(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
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`(19) World Intellectual Property Organization
`International Bureau
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`1111111111111111111111111111111010111111110111111111111111111111111111111111
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`(43) International Publication Date
`4 October 2001 (04.10.2001)
`
`PCT
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`(10) International Publication Number
`WO 01/72732 A2
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`(51) International Patent Classification": (cid:9)
`307/46, 307/48
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`CO7D 307/36,
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`(21) International Application Number: PCT/US01/09701
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`(22) International Filing Date: 27 March 2001 (27.03.2001)
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`(25) Filing Language: (cid:9)
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`(26) Publication Language: (cid:9)
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`English
`
`English
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`DE 19707 (US). PARTENHEIMER, Walter [US/US]; 16
`Clermont Road, Wilmington, DE 19803 (US). MANZER,
`Leo, E. [US/US]; 714 Burnley Road, Wilmington, DE
`19803 (US).
`
`(74) Agent: SIEGELL, Barbara, C.; E.1. Dupont De Nemours
`and Company, Legal Patent Records Center, 1007 Market
`Street, Wilmington, DE 19898 (US).
`
`(81) Designated States (national): CA, JP, US.
`
`(30) Priority Data:
`60/192,271 (cid:9)
`
`27 March 2000 (27.03.2000) US
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`(84) Designated States (regional): European patent (AT, BE,
`CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC,
`NL, PT, SE, TR).
`
`(71) Applicant (for all designated States except US): E.I.
`DUPONT DE NEMOURS AND COMPANY [US/US];
`1007 Market Street, Wilmington, DE 19898 (US).
`
`Published:
`(cid:9) without international search report and to be republished
`upon receipt of that report
`
`(72) Inventors; and
`GRUSHIN,
`(75) Inventors/Applicants (for US only): (cid:9)
`Vladimir [CA/US]; 533 Runnymeade Road, Hockessin,
`
`For two-letter codes and other abbreviations, refer to the "Guid-
`ance Notes on Codes and Abbreviations" appearing at the begin-
`ning of each regular issue of the PCT Gazette.
`
`N
`„IN (54) Title: OXIDATION OF 5 -(HYDROXYMETHYL) FURFURAL TO 2,5 -DIFORMYLFURAN AND SUBSEQUENT DECAR-
`11 BONYLATION TO UNSUBSTITUTED FURAN
`O
`C (57) Abstract: Alcohols are catalytically oxidized to aldehydes, in particular to benzaldehyde and diformylfuran, which are useful
`
`as intermediates for a multiplicity of purposes. The invention also relates to the polymerization of the dialdehyde and to the decar-
`Oi" bonylation of the dialdehyde to furan.
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`Petitioners' Exhibit 1002, Page 1 of 23
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`TITLE
`OXIDATION OF 5-(HYDROXYMETHYL) FURFURAL TO
`2,5-DIFORMYLFURAN AND SUBSEQUENT DECARBONYLATION
`TO UNSUBSTITUTED FURAN
`FIELD OF INVENTION
`The invention relates to the catalytic oxidation of alcohols to aldehydes, in
`particular the formation of benzaldehyde and diformylfuran, which are useful as
`intermediates for a multiplicity of purposes. The invention also relates to the
`polymerization and the decarbonylation of a dialdehyde.
`BACKGROUND
`5-(Hydroxymethyl)furfural (HMF) is a versatile intermediate that can be
`obtained in high yield from biomass sources such as naturally occurring
`carbohydrates, including fructose, glucose, sucrose, and starch. Specifically,
`HMF is a conversion product of hexoses with 6 carbon atoms. It is known that
`15 HMF can be oxidized using a variety of reagents to form any of four different
`products, which can themselves be converted to one or more of the others:
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`10 (cid:9)
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`HOH2C
`
`0 CHO
`
`5-(hydroxymethyl)furfural
`HMF
`
`0 COOH
`HOH2C
`5-(hydroxymethyl)furan-2-
`carboxylic acid
`
`OHCJN0
`
`—CHO
`
`2,5-diformylfuran
`DFF
`
`H000--0 0 COOH---
`
`furan-2,5-dicarboxylic acid
`FDA
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`OHC
`0 COOH
`• •
`2-carbov-5-(formyl)furan
`CFF
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`20 (cid:9)
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`25 (cid:9)
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`The selective oxidation of an alcohol functionality in the presence of an
`aldehyde functionality on the same compound is difficult because of the high
`reactivity of the aldehyde group. Furthermore, if HMF is reacted with molecular
`oxygen (02), the aldehyde functionality would be expected to oxidize more
`rapidly than the alcohol and the expected product would be predominantly
`5-(hydroxymethyl)furan-2-carboxylic acid (Sheldon, R. A. and Kochi, J. K.
