comprising at least one unsaturation and / or of the fatty acid ester comprising at least one unsaturation, with a metathesis reaction time. limit. In a limited reaction time, a time of less than 6 hours, preferably less than 4 hours, more preferably of the order of 2 hours, is aimed at. . Alternatively, in the case where the reaction of the process according to the invention is a homometathesis of a fatty acid, the reaction may be carried out for at least 12 hours, preferably for 24 hours. In this reaction time, by combining the maintenance in the reaction medium of the sorbent during the metathesis reaction, the treatment with the selected sorbents and the possible heat treatment, the conversion rate obtained can be greater than 80% of the theoretical maximum conversion. .

The metathesis reaction of the process according to the invention can make it possible to obtain different reaction products, in particular: a diacid and / or one or more monocarboxylic acid (s) in the case where the metathesis reaction is carried out at from compound (s) of formula (I) in which R 1 is a hydrogen atom, a diester and / or one or more monoesters (s) in the case where the metathesis is carried out from compound (s) of formula (I) wherein R1 is a linear or branched alkyl chain of 1 to 10 carbon atoms. Depending on the reaction conditions, it is possible to preferentially obtain the bifunctional compound or the monofunctional compound (s).

In the case where the metathesis reaction is carried out starting from compound (s) of formula (I) in which R 1 is a hydrogen atom, a particular embodiment of the invention aims at obtaining preferentially the diacid, for example a compound of formula (III) below: in which n is an integer from 1 to 21, this compound of formula (III) being obtained by metathesis reaction from an acid of formula (I) above wherein n is an integer from 1 to 21. The metathesis reaction is then preferably conducted at a temperature less than or equal to the temperature at which the compound of formula (III) precipitates. In addition, it is advantageous to choose this temperature so that it is greater than or equal to the melting point of the compound of formula (I) and / or of the other compounds produced during the metathesis reaction. This temperature range thus makes it possible to precipitate the compound of formula (III) selectively and rapidly, while keeping the other compounds of the reaction medium in soluble form. This makes it possible to promote equilibrium displacements in the desired direction. Advantageously, the metathesis reaction can be carried out in the presence of a hydrocarbon compound in gaseous form and / or at a pressure between atmospheric pressure (under normal conditions of temperature and pressure) and 100 bar. Preferably, the reaction is carried out at a pressure ranging from 2 to 30 bar, more preferably from 5 to 20 bar, more preferably still from 1 to 3 bar. Advantageously, the reaction is carried out at a pressure ranging from 1.5 bar to 2.5 bar, more preferably from 1.7 to 2.3 bar, typically the pressure is 2 bar plus or minus 1 bar. Under these conditions, the process makes it possible to obtain a very good degree of conversion of at least 80% in order to lead predominantly to a yield greater than 20% of compound of formula (III).

Still in the case where the metathesis reaction is carried out from compound (s) of formula (I) in which R 1 is a hydrogen atom, another particular embodiment of the invention aims to obtain preferentially the ) monoacid (s). According to this particular mode, the metathesis reaction can also be carried out in the presence of a hydrocarbon compound such as those described above in gaseous form and / or at a pressure between atmospheric pressure and 100 bar. Preferably, the reaction is conducted at a pressure ranging from 10 to 50 bar, and more preferably from 20 to 40 bar. Typically the pressure is 30 bars. Under these conditions, the process makes it possible to obtain a very good degree of conversion of at least 80% in order to lead predominantly to a yield greater than 30% in monoacid (s). Other features and advantages of the invention will appear in the examples which follow, given by way of illustration, and with reference to the figures: FIG. 1 represents a list of chemical structures of catalysts, some being particularly advantageous for the implementation of The invention (Fig. 1A and 1B), Fig. 2 is a comparative diagram showing the conversion rates of methyl oleate and the percentages by weight (mass) of methyl octadec-9-enedioate, in According to the catalyst used in the metathesis reaction, FIG. 3 is a comparative diagram showing the conversion rates of methyl oleate and the weight percentages (by weight) of methyl octadec-9-enedioate, in the function of the sorbent having treated the methyl oleate, and FIG. 4 is a comparative diagram showing the conversion rates of oleic acid and the percentages by weight (mass) of octadec-9-enedi acid. oique, depending on the sorbent having treated the oleic acid.

