Process for the Oxidation of Alcohol And/Or Aldehyde

(19) TZZ ¥Z¥_T

(11) EP 2 307 395 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.: of the grant of the patent: C07C 51/285 (2006.01) C07C 57/145 (2006.01) 11.09.2013 Bulletin 2013/37 C07C 51/56 (2006.01) C07D 307/58 (2006.01) C07D 307/68 (2006.01) (21) Application number: 09780732.5 (86) International application number: (22) Date of filing: 16.07.2009 PCT/EP2009/059180

(87) International publication number: WO 2010/007139 (21.01.2010 Gazette 2010/03)

(54) PROCESS FOR THE OXIDATION OF ALCOHOL AND/OR ALDEHYDE GROUPS VERFAHREN ZUR OXIDIERUNG VON ALKOHOL- UND/ODER ALDEHYD-GRUPPEN PROCÉDÉ POUR L’OXYDATION D’UN ALCOOL ET/OU DE GROUPES D’ALDÉHYDES

(84) Designated Contracting States: (56) References cited: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR • SALADINO R ET AL: "A new and efficient HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL synthesis of ortho- and para-benzoquinones of PT RO SE SI SK SM TR cardanol derivatives by the catalytic system MeReO3-H2O2" J.CHEM.SOC.,PERKIN TRANS. (30) Priority: 18.07.2008 EP 08160771 1, 2000, pages 581-586, XP002506581 cited in the application (43) Date of publication of application: • SALADINO R ET AL: "Selective oxidation of 13.04.2011 Bulletin 2011/15 phenol and anisole derivatives to quinones with hydrogen peroxide and polymer-supported (73) Proprietor: SOLVAY SA methylrhenium trioxide systems" 1120 Bruxelles (BE) TETRAHEDRON, ELSEVIER SCIENCE PUBLISHERS, AMSTERDAM, NL, vol. 58, no. 42, (72) Inventors: 14 October 2002 (2002-10-14), pages 8493-8500, • SALADINO, Raffaele XP004388260 ISSN: 0040-4020 I-00175 Rome (IT) • CRESTINI ET AL: "Immobilized methyltrioxo • FARINA, Angela rhenium (MTO)/H2O2 systems for the oxidation I-00142 Rome (IT) of lignin and lignin model compounds" BIOORGANIC & MEDICINAL CHEMISTRY, (74) Representative: Vande Gucht, Anne et al ELSEVIER SCIENCE LTD, GB, vol. 14, no. 15, 1 Solvay S.A. August 2006 (2006-08-01), pages 5292-5302, Département de la Propriété Industrielle XP005508668 ISSN: 0968-0896 Rue de Ransbeek, 310 • HERRMANN W A ET AL: "The selective catalytic 1120 Bruxelles (BE) oxidation of terminal alcohols: a novel four- component system with MTO as catalyst" JOURNAL OF ORGANOMETALLIC CHEMISTRY, ELSEVIER-SEQUOIA S.A. LAUSANNE, CH, vol. 579, no. 1-2, 5 May 1999 (1999-05-05), pages 404-407, XP004170591 ISSN: 0022-328X

Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 2 307 395 B1

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Description

[0001] The present application claims the benefit of the European application no. 08160771.5 filed on July 18, 2009. [0002] The present invention relates to a process for the oxidation of alcohol and/or aldehyde groups. In particular, it 5 relates to an oxidizing process based on peroxo compounds, heterogeneous rhenium based catalysts and co- catalysts. [0003] The use of rhenium based catalysts to activate hydrogen peroxide for the oxidation of various functional groups, and especially alcohol and/or aldehyde groups, is known in the prior art. The catalytic cycle of methyltrioxorhenium is for example disclosed in W.A. Hermann et al., Chemische Berichte, 126, 4 (1993) and in J.H. Espenson et al., J. Am. Chem. Soc., 117, 9243 (1995). 10 [0004] Applications of rhenium based catalysts are disclosed, for example, in the international patent application WO 00/61639 which relates to oxidized starch obtained by oxidizing native starch in an acidic solvent in the presence of hydrogen peroxide, rhenium (VI) or (VII) oxide, methyltrioxorhenium (MTO) or alkyl rhenium oxide in homogeneous phase, a ditertiary alkyl nitroxyl and hydrogen halide. [0005] Another use is disclosed in the US patent application 2006/0070953 A1 which relates to the catalytic oxidation 15 of tyrosol into hydroxytyrosol in the presence of hydrogen peroxide, a protic solvent, and methyltrioxorhenium (MTO), preferably in homogeneous phase. [0006] A third example is the use of hydrogen peroxide and of methyltrioxorhenium (MTO) in homogeneous phase for the synthesis of ortho- and para-benzoquinones of cardanol derivatives, disclosed in an article from R. Saladino et al., J. Chem. Soc., Perkin Trans. 1, 581-586 (2000). The oxidation reaction of various benzoquinones of cardanol 20 derivatives was tested in various solvents selected from acetic acid, ethanol, and a mixture ethanol - tetrafluoroboric acid (HBF4) in excess. Depending on the derivatives tested, the best results were obtained using acetic acid or the mixture ethanol - HBF4. [0007] These processes have the disadvantage to be conducted in homogeneous phase, which do not allow an easy recovery of the catalyst. 25 [0008] It is also known to proceed to the oxidation of olefins into epoxides in heterogeneous phase, using polymer- supported rhenium based catalysts. Such polymer-supported catalysts are disclosed, for example, in an article from R. Saladino et al., J. Org. Chem., 67, 1323-1332 (2002). The heterogeneization of rhenium based catalysts by using a polymeric support allows an easier recovery of the catalyst and, sometimes, may improve the reactivity. [0009] Nevertheless, there is still a need for improved processes for the oxidation of alcohol and/or aldehyde groups, 30 leading to high yields, an easy recovery of the catalyst, and a good stability and reuse of the catalyst. [0010] The purpose of the present invention is to provide a new process for the oxidation of alcohol and/or aldehyde groups having improved properties compared to the processes of the prior art. [0011] The present invention therefore relates to a process for the oxidation of alcohol and/or aldehyde groups comprising the treatment of said alcohol and/or aldehyde groups with at least one oxidizing agent chosen from peroxo 35 compounds in the presence of at least one solvent, of at least one heterogeneous rhenium based catalyst, and of a co-