`
`1
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`Petitioners' Exhibit 1002, Page 2 of 23
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`"Metal Catalyzed Oxidations of Organic Compounds", Academic Press, New
`York, NY 1981, p 19).
`Diformylfuran (DFF) has been prepared from HMF using Cr03 and
`K2Cr207 (L. Cottier et al., Org. Prep. Proced. Int. (1995), 27(5), 564;
`5 JP 54009260) but these methods are expensive and results in large amounts of
`inorganic salts as waste. Heterogeneous catalysis using vanadium compounds has
`also been used, but the catalysts have shown low turnover numbers
`(DE 19615878, Moreau, C. et al., Stud. Surf. Sci. CataL (1997), 108, 399-406).
`Catalytic oxidation has been demonstrated using hydrogen peroxide (M. P. J. Van
`Deurzen, Carbohydrate Chem. (1997), 16(3), 299) and dinitrogen tetraoxide (JP
`55049368) which are expensive. The relatively inexpensive molecular oxygen
`(02) has been used with a Pt/C catalyst (U.S. Patent No. 4,977,283) to form both
`DFF and furan-2,5-dicarboxlic acid (FDA), but yielded low amounts of DFF.
`Good yields were found for FDA, but only as the disodium salt which resulted in
`15 wasteful salt formation during conversion to the acid form.
`Metal bromide catalysts have been used to oxidize substituted
`alkylbenzenes to various products including the oxidation of alkyl to aldehydes,
`alkyl to alcohols, alkyl to acids, alcohol to acid, and aldehydes to acids
`(W. Partenheimer, Catalysis Today, 23(2), 69-158, (1995)). However, in such
`20 cases, the aldehyde product is either a minor component or is quickly oxidized
`further. FDA has also been prepared using a Co/Mn/Br catalyst from 5-
`methylfurfural with DFF seen as a minor byproduct (V. A. Slavinskaya, et al.,
`React. Kinet. Catal. Lett. (1979), 11(3), 215-20).
`DFF has been polymerized to form polypinacols and polyvinyls (Cooke,
`et al., Macromolecules 1991, 24, 1404). However, preparation of polyesters
`prepared from diformylfuran is not known in the literature.
`DFF can also be used to produce unsubstituted furan. Unsubstituted furan
`is an important commodity in the chemical industry used in the production of
`tetrahydrofuran. Supported metal catalysts have been used in the decarbonylation
`30 of the monoaldehyde furfural to furan, but a basic promoter is required, adding
`expense and complexity to the process (U.S. Patent No. 3,007,941, U.S. Patent
`No. 4,780,552).
`Considering the aforementioned discussion, there is a need for an
`inexpensive, high yield process for the preparation of both DFF and FDA that
`35 does not produce large amounts of waste products and which lends itself to easy
`separation and purification. Additionally, there is a need for a high yielding. (cid:9)
`process to prepare unsubstituted furan from relatively inexpensive, renewable
`sources.
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`25 (cid:9)
`
`•
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`2
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`Petitioners' Exhibit 1002, Page 3 of 23
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`SUMMARY OF THE INVENTION
`The invention is directed to a first process for the preparation of a
`dialdehyde comprising a) contacting a compound containing an alcohol
`functionality and an aldehyde functionality with an oxidant in the presence of a
`metal bromide catalyst; and b) optionally isolating the dialdehyde produCt. A
`preferred metal bromide catalyst comprises a source of bromine and at least one
`metal selected from the group consisting of Co and Mn, and optionally containing
`Zr. More preferably the metal bromide catalyst contains Co.
