Methylcyclohexane as allyl alcohol hydroformylation solvent
Patent Information
- Authority / Receiving Office
- TW · TW
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-03-24
- Publication Date
- 2022-10-16
Abstract
Description
[Technical Field]
[0001] Previous related applications
[0002] This application claims priority to U.S. Provisional Patent No. 63 / 172,763, filed April 9, 2021, the entire contents of which are incorporated herein by reference. Federally Funded Research Statement
[0003] None. Refer to the microfilm appendix.
[0004] None.
[0005] This invention relates generally to the generation of hydroxyl compounds, and more specifically to the hydrogenation of allyl alcohol for the generation of 4-hydroxybutyraldehyde. [Previous Technology]
[0006] 1,4-Butanediol (BDO) is an important raw material for the manufacture of plastics, elastic fibers, and films. BDO is used as an intermediate in common industrial and commercial products, such as polyether glycols, urethane polymers, and polyester polymers. A significant amount of BDO is also used to manufacture γ-butyrolactone (GBL), which is used in electronics, pharmaceuticals, agrochemicals, and high-performance polymers. This diverse range of applications leads to high demand for BDO.
[0007] BDO can be produced in several ways. BDO can be derived from tetrahydrofuran, succinic acid, maleic anhydride, and other four-carbon organic compounds, but this method is not economically attractive. Another method for producing BDO involves reacting formaldehyde with acetylene to produce 1,4-butynediol as an intermediate, which is then hydrogenated to the desired BDO product. See, for example, U.S. Patents 4,064,145; 4,215,077; 4,238,419; 4,678,857; 5,290,743 and 7,612,241.
[0008] A more economically attractive method of production involves the hydromethoxylation of allyl alcohol. The hydromethoxylation of olefins is well-known in noble metal and phosphine compound catalyst systems. The hydromethoxylation of allyl alcohol yields 4-hydroxybutyraldehyde (HBA) as an intermediate, which is subsequently hydrogenated to BDO. A disadvantage of the hydromethoxylation method is that, in addition to the desired linear HBA product, other coproducts or byproducts are formed. The hydromethoxylation of allyl alcohol produces several 3-hydroxy-2-methylpropanal (HMPA) branched coproducts and C3 byproducts, such as n-propanol and propanal (PA).
[0009] All aldehyde products must be extracted from the hydromethionization product stream and hydrogenated. Although HMPA can be hydrogenated to produce 2-methyl-1,3-propanediol (MPD), a useful material, the MPD co-product reduces the yield of BDO from HBA. The formation of C3 byproducts effectively represents another yield loss in this process, which can have a seriously adverse impact on the economics of the method. Furthermore, the hydrogenation catalyst used to convert aldehydes to hydroxyl compounds tends to deactivate over time.
[0010] Therefore, improvements are needed in the hydromethionization process to increase BDO yield while reducing less desirable coproducts / byproducts. Ideally, these improvements would also extend the lifetime of the hydromethionization catalyst to further increase BDO yield. [Summary of the Invention]
[0011] This invention relates to an improved hydromethionization method for producing 4-hydroxybutyraldehyde. Specifically, a hydromethionization method utilizing a catalyst system incorporating a rhodium complex and a substituted or unsubstituted diphosphine ligand has been modified to use methylcyclohexane as the reaction solvent. Compared to 3-hydroxy-2-methylpropionaldehyde, this particular reaction solvent unexpectedly increases the reaction rate of the hydromethionization process while maintaining a high yield of 4-hydroxybutyraldehyde. Furthermore, it has been found that methylcyclohexane is immiscible with the aldol product, which reduces the amount of water required in subsequent extraction steps, allowing for greater recovery of the desired product. These improvements can reduce method costs due to the lower rhodium requirement in the catalyst system and the reduced water requirement in the extraction steps.
[0012] The method of the present invention includes any one or any combination of the following embodiments:
[0013] A method for producing 4-hydroxybutyraldehyde, comprising reacting allyl alcohol with carbon monoxide and hydrogen in the presence of a methylcyclohexane reaction solvent and a catalyst system, said catalyst system comprising a rhodium complex and a substituted or unsubstituted diphosphine ligand.
[0014] In any of the methods described herein, the substituted or unsubstituted diphosphine ligand is trans-1,2-bis(bis(3,5-di-n-alkylphenyl)phosphinemethyl)-cyclobutane or 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-di-n-alkylphenyl)phosphine]-butane, wherein the n-alkyl group is methyl, ethyl or propyl.
[0015] In any of the methods described herein, the substituted or unsubstituted diphosphine ligand is 4,5-bis(di-n-alkylphosphine) saxon, and the n-alkyl group is a C1-C6 group.
[0016] In any of the methods described herein, the 4,5-bis(di-n-alkylphosphino)xanthon ligand is 9,9-dimethyl-4,5-bis(dimethylphosphino)xanthon.