catalyst selected from the group consisting of HBF 4 and salts thereof. [0012] According to the present invention, it has been surprisingly found that, when alcohol and/or aldehyde groups are oxidized with a peroxo compound in the presence of a heterogeneous rhenium based catalyst and a co-catalyst such as HBF4 or a salt thereof, the stability and reuse of the catalyst is improved. Furthermore, according to the process 40 of the invention, it is easier to recover the catalyst from the reaction mixture compared to reactions conducted in homogeneous phase, the selectivity of the reaction can be modified, and the amount of active rhenium compound added to the reaction mixture can be drastically reduced. This process is thus especially advantageous compared to the processes of the prior art. [0013] By alcohol and aldehyde groups, it is intended primary and secondary alcohol and aldehyde groups. According 45 to the present invention, such groups may be present on any substrates. For example, the compounds may be linear, branched or cyclic alkyl alcohols or aldehydes, as well as high and low molecular weight carbohydrates and carbohydrate derivatives. In a preferred embodiment, the oxidation process of the present invention is applied to at least one compound selected from the group consisting of linear, branched or cyclic alkyl alcohols and linear, branched or cyclic alkyl aldehydes, especially to carbohydrates and carbohydrate derivatives, for example to high and low molecular weight carbo- 50 hydrates and carbohydrate derivatives, advantageously to low molecular weight carbohydrates and low molecular weight carbohydrate derivatives. High molecular weight carbohydrates, also called polysaccharides, are composed of monosaccharide units, usually in an amount of more than 10 to 10000 units, preferably from 25 to 5000 units, for example from 50 to 500 units, a few of them being made up of considerably more units. High molecular weight carbohydrates include, for example, starch, cellulose, hemicellulose and chitin. Cellulose has an average molecular mass equivalent 55 to about 5000 units. Low molecular weight carbohydrates include mono and oligosaccharides, composed of 1 to 10 monosaccharide residues, preferably mono- and disaccharides. The term "monosaccharide" denotes a single sugar unit without glycosidic connection to other such units. Chemically, monosaccharides are either polyhydroxyaldehydes or aldoses, such as glucose, or polyhydroxyketones or ketoses, such as fructose. Depending on their number of carbon