EXAMPLE 1 Metathesis Process According to the Invention Prior to Substrate for a Macro Acid Ester 1.1 Measurement of the Peroxide Number The peroxide value of the 85% methyl oleate (Radia 7072, Oleon) is measured according to the following method: In a bottle, introduce about 2g (to the nearest milligram) of the product to be analyzed. Add 25 ml of acetic acid / chloroform mixture (3/2). Dissolve the product with stirring. Add 1 ml of saturated aqueous solution of potassium iodide and stir. Allow 5 minutes to rest away from light.

Add 75 ml of distilled water. Titrate with 0.01 mol / L sodium thiosulfate solution. The peroxide number is determined by the following formula: 1000 (v1-v0) N in which: P is the weight in g of the test sample; - Vo the volume in ml of thiosulphate poured during the blank test; - V1 the volume in ml of thiosulphate poured during the determination; N the normality of thiosulfate. The peroxide value measured for this methyl oleate is 17 meq O 2 / kg. 1.2 Method of metathesis In a jacketed reactor, introduce 3 g of Tonsil Supreme 112 FF (previously dried in an oven at 90 ° C). Vacuum then under argon and add 300g (0.86 mol) of 85% methyl oleate (Radia 7072, Oleon). Stir at 50 ° C for 2 hours.

Add 0.35 ml (4.3 × 10 -3 mmol, 0.0005 mol%) of 10 g / L solution of M71-SIPr in the peroxides index (meq 02 / kg) - degassed and distilled dichloromethane. Stop the reaction by adding a few drops of ethyl vinyl ether after 30 minutes. The reaction scheme is as follows: Me0 0 (a) Me0 (b) (c) 2 Me0 The reaction crude is analyzed by gas chromatography. The conversion of methyl oleate is 35%. The weight percentage of methyl octadec-9-enedioate (a) is 8%, the weight percentage of octadec-9-ene (b) is 6%, the weight percentage of methyl elaidate ( c) is 7%, the percentages by weight being given on the total weight of crude reaction. EXAMPLE 2 Metathesis Process According to the Invention Prior to Substrate a Ciras Acid a) Crossed Metathesis: Etholysis Reaction In an autoclave, introduce 3.52 g of 85% oleic acid (Nouracid HE 1885, Oleon) (either 10.6 mmol of oleic acid) and 105 mg of Tonsil Supreme 110 FF (previously dried in an oven at 90 ° C.). Vacuum and then under nitrogen. Stir and heat at 50 ° C for 2 hours. Add 100 μl (2.1 × 10 -3 mmol, 0.02 mol%) of M71-SIPr solution at 17.5 g / l in degassed and distilled dichloromethane. Perform two purges of the reactor with ethylene. Adjust the ethylene pressure to 2 bar. Stop the reaction by return under an air atmosphere and by adding a few drops of ethyl vinyl ether after 2 hours. The reaction scheme is as follows: (c) (d) (e) The crude reaction product is treated with (BF 3 .MeOH) in order to esterify the acid functions and is then analyzed by gas chromatography. The conversion of oleic acid is 91%. The weight percentage of octadec-9-diene acid (a) is 30.47%, the weight percentage of octadec-9-ene (b) is 13.76%, the weight percentage of acid is Elaidic (e) is 20.29%. The formation of 2.1% by weight of ethenolysis products (dec-9-enenoic acid (c) + 1-decene (d)) is also observed, the percentages by weight being given on the total weight of crude reaction product. b) Cross metathesis: butenolysis reaction In an autoclave, introduce 3.52 g of 85% oleic acid (Nouracid HE 1885, Oleon) (ie 10.6 mmol of oleic acid) and 35 mg of Tonsil Supreme 110 FF. (previously dried in an oven at 90 ° C). Vacuum and then under nitrogen. Stir and heat at 50 ° C for 15 hours. Add 50 ml (1.05 × 10 -3 mmol, 0.01 mol%) of M71-SIPr solution at 17.5 g / l in degassed and distilled dichloromethane. Perform two purges of the reactor with a mixture of 1-butene 15% in nitrogen. Adjust the pressure of the 1-butene mixture to 15% in nitrogen at 2 bar. Stop the reaction by return under an air atmosphere and by adding a few drops of ethyl vinyl ether after 2 hours. The reaction scheme is as follows: The crude reaction product is treated with (BF 3 .MeOH) in order to esterify the acid functions and is then analyzed by chromatography. gas phase. The conversion of oleic acid is 94%. The weight percentage of octadec-9-denedic acid (a) is 28.68%, the weight percentage of octadec-9-ene (b) is 11.51%, the weight percentage of acid is Elaidic (e) is 20.31%. The formation of 6.43% by weight of ethenolysis products (dec-9-enenoic acid (c) + 1-decene (d)) and butenolysis (dodec-9-ennoic acid (f) + dodec -1-ene (g)), the percentages by weight being given on the total weight of crude reaction. c) Homometathesis reaction In a 250 mL three-necked flask, introduce 89 g of 90% oleic acid (Technical Grade, Sigma-Aldrich) (ie 0.315 mol of oleic acid) and 890 mg of Tonsil Supreme 112 FF ( g) (previously dried in an oven at 90 ° C). Vacuum and then under nitrogen. Stir and heat at 50 ° C for 15 hours. Add 26 mg (0.031 mmol, 0.01 mol%) of M71-SIPr. Stir (mechanical stirring, pale half-moon, 330 rpm) then heat at 50 ° C for 24 hours. Stop the reaction by adding 20 mL of ethyl vinyl ether.