`Preferably the dialdehyde is of the formula H(C=0)-R-(C=0)H and the
`10 compound is of the formula HOH2C-R-(C=0)H, wherein R is selected from the
`group consisting of an optionally substituted C1-C20 alkyl or aryl group. The R
`groups can be linear or cyclic, or a heterocyclic group. More preferably, R is
`furan, and most preferably the dialdehyde is 2,5-di(formyl)furan. The process of
`the present invention can be run in a solvent mixture comprising at least one
`15 aliphatic C2-C6 monocarboxylic acid compound, preferably acetic acid.
`The invention is further directed to a second process for the preparation of
`a diacid of the formula HOOC-R'-COOH from an alcohol/aldehyde of the formula
`HOH2C-R'-(C=0)H, wherein R' is an optionally substituted furan ring,
`comprising the steps:
`(a) contacting the alcohol/aldehyde with an oxidant in the presence of
`a metal bromide catalyst forming an alcohol/acid having the
`formula HOH2C-R'-COOH, and optionally isolating the
`alcohol/acid;
`(b) contacting the alcohol/acid with an oxidant in the presence of a
`metal bromide catalyst forming an acid/aldehyde having the
`formula HOOC-R'-(C=0)H, and optionally isolating the
`acid/aldehyde;
`(c) contacting the acid/dialdehyde with an oxidant in the presence of
`a metal bromide catalyst forming the diacid, optionally isolating
`the diacid.
`The invention is further directed to a third process for the preparation of a
`diacid of the formula HOOC-R'-COOH from an alcohol/aldehyde of the formula
`HOH2C-R'-(C=0)H, wherein R' is an optionally substituted furan ring,
`comprising the steps:
`(a') contacting the alcohol/aldehyde with an oxidant in the presence of
`a metal bromide catalyst forming a dialdehyde having the formula
`H(C=0)-R'-(C=0)H, and optionally isolating the dialdehyde;
`
`30 (cid:9)
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`35 (cid:9)
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`3
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`Petitioners' Exhibit 1002, Page 4 of 23
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`(b') contacting the dialdehyde with an oxidant in the presence of a
`metal bromide catalyst forming an acid/aldehyde having the
`formula HOOC-R'-(C=O)H, and optionally isolating the
`acid/aldehyde; and
`(c') contacting the acid/dialdehyde with an oxidant in the presence of
`a metal bromide catalyst forming the diacid, and optionally
`isolating the diacid.
`The process further comprises the steps of a', b', and c' and wherein before
`step c' the acid/aldehyde is converted to an acetate ester of the formula
`10 CH3(C=0)0CH2-12.'-(C=0)H.
`Preferably, in the above process the diacid is furan-2,5-dicarboxlic acid
`and the alcohol/aldehyde is 5-(hydroxymethyl)furfural.
`The process can optionally be run in a solvent or solvent mixture
`comprising at least one aliphatic C2-C6 monocarboxylic acid compound,
`preferably acetic acid.
`The invention is also directed to a fourth process for the preparation of an
`aldehyde comprising a) contacting a compound of the formula AR-CH2-OH
`wherein AR is an optionally substituted aryl with an oxidant in the presence of a
`metal bromide catalyst; and b) optionally isolating the aldehyde product.
`20 Preferably, AR an optionally substituted phenyl group. Most preferably, AR is an
`unsubstituted phenyl group. A preferred metal bromide catalyst is comprised of a
`source of bromine and at least one metal selected from the group consisting of Co
`and Mn. More preferably the metal bromide catalyst contains Co.
`The process can be run in a solvent or solvent mixture comprising at least
`25 one aliphatic C2-C6 monocarboxylic acid compound, preferably acetic acid.
`The invention is also directed to a fifth process to form a polyester
`polymer and the polyester polymer so produced from 2,5-diformylfuran
`comprising the repeat units A and B and C.
`
`15 (cid:9)
`
`30
`
`A
`
`B
`
`/ \
`O
`
`C
`
`wherein said process comprises polymerization of di(formyl)furan. The
`process can be performed in the presence of a catalyst of the formula M+n(0-Q)n
`wherein M is a metal, n is the positive charge on the metal, and Q is an alkyl
`
`4
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`Petitioners' Exhibit 1002, Page 5 of 23
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`group of 1-4 carbons. Preferably, M is aluminum and n is three. Preferably the
`polyester polymer formed from the process is a homopolymer.