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atoms, monosaccharides are classified in hexoses (6C) and pentoses (5C). Monosaccharides with fewer (trioses, tet- roses) or more carbon atoms (heptoses, octoses) are rare. Preferred low molecular weight carbohydrates according to the present invention are monosaccharides, especially pentoses and hexoses. Carbohydrate derivatives may be glyco- sides, alditols, furan derivatives, such as furfural and 5-hydroxymethylfurfural (HMF), etc. Some general information 5 about carbohydrates and carbohydrate derivatives may for example be found in online Ullmann’s Encyclopedia of In- dustrial Chemistry, DOI 10.100214356007.a05_079, "Carbohydrates" (2003). [0014] One of the essential features of the present invention resides in the nature of the heterogeneous catalyst. The term "homogeneous catalyst" means that the catalyst and reactants or their solution form a common physical phase, then the reaction is called homogeneously catalyzed. The term "heterogeneous catalyst" is used when the system is 10 such that catalyst and reactants form separate physical states. The heterogeneous catalysts may be unsupported (bulk) catalysts insoluble in the reactant mixture, or supported catalysts. [0015] The heterogeneous catalyst of the invention may be chosen from insoluble unsupported rhenium based catalysts and supported rhenium based catalysts, preferably from supported rhenium based catalysts. Supported rhenium based catalysts usually comprise an inert polymeric matrix (support) and a rhenium compound (active part of the catalyst). 15 [0016] The rhenium compound according to the process of the invention is usually selected from rhenium (VI) oxide (ReO3), rhenium (VII) oxide (R2O7), methyl rhenium trioxide (CH3ReO3), a C2 to C20 alkyl rhenium oxide, a C3 to C10 cycloalkyl rhenium oxide. The rhenium compound of the invention is preferably methyltrioxorhenium (MTO). [0017] The inert polymeric matrix of the catalyst according to the invention may be selected from poly (4- vinylpyridine) (PVP) , poly (4- vinylpyridine N- oxide) (PVPN) , polystyrene (PS) and mixtures thereof. Such catalyst supports are 20 disclosed, for example, in an article from R. Saladino et al., J. Chem. Soc., Perkin Trans. 1, 581- 5586 (2000) . It has to be noted that the supports may differ by their crosslinking with divinylbenzene. The crosslinking of PVP, PVPN or PS with divinylbenzene is usually of from 1 to 50%, preferably of from 2 to 25%. [0018] In the process of the invention, the amount of rhenium compound by weight of the support, expressed as the loading factor (mmol/g), is usually at least 0,1, in particular at least 0,3, especially at least 0,5, values of at least 1 giv ing 25 good results. The amount of rhenium compound by weight of the support, expressed as the loading factor (mmol/g), is in general of at most 10, in many cases at most 5, preferably at most 3. Suitable ranges for the loading factor of the catalyst are from 0,1 to 10, preferably from 0,5 to 5, more preferably from 1 to 3. [0019] Another essential feature of the present invention is the presence of a peroxo compound which may be selected from hydrogen peroxide or hydrogen peroxide sources such as alkali or alkaline earth metal percarbonates, for example 30 sodium percarbonate; alkali or alkaline earth metal perborates, such as sodium perborate; alkaline earth metal or metal peroxides, such as calcium peroxide, magnesium peroxide, zinc peroxide and mixed calcium / magnesium peroxide; and their mixtures. The peroxo compound is preferably an aqueous hydrogen peroxide solution. Such aqueous hydrogen peroxide solution usually has a concentration of from 5 to 70 weight %, preferably of from 20 to 50 weight %, in general about 35 weight %. 35 [0020] A third essential feature of the present invention resides in the presence of at least one solvent. In the invention, the solvent may be selected from water; carboxylic acids such as acetic acid; organic solvents such as methanol, ethanol, propanol, acetonitrile, dichloromethane; ionic liquids such as 1- butyl- 3- methylimidazolium tetrafluoroborate ([BMIM] [BF4] ) ; and mixtures thereof. According to the present invention, the solvent is preferably selected from protic solvents such as water; acetic acid; C1 to C3 alcohols, especially methanol or ethanol; and mixtures thereof. 40 [0021] In the process of the invention, the amount of heterogeneous rhenium based catalyst is generally of at least 0.1 % by weight of the compound to be oxidized, preferably at least 0,5%, more preferably at least 1%, in particular at least 2%. The amount of heterogeneous rhenium based catalyst used in the process of the invention is in general of at most 15% by weight of the compound to be oxidized, especially at most 12%, particularly at most 10%, especially at most 7%. In most cases, the amount of heterogeneous rhenium based catalyst by weight of the compound to be oxidized 45 is of from 0,1 to 10 %, ranges of from 1 to 7% giving good results, for example around 5%. [0022] A fourth essential feature of the present invention is the presence of a co-catalyst. Said co-catalyst may be

selected from HBF4, salts thereof and mixtures thereof. According to the process of the invention, the salt of HBF4 is preferably selected from the group consisting of the sodium salt, ammonium salt, lithium salt and mixtures thereof. The co-catalyst is usually present in an amount of at least 0.1 % by volume of the solvent, preferably at least 0.5% and of at 50 most 10 %, especially at most 5 %. An amount of about 1 % of co- catalyst by weight of compound to be oxidized is for example suitable. In the process of the present invention, said co- catalyst is preferably HBF4. [0023] The amount of peroxo compound used in the present invention is usually of at least 1 equivalent of the optionally substituted furfural, in particular at least 2 equivalents, values of at least 4 equivalents and more specifically at least 5 equivalents giving good results. The amount of peroxo compound is in general of at most 20 equivalents of the optionally 55 substituted furfural, in many cases at most 15 equivalents, values of at most 10 equivalents being common. [0024] The oxidation process according to the present invention is usually carried out at a temperature of at least 5°C, preferably at least 10°C, more preferably at least 15°C. The process of the invention is in general carried out at a temperature of at most 100°C, particularly at most 75°C, especially at most 50°C, with particular preference at most