The reaction scheme is as follows: The crude reaction product is treated with (BF 3 .MeOH) in order to esterify the acid functions and is then analyzed by gas chromatography. The conversion of oleic acid is 91%. The weight percentage of octadec-9-denedic acid (a) is 34.82%, the weight percentage of octadec-9-ene (b) is 17.4%, the weight percentage of acid is elaïdique (e) is 18.81%, the percentages by weight being given on the total weight of crude reaction. EXAMPLE 3 Metathesis Process According to the Invention Prior to Substrate a Ciras Acid Ester With Pre-Heat Treatment In a 500 ml three-necked flask, 300 ml of 85% methyl oleate (Radia 7072, Oleon) was added. Stir at 185 ° C. for 2 hours at 0.1 mbar. Cool the medium under argon. Take the peroxide number (according to the method described in Example 1), IP = 1.58 meq 02 / kg. In a schlenk, introduce 80 mg of Tonsil Supreme 112 FF (previously dried in an oven at 90 ° C). Put under vacuum and then under argon and add 8 g (23 mmol) of methyl oleate previously treated. Stir at 50 ° C for 2 hours. Add 9.4 μl (1.2 × 10 -4 mmol, 0.0005 mol%) of M71-SIPr solution at 10 g / L in degassed and distilled dichloromethane. Stop the reaction by adding a few drops of ethyl vinyl ether after 15 minutes. The scheme of the reaction is identical to that indicated in point 1.2 of Example 1.

The crude reaction product is analyzed by gas chromatography. The conversion of methyl oleate is 92%. The weight percentage of methyl octadec-9-enedioate (a) is 25%, the weight percentage of octadec-9-ene (b) is 18%, the weight percentage of methyl elaidate ( c) is 34%, the percentages by weight being given on the total weight of crude reaction.

EXAMPLE 4 Comparative Test with Example 3 - Metathesis Method Having as Substrate a RASA Ester With Pre-Heat Treatment and With Prior Removal of the Sorbant In a 300 mL three-necked flask, add 300 mL of methyl oleate % (Radia 7072, Oleon). Stir at 185 ° C. for 2 hours at 0.1 mbar. Cool the medium under argon. Take the peroxide number (according to the method described in Example 1), IP = 0.25 meq 02 / kg. In a schlenk, introduce 80 mg of Tonsil Supreme 112 FF (previously dried in an oven at 90 ° C). Put under vacuum then under argon and add 8 g (23 mmol) of methyl oleate previously treated (by heat treatment). Stir at 50 ° C for 2 hours. Filter the mixture on sintered. Introduce the filtered methyl oleate into a schlenk. Put under vacuum and then under argon and add 9.4 μl (1.2 × 10 -4 mmol, 0.0005 mol%) of M71-SIPr solution at 10 g / l in degassed and distilled dichloromethane. Stop the reaction by adding a few drops of ethyl vinyl ether after 15 minutes.