`An embodiment of the invention is a polyester polymer comprising
`repeating units A, B and C. Preferably, the polyester polymer is a homopolymer.
`Another aspect of the invention is a sixth process for the preparation of
`furan comprising converting 2,5-diformylfuran into furan and furfural via
`decarbonylation in the presence of a catalytic amount of a compound consisting
`essentially of a optionally supported metal selected from Periodic Group VIII.
`The furan and furfural product may further be converted via decarbonylation into
`10 unsubstituted furan in the presence of a catalytic amount of a compound
`consisting of an optionally supported metal selected from Periodic Group VIII.
`Preferably the catalyst is supported on a catalyst support member, more
`preferably the metal is palladium and the catalyst support member is carbon.
`Another aspect of the invention is to convert the dialdehyde prepared using
`15 the above processes, wherein the dialdehyde is 2,5-di(formyl)furan, into furan via
`decarbonylation in the presence of a catalytic amount of a compound consisting of
`a optionally supported metal selected from Periodic Group VIII.
`DETAILED DESCRIPTION OF THE INVENTION
`The present invention concerns a first process for the preparation of a
`20 dialdehyde comprising contacting a first compound containing an alcohol
`functionality and an aldehyde functionality with an oxidant in the presence of a
`metal bromide catalyst. More specifically, the alcohol can be HMF, the
`dialdehyde can be DFF, and the catalyst can be comprised of Co and/or Mn, and
`Br, and optionally Zr.
`In addition to the alcohol and the aldehyde, other functional groups may be
`attached to the first compound as long as the other functional groups are
`substantially inert under reaction conditions. In a preferred process the first
`compound is of the formula HOH2C-R-(C=O)H, and the resulting dialdehyde
`product that is prepared is of the formula H(C=O)-R-(C=O)H. In the above
`30 formula for the first compound and the dialdehyde product of this invention, R is
`selected from the group consisting of an optionally substituted C1-C20 alkyl and
`optionally substituted C1-C20 aryl group. The R groups are either linear, cyclic,
`or heterocyclic. More preferred is where R is selected from the group consisting
`of an optionally substituted C1-C20 alkyl group, linear or cyclic, and a
`35 heterocyclic group. Most preferred is where R is a furan. By optionally
`substituted herein is meant a group that may be substituted and may contain one
`or more substituent groups that do not cause the compound to be unstable or
`unsuitable for the use or reaction intended. Substituent groups which are
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`5
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`generally useful include nitrile, ether, alkyl, ester, halo, amino (including primary,
`secondary and tertiary amino), hydroxy, silyl or substituted silyl, nitro, and
`thioether.
`The term "aryl" refers to an aromatic carbo-cyclic group having a single,
`ring (e.g., phenyl), multiple rings (e.g., biphenyl), or multiple condensed rings of
`which at least one is aromatic (e.g., l,2,3,4-tetrahydronaphthyl, naphthyl, anthryl,
`or phenanthryl), and which is optionally mono-, di-, or tri- substituted with a
`functional group such as halogen, lower alkyl, lower alkoxy, lower alkylthio,
`trifluoromethyl, lower acyloxy, aryl , heteroaryl, and hydroxy. The term "aryl"
`also refers to heteroaryl groups where heteroarYI is defined as 5-, 6-, or
`7-membered aromatic ring systems having at least one hetero-atom selected from
`the group consisting of nitrogen, oxygen and sulfur. Examples of heteroaryl
`groups are pyridyl, pyrimidinyl, pyrrolyl, pyrazolyl, pyrazinyl, pyridazinyl,
`oxazolyl, furanyl, quinolinyl, isoquinolinyl, thiazolyl, and thienyl, which can
`optionally be substituted with, e.g., halogen, lower alkyl, lower alkoxy, lower
`alkylthio, trifluoromethyl, lower acyloxy, aryl, heteroaryl, and hydroxy.
`A particularly preferred process is where R is 2,5-disubstituted furan, i.e.,
`where the first compound is HMF and the dialdehydels DFF.