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30°C. The process is advantageously carried out at a temperature from 5 to 50°C, preferably from 10 to 45°C, especially from 15 to 30°C, advantageously around room temperature, for example around 20°C. [0025] The process of the invention may be carried out at sub-atmospheric pressures, atmospheric pressure, or elevated pressure, preferably at atmospheric pressure. 5 [0026] The process of the invention is usually carried out during from 1 to 100 hours, preferably from 12 to 72 hours, more preferably from 24 to 48 hours. [0027] The oxidation process of the invention may be carried out in any suitable reactor. An example of a suitable reactor is a plug-flow reactor equipped with a catalytic bed. Another example is any suitable reactor wherein the catalyst is maintained in suspension. 10 [0028] The process of this invention may be carried out in a batch, continuous, or semi- continuous manner, preferably as a continuous process. [0029] In a preferred embodiment, the process of the invention may be applied to carbohydrates, especially to low molecular weight carbohydrates and derivatives thereof. The invention may for example be applied to low molecular weight carbohydrate derivatives such as furfural, 5-hydroxymethyl furfural and mixtures thereof. 15 [0030] Furfural, or 2- furancarbonal or 2- furaldehyde, is a well known chemical product produced by acid- catalyzed hydrolysis of hemicellulose, especially from hemicellulose- rich agricultural wastes, the resulting monosaccharides being then dehydrated to furfural. 5- hydroxymethyl furfural (HMF) is produced according to a similar process applied to cellulose or starch. The hexoses resulting from the acid- catalyzed hydrolysis of cellulose or starch can be readily transformed into HMF by acid- induced elimination of three moles of water. General information on these compounds 20 is found in online Ullmann’s Encyclopedia of Industrial Chemistry, DOI 10.1002/14356007.a12_119.pub2, "Furfural and Derivatives" (2007) . [0031] If the process of the invention is applied to furfural and/or to 5-hydroxymethyl furfural (HMF), it is possible to prepare various monocarboxylic acids such as glycolic acid, furoic acid, and 5-hydroxy methyl furoic acid, as well as various dicarboxylic acids such as maleic acid, succinic acid, fumaric acid, and malic acid. In a particularly preferred 25 embodiment, the process of the present invention is used for the preparation of maleic acid with high yields. [0032] The present invention thus also relates to a process for the preparation of maleic acid as well as to a process for the preparation of maleic anhydride, comprising the preparation of maleic acid according to the process of the present invention applied to carbohydrate derivatives selected from furfural, 5- hydroxymethyl furfural and mixtures thereof, and a further dehydration step. Such dehydration step can be performed according to any method known in the prior art. For 30 general information, see for example online Ullmann’s Encyclopedia of Industrial Chemistry, DOI 10.1002/14356007.a16_053, "Maleic and Fumaric Acids" (2000). The maleic acid dehydration can for example be performed by heating maleic acid up to 160°C while eliminating the water. This reaction is quantitative. [0033] If maleic acid is not very important economically, maleic anhydride is a commodity chemical having considerable industrial importance. Indeed, maleic anhydride can be used for both polycondensation and polyaddition. Polyester and 35 alkyd resins, lacquers, plasticizers, copolymers, and lubricants are the most important technical end products. Polyester and alkyd resins are especially used in the production of fiberglass reinforced plastics, in the construction and electrical industries, and in pipeline and marine construction. Smaller amounts of maleic anhydride are used in the production of pesticides and growth inhibitors, or of surfactants. More information about maleic acid and maleic anhydride is found, for example, in online Ullmann’s Encyclopedia of Industrial Chemistry, DOI 10.1002/14356007.a16_053, "Maleic and 40 Fumaric Acids" (2000). [0034] The industrial preparation process of maleic anhydride is usually based on the catalytic oxidation of suitable

hydrocarbons in the gas phase, especially benzene and, more recently, C4 hydrocarbons. Maleic anhydride can also be obtained by dehydration from maleic acid but this is not the preferred industrial manufacturing process. [0035] Thus, a particular advantage of the present invention applied to the oxidation of furfural and/or 5- hydroxymethyl 45 furfural is the possibility to prepare specialty and commodity chemicals starting from a renewable feedstock as furfural and 5- hydroxymethyl furfural (HMF) are biomass based products, produced from carbohydrate sources and especially from hemicellulose and cellulose wastes such as agricultural and forestry wastes, which are interesting alternative to petrochemical products. This advantage is particularly important in the framework of the responsible care and the sustainable development. 50 [0036] The present invention is further illustrated below without limiting the scope thereto. [0037] Comparative examples 1 to 3: Oxidation of 5-hydroxymethyl furfural in homogeneous conditions [0038] 5- hydroxymethyl furfural (HMF) was oxidized with 10 equivalents of hydrogen peroxide (35% by weight in aqueous solution) in the presence of methyltrioxorhenium in an amount of 5% by weight of HMF, at a temperature about 20°C during 24 to 48 hours, until the conversion of furfural was complete, in various solvents. 55 [0039] The results of the reactions are summarized in Table 1 below.

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Table 1 Example n° (solvent) Comp. Ex. 1 (acetic Comp. Ex. 2 Comp. Ex. 3

5 acid) (ethanol) (dichloromethane / acetonitrile 1:1 v/v) Resulting products Glycolic acid 55 23 19 (%) Maleic acid 14 29 20

10 Succinic acid 1 16 35 Fumaric acid 1 0 8 Malic acid 29 11 0 5-hydroxymethyl-2- 0610 15 furoic acid

[0040] Comparative examples 4 to 9: Oxidation of furfural in homogeneous conditions Furfural was oxidized with 9 equivalents of hydrogen peroxide (35% by weight in aqueous solution) in the presence of methyltrioxorhenium in an 20 amount of 5% by weight of furfural, at a temperature about 20°C during 24 to 48 hours, until the conversion of furfural was complete in various solvents and in the optional presence of HBF 4 as co-catalyst. [0041] The results of the reactions are summarized in Table 2 below.