The scheme of the reaction is identical to that indicated in point 1.2 of Example 1. The reaction crude is analyzed by gas chromatography. The conversion of methyl oleate is 0%. EXAMPLE 5 Comparative Test in Example 3 Metathesis Process Having as Substrate a RASA Ester with Pre-heat Treatment and Simultaneous Treatment of the Sorbant and the Catalyst In a 500 mL tricolor, introduce 300 ml of oleate 85% methyl (Radia 7072, Oleon). Stir at 185 ° C. for 2 hours at 0.1 mbar. Cool the medium under argon. Take the peroxide number (according to the method described in Example 1), IP = 0.16 meq 02 / kg. In a slurry, add 8 g (23 mmol) of previously treated methyl oleate (by heat treatment). Stir at 50 ° C. Add 80 mg of Tonsil Supreme 112 FF (previously dried in an oven at 90 ° C) and 9.4 μl (1.2.104 mmol, 0.0005% mol) of M71-SIPr solution at 10 g / L in the dichloromethane degassed and distilled. Stop the reaction by adding a few drops of ethyl vinyl ether after 15 min.

The scheme of the reaction is identical to that indicated in point 1.2 of Example 1. The reaction crude is analyzed by gas chromatography. The conversion of methyl oleate is 10%. The weight percentage of methyl octadec-9-enedioate (a) is 4%, the weight percentage of octadec-9-ene (b) is 3%, the weight percentage of methyl elaidate ( c) is 3%, the percentages by weight being given on the total weight of crude reaction.

EXAMPLE 6 Metathesis Process According to the Invention With a Substrate of a Rinca Acid Ester with Various Catalysts In a 300 ml three-necked flask, 300 ml of 85% methyl oleate (Radia 7072, Oleon) was added. Stir at 185 ° C. for 2 hours at 0.1 mbar. Cool the medium under argon. Take the peroxide number (according to the method described in Example 1), IP = 0.05 meq 02 / kg. In a schlenk, introduce 80 mg of Tonsil Supreme 112 FF (previously dried in an oven at 90 ° C). Put under vacuum then under argon and add 8 g (23 mmol) of methyl oleate previously treated (by heat treatment). Stir at 50 ° C for 2 hours. Add the catalyst (3.6 × 10 -4 mmol, 0.0015 mol%) in solution (10 g / l in degassed and distilled dichloromethane). Stop the reaction by adding a few drops of ethyl vinyl ether after one hour. The scheme of the reaction is identical to that indicated in point 1.2 of Example 1. The various catalysts tested are illustrated in FIG. 1. The crude reaction product is analyzed by gas chromatography.

