Production of 2,2,4,4-tetramethylcyclobutane-1,3-diol from secondary alcohols and 2,2,4,4-tetramethylcyclobutanedione using homogeneous catalysts

Abstract

Disclosed is a method for preparing 2,2,4,4-tetramethylcyclobutane-1,3-diol by reacting 2,2,4,4-tetramethylcyclobutanedione with a secondary alcohol in the presence of a transfer hydrogenation catalyst.

Description

Technical Field

[0001] This disclosure generally relates to a homogeneous catalytic method for preparing 2,2,4,4-tetramethylcyclobutane-1,3-diol (TMCD) by reacting 2,2,4,4-tetramethylcyclobutanedione (dione) with a secondary alcohol. Background Technology

[0002] Conventionally, 2,2,4,4-tetramethylcyclobutane-1,3-diol (TMCD) can be produced by hydrogenating 2,2,4,4-tetramethylcyclobutanedione (diketone) using a heterogeneous catalyst.

[0003] In this conventional method, TMCD can be produced by (i) converting isobutyric acid to isobutyric anhydride, (ii) converting isobutyric anhydride to a diketone, and (iii) hydrogenating the diketone to TMCD.

[0004] Hydrogen is required in this conventional method. This method operates at relatively high hydrogen pressure and is subject to the generation of many byproducts, some of which are generated by acid-catalyzed ring-opening of cyclobutane during the hydrogenation process.

[0005] This disclosure presents a novel method using diketones and secondary alcohols as feedstocks to selectively reduce diketones in a transfer hydrogenation (TH) reaction using a ruthenium-containing homogeneous catalyst, simultaneously producing ketones. In contrast, conventional TH heterogeneous catalysts do not promote this conversion.

[0006] This novel hydrogenation (TH) method provides an efficient alternative to traditional hydrogenation (using H2) for the conversion of diketones to TMCD. This new method offers the following benefits: (1) it is inherently safer (low pressure and no H2 is used, which poses an explosion hazard), (2) it saves costs due to reduced H2 usage, (3) it has lower associated capital costs, and (4) it produces significantly fewer byproducts and therefore higher yields. The reduced byproducts significantly simplify TMCD purification, requiring less purification.

[0007] This disclosure addresses these unmet needs, as well as other needs, as will become apparent from the following description and the appended claims. Summary of the Invention

[0008] The method disclosed herein is as described in the appended claims.

[0009] One embodiment of this disclosure is a method for producing 2,2,4,4-tetramethylcyclobutane-1,3-diol, comprising:

[0010] (i) In the presence of a transfer hydrogenation catalyst, 2,2,4,4-tetramethylcyclobutanedione is contacted with a secondary alcohol to produce 3-hydroxy-2,2,4,4-tetramethylcyclobutanone (ketol) and the corresponding ketone derived from said secondary alcohol; and

[0011] (ii) In the presence of a transfer hydrogenation catalyst, 3-hydroxy-2,2,4,4-tetramethylcyclobutanone is contacted with a secondary alcohol to produce 2,2,4,4-tetramethylcyclobutane-1,3-diol and the corresponding ketone derived from the secondary alcohol, wherein the ketone is optionally removed by reactive distillation.

[0012] In one implementation, the transfer hydrogenation catalyst is a ruthenium complex.

[0013] In one embodiment, the transfer hydrogenation catalyst is H2Ru(PPh3)4 or Ru3(CO). 12 One or more of (Ar4C4CO)Ru(CO)3 and (Ar4C4CO)2H(μ-H)(CO)4Ru2

[0014] The general formula for (Ar4C4CO)Ru(CO)3 is as follows:

[0015]

[0016] And Ar is represented by the following general formula:

[0017]

[0018] And the groups R are the same or different, selected from H, methyl, ethyl, or straight-chain or branched alkyl containing 3 to 10 carbon atoms, substituted or unsubstituted aryl, carbonyl groups such as ester or amide groups having 2 to 12 carbon atoms, amino groups having 2 to 12 carbon atoms, alkoxy groups having 3 to 10 carbon atoms, nitrile, fluorine, trifluoromethyl or fluorinated hydrocarbon groups such as perfluorobutyl or pentafluorophenyl;

[0019] Furthermore, (Ar4C4CO)2H(μ-H)(CO)4Ru2 is represented by the following general formula:

[0020]

[0021] And Ar is represented by the following general formula:

[0022]

[0023] And the groups R may be the same or different, selected from H, methyl, ethyl, or straight-chain or branched alkyl containing 3 to 10 carbon atoms, substituted or unsubstituted aryl, carbonyl groups such as ester or amide groups having 2 to 12 carbon atoms, amino groups having 2 to 12 carbon atoms, alkoxy groups having 3 to 10 carbon atoms, nitrile, fluorine, trifluoromethyl or fluorinated hydrocarbon groups such as perfluorobutyl or pentafluorophenyl.

[0024] In one embodiment, the transfer hydrogenation catalyst is selected from (Ph4C4CO)2H(μ-H)(CO)4Ru2, [(4-ClC6H4)4C4CO]2H(μ-H)(CO)4Ru2, [2,5-(C6H4)2-3,4-(4-MeOC6H4)2C4CO]2H(μ-H)(CO)4Ru2 or [2,5-(C6H4)2-3,4-(4-FC6H4)2C4CO]2H(μ-H)(CO)4Ru2.