`DFF may be further converted via loss of CO to furan, which can be
`20 hydrogenated to tetrahydrofuran using standard techniques familiar to those
`skilled in the art.
`The second process concerns preparation of a diacid of the formula
`HOOC-R'-COOH from an alcohol/aldehyde of the formula HOH2C-R'-(C=0)H.
`The third process concerns preparation of a diacid of the formula
`25 HOOC-R'-COOH from an alcohol/aldehyde of the formula HOH2C-R'-(C=O)H.
`In the second and third processes, R is preferably an optionally substituted
`furan ring. More preferably, R' is a 2,5-disubstituted furan ring. A preferred
`metal bromide catalyst is comprised of a source of bromine and at least one metal
`selected from the group consisting of Co and Mn, and optionally containing Zr.
`30 More preferably the metal bromide catalyst contains Co.
`Any of the intermediates, the alcohol/acid, acid/aldehyde, or the
`dialdehyde, may be isolated at any step, or the reaction may proceed without any
`purification. It is contemplated that the processes of the invention in which DFF
`and/or FDA is prepared can be run using a biomass feedstock containing HMF,
`such that only the final product need be isolated and purified.
`For the preparation of the dialdehyde, the preferred temperatures are about
`20° to 200°C, most preferably about 40° to 130°C. The corresponding pressure is
`such to keep the solvent mostly in the liquid phase. The preferred time of the
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`reaction is determined by the temperature, pressure, and catalyst concentration
`such that maximum yield of dialdehyde is obtained. For preparation of diacid, the
`preferred temperatures are about 50° to 250°C, most preferentially about 50° to
`160°C. The corresponding pressure is such to keep the solvent mostly in the
`5 liquid phase. The preferred time of the reaction is determined by the temperature,
`pressure and catalyst concentration such that a maximum yield of diacid is
`obtained.
`The fourth process concerns preparation of an aldehyde comprising
`contacting a compound of the formula AR-CH2-0H, wherein AR is an optionally
`10 substituted aryl group, with an oxidant in the presence of a metal bromide catalyst.
`Preferably, AR an optionally substituted phenyl group. Most preferably, AR is an
`unsubstituted phenyl group. In addition to the alcohol, other functional groups
`may be attached to the compound as long as the other functional groups are
`substantially inert under reaction conditions.
`A preferred metal bromide catalyst is comprised of a source of bromine
`and at least one metal selected from the group consisting of Co and Mn, and
`optionally containing Zr. More preferably the metal bromide catalyst contains Co.
`The process can be run in a solvent or solvent mixture comprising at least
`one aliphatic C2-C6 monocarboxylic acid compound, preferably acetic acid.
`Metal bromide catalysts employed in all of the processes of this invention
`comprise a soluble transition metal compound and soluble bromine-containing
`compound. One metal or a combination of two or more metals may be present.
`Many such combinations are known and may be used in the processes of the
`instant invention. These metal bromide catalysts are described further in
`25 (cid:9) W. Partenheimer, Catalysis Today, 23(2), 69-158, (1995), in particular
`pages 89-99, herein incorporated by reference. Preferably the metal is cobalt
`and/or manganese, optionally containing zirconium. More preferably, the catalyst
`is comprised of Co/Mn/Zr/Br in the molar ratios of 1.0/1.0/0.1/2.0. The amount
`of catalyst in the reaction mixture can be 59/55/203/4 ppm to
`30 5900/5500/20000/390 ppm Co/Mn/Br/Zr, preferably 150/140/510/10 ppm to
`2400/2200/8100/160 ppm (g of metal/g of solvent). As used herein, the molar
`ratio is the ratio of moles of the metals alone, not the metals as in their compound
`forms.
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`20 (cid:9)
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`Each of the metal components can be provided in any of their known ionic
`35 or combined forms. Preferably the metal or metals are in a form that is soluble in
`the reaction solvent. Examples of suitable forms include, but are not limited to,
`metal carbonate, metal acetate, metal acetate tetrahydrate, and metal bromide.
`Preferably metal acetate tetrahydrates are used.