The results are presented in FIG. 2. EXAMPLE 7 Metathesis Process According to the Invention With a Substrate for a RASA Ester with Various Sorbents In a 500 mL three-neck, 300 ml of 85% methyl oleate is introduced (Radia 7072, Oleon). Stir at 185 ° C. for 2 hours at 0.1 mbar. Cool the medium under argon. The peroxide number (according to the method described in Example 1) is measured: IP = 1.12 meq O 2 / kg. In a slide, add 80 mg of sorbent (previously dried in an oven at 90 ° C). Put under vacuum then under argon and add 8 g (23 mmol) of methyl oleate previously treated (by heat treatment). Stir at 50 ° C for 2 hours. Add 38 μl (4.8 × 10 -4 mmol, 0.002 mol%) of 10 g / L solution of M71-SIPr in degassed and distilled dichloromethane. Stop the reaction by adding a few drops of ethyl vinyl ether after 15 minutes. The crude reaction product is analyzed by gas chromatography. The pH of the various sorbents was measured according to the method proposed by the ISO 787-9 standard described below: In a beaker, weigh 4 g of sorbent. Add 48 g of methanol and 48 g of water. The mixture is stirred for 5 minutes with a magnetic stirrer (speed 600-1000 rpm). Stop agitation and measure the pH of the suspension after one minute using a pH meter. The results are shown in the table below: Table 1 Sorbant PH Fulcat 200 8.7 Fulcat 400 9.3 Pure Flo 80 6.6 Magnesol D60 9.8 Magnesol R60 9.0 Durcal 2 8.8 Trisyl 7.9 Fulcat 22B 2.4 Trisyl 300 2.9 Tonsil Supreme 110FF 3.2 Tonsil Supreme 112FF 2.8 The reaction scheme is identical to that indicated in point 1.2 of Example 1. The results of the synthesis are presented in the table below. Figure 3. These are given in methyl oleate conversion and percentages by weight of methyl octadec-9-enedioate, the weight percentage being given on the total weight of crude reaction. EXAMPLE 8 Metathesis Process According to the Invention Prior to Substrate a Ciras Acid with Various Sorbents In an autoclave, introduce 3.52 g of 85% oleic acid (Nouracid HE 1885, Oleon) (ie 10.6 mmol d oleic acid) and 105 mg of sorbents (previously dried in an oven at 90 ° C.). Vacuum and then under nitrogen. Stir and heat at 50 ° C for 2 hours. Add 100 μl (2.1 × 10 -3 mmol, 0.02 mol%) of M71-SIPr solution at 17.5 g / L in degassed and distilled dichloromethane. Perform two purges of the reactor with ethylene. Adjust the ethylene pressure to 2 bar. Stop the reaction by return under an air atmosphere and by adding a few drops of ethyl vinyl ether after 2 hours. The crude reaction product is treated with (BF 3 .MeOH) in order to esterify the acid functions and is then analyzed by gas chromatography.

The results of the synthesis are presented in FIG. 4. These are given in oleic acid conversion rate and in percentages by weight of octadecalidene acid, the percentages by weight (or mass) being given on the total weight of crude reaction.

EXAMPLE 9 Metathesis Process According to the Invention Prior to Substrate Different Ciras Acid Esters The procedure of Example 3 is reproduced with as substrates, methyl esters of canola and soya.

The composition of these methyl esters is analyzed by gas chromatography, using a Shimadzu GO-2014 apparatus equipped with an Agilent J & VV GO column, DB-23, 60 m × 0.250 mm × 0.25 a FID detector. The carrier gas is helium. The analysis parameters are as follows: column flow rate: 0.82 mL / min, injector temperature: 270 ° C, detector temperature: 280 ° C, temperature ramp: 80 ° C for 2 minutes, 4 ° C / min up to 240 ° C and hold 2 minutes.

The results are given as percentage of area in the following Tables 2 and 3. Table 2: Methyl esters of soybeans before reaction% methyl palmitate 10.5 methyl stearate 4.1 24.6 methyl oleate methyl linoleate 53.3 methyl linolenate 7.1 0.4 methyl arachidate Table 3: Methyl esters of canola before reaction% methyl palmitate 4,4 methyl stearate 9,6 methyl oleate 58,4 methyl linoleate 21,0 methyl linolenate 1,3 methyl arachidate 5,3 At the end of the reaction, carried out according to the procedure described in Example 3, the composition of the methyl esters in the crude reaction is analyzed by gas chromatography under conditions identical to those presented above. The results are given as percentage of area in the following Tables 4 and 5.

Table 4: Methyl soy esters after reaction% methyl palmitate 11.4 methyl stearate 4.4 methyl oleate 17.4 methyl linoleate 9.1 methyl linolenate 0.5 methyl arachidate 1.1 Table 5: Methyl ester of canola after reaction% methyl palmitate 4.7 methyl stearate 10.0 methyl oleate 46.9 methyl linoleate 11.5 methyl linolenate 1.6 methyl arachidate 4.7 The margin of error of this measurement method is 1% on the percentage of area values. Absorbent Substrate Catalytic Load (ppm / db) GC Conversion (° / 0) Canola Methyl Esters 1wt% Tonsil Supreme 112FF * 5 26 Methyl Ester Soybeans 1wt% Tonsil Supreme 112FF * 5 68 c / owt: weight percent by weight of products to be treated.