[0025] In one embodiment, the transfer hydrogenation catalyst is a Shvo catalyst or ((Ph4C4CO)2H(μ-H)(CO)4Ru2).

[0026] In one embodiment, the secondary alcohol and the corresponding ketone are one or more of the following: propan-2-ol and propan-2-one, butan-2-ol and butan-2-one, penta-2-ol and penta-2-one, 3-methylbutan-2-ol and 3-methylbutan-2-one, penta-3-ol and penta-3-one, hexan-2-ol and hexan-2-one, 4-methylpentan-2-ol and 4-methylpentan-2-one, 3-methylpentan-2-ol and 3-methylpentan-2-one, 3,3-dimethylbutan-2-ol and 3,3-dimethylbutan-2-one, hexan-3-ol and hexan-3-one, 2-methylpentan-3-ol and 2-methylpentan-3-one, and cyclohexanol and cyclohexanone.

[0027] In one embodiment, the secondary alcohol and the corresponding ketone are isopropanol and acetone.

[0028] In one embodiment, the conversion of 2,2,4,4-tetramethylcyclobutanedione (dione) is at least 50%, or at least 70%, or at least 90%.

[0029] In one embodiment, the selectivity for 2,2,4,4-tetramethylcyclobutane-1,3-diol (TMCD) is at least 30%, or at least 60%. Attached Figure Description

[0030] Figure 1 This is the GC / MS chromatogram of the reaction product.

[0031] Figure 2The TH kinetics study was conducted at 150°C. (Note: There was a 12-minute heating period before sampling at t=0 minutes; see Example 4 in the Experimental Section).

[0032] Figure 3 The TH kinetics were studied at 100°C. (Note: There was a 12-minute heating period before sampling at t=0 minutes). The cis / trans ratio of TMCD remained at approximately 1.3 during the reaction (see Example 5 in the Experimental Section). Detailed Implementation

[0033] In this disclosure, it has been found that ruthenium-containing homogeneous catalysts can be used to catalyze the transfer hydrogenation (TH) reaction between diketones and secondary alcohols to highly selectively reduce diketones while simultaneously producing the corresponding ketones.

[0034] In one embodiment, this disclosure provides a method for preparing 2,2,4,4-tetramethylcyclobutane-1,3-diol. The method comprises contacting 2,2,4,4-tetramethylcyclobutanedione with a secondary alcohol in the presence of a ruthenium-containing homogeneous catalyst or a Shvo catalyst.

[0035] In one embodiment of this disclosure, Shvo catalyst 1 has been found to be useful for catalyzing a transfer hydrogenation (TH) reaction between 2,2,4,4-tetramethylcyclobutanedione (diketone) and isopropanol (iPrOH) to reduce the diketone with high selectivity while co-producing acetone, Equations 1-2.

[0036]

[0037] In one embodiment of this disclosure, the method is as follows:

[0038] (ia) Using isopropanol as a hydrogen donor, 2,2,4,4-tetramethylcyclobutanedione is hydrogenated by transfer to produce ketools and acetone, and

[0039] (ii.a) TMCD and acetone are produced by transferring hydrogenated ketols by adding isopropanol.

[0040] In one embodiment of this disclosure, the method requires the following steps:

[0041] (iii) Using a secondary alcohol as a hydrogen donor, 2,2,4,4-tetramethylcyclobutanedione is hydrogenated by transfer to produce TMCD and the corresponding ketone.

[0042] In one embodiment of this disclosure, a list of possible secondary alcohols and corresponding ketones is provided below.

[0043]

[0044] Boiling points of alcohols, their corresponding ketones, and the difference between their boiling points (Δ).

[0045] One embodiment of this disclosure is a method for producing 2,2,4,4-tetramethylcyclobutane-1,3-diol, comprising:

[0046] (i) In the presence of a transfer hydrogenation catalyst, 2,2,4,4-tetramethylcyclobutanedione is contacted with a secondary alcohol to produce 3-hydroxy-2,2,4,4-tetramethylcyclobutane and the corresponding ketone derived from said secondary alcohol; and

[0047] (ii) In the presence of a transfer hydrogenation catalyst, 3-hydroxy-2,2,4,4-tetramethylcyclobutanone is contacted with a secondary alcohol to produce 2,2,4,4-tetramethylcyclobutane-1,3-diol and the corresponding ketone derived from the secondary alcohol, wherein the ketone is optionally removed by reactive distillation.

[0048] In one implementation, the transfer hydrogenation catalyst is a ruthenium complex.

