Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2002-04-18
2003-02-18
Trinh, Ba K. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S429000, C549S497000, C549S508000
Reexamination Certificate
active
06521765
ABSTRACT:
FIELD OF THE INVENTION
This invention pertains to a novel process for the preparation of 3-methyltetrahydrofuran (MeTHF) from 3-(hydroxymethyl)tetrahydrofuran (HOMeTHF). More specifically, this invention pertains to a process for the conversion of HOMeTHF to MeTHF by contacting HOMeTHF with hydrogen in the presence of an acidic, supported catalyst comprising a Group VIII metal.
BACKGROUND OF THE INVENTION
MeTHF has been produced in commercial quantities by the high pressure hydrogenation of citraconic anhydride and some of its derivatives according to the procedures disclosed in U.S. Pat. No. 5,536,854 and Published Japanese Patent Application (Kokai) 08-217,771. Since citraconic acid is formed from citric acid or, more economically, as a minor by-product, during maleic anhydride production, these routes to MeTHF are expensive and use a starting material which is not plentiful.
Processes for the production of MeTHF based on less expensive precursors and precursors independent of the production of other materials have been developed. Thus, U.S. Pat. No. 3,932,468, describes a process for isomerizing isoprene monoepoxide into 4-methyl-2,3-dihydrofuran using a nickel and hydrohalic acid catalyst. Although the hydrogenation of 4-methyl-2,3-dihydrofuran into MeTHF is relatively simple, the synthesis of the starting material, isoprene monoepoxide, is not. For example, the preparation of isoprene monoepoxide would require the use of classical (and expensive) epoxide manufacturing techniques such as the use of halohydrins or co-oxidation with aldehydes. Japanese Published Patent Application (Kokai) JP 08-291,158 describes another method for preparing MeTHF in which propylene is converted into 2-methylsuccinate esters by a double oxidative carbonylation in the presence of an alcohol. Although the reductive cyclization of the 2-methylsuccinate esters to MeTHF is facile, the double oxidative carbonylation reaction usually gives limited yields of the dicarbonylated products and requires expensive, reactive solvents to keep the reagents anhydrous.
Another method for the synthesis of MeTHF is disclosed in U.S. Pat. No. 3,859,369 and comprises the hydroformylation and reduction of 2-buten-1,4-diol into 2-methyl-1,4-butanediol which is converted to MeTHF by acid catalysis. U.S. Pat. Nos. 4,590,312 and 4,879,420 describe the conversion of 4-hydroxybutyraldehyde and its immediate precursor, 2-buten-1,4-diol, into MeTHF by reductive alkylation with formaldehyde followed by acid-catalyzed cyclization. In each case, the products were mixtures of MeTHF and tetrahydrofuran, which occurs in the hydroformylation process because isomerization accompanies the hydroformylation, limiting the yield of MeTHF by forming a tetrahydrofuran precursor. In the reductive alkylation processes, the intermediate products as well as the starting materials may form alcohols by hydrogenation. Only those hydrogenations occurring after an initial aldol condensation of the reactants with formaldehyde can form MeTHF. All other hydrogenations gave tetrahydrofuran or other byproducts.
The preparation of MeTHF also is disclosed in Published European Patent Application EP 0 727 422 and involves the hydrocyanation of methacrylate esters. A series of hydrolyses and esterifications form a diester which may be reductively cyclized to MeTHF using an acidic, copper chromite catalyst. In this case, not only were the starting materials expensive (although not as expensive as the citraconic anhydride derivatives), but also the synthesis required four steps. Japanese Published Patent Application (Kokai) JP 08-217,708 describes a process for producing MeTHF by the hydroformylation of methacrylate esters to form mixtures of the &agr;-formylisobutyrate and the &bgr;-formylisobutyrate esters using synthesis gas. Japanese Published Patent Application (Kokai) JP 08-217,770 discloses a similar hydroformylation using methyl formate as the C-1 source. In both of these hydroformylation processes, hydrogenation of the resulting &bgr;-formylisobutyrate ester over a copper chromite catalyst produced MeTHF. One further hydroformylation route reported in Published European Patent Application Publication EP 747,373 consists of (1) the hydroformylation of isobutenyl alcohol (2-methyl-2-propen-1-ol) to form 4-hydroxy-3-methylbutyraldehyde which (2) was readily hydrogenated with nickel catalysts to 2-methyl-1,4-butanediol and which (3) was cyclized to MeTHF by acid catalysis.