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`The source of bromide can be any compound that produces bromide ions
`in the reaction mixture. These compounds include, but are not limited to,
`hydrogen bromide, hydrobromic acid, sodium bromide, elemental bromine,
`benzyl bromide, and tetrabromoethane. Preferred is sodium bromide or
`5 hydrobromic acid. As used herein, the amount of bromine means the amount
`measured as Br. Thus, the molar ratio of bromine to total of the metals used in the
`catalyst is the moles of Br divided by the sum of the moles of the metal.
`As described in Partenheimer, ibid, pages 86-88, suitable solvents for use
`in the processes of the present invention, described above, must have at least one
`10 component that contains a monocarboxylic acid functional group. The solvent
`may also function as one of the reagents. The processes may be run in a solvent
`or solvent mixture that does not contain an acid group, provided that one of the
`reagents does contain such a group. Suitable solvents can also be aromatic acids
`such as benzoic acid and derivatives thereof. A preferred solvent is an aliphatic
`C2-C6 monocarboxylic acid, such as but not limited to acetic acid, propionic acid,
`n-butyric acid, isobutyric acid, n-valeric acid, trimethylacetic acid, and caproic
`acid and mixtures thereof. Components of said mixtures can include benzene,
`acetonitrile, heptane, acetic anhydride, chlorobenzene, o-dichlorobenzene, and
`water. Most preferred as solvent is acetic acid. One advantage of using a solvent
`such as acetic acid is that furan-2,5-dicarboxylic acid is insoluble, facilitating
`purification of the insoluble product.
`The oxidant in the processes of the present invention is preferably an
`oxygen-containing gas or gas mixture, such as, but not limited to air. Oxygen by
`itself is also a preferred oxidant.
`The processes of the instant invention described above can be conducted in
`the batch, semi-continuous or continuous mode. Especially for the manufacture of
`FDA, operation in the batch mode with increasing temperature at specific times,
`increasing pressure at specific times, variation of the catalyst concentration at the
`beginning of the reaction, and variation of the catalyst composition during the
`30 reaction is desirable. For example, variation of the catalyst composition during
`reaction can be accomplished by addition of cobalt and/or manganese and/or
`zirconium, and/or bromide at specified times.
`The fifth process concerns the polymerization of di(formyl)furan to form a
`novel polyester polymer comprising the repeat units A, B and C, as shown in the
`35 summary above. The catalysts employed in the polymerization of
`di(formyl)furan can be selected from any catalyst used for the esterification of a.
`dialdehyde or two separate aldehydes. This esterification is commonly known as
`the " Tishchenko reaction". A partial list of catalysts used for this reaction are
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`those listed in Mascarenhas, et al., Org. Letters, 1999, Vol. 1, 9, pg. 1427; U.S.
`Patent No. 3,852,335; and Reagents for Organic Synthesis, Fieser (ed.), 1969,
`Vol. 5, pg. 48, and are herein incorporated by reference. An alternate catalyst is
`the Shvo catalyst, [(Ph4C5OH005Ph4)Ru2(C0)4(1—H)], as described in Menashe,
`et al., Organometallics 1991, 10, 3885. This discussion concerning the Shvo
`catalyst is also incorporated herein by reference. Preferred catalysts are metal
`alkoxides of the formula M+n(0-Q)n where M is a metal, n is the positive charge
`on the metal, and Q is an alkyl group of 1-4-carbons. Most preferred is where M
`is aluminum and n is three. The catalysts of the invention can be obtained already
`10 prepared from manufacturers, or they can be prepared from suitable starting
`materials using methods known in the art.
`The repeat units A, B, and C can all be present in the polyester polymer
`product but are present in varying ratios, in any order in which an ester linkage is
`present and a polyester is formed. The term polymer is herein defined to include
`oligomers of 3 or more repeating units as well as higher polymers. This polymer
`would be useful as a molding resin or may be spun into a fiber.
`The polyester polymer produced by the present process may include other
`repeat units in addition to those shown above. Other polyesters having the above
`repeat units include, but are not limited to, polyesteramides, polyesterimides, and
`20 polyesterethers. A preferred version of the polymer is a homopolymer.
`A preferred embodiment of the present invention is the catalytic
`decarbonylation of DFF to form a mixture of unsubstituted furan and furfural.