[0049] In one embodiment, the transfer hydrogenation catalyst is H2Ru(PPh3)4 or Ru3(CO). 12 One or more of (Ar4C4CO)Ru(CO)3 and (Ar4C4CO)2H(μ-H)(CO)4Ru2

[0050] The general formula for (Ar4C4CO)Ru(CO)3 is as follows:

[0051]

[0052] And Ar is represented by the following general formula:

[0053]

[0054] And the groups R are the same or different, selected from H, methyl, ethyl, or straight-chain or branched alkyl containing 3 to 10 carbon atoms, substituted or unsubstituted aryl, carbonyl groups such as ester or amide groups having 2 to 12 carbon atoms, amino groups having 2 to 12 carbon atoms, alkoxy groups having 3 to 10 carbon atoms, nitrile, fluorine, trifluoromethyl or fluorinated hydrocarbon groups such as perfluorobutyl or pentafluorophenyl;

[0055] Furthermore, (Ar4C4CO)2H(μ-H)(CO)4Ru2 is represented by the following general formula:

[0056]

[0057] And Ar is represented by the following general formula:

[0058]

[0059] And the groups R may be the same or different, selected from H, methyl, ethyl, or straight-chain or branched alkyl containing 3 to 10 carbon atoms, substituted or unsubstituted aryl, carbonyl groups such as ester or amide groups having 2 to 12 carbon atoms, amino groups having 2 to 12 carbon atoms, alkoxy groups having 3 to 10 carbon atoms, nitrile, fluorine, trifluoromethyl or fluorinated hydrocarbon groups such as perfluorobutyl or pentafluorophenyl.

[0060] In one embodiment, the transfer hydrogenation catalyst is selected from (Ph4C4CO)2H(μ-H)(CO)4Ru2, [(4-ClC6H4)4C4CO]2H(μ-H)(CO)4Ru2, [2,5-(C6H4)2-3,4-(4-MeOC6H4)2C4CO]2H(μ-H)(CO)4Ru2 or [2,5-(C6H4)2-3,4-(4-FC6H4)2C4CO]2H(μ-H)(CO)4Ru2.

[0061] In one embodiment, the transfer hydrogenation catalyst is ((Ph4C4CO)2H(μ-H)(CO)4Ru2).

[0062] In one embodiment, the secondary alcohol and the corresponding ketone are one or more of the following: propan-2-ol and propan-2-one, butan-2-ol and butan-2-one, penta-2-ol and penta-2-one, 3-methylbutan-2-ol and 3-methylbutan-2-one, penta-3-ol and penta-3-one, hexan-2-ol and hexan-2-one, 4-methylpentan-2-ol and 4-methylpentan-2-one, 3-methylpentan-2-ol and 3-methylpentan-2-one, 3,3-dimethylbutan-2-ol and 3,3-dimethylbutan-2-one, hexan-3-ol and hexan-3-one, 2-methylpentan-3-ol and 2-methylpentan-3-one, and cyclohexanol and cyclohexanone. In one embodiment, the secondary alcohol and the corresponding ketone are isopropanol and acetone.

[0063] In one embodiment, the conversion of 2,2,4,4-tetramethylcyclobutanedione is at least 50%, or at least 70%, or at least 90%.

[0064] In one embodiment, the selectivity of 2,2,4,4-tetramethylcyclobutane-1,3-diol is at least 30% or at least 60%.

[0065] In one embodiment, the method of this disclosure includes contacting a diketone with a secondary alcohol at a molar ratio of alcohol to diketone greater than 1:1 and at most 50:1, under conditions of efficient diol production, in the presence of a ruthenium-containing homogeneous catalyst.

[0066] In one embodiment, the method of this disclosure is carried out in a molar ratio of isopropanol to 2,2,4,4-tetramethylcyclobutanedione greater than 1:1 and at most 50:1.

[0067] In one embodiment, an excess of secondary alcohol or isopropanol is used to maximize the conversion of the diketone to TMCD. In some embodiments, the molar ratio of isopropanol to 2,2,4,4-tetramethylcyclobutanedione includes 1:1 to 50:1, 2:1 to 25:1, 3:1 to 25:1, 4:1 to 25:1, 8:1 to 25:1, 12:1 to 25:1, 16:1 to 25:1, 2:1 to 24:1, 3:1 to 24:1, 4:1 to 24:1, 8: 1 to 24:1, 12:1 to 24:1, 16:1 to 24:1, 2:1 to 20:1, 3:1 to 20:1, 4:1 to 20:1, 8:1 to 20:1, 12:1 to 20:1, 16:1 to 20:1, 2:1 to 16:1, 3:1 to 16:1, 4:1 to 16:1, 8:1 to 16:1 and 12:1 to 16:1.

[0068] In one embodiment, the secondary alcohol used in the methods of this disclosure is not particularly limited. For example, in one embodiment, the secondary alcohol may be one or more of propan-2-ol, butan-2-ol, penta-2-ol, 3-methylbutan-2-ol, penta-3-ol, hexan-2-ol, 4-methylpentan-2-ol, 3-methylpentan-2-ol, 3,3-dimethylbutan-2-ol, hexan-3-ol, 2-methylpentan-3-ol, or cyclohexanol. In one embodiment, the secondary alcohol may have 1 to 12 carbon atoms and may be straight-chain, branched, alicyclic, or aromatic. In one embodiment, suitable secondary alcohols include n-propanol, isopropanol, n-butanol, isobutanol, and 2-ethylhexanol. In one embodiment, the alcohol is isobutanol or isobutanol. In one embodiment, the alcohol is isopropanol or isobutanol.

[0069] In one embodiment, the method of this disclosure is carried out in the presence of a transfer hydrogenation catalyst. In one embodiment, a ruthenium complex is used as the catalyst. In one embodiment, the catalyst is Shvo catalyst 1.