Claims (16)

REVENDICATIONS1. A method of metathesis comprising contacting at least one fatty acid or fatty acid ester with a metathesis catalyst, said fatty acid or fatty acid ester having at least one unsaturation, wherein the fatty acid or The ester is treated with a sorbent before it is brought into contact with the metathesis catalyst, the sorbent being maintained in the reaction medium when the fatty acid or the ester is brought into contact with the metathesis catalyst. 2. Process according to claim 1, in which the fatty acid or the fatty acid ester has the following formula (I): n n ORi (I) in which: n is an integer between 1 and 21; , R1 is a hydrogen atom in the case of a fatty acid or a linear or branched alkyl chain of 1 to 10 carbon atoms in the case of a fatty acid ester, - R2 is a hydrogen atom; hydrogen or a linear or branched alkyl or alkenyl chain of 1 to 20 carbon atoms, optionally substituted by one or more hydroxyl groups, carboxyl and / or ester (s). 3. Method according to claim 1 or 2, wherein: n is an integer between 5 and 13, R2 is a linear or branched alkyl chain of 2 to 10 carbon atoms, optionally substituted by a hydroxyl group. 4. Process according to any one of claims 1 to 3, wherein the fatty acid of the fatty acid ester is a monounsaturated fatty acid selected from myristoleic acid, palmitoleic acid, oleic acid, elaidic acid, ricinoleic acid, gadoleic acid and or erucic. 5. Process according to any one of claims 1 to 4, wherein the fatty acid is oleic acid and the ester is methyl oleate. 6. Process according to any one of claims 1 to 5, wherein the treatment with the sorbent is carried out with a quantity of sorbent equal to 0.01 to 10% by weight relative to the total weight of product to be treated, comprising the fatty acid or the fatty acid ester. The process according to any of claims 1 to 6, wherein the treatment with the sorbent is carried out at a temperature of 20 to 80 ° C for at least one hour. 28 8. Process according to any one of claims 1 to 7, wherein the metathesis catalyst is a ruthenium catalyst. 9. Process according to claim 8, in which the catalyst has the following formula (II): in which: R 3 is an alkyl chain of 1 to 5 carbon atoms, optionally branched, R 4 is a hydrogen atom, a alkyl chain of 1 to 3 carbon atoms or an alkyl ether with an alkyl chain of 1 to 10 carbon atoms, - R5 is a hydrogen atom or a group -NH-CO-R6, wherein R6 is an oxyalkyl chain from 1 to 15 carbon atoms, optionally branched or an alkyl chain of 1 to 5 carbon atoms, optionally substituted with halogen atoms. The process according to claim 9, wherein the catalyst is selected from the group consisting of M71-S1Pr, M73-S1Pr, M73-like (tBu), M73-like (C12), Hoveyda-Grubbs 2 and Hoveyda-Grubbs 2 -SiPr. 11. Process according to any one of claims 1 to 10, wherein the sorbent comprises at least 50% of silica and has a pH of less than 8. The process according to claim 11, wherein when a fatty acid is contacted with a metathesis catalyst, the sorbent has a pH of less than or equal to 7.5 and comprises at least 50% by weight of SiO 2 and at least 5% by weight of Al 2 O 3, the percentages by weight being given on the total weight of sorbent. The process according to claim 11, wherein when a fatty acid ester is contacted with a metathesis catalyst, the sorbent has a pH of less than 6 and has at least 65% by weight SiO 2, the percentage by weight given on the total weight of sorbent. The process according to any one of claims 1 to 11, 13, wherein when a fatty acid ester is contacted with a metathesis catalyst, said fatty acid ester is heat-treated at a temperature of at least 150 ° C for at least one hour. 15. The method of claim 14, wherein the treatment with the sorbent is carried out concomitantly with the heat treatment. The process according to any of claims 1 to 15, wherein the metathesis reaction is a homometathesis reaction of fatty acids or fatty acid esters.