[0017] In any of the methods described herein, the 4,5-bis(di-n-alkylphosphine)xanthon ligand is 9,9-dimethyl-4,5-bis(dihexylphosphine)xanthon.
[0018] In any of the methods described herein, the 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-di-n-alkylphenyl)phosphine]-butane complex is 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-dimethylphenyl)phosphine]butane.
[0019] In any of the methods described herein, the 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-di-n-alkylphenyl)phosphine]-butane complex is 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-dihexylphenyl)phosphine]butane.
[0020] In any of the methods described herein, the trans-1,2-bis(bis(3,5-di-n-alkylphenyl)phosphinomethyl)-cyclobutane is a trans-1,2-bis(bis(3,5-dimethylphenyl)phosphinomethyl)-cyclobutane.
[0021] In any of the methods described herein, the trans-1,2-bis(bis(3,5-di-n-alkylphenyl)phosphinomethyl)-cyclobutane is a trans-1,2-bis(bis(3,5-dihexylphenyl)phosphinomethyl)-cyclobutane.
[0022] In any of the methods described herein, the rhodium complex comprises rhodium and one or more ligands selected from the group consisting of hydrides, carbonyl groups, trialkyl or triarylphosphine, diphosphine, cyclopentadienyl groups, 2,4-alkane diacid salts and mixtures thereof.
[0023] In any of the methods described herein, the reaction is carried out in a temperature range of about 45°C to about 85°C and a pressure range of about 30 (~0.21 MPa) to about 400 psig (~2.76 MPa).
[0024] In any of the methods described herein, the reaction is carried out in a temperature range of about 65°C to about 85°C and a pressure of about 200 psig (~1.37 MPa).
[0025] In any of the methods described herein, the catalyst system further comprises a monophosphine compound.
[0026] In any of the methods described herein, the monophosphine compound is triphenylphosphine.
[0027] In any of the methods described herein, the concentration of carbon monoxide in the liquid phase is maintained in the range of about 2 mmol / L (0.002 M) to about 10 mmol / L (0.010 M).
[0028] In any of the methods described herein, the concentration of carbon monoxide in the liquid phase is maintained in the range of about 3 mmol / L (0.003 M) to about 6 mmol / L (0.006 M).
[0029] In any of the methods described herein, the concentration of carbon monoxide in the liquid phase is maintained in the range of about 4 mmol / L (0.004 M) to about 8 mmol / L (0.008 M).
[0030] In any of the methods described herein, the concentration of carbon monoxide in the liquid phase is maintained in the range of about 4 mmol / L (0.004 M) to about 25 mmol / L (0.025 M).
[0031] In any of the methods described herein, the concentration of carbon monoxide in the liquid phase is maintained in the range of about 4 mmol / L (0.004 M) to about 50 mmol / L (0.050 M).
[0032] In any of the methods described herein, the concentration of carbon monoxide in the liquid phase is maintained in the range of about 4 mmol / L (0.004 M) to about 100 mmol / L (0.100 M).
[0033] In any of the methods described herein, the concentration of carbon monoxide in the liquid phase is maintained above 4 mmol / L (0.004 M).
[0034] Any of the methods described herein further includes hydrogenating 4-hydroxybutyraldehyde in the presence of a hydrogenation catalyst to form 1,4-butanediol.
[0035] In any of the methods described herein, the hydrogenation catalyst is a nickel catalyst.
[0036] This invention provides a selection of concepts, which will be further described in the following detailed description. This invention is not intended to identify key or essential features of the claimed objective, nor is it intended to limit the scope of the claimed objective. Definitions
[0037] Unless the context otherwise indicates, when used in conjunction with the term “comprising” in the claims or specification, the words “a” or “an” mean one or more.
[0038] The term “about” means the value plus or minus the measurement error range, or, if the measurement method is not indicated, plus or minus 10%.
[0039] Unless it is explicitly stated that only alternatives are referred to or if the alternatives are mutually exclusive, the term “or” is used in the scope of the patent application to mean “and / or”.
[0040] The terms “contains,” “has,” “includes,” and “contains” (and their variations) are open-ended connecting verbs and allow additional elements to be added when used in a request item.
[0041] The phrase “composed of” is closed and excludes all other elements.
[0042] The phrase “consistently made of” excludes other material elements, but allows the inclusion of non-material elements that do not substantially change the nature of the invention.
[0043] The following abbreviations are used in this document: abbreviation the term BDO 1,4-Butanediol HBA 4-Hydroxybutyraldehyde HMPA 3-Hydroxy-2-methylpropanal PA propionaldehyde MPD 2-Methyl-1,3-propanediol GC Gas chromatography
Implementation Method
[0045] Description of embodiments of this disclosure
[0046] This invention relates to an improved method for forming 1,4-butanediol (BDO). The improvement includes using methylcyclohexane as a reaction solvent to improve the efficiency of allyl alcohol hydrogenation and methoxylation, followed by water extraction of the aldol product and hydrogenation of the extracted aldol product to an alcohol.