[0070] A "ruthenium complex" is a complex containing one or more ruthenium atoms and one or more ligands linked by direct metal-ligand bonding. There are no particular limitations on the form or oxidation state of the ruthenium atoms, or the type and number of groups acting as ligands. Examples of such ligands include carbon monoxide, phosphine, hydrides, and substituted cyclopentadienones. Substituted cyclopentadienones are preferred ligands.

[0071] In one implementation, suitable examples of RuCC include H2Ru(PPh3)4 and Ru3(CO). 12, (Ar4C4CO)Ru(CO)3 and (Ar4C4CO)2H(μH)(CO)4Ru2, (Ph4C4CO)Ru(CO)3, [(4-ClC6H4)4C4CO]Ru(C O)3, [2,5-(C6H4)2-3,4-(4-MeOC6H4)2C4CO]Ru(CO)3, [2,5-(C6H4)2-3,4-(4-FC6H4)2C4CO]Ru( CO)3, (Ph4C4CO)2H(μ-H)(CO)4Ru2, [(4-ClC6H4)4C4CO]2H(μ-H)(CO)4Ru2, [2,5-(C6H4)2-3,4-(4-MeOC6H4)2C4CO]2H(μ-H)(CO)4Ru2, and [2,5-(C6H4)2-3,4-(4-FC6H4)2C4CO]2H(μ-H)(CO)4Ru2. These compounds can be synthesized using well-known methods (e.g., N. Menashe et al., Organometallics, Vol. 10, p. 3885 (1991)).

[0072] In one implementation, (Ar4C4CO)Ru(CO)3 is represented by the following general formula:

[0073]

[0074] And Ar is represented by the following general formula:

[0075]

[0076] And the groups R are the same or different, selected from H, methyl, ethyl, or straight-chain or branched alkyl containing 3 to 10 carbon atoms, substituted or unsubstituted aryl, carbonyl groups such as ester or amide groups having 2 to 12 carbon atoms, amino groups having 2 to 12 carbon atoms, alkoxy groups having 3 to 10 carbon atoms, nitrile, fluorine, trifluoromethyl or fluorinated hydrocarbon groups such as perfluorobutyl or pentafluorophenyl;

[0077] In one embodiment, (Ar4C4CO)2H(μH)(CO)4Ru2 is represented by the following general formula:

[0078]

[0079] And Ar is represented by the following general formula:

[0080]

[0081] And the groups R may be the same or different, selected from H, methyl, ethyl, or straight-chain or branched alkyl containing 3 to 10 carbon atoms, substituted or unsubstituted aryl, carbonyl groups such as ester or amide groups having 2 to 12 carbon atoms, amino groups having 2 to 12 carbon atoms, alkoxy groups having 3 to 10 carbon atoms, nitrile, fluorine, trifluoromethyl or fluorinated hydrocarbon groups such as perfluorobutyl or pentafluorophenyl.

[0082] In one embodiment, the amount of catalyst used may be 10 relative to the diketone. -7 : 1 to 1:1 (molar ratio). In one embodiment, the amount of catalyst used can be 10 relative to the diketone. -3 The molar ratio is 1 to 0.01:1. In one embodiment, the catalyst concentration is about 0.001 mol% to 10 mol% based on the diketone concentration. In one embodiment, the catalyst concentration is about 0.001 mol% to 9 mol%, or about 0.001 mol% to 5 mol%, or about 0.001 mol% to about 1 mol%, or about 0.01 mol% to about 10 mol%, or about 0.01 mol% to about 5 mol%, or about 0.01 mol% to about 1 mol%, or about 0.1 mol% to about 10 mol%, or about 0.1 mol% to about 5 mol%, or about 0.1 mol% to about 1 mol%.

[0083] After the reaction, the catalyst can be separated from the product by distillation, extraction, adsorption or other conventional methods and then reused.

[0084] The method disclosed herein can be carried out without a solvent. However, if RuCC has low solubility in a reaction medium containing diketones and alcohols, the reaction can be carried out in a suitable solvent to dissolve the RuCC, or otherwise, as required. Examples of suitable solvents include hydrocarbons, such as hexane, benzene, and toluene; ethers, such as diethyl ether, dimethoxyethane, tetrahydrofuran, and dioxane; and esters, such as ethyl acetate, butyl acetate, and 2-ethylhexyl acetate.

[0085] Typically, the reaction is carried out by introducing a diketone, a secondary alcohol, and a catalyst into a vessel, followed by mixing the contents. In one embodiment, the reaction is carried out by introducing a diketone, a secondary alcohol, and a transfer hydrogenation catalyst into a vessel, followed by mixing the contents. In one embodiment, the reaction temperature can be 50 to 300°C, or 50 to 200°C, or 60 to 200°C, or 70 to 200°C, or 80 to 200°C, or 90 to 200°C, or 100 to 200°C, or 150 to 200°C, or 50 to 150°C, or 100 to 150°C, or 50 to 100°C. In one embodiment, the method temperature range is from about 50°C to about 300°C. In another embodiment, the method temperature range is from about 50°C to about 200°C.