Japanese Published Patent Application (Kokai) JP 2001-226366 (Kuraray Co. Ltd.) discloses dehydrating 3-hydroxy-3-methyltetrahydrofuran in the presence of an acidic substance to produce 3-methyldihydrofuran which may be hydrogenated to 3-methyltetrahydrofuran. Japanese Published Patent Applications (Kokai) JP 2001-039965 and JP 2001-163866 (Kuraray Co. Ltd.) disclose the preparation of 3-hydroxy-3-methyltetrahydrofuran by oxidizing 3-methyl-3-buten-ol with hydrogen peroxide in the presence of a zeolite. This method has limitations for commercial use since it requires relatively expensive and potentially explosive hydrogen peroxide.
U.S. Pat. No. 5,856,527 discloses a process for the preparation of 3-alkyltetrahydrofurans by a two-step process, wherein 2,3-dihydrofuran is reacted with an acetal to form an intermediate compound, which may be converted to a 3-alkyltetrahydrofuran by contacting the intermediate with hydrogen in the presence of a catalytic amount of a Group VIII noble metal or rhenium and a strong acid catalyst. U.S. Pat. No. 5,856,531 discloses a two-step process wherein (1) 2,3-dihydrofuran is reacted with a trialkyl orthoformate in the presence of an acidic catalyst to produce 2-alkoxy-3-dialkoxymethyl)-tetrahydrofuran, and (2) the intermediate is contacted with hydrogen in the presence of a catalyst system comprising a Group VIII noble metal or rhenium and a strong acid to convert the intermediate to a mixture of MeTHF and HOMeTHF.
U.S. Pat. No. 5,912,364 discloses the preparation of MeTHF by contacting 3-formyltetrahydrofuran (3-FTHF) with hydrogen in the presence of a catalyst system comprising a Group VIII noble metal or rhenium and a strong acid under hydrogenolysis conditions of temperature and pressure. The disclosed process typically produces a mixture of MeTHF and HOMeTHF. This patent also discloses processes for the preparation of 3-FTHF by contacting 2,5-dihydrofuran with synthesis gas comprising carbon monoxide and hydrogen in the presence of a rhodium-phosphorus catalyst system according to known hydroformylation procedures. U.S. Pat. No. 5,945,549 discloses a process for the recovery of an aqueous solution of 2- and 3-formyltetrahydrofurans (FTHF's) produced by the rhodium-catalyzed hydroformylation of 2,5-dihydrofuran wherein the FTHF's are recovered as an equilibrium mixture of 2- and 3-FTHF and their hydrates (2- and 3-[di(hydroxy)methyl]tetrahydrofuran) from a hydroformylation product solution comprising a rhodium catalyst, 2- and 3-FTHF and an organic hydroformylation solvent. These known methods for the production of MeTHF starting with 3-FTHF suffer from one or more disadvantages such as low reaction yields, the co-production of other compounds, which have limited utility and/or the use of corrosive acids.
BRIEF SUMMARY OF THE INVENTION
A process has been developed for the conversion of HOMeTHF to MeTHF by contacting HOMeTHF with hydrogen in the presence of certain acidic, supported catalysts. In its broader aspects, the present invention provides a process for the preparation of MeTHF which comprises contacting HOMeTHF with hydrogen in the presence of an acidic, supported catalyst comprising a Group VIII metal such as nickel, cobalt, platinum, palladium, and the like on a catalyst support material under hydrogenation conditions of temperature and pressure.
The MeTHF produced in accordance with the present invention is useful as an industrial solvent and, more importantly, as a monomer in the manufacture of polymers such as elastomers. MeTHF is used extensively as a co-monomer for elastomers giving modified glass transition temp
Beavers William Anthony
Ignatchenko Alexey Victorovitch
Liu Zhufang
Blake Michael J.
Eastman Chemical Company
Graves, Jr. Bernard J.
Trinh Ba K.
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