Table 2 Example n° (solvent + optional co-catalyst) 25 Comp. Ex. Comp. Ex. Comp.Ex. 6 Comp. Ex. 7 Comp. Ex. Comp. Ex. 9 4 (H2O) 5 (acetic (ethanol) (ethanol + 8 (CH2Cl2 / ([BMIM] acid) 1% v/v CH3CN 1:1 [BF4]) HBF4) v/v) 30 Resulting Maleic acid 44 81 49 60 66 66 products Succinic- 26 0.5 8 1 3 12 (%) acid Malic acid656480 35 Fumaric 25 2 3 4 13 acid 2-furoic 12 4 20 13 10 7 acid 40 [0042] Comparative examples 10 to 12 and examples 13 to 14: Oxidation of furfural in heterogeneous conditions (catalyst supported on poly (4- vinylpyridine) ) [0043] Furfural was oxidized with 5 equivalents of hydrogen peroxide (35% by weight in aqueous solution) in the presence of 5% by weight of methyltrioxorhenium supported onto poly (4- vinylpyridine) with a loading factor of 2 mmol/g, 45 at a temperature about 20°C during 24 hours, in various solvents and in the optional presence of HBF 4 as co- catalyst. [0044] The results of the reactions are summarized in Table 3 below.

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Table 3 Example n° (solvent + optional co-catalyst)

Comp. Ex. 10 Comp. Ex. 11 Comp.Ex. 12 Ex. 13 (H 2O + Ex. 14 (EtOH + (H2O) (acetic acid) (H2O+ acetic 1% v/v HBF4) 1% v/v HBF4) 5 acid (50:50 v/v) Resulting Maleic acid 5 51 40 52 62 products (%) Succinic acid 5 0 6 5 0 10 Malic acid0500 0 Fumaric acid3433 3 2-furoic acid 72 7 41 33 19

15 [0045] Comparative example 15 and example 16: Stability and reuse of the catalyst of examples 11 and 14 [0046] Examples 11 and 14 were reproduced respectively 4 and 3 times, reusing the same catalyst. [0047] The results are summarized in Table 4 below.

20 Table 4 Comp. Ex. 15 (acetic acid) Ex. 16 (EtOH + 1% v/v HBF 4) Yields (%) Yields (%) Maleic acid 2-furoic acid Maleic acid 2-furoic acid Run 1 51 7 60 30

25 Run 2 10 42 58 40 Run 3 20 33 32 44 Run 4 26 11 Not measured Not measured

30 [0048] Comparative examples 17 and 19 and example 18: Oxidation of furfural in heterogeneous conditions (catalyst supported on polystyrene) [0049] Furfural was oxidized with 9 equivalents of hydrogen peroxide (35% by weight in aqueous solution) in the presence of 5% by weight of methyltrioxorhenium supported onto polystyrene with a loading factor of 2 mmol/g, at a temperature about 20°C during 48 to 72 hours, until the conversion of furfural was complete, in various solvents and in 35 the optional presence of HBF4 as co-catalyst. [0050] The results of the reactions are summarized in Table 5 below.

Table 5 Example n° (solvent + optional co-catalyst

40 Comp. Ex. 17 (acetic Ex. 18 (EtOH + 1% v/v Comp.Ex. 19 (CH 2Cl2 acid) HBF4) / CH3CN 1:1) Resulting products Maleic acid 84 84 44 (%) Succinic acid 3 5 10 45 Malic acid 9 0 11 Fumaric acid 1 0 2 2-furoic acid 0 8 10

50 005

[0051] Comparative examples 20 to 21: Stability and reuse of the catalyst of examples 17 and 19 55 [0052] Examples 17 and 19 were reproduced 5 times, reusing the same catalyst. The only difference is that runs 3, 4 and 5 of example 21 were conducted at 40°C rather than 20°C. [0053] The results are summarized in Table 6 below.

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Table 6 Comp. Ex. 20 (acetic acid) Yields (%) Comp. Ex. 21 (CH 2Cl2 / CH 3CN 1:1) Yields (%) Maleic acid Malic acid Maleic acid Malic acid 5 Run 1 84 8 44 11 Run 2 31 20 54 9 Run 3 44 23 29 17 Run 4 40 20 35 8 10 Run 5 32 15 42 19

[0054] Comparative examples 22 to 24 and example 25: Oxidation of furfural in heterogeneous conditions (catalyst supported on polystyrene) 15 [0055] Furfural was oxidized with 5 equivalents of hydrogen peroxide (35% by weight in aqueous solution) in the presence of 5% by weight of methyltrioxorhenium supported onto polystyrene, at a temperature about 20°C during 24 hours, in various solvents and in the optional presence of HBF 4 as co-catalyst. [0056] The results of the reactions are summarized in Table 7 below.

20 Table 7 Example n° (solvent + optional co-catalyst

Comp.Ex. 22 (No Comp. Ex. 23 Comp. Ex. 24 Ex. 25 (H 2O + 1% catalyst) (H2O) (H2O + acetic v/v HBF4) acid 50:50 v/v) 25 Resulting Maleic acid 2 82 76 71 products (%) Succinic acid 0 0 6 17 2-furoic acid 4 18 3 4

30 [0057] Comparative examples 26 to 27 and example 28: Stability and reuse of the catalyst of examples 23, 24 and 25 [0058] Examples 23, 24 and 25 were reproduced respectively 4, 3 and 7 times, reusing the same catalyst. [0059] The results are summarized in Table 8 below.