[0086] The reaction pressure is not particularly limited. The reaction can be carried out at atmospheric pressure or under high pressure. In one embodiment, the reaction is carried out in an inert atmosphere. In one embodiment, the reaction is carried out under nitrogen pressure to keep the secondary alcohol liquid. In one embodiment, the reaction is carried out under an inert atmosphere pressure of at least 200 psig (to keep the secondary alcohol liquid).

[0087] In one embodiment, the reaction time depends on the reaction temperature and catalyst concentration, and the reaction time can be, for example, 0.1 to 10 hours, or 0.5 to 3 hours, or 5 minutes to 5 hours, or 5 minutes to 4 hours, or 5 minutes to 3 hours, or 5 minutes to 2 hours, or 5 minutes to 1 hour, or 5 minutes to 30 minutes, or 30 minutes to 5 hours, or 30 minutes to 4 hours, or 30 minutes to 2 hours, or 30 minutes to 1 hour.

[0088] In one embodiment, the method of this disclosure is carried out in the presence of a transfer hydrogenation catalyst, under conditions that effectively produce the corresponding ketone and TMCD, at a molar ratio of isopropanol to diketone greater than 1:1 and at most 50:1. In one embodiment, the concentration of isopropanol to diketone is from 1:1 to 40:1 molar ratio. In one embodiment, the concentration of isopropanol to diketone is from 1:1 to 30:1 molar ratio. In one embodiment, the concentration of isopropanol to diketone is from 1:1 to 20:1 molar ratio. In one embodiment, the concentration of isopropanol to diketone is from 1:1 to 10:1 molar ratio. In one embodiment, the concentration of isopropanol to diketone is from 1:1 to 5:1 molar ratio. In one embodiment, the concentration of isopropanol to diketone is from 1:1 to 2.5:1 molar ratio.

[0089] In one embodiment, the method of this disclosure is capable of converting diketones with a conversion rate of at least 50%; or at least 55%, or at least 60%, or at least 65%, or at least 70%, or at least 75%, or at least 80%, or at least 85%, or at least 90%, or at least 95%. In one embodiment, the diketone conversion rate is at least 70%. In one embodiment, the diketone conversion rate is at least 80%. In one embodiment, the diketone conversion rate is at least 90%. In some embodiments, the conversion rate is determined by the following equation:

[0090]

[0091] In some embodiments, the method of this disclosure may have a selectivity for TMCD of at least 30%, or at least 40%, or at least 50%, or at least 60%, or at least 70%, or at least 80%, or at least 90%, or at least 95%. In one embodiment, the selectivity for TMCD is at least 30%. In one embodiment, the selectivity for TMCD is at least 50%. In one embodiment, the selectivity for TMCD is at least 60%.

[0092] Example 1 illustrates the sensitivity of diketones to heterogeneous catalysis. A TH reaction of iPrOH and a diketone was attempted in the presence of a 7 wt% Ru / C (BASF) heterogeneous catalyst. The experiment was conducted at 165 °C for 3 hours, and samples were taken. GC analysis (see Table 1, Example 1) showed that only very small amounts of the desired ketol and / or TMCD products were formed. The major product of this reaction was diisopropyl ketone (DIPK), which was clearly formed by the decarbonylation reaction of the diketone reactant catalyzed by a ruthenium catalyst (Equation 3).

[0093]

[0094] In one embodiment of the TH reaction of a diketone with iPrOH (1:4 molar ratio) using a homogeneous catalyst, Shvo catalyst 1 was used. The experiment was conducted at 150 °C for 3 hours using 0.1 mol% catalyst (relative to the diketone). After 3 hours of reaction, the reaction products were analyzed using gas chromatography-mass spectrometry (GC-MS). Chromatogram ( Figure 1 Example 3 shows that the reaction proceeds directly to produce a mixture of acetone and ketools with the TMCD product (Equation 4). Trace amounts of isobutyric acid in the final reaction product were also analyzed using a ppm GC method. The isobutyric acid level in the final reaction product was below the detection limit (50 ppm).

[0095]

[0096] TH kinetics were studied at 150 °C using iPrOH and diketone feed in a 4:1 molar ratio and 0.1 mol% Shvo catalyst. The reaction reached equilibrium in less than 1 hour. Figure 2 (Example 4). Because the reaction is equilibrium-limited, the conversion can be improved by removing volatile acetone products (reactive distillation). The combined selectivity for keto-alcohol and TMCD products remains very high during the reaction (Table 3, Example 4). Furthermore, the selectivity for isopropanol to acetone remains above 97%.

[0097] When TH kinetic studies were conducted at a lower temperature, i.e., 100°C, using the same conditions as above (molar ratio of iPrOH to diketone feed of 4:1, Shvo catalyst loading of 0.1 mol%), the reaction reached equilibrium in approximately 2 hours. Figure 3 (Example 5). This shows that the TH reaction can be carried out at a reasonable rate at a lower temperature, which will benefit the catalyst lifetime.

[0098] This disclosure includes and expressly contemplates any and all combinations of the embodiments, features, characteristics, parameters, and / or scopes disclosed herein. In other words, this disclosure may be defined by any combination of the embodiments, features, characteristics, parameters, and / or scopes mentioned herein.

[0099] As used in this text, the indefinite articles “one” and “a / a kind” refer to one or more / a variety of things, unless the context clearly indicates otherwise. Similarly, the singular form of a noun includes its plural form, and vice versa, unless the context clearly indicates otherwise.