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`OHC
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`CHO
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`CHO
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`25
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`DFF
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`Furan (cid:9)
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`Furfural
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`in the presence of a catalytic amount of a metal selected from Periodic Group
`VIII, herein defined as Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, and Pt. Preferably, the
`catalyst consists essentially of one or more of the Periodic Group VIII metals. A
`particularly preferred catalyst consists essentially of Pd.
`The metals may be in any form including Raney catalysts as known to
`those skilled in the art. The catalysts are preferably supported on a catalyst solid
`support. The catalyst solid support, which includes but not limited to Si02,
`A1203, carbon, MgO, zirconia, or Ti02, can be amorphous or crystalline, or a
`mixture of amorphous and crystalline forms. Selection of an optimal average
`35 particle size for the catalyst supports will depend upon such process parameters as
`
`9
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`PCT/US01/09701
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`reactor residence time and desired reactor flow rates. The amount of metal on the
`support is preferably about 0.5-10% and most preferably 1-5%. The catalysts of
`the invention can be obtained already prepared from manufacturers, or they can be
`prepared from suitable starting materials using methods known in the art. One
`5 typical procedure is by impregnation of the support by incipient wetness using a
`soluble metal salt precursor, such as the chloride, acetate, nitrate salt, following by
`reduction under hydrogen gas.
`A preferred embodiment of the fifth process is a liquid phase reaction in
`which the DFF is dissolved in a suitable, inert solvent. The catalysts are placed in
`the solvent in a pressure vessel, and pressured'to about 200-1000 psi,
`(1.4-6.9 MPa), more preferably about 500 psi (3.4 MPa) with an inert gas,
`preferably nitrogen. The reaction temperature is about 150°C-250°C, more
`preferably about 200°C. The reaction product containing furan and furfural can
`be recycled through the process one or more times, to eventually form a reaction
`product consisting essentially of furan.
`The above process can also be combined with the process to prepare DFF
`described above, to create a single integrated process wherein DFF is prepared
`using the metal bromide catalysts described above, then decarbonylated to furan
`or furfural.
`
`10 (cid:9)
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`15 (cid:9)
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`25 (cid:9)
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`20 (cid:9)
`
`Materials and Methods
`HMF was obtained from Lancaster Synthesis, Windham, NH. Unless
`otherwise stated, all materials were used as received without further purification.
`All percentages are by mole percent unless otherwise specified.
`EXAMPLES 1-6
`Reaction of HMF to DFF at ambient air Pressure
`In a cylindrical glass fitted with a stirrer and baffles, 0.165 g of cobalt(II)
`acetate tetrahydrate, 0.169 g of manganese(II) acetate tetrahydrate, 0.142 g of
`sodium bromide, 0.220 g biphenyl (GC internal standard), and 10.02 g of
`5-hydroxymethyl(furfural) were admixed with 100 g of acetic. The solution was
`30 purged with nitrogen gas and the temperature raised to 75°C using an external oil
`bath. The nitrogen was replaced with air at a flow rate of 100 ml/min at ambient
`atmospheric pressure. The vent oxygen was constantly monitored and
`occasionally liquid and vent gas samples for GC analysis were taken at the times
`shown in Table 2. After 30 hrs the reaction was terminated. The results from the
`35 liquid samples taken from the reactor during reaction of Example 1 are given in
`Table 1. The DFF yield increased with time to a maximum yield of 51% and then
`decreases thereafter. The mini-reactor data is summarized in Table 3. The rate of
`reaction, as given by the rate of disappearance of HMF, was dependent upon the
`
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`15 (cid:9)
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`concentration of the catalyst, see especially. ,Examples 3, 4. The maximum yields
`and chemical species selectivities were also dependent on the concentration of the
`catalyst, see Examples 1, 3-6. The dependence of the selectivity on the
`concentration of catalyst is given in detail for Examples 3, 4, and 6 in Table 2.
`5 The formation of carbon dioxide and carbon monoxide are undesirable because
`they are caused by the decomposition of HMF and its products, as well as from
`the solvent, acetic acid. As can be seen in Table 2, increasing the catalyst
`concentration greatly decreases the formation of these carbon oxides. Example 4
`combines the best yield, shortest reaction time, and one of the lowest rates of
`10 carbon oxide formation.