35 Table 8 Comp. Ex. 26 (H 2O) Yields Comp. Ex. 27 (H 2O + acetic Ex. 28 (H2O + 1% v/v HBF4) Yields (%) (%) acid) Yields (%) Maleic acid 2-furoic acid Maleic acid 2- furoic acid Maleic acid Succin ic 2-furoic acid acid 40 Run 1821876 3 7117 4 Run 2 8 63 36 49 90 10 0 Run 3 6 63 2 80 89 6 5 Run 4 1 87 Not Not 81 10 9 45 measured measured Run 5 Not Not Not Not 82 10 7 measured measured measured measured Run 6 Not Not Not Not 66 27 3 50 measured measured measured measured Run 7 Not Not Not Not 77 12 10 measured measured measured measured

55 [0060] These examples show that it is possible to prepare various specialty and commodity chemicals, especially maleic acid, according to the process of the present invention. These examples also show that it is possible, using an heterogeneous supported rhenium based catalyst and a co-catalyst according to the invention, to improve the stability

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and reuse of the catalyst. [0061] Furthermore, depending on the reaction conditions, a yield conversion of up to 85% by weight of maleic acid can be obtained. This maleic acid can then be subsequently dehydrated to yield maleic anhydride with a quantitative yield, by a thermal treatment around 160°C while eliminating the water. The overall yield to produce maleic anhydride 5 from furfural and/or 5- hydroxymethyl furfural can thus be higher than 80%, depending on the reaction conditions. This yield is higher than the yield usually reached when maleic anhydride is prepared according to usual manufacturing processes, from benzene or butane (respectively about 70 and 60% yield) .

10 Claims

1. Process for the oxidation of alkyl alcohol and/or aldehyde groups of at least one compound selected from the group consisting of linear, branched or cyclic alkyl alcohols and linear, branched or cyclic alkyl aldehydes, said process comprising the treatment of said alcohol and/or aldehyde groups with at least one oxidizing agent chosen from 15 peroxo compounds in the presence of at least one solvent, of at least one heterogeneous rhenium based catalyst, and of a co-catalyst selected from the group consisting of HBF4 and salts thereof

2. Process according to claim 1, wherein the peroxo compound is selected from hydrogen peroxide or hydrogen peroxide sources selected from alkali or alkaline earth metal percarbonates, alkali or alkaline earth metal perborates, 20 and alkaline earth metal or metal peroxides, preferably an aqueous hydrogen peroxide solution.

3. Process according to claim 1 or 2, wherein the heterogeneous rhenium based catalyst is a supported rhenium based catalyst comprising an inert polymeric matrix and a rhenium compound.

25 4. Process according to claim 3, wherein the inert polymeric matrix is selected from poly(4-vinylpyridine), poly(4- vinylpyridine N-oxide) and polystyrene.

5. Process according to claim 3 or 4, wherein the rhenium compound is selected from rhenium (VI) oxide, rhenium

(VII) oxide, methyltrioxorhenium, a C 2 to C 20 alkyl rhenium oxide, and a C 3 to C 10 cycloalkyl rhenium oxide, preferably 30 methyltrioxorhenium.

6. Process according to any one of claims 1 to 5, wherein the solvent is selected from water, carboxylic acids, organic solvents, ionic liquids, and mixtures thereof, preferably a protic solvent selected from water, acetic acid, C1 to C3 alcohols, and mixtures thereof 35

7. Process according to any one of claims 1 to 6, wherein the salt of HBF 4 is selected from the group consisting of the sodium salt, ammonium salt, lithium salt and mixtures thereof

8. Process according to any one of claims 1 to 7, wherein the oxidation is conducted at a temperature of from 5 to 40 50°C, preferably from 10 to 45°C, more preferably at room temperature, during from 12 to 72 hours, preferably during from 24 to 48 hours.

9. Process according to any one of claims 1 to 8, wherein the heterogeneous rhenium based catalyst is used in an amount of from 0.1 to 10% by weight of the compound to be oxidized, preferably of from 1 to 7%. 45 10. Process according to any one of claims 3 to 9, wherein the supported rhenium based catalyst has a loading factor, defined as mmol of rhenium compound per g of support, of from 0.1 to 10, preferably from 0.5 to 5, more preferably from 1 to 3

50 11. Process according to any one of claims 1 to 10, wherein the oxidizing agent is used in an amount of from 1 to 20 equivalents of the compound to be oxidized, preferably of from 2 to 15, especially of from 4 to 10.

12. Process according to any one of claims 1 to 11 applied to at least one compound selected from the group consisting of linear, branched or cyclic alkyl alcohols and linear, branched or cyclic alkyl aldehydes, preferably to carbohydrates 55 and carbohydrate derivatives, especially to low molecular weight carbohydrates and low molecular weight carbohydrate derivatives.

13. Process according to claim 12, wherein the low molecular weight carbohydrates are selected from furfural, 5-

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hydroxymethyl furfural and mixtures thereof.

14. Process according to claim 13, for the preparation of maleic acid.

5 15. Process according to claim 14 comprising a further dehydration step of the maleic acid into maleic anhydride.