[0100] As used herein, the term “and / or” when used in a list of two or more items means that any one of the listed items may be used alone, or any combination of two or more of the listed items may be used. For example, if a composition is described as containing components A, B and / or C, the composition may contain A alone; B alone; C alone; a combination of A and B; a combination of A and C; a combination of B and C; or a combination of A, B and C.

[0101] Although attempts have been made to be precise, the numerical values ​​and ranges described herein should be considered approximate (even when not limited by the term "about"). These values ​​and ranges may differ from their specified values ​​depending on the desired properties sought to be obtained by this disclosure and the variations arising from standard deviations present in the measurement techniques. Furthermore, the ranges described herein are intended and specifically anticipated to include all subranges and values ​​within the said ranges. For example, a range of 50 to 100 is intended to describe and include all values ​​within that range, including subranges such as 60 to 90 and 70 to 80.

[0102] All references cited herein, including both patent and non-patent literature, are incorporated herein in their entirety for reference. Where any incorporated subject matter contradicts any disclosure herein, the disclosure herein shall prevail over the incorporated content.

[0103] This disclosure may be further illustrated by the following embodiments of its preferred implementation, but it should be understood that these embodiments are included for illustrative purposes only and are not intended to limit the scope of this disclosure.

[0104] Experimental Section

[0105] Materials: Isopropanol and toluene were obtained from Aldrich. Shvo catalyst was obtained from Strem. 7 wt% Ru / C catalyst was obtained from BASF.

[0106] Gas chromatography. The method sample was analyzed using an Agilent 6890 gas chromatograph equipped with a split / heated injector (250°C) and a thermocouple detector (250°C). A capillary column (30 m × 0.32 mm ID) coated with a .25 μm film thickness of (50% methyl, 50% phenylsiloxane) was used (e.g., DB-Wax or equivalent). Helium was used as the carrier gas, with an initial column top pressure of 7.42 psi and an initial column flow rate of 1.56 mL / min, while maintaining a carrier gas linear velocity of 45 cm / s throughout the oven temperature program. The column temperature was programmed as follows: an initial oven temperature of 40°C was set and held for 3 minutes, followed by ramping the oven to 200°C at 8°C / min and holding at 200°C for 2 minutes (total run time 25 minutes). 0.5 μL of the prepared sample solution was injected at a split ratio of 75:1. EZ-Chrom Elite chromatographic data system software was used for data acquisition and processing. Sample preparation was performed by weighing 0.1 g (accurate to 0.1 mg) of sample into a GC vial and adding 1.0 mL of ISTD solution (1% by volume diethylene glycol dimethyl ether in acetonitrile). The GC composition of this method is shown below.

[0107]

[0108] The chemical structure of GC components was analyzed using this method.

[0109] Gas chromatography (ppm isobutyric acid method): The method sample was analyzed using an Agilent 6890 gas chromatograph equipped with a split / heated injector (250°C) and a thermocouple detector (250°C). A capillary column (30 m × 0.32 mm ID) coated with a .25 μm film thickness (50% vial. methyl, 50% phenylsiloxane) was used (e.g., DB-Wax or equivalent). Helium was used as the carrier gas, with an initial column top pressure of 7.42 psi and an initial column flow rate of 1.56 mL / min, while maintaining a constant carrier gas linear velocity of 45 cm / s throughout the oven temperature program. The column temperature was programmed as follows: an initial oven temperature of 40°C was set and held for 3 minutes, followed by ramping the oven to 200°C at 8°C / min and holding at 200°C for 2 minutes (total run time 25 minutes). 0.5 μL of the prepared sample solution was injected at a split ratio of 75:1. EZ-Chrom Elite chromatographic data system software was used for data acquisition and data processing. Sample preparation was performed by weighing 0.1 g (accurate to 0.1 mg) of sample into a GC sample vial and adding 1.0 mL of ISTD solution (1% by volume diethylene glycol dimethyl ether in acetonitrile) to the GC.

[0110] Example

[0111] Example 1. 2.0 g (1.39 mmol) of 7 wt% Ru / C catalyst was charged into a 300 mL titanium autoclave equipped with a catalyst basket. Stainless steel packing was added on top of the catalyst to fill the basket. The autoclave was pressurized to 500 psig with N2 and then vented twice. 31.0 g (514.78 mmol) of iPrOH, 18.0 g (128.41 mmol) of diketone and 101.0 g of toluene were charged into the blowcase. The autoclave was equipped with a purging system, a rotor flow meter, a back pressure regulator (BPR), and a condenser. The BPR was set to 50 psig with N2, bypassing the blowcase. The manifold was purged three times with H2. The autoclave stirrer speed was set to 1000 rpm, and the autoclave was pressurized to 50 psig with H2. An H2 flow rate of 0.53 SCFH was established. Once the H2 flow is established, heat the autoclave to 180°C and maintain these conditions (180°C, 0.53 H2 flow rate) for 1 hour. While maintaining this condition for 1 hour, pressurize the pressure chamber with ~100 psig of N2, then close the inlet valve and heat the pressure chamber to 175°C. After maintaining this condition for 1 hour, stop the H2 flow, switch to N2 (purge the manifold three times with N2), and supply 500 sccm of N2 at 50 psig at 180°C for 1 hour. Once the pressure chamber and autoclave have reached the desired temperatures, pressurize the pressure chamber to 500 psig of N2. Equalize the pressures in the pressure chamber and autoclave, then separate the pressure chamber from the autoclave. Purge the material from the pressure chamber into the autoclave, allowing sufficient time for temperature equilibration to 165°C while stirring. Take a sample at t=0 and record the mass. Turn off the heating of the pressure chamber. Samples were taken at t = 15 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, and 180 minutes. After 3 hours, the autoclave was cooled to room temperature and the pressure was reduced. The results are shown in Table 1.