`2,5-Diformylfuran was isolated from the reaction mass as follows. The
`liquid from the reaction mixture was allowed to evaporate. The residue after
`evaporation of the reaction mixture was (a) sublimed under vacuum, followed by
`recrystallization of the sublimate from toluene or cyclohexane; or (b) mixed with
`silica gel and extracted with hexanes or cyclohexane in a Soxhlet extractor; or
`(c) extracted with hot toluene, with subsequent filtration of the hot toluene
`solution through silica, evaporation of the filtrate, and recrystallization of the
`product from toluene or cyclohexane.
`One specific example of isolation of DFF is as follows. The dark reaction
`20 mixture that was obtained from Example 5, was evaporated to dryness on a
`vacuum line. The resulting waxy green-tan material was transferred to a
`sublimation apparatus and sublimed under vacuum (10-50 millitorr) at 90°C (oil
`bath) to produce 5.2 g (51 mol % based on initial HMF used) of DFF. The
`resulting DFF (95% pure; 111 NMR and GC-MS analysis) contained 3-5% of
`25 5-acetoxymethylfurfural. DFF that was pure to the limits of spectroscopic
`detection was obtained by recrystallization of the sublimate from cyclohexane or
`toluene/hexanes. 1H NMR (CDC13, 25°C), ppm: 7.4 (s; 2H; furane CH), 9.8 (s;
`2H; CHO). 13C NMR (CD2C12, 25°C), ppm: 120.4 (s; CH), 154.8 (s; q C), 179.7
`(s, CHO). m/z = 124. Alternatively, crude DFF can be purified by filtration of its
`30 concentrated dichloromethane solution through a short silica plug, followed by
`precipitation from the filtrate with hexanes.
`
`11
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`PCT/US01/09701
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`TABLE 1
`Formation of Diformylfuran in Example 1
`Conversion, %
`Selectivity, %
`31.9
`44.5
`40.3
`52.6
`46.6
`54.9
`54.7
`51.2
`54.5
`59.4
`62.5
`55.4
`66.9
`55.5
`71.0
`52.7
`82.9
`56.6
`88.3
`56.1
`92.1
`55.5
`95.2
`53.3
`100
`35.1
`100
`35.7
`100
`19.8
`100
`19.5
`
`Yield, molar, %
`14.2
`21.2
`25.6
`28.0
`32.4
`34.6
`37.1
`37.4
`46.9
`49.5
`51.1
`50.7
`35.1
`35.7
`19.8
`19.5
`
`Time, min
`66
`96
`111
`130
`144
`171
`190
`204
`310
`384
`450
`516
`1368
`1410
`1728
`1800
`
`5 (cid:9)
`
`TABLE 2
`Summary of Mini-reactor Oxygenations of Hydroxymethyl furfural
`Ex. 1
`Ex. 2
`Ex. 3
`Ex. 4
`Ex. 5
`Temp, °C
`75
`50 then 95(5)
`75
`75
`50 then 75(6)
`10.015
`9.143
`HMF, g
`10.139
`10.051
`10.04
`HOAc, g
`100
`100
`100
`100
`100
`0.066
`0.026
`0.066
`0.135
`Co, M
`0.268
`0.069
`0.025
`Mn, M
`0.069
`0.139
`0.274
`0.137
`0.050
`0.137
`Br, M
`0.279
`0.557
`0.005
`0.000
`0.005
`0.005
`0.005
`Zr, M
`HMF rate, s'l (1) 9.68E-05
`9.28E-05
`8.13E-05 1.64E44
`-
`119
`HMF half-life
`124
`142
`70
`-.
`R2
`-
`0.998
`0.878
`0.972
`0.999
`DFF Y, max (2)
`41
`51
`50
`57
`51
`450
`Time, max
`414
`642
`310
`550
`92
`C, max '
`98
` 95
`91 95.
`S, max
`55
`42
`53
`63
`54
`
`Ex. 6
`75
`10.158
`100.1
`0.273
`0.278
`0.580
`0.005
`1.37E-04
`84
`0.994
`52
`.430
`97
`54
`
`12
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`Petitioners' Exhibit 1002, Page 13 of 23
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`(cid:9)
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`W