Patentansprüche

10 1. Verfahren zur Oxidation von Alkylalkohol- und/ oder Alkylaldehydgruppen von mindestens einer Verbindung aus der Gruppe bestehend aus linearen, verzweigten oder cyclischen Alkylalkoholen und linearen, verzweigten oder cyclischen Alkylaldehyden, bei dem man die Alkohol- und/oder Aldehydgruppen in Gegenwart mindestens eines Lö- sungsmittels, mindestens eines heterogenen Rheniumkatalysators und eines Cokatalysators aus der Gruppe be-

stehend aus HBF 4 und Salzen davon mit mindestens einem aus Peroxoverbindungen ausgewählten Oxidationsmittel 15 behandelt.

2. Verfahren nach Anspruch 1, bei dem man die Peroxoverbindung aus Wasserstoffperoxid oder Wasserstoffperoxid- quellen, ausgewählt aus Alkali- oder Erdalkalimetallpercarbonaten, Alkali- oder Erdalkalimetallperboraten und Erd- alkalimetall- oder Metallperoxiden, vorzugsweise einer wässrigen Wasserstoffperoxidlösung, auswählt. 20 3. Verfahren nach Anspruch 1 oder 2, bei dem es sich bei dem heterogenen Rheniumkatalysator um einen geträgerten Rheniumkatalysator mit einer inerten polymeren Matrix und einer Rheniumverbindung handelt.

4. Verfahren nach Anspruch 3, bei dem die inerte polymere Matrix aus Poly(4-vinylpyridin), Poly (4-vinylpyridin-N-oxid) 25 und Polystyrol ausgewählt ist.

5. Verfahren nach Anspruch 3 oder 4, bei dem die Rheniumverbindung aus Rhenium(VI)-oxid, Rhenium(VII)-oxid, Methyltrioxorhenium, einem C2- bis C20-Alkylrheniumoxid und einem C3- bis C10-Cycloalkylrheniumoxid, vorzugsweise Methyltrioxorhenium, ausgewählt ist. 30 6. Verfahren nach einem der Ansprüche 1 bis 5, bei dem man das Lösungsmittel aus Wasser, Carbonsäuren, orga- nischen Lösungsmitteln, ionischen Flüssigkeiten und Mischungen davon, vorzugsweise einem protischen Lösungs- mittel, ausgewählt aus Wasser, Essigsäure, C1- bis C3-Alkoholen und Mischungen davon, auswählt.

35 7. Verfahren nach einem der Ansprüche 1 bis 6, bei dem man das Salz von HBF 4 aus der Gruppe bestehend aus dem Natriumsalz, Ammoniumsalz, Lithiumsalz und Mischungen davon auswählt.

8. Verfahren nach einem der Ansprüche 1 bis 7, bei dem man die Oxidation bei einer Temperatur von 5 bis 50°C, vorzugsweise von 10 bis 45°C, weiter bevorzugt bei Raumtemperatur, über einen Zeitraum von 12 bis 72 Stunden, 40 vorzugsweise über einen Zeitraum von 24 bis 48 Stunden, durchführt.

9. Verfahren nach einem der Ansprüche 1 bis 8, bei dem man den heterogenen Rheniumkatalysator in einer Menge von 0,1 bis 10 Gew.- %, bezogen auf die zu oxidierende Verbindung, vorzugsweise von 1 bis 7 Gew.- %, verwendet.

45 10. Verfahren nach einem der Ansprüche 3 bis 9, bei dem der geträgerte Rheniumkatalysator einen Beladungsfaktor, definiert als mmol Rheniumverbindung pro g Träger, von 0,1 bis 10, vorzugsweise von 0,5 bis 5 und weiter bevorzugt von 1 bis 3 aufweist.

11. Verfahren nach einem der Ansprüche 1 bis 10, bei dem man das Oxidationsmittel in einer Menge von 1 bis 20 50 Äquivalenten, bezogen auf die zu oxidierende Verbindung, vorzugsweise von 2 bis 15, speziell von 4 bis 10, verwendet.

12. Verfahren nach einem der Ansprüche 1 bis 11, angewendet auf mindestens eine Verbindung aus der Gruppe bestehend aus linearen, verzweigten oder cyclischen Alkylalkoholen und linearen, verzweigten oder cyclischen 55 Alkylaldehyden, vorzugsweise auf Kohlenhydrate und Kohlenhydratderivate, speziell auf niedermolekulare Kohlen- hydrate und niedermolekulare Kohlenhydratderivate.

13. Verfahren nach Anspruch 12, bei dem man die niedermolekularen Kohlenhydrate aus Furfural, 5-Hydroxymethyl-

9 EP 2 307 395 B1

furfural und Mischungen davon auswählt.

14. Verfahren nach Anspruch 13 zur Herstellung von Maleinsäure.

5 15. Verfahren nach Anspruch 14, bei dem man ferner die Maleinsäure zu Maleinsäureanhydrid dehydratisiert.