[0112] Table 1. Hydrogen transfer reaction of iPrOH and diketone. a

[0113] Time (hr) iPrOH Ketones cisTMCD transTMCD acetone diketone DIPK 0.25 19.80 0.00 0.20 0.15 0.01 0.34 12.14 0.5 19.70 0.00 0.31 0.20 0.02 0.35 12.03 1 19.59 0.00 0.56 0.39 0.02 0.34 11.73 1.5 19.28 0.00 0.00 0.55 0.03 0.33 11.42 2 19.12 0.00 0.00 0.73 0.04 0.36 11.19 3 18.43 0.00 0.00 1.13 0.05 0.34 11.19

[0114] a A 7 wt% Ru / C (BAsF) catalyst was used. iPrOH and a diketone were used as feed in a 4:1 molar ratio. The reaction was carried out at 165 °C. Results were reported as wt% by gas chromatography (see Example 1 in the Experimental Section).

[0115] Example 2. Example 1 was repeated at 120°C. The results are shown in Table 2. A diketone conversion of less than 4% was observed.

[0116] Table 2. Hydrogen transfer reaction of iPrOH and diketone. a

[0117] Time (hr) iPrOH Ketones cisTMCD transTMCD acetone DIPK diketone 0.25 20.81 0.33 0.02 0.02 0.10 0.010 12.02 0.5 20.64 0.44 0.02 0.02 0.12 0.011 11.83 1 20.55 0.62 0.02 0.02 0.12 0.012 11.70 1.5 20.04 0.74 0.02 0.02 0.12 0.013 11.56 2 20.38 0.84 0.02 0.02 0.13 0.014 11.47 3 20.44 0.86 0.02 0.02 0.13 0.014 11.35

[0118] a The reaction was carried out using a Ru / C (7wt%, BASF) catalyst and a 4:1 molar feed ratio of iPrOH:diketone. The reaction was conducted at 120 °C. Analysis was performed using gas chromatography, and results are reported in weight percent (see Example 2 in the Experimental Section).

[0119] Example 3. 20.0 g (332.1 mmol) iPrOH, 11.6 g (82.75 mmol) diketone, and 0.1 g (0.082 mmol) Shvo catalyst were charged into a 100 mL titanium autoclave. The autoclave was pressurized with approximately 100 psig of N2, and then vented twice. The autoclave was then pressurized again with 200 psig of N2, heated to 150 °C, and maintained at the reaction temperature for 3 hours. It was then cooled to room temperature and the pressure was reduced. The liquid products were analyzed by GC / MS chromatography and the ppm level isobutyric acid GC method. The results are shown in... Figure 1 middle.

[0120] Example 4. 60.0 g (996.3 mmol) of iPrOH, 34.8 g (248.25 mmol) of diketone (iPrOH to diketone molar ratio = 4.0:1.0), and 0.3 g (0.25 mmol) of Shvo catalyst were charged into a 300 mL titanium autoclave. The autoclave was pressurized with approximately 100 psig of N2, and then vented twice. The autoclave was then pressurized again with 200 psig of N2, heated to 150 °C, and maintained at the reaction temperature for 3 hours. Samples were taken and their masses recorded at t = 0. Samples were also taken at t = 15 min, 30 min, 60 min, 90 min, 120 min, and 180 min. After 3 hours, the autoclave was cooled to room temperature and the pressure was reduced. The samples were analyzed by gas chromatography. The conversion and selectivity are summarized in Table 3.

[0121] Table 3. Transfer hydrogenation reaction of isopropanol and diketone. a

[0122]

[0123] a A 4:1 molar ratio of iPrOH to diketone was used as the feed. The catalyst loading was 0.1 mol% shvo. Experiments were conducted at 150 °C. A 12-minute heating period was allowed before sampling at t=0 minutes. b Selectivity was calculated by dividing the number of moles of product in the liquid phase by the number of moles of reactants charged. The cis / trans ratio of TMCD remained at approximately 1.3 during the reaction (see Example 4 in the Experimental section).

[0124] Example 5. Example 4 was repeated at 100°C. The results are shown in... Figure 3 middle.

[0125] This disclosure has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications may be made within the spirit and scope of the invention.