Revendications

10 1. Procédé d’oxydation de groupes alcools et/ou aldéhydes alkyliques d’au moins un composé choisi dans le groupe constitué par des alcools alkyliques linéaires, ramifiés ou cycliques et des aldéhydes alkyliques linéaires, ramifiés ou cycliques, ledit procédé comprenant le traitement desdits groupes alcools et/ou aldéhydes avec au moins un agent oxydant choisi parmi des composés peroxo en présence d’au moins un solvant, d’au moins un catalyseur

hétérogène à base de rhénium, et d’un co- catalyseur choisi dans le groupe constitué par l’HBF 4 et des sels de celui- ci. 15 2. Procédé selon la revendication 1, caractériséen ce que le composé peroxo est choisi parmi leperoxyde d’hydrogène ou des sources de peroxyde d’hydrogène choisies parmi les percarbonates de métaux alcalins ou alcalino- terreux, les perborates de métaux alcalins ou alcalino-terreux, et les peroxydes de métaux alcalino-terreux ou de métaux, de préférence une solution aqueuse de peroxyde d’hydrogène. 20 3. Procédé selon la revendication 1 ou 2, caractérisé en ce que le catalyseur hétérogène à base de rhénium est un catalyseur à base de rhénium supporté comprenant une matrice de polymère inerte et un composé de rhénium.

4. Procédé selon la revendication 3, caractérisé en ce que la matrice de polymère inerte est choisie parmi la poly (4- 25 vinylpyridine), le poly(4-vinylpyridine N-oxyde) et le polystyrène.

5. Procédé selon la revendication 3 ou 4, caractérisé en ce que le composé de rhénium est choisi parmi l’oxyde de rhénium (VI), l’oxyde de rhénium (VII), le méthyltrioxorhénium, un oxyde d’alkylrhénium en C2 à C20, et un oxyde de cycloalkylrhénium en C3 à C10, de préférence le méthyltrioxorhénium. 30 6. Procédé selon l’une quelconque des revendications 1 à 5, caractérisé en ce que le solvant est choisi parmi l’eau, les acides carboxyliques, les solvants organiques, les liquides ioniques et des mélanges de ceux- ci, de préférence un solvant protique choisi parmi l’eau, l’acide acétique, les alcools en C 1 à C3, et des mélanges de ceux-ci.

35 7. Procédé selon l’une quelconque des revendications 1 à 6, caractérisé en ce que le sel d’HBF4 est choisi dans le groupe constitué par le sel de sodium, le sel d’ammonium, le sel de lithium et des mélanges de ceux-ci.

8. Procédé selon l’une quelconque des revendications 1 à 7, caractérisé en ce que l’oxydation est effectuée à une température de 5 à 50°C, de préférence de 10 à 45°C, plus préférablement à la température ambiante, pendant 12 40 à 72 heures, de préférence pendant 24 à 48 heures.

9. Procédé selon l’une quelconque des revendications 1 à 8, caractérisé en ce que le catalyseur hétérogène à base de rhénium est utilisé dans une quantité de 0,1 à 10 % en poids du composé à oxyder, de préférence de 1 à 7 %.

45 10. Procédé selon l’une quelconque des revendications 3 à 9, caractérisé en ce que le catalyseur à base de rhénium supporté a un facteur de charge, défini en mmol de composé de rhénium par g de support, de 0,1 à 10, de préférence de 0,5 à 5, plus préférablement de 1 à 3.

11. Procédé selon l’une quelconque des revendications 1 à 10, caractérisé en ce que l’agent oxydant est utilisé dans 50 une quantité de 1 à 20 équivalents du composé à oxyder, de préférence de 2 à 15, notamment de 4 à 10.

12. Procédé selon l’une quelconque des revendications 1 à 11, appliqué à au moins un composé choisi dans le groupe constitué par des alcools alkyliques linéaires, ramifiés ou cycliques et des aldéhydes alkyliques linéaires, ramifiés ou cycliques, de préférence à des glucides et des dérivés de glucides, notamment à des glucides de faible poids 55 moléculaire et des dérivés de glucides de faible poids moléculaire.

13. Procédé selon la revendication 12, caractérisé en ce que les glucides de faible poids moléculaire sont choisis parmi le furfural, le 5-(hydroxyméthyl) furfural et des mélanges de ceux- ci.

10 EP 2 307 395 B1

14. Procédé selon la revendication 13, pour la préparation d’acide maléique.

15. Procédé selon la revendication 14, comprenant une autre étape de déshydratation de l’acide maléique en anhydride maléique. 5

11 EP 2 307 395 B1

REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• EP 08160771 A [0001] • US 20060070953 A1 [0005] • WO 0061639 A [0004]

Non-patent literature cited in the description

• W.A. HERMANN et al. Chemische Berichte, 1993, • Carbohydrates. Ullmann’s Encyclopedia of Industrial vol. 126, 4 [0003] Chemistry. 2003 [0013] • J.H. ESPENSON et al. J. Am. Chem. Soc., 1995, vol. • R. SALADINO et al. J. Chem. Soc., Perkin Trans. 1, 117, 9243 [0003] 2000, 581-5586 [0017] • R. SALADINO et al. J. Chem. Soc., Perkin Trans., • Furfural and Derivatives. Ullmann’s Encyclopedia of 2000, vol. 1, 581-586 [0006] Industrial Chemistry. 2007 [0030] • SALADINO et al. J. Org. Chem., 2002, vol. 67, • Maleic and Fumaric Acids. Ullmann’s Encyclopedia 1323-1332 [0008] of Industrial Chemistry. 2000 [0032] [0033]