Claims

1. A method for producing 2,2,4,4-tetramethylcyclobutane-1,3-diol, comprising: (i) In the presence of a transfer hydrogenation catalyst, 2,2,4,4-tetramethylcyclobutanedione is contacted with a secondary alcohol to produce 3-hydroxy-2,2,4,4-tetramethylcyclobutane and the corresponding ketone derived from said secondary alcohol; and (ii) In the presence of a transfer hydrogenation catalyst, 3-hydroxy-2,2,4,4-tetramethylcyclobutanone is contacted with a secondary alcohol to produce 2,2,4,4-tetramethylcyclobutane-1,3-diol and the corresponding ketone derived from the secondary alcohol, wherein the ketone is optionally removed by reactive distillation. The transfer hydrogenation catalysts mentioned above are H2Ru(PPh3)4 and Ru3(CO). 12 One or more of (Ar4C4CO)Ru(CO)3 and (Ar4C4CO)2H(μ-H)(CO)4Ru2, and The general formula for (Ar4C4CO)Ru(CO)3 is as follows: And Ar is represented by the following general formula: And the groups R may be the same or different, selected from H, methyl, ethyl, or straight-chain or branched alkyl containing 3 to 10 carbon atoms, substituted or unsubstituted aryl, groups containing carbonyl, amino having 2 to 12 carbon atoms, alkoxy, nitrile, fluorine or fluorinated hydrocarbon groups having 3 to 10 carbon atoms. Furthermore, (Ar4C4CO)2H(μ-H)(CO)4Ru2 is represented by the following general formula: And Ar is represented by the following general formula: And the groups R may be the same or different, selected from H, methyl, ethyl, or straight-chain or branched alkyl containing 3 to 10 carbon atoms, substituted or unsubstituted aryl, groups containing carbonyl, amino having 2 to 12 carbon atoms, alkoxy having 3 to 10 carbon atoms, nitriles, fluorine or fluorinated hydrocarbon groups.

2. The method according to claim 1, wherein the groups R are the same or different and are selected from ester groups or amide groups having 2 to 12 carbon atoms, perfluorobutyl groups or pentafluorophenyl groups.

3. The method according to claim 1, wherein group R is trifluoromethyl.

4. The method according to claim 1, wherein the transfer hydrogenation catalyst is selected from (Ph4C4CO)2H(μ-H)(CO)4Ru2, [(4-ClC6H4)4C4CO]2H(μ-H)(CO)4Ru2, [2,5-(C6H4)2-3,4-(4-MeOC6H4)2C4CO]2H(μ-H)(CO)4Ru2 or [2,5-(C6H4)2-3,4-(4-FC6H4)2C4CO]2H(μ-H)(CO)4Ru2.

5. The method according to claim 1, wherein the transfer hydrogenation catalyst is ((Ph4C4CO)2H(μ-H)(CO)4Ru2).

6. The method according to claim 1, wherein the secondary alcohol and the corresponding ketone are one or more selected from propylene-2-ol and propylene-2-one, butan-2-ol and butan-2-one, penta-2-ol and penta-2-one, 3-methylbutan-2-ol and 3-methylbutan-2-one, penta-3-ol and penta-3-one, hexan-2-ol and hexan-2-one, 4-methylpentan-2-ol and 4-methylpentan-2-one, 3-methylpentan-2-ol and 3-methylpentan-2-one, 3,3-dimethylbutan-2-ol and 3,3-dimethylbutan-2-one, hexan-3-ol and hexan-3-one, 2-methylpentan-3-ol and 2-methylpentan-3-one, and cyclohexanol and cyclohexanone.

7. The method according to claim 1, wherein the secondary alcohol and the corresponding ketone are isopropanol and acetone.

8. The method according to claim 1, wherein the conversion of 2,2,4,4-tetramethylcyclobutanedione is at least 50%.

9. The method according to claim 1, wherein the conversion of 2,2,4,4-tetramethylcyclobutanedione is at least 70%.

10. The method according to claim 1, wherein the conversion of 2,2,4,4-tetramethylcyclobutanedione is at least 90%.

11. The method of claim 1, wherein the selectivity of 2,2,4,4-tetramethylcyclobutane-1,3-diol is at least 30%.

12. The method of claim 1, wherein the selectivity of 2,2,4,4-tetramethylcyclobutane-1,3-diol is at least 60%.

13. The method according to claim 1, wherein the method temperature range is 50°C to 300°C.

14. The method according to claim 1, wherein the method temperature range is 50°C to 200°C.

15. The method of claim 1, wherein the method is carried out under a nitrogen pressure of at least 200 psig to keep the secondary alcohol in a liquid state.

16. The method of claim 1, wherein the method time is from 5 minutes to 5 hours.

17. The method of claim 1, wherein the catalyst concentration is from 0.001 mol% to 10 mol% based on the concentration of 2,2,4,4-tetramethylcyclobutanedione.

18. The method according to claim 1, wherein the concentrations of the secondary alcohol and 2,2,4,4-tetramethylcyclobutanedione are in a molar ratio of 1:1 to 50:

1.

19. The method according to claim 1, wherein the concentrations of the secondary alcohol and 2,2,4,4-tetramethylcyclobutanedione are in a molar ratio of 1:1 to 20:

1.

20. The method according to claim 1, wherein the concentrations of the secondary alcohol and 2,2,4,4-tetramethylcyclobutanedione are in a molar ratio of 1:1 to 10:

1.

21. The method according to claim 1, wherein the concentrations of the secondary alcohol and 2,2,4,4-tetramethylcyclobutanedione are in a molar ratio of 1:1 to 5:1.

Images