[0047] Previous allyl alcohol hydromethionization methods used organic solvents, such as toluene, cyclohexane, methyl tert-butyl ether, and mixtures thereof, as reaction solvents in the presence of a catalyst system containing a rhodium complex and substituted or unsubstituted diphosphine ligands. Compared to 3-hydroxy-2-methylpropionaldehyde (HMPA), the combination of reaction solvent and catalyst system resulted in a higher yield of 4-hydroxybutyraldehyde (HBA), leading to a higher yield of BDO. However, these reaction solvents were difficult to separate from the aldol product during subsequent water extraction, resulting in reduced efficiency of the hydromethionization process and subsequent hydrogenation.
[0048] Specifically, in the water extraction step, HBA and HMPA remain dissolved in the aqueous phase and are separated from the organic reaction solvent / catalyst phase. However, if the aqueous phase and the reaction solvent are only slightly miscible, it is difficult to completely separate the two phases. Subsequently, some water is carried away by the recovered catalyst system, thereby reducing the efficiency of the hydromethionization process. Some organic reaction solvents are carried into the hydrogenation process, which can deactivate the hydrogenation catalyst. In addition, not all aldol products enter the aqueous phase, resulting in product loss.
[0049] In the method disclosed herein, methylcyclohexane is used as the reaction solvent. Compared with conventional organic reaction solvents, methylcyclohexane unexpectedly increases the reaction rate of the hydromethionization process, while also improving the subsequent water extraction and hydrogenation processes. These unexpected improvements result in a more cost-effective process due to the reduced amount of catalyst required for the hydromethionization process, the reduced water required for the extraction process, and the overall lower energy consumption.
[0050] More specifically, compared to the reaction solvents previously used for the hydromethionization of allyl alcohol, methylcyclohexane can increase the hydromethionization reaction rate by at least approximately 30%. Furthermore, it was unexpectedly found that methylcyclohexane is not only immiscible with water, but also largely immiscible with the aldol products. Therefore, during extraction, when the methylcyclohexane phase floats on the water surface, more aldol products are partitioned into the aqueous phase. This results in better separation and requires less water. In addition, there is less carryover in the remaining process. The circulating catalyst system contains almost no water, thereby improving the efficiency of the hydromethionization reaction. Less methylcyclohexane also enters the hydrogenation reactor, thus reducing deactivation of the hydrogenation catalyst.
[0051] The remaining forms of the hydromethionization, extraction and hydrogenation processes may be the same as those known in the art.
[0052] Hydromethoxylation:
[0053] The process described herein can be carried out in batch or continuous manner, and is particularly well-suited for continuous operation. Typical reaction conditions for hydromethionization are mild and favor the formation of linear 4-hydroxybutyraldehyde (HBA) rather than the branched 3-hydroxy-2-methylpropionaldehyde (HMPA) coproduct.
[0054] In some embodiments, the reaction conditions are in the range of about 20 to 120°C and the pressure is in the range of about 20 psig (~0.14 MPa) to 600 psig (~4.14 MPa). In other embodiments, the reaction conditions are in the range of about 45 to 85°C and 30 psig (~0.21 MPa) to 400 psig (~2.76 MPa); or, the reaction conditions are in the range of about 50 to 80°C and 40 psig (~0.28 MPa) to 300 psig (~2.07 MPa). In other embodiments, the reaction conditions are in the range of about 65°C to about 85°C and at a pressure of about 200 psig (~1.37 MPa).
[0055] The catalyst system used in the method of the present invention includes a rhodium complex and substituted or unsubstituted diphosphine ligands.
[0056] In some embodiments, the diphosphine ligand is -1,2-bis(bis(3,5-di-n-alkylphenyl)phosphinomethyl)-cyclobutane, having the general formula:
[0057] where R is an alkyl group, such as methyl, ethyl or propyl.
[0058] In some embodiments, the diphosphine ligand is trans-1,2-bis(bis(3,5-dimethylphenyl)phosphinomethyl)-cyclobutane or trans-1,2-bis(bis(3,4,5-trimethylphenyl)phosphinomethyl)-cyclobutane.
[0059] Trans-1,2-bis(bis(3,5-di-n-alkylphenyl)phosphinomethyl)cyclobutene or trans-1,2-bis(bis(3,4,5-trimethylphenyl)phosphinomethyl)cyclobutene can be prepared by any possible method. For example, it can be prepared by reacting trans-1,2-cyclobutanediol, bis(toluenesulfonate), and lithium bis(3,5-di-n-alkylphenyl)phosphine or lithium bis(3,4,5-di-n-alkylphenyl)phosphine.
[0060] In other embodiments, the diphosphine ligand is 4,5-bis(di-n-alkylphosphino)xanthine, having the general formula:
[0061] Wherein R is an n-alkyl group, and any cyclic carbon may be substituted or unsubstituted. The R groups may be the same or different, but are preferably the same. In some embodiments, the R group is a C1-C6 n-alkyl group, such as methyl, ethyl or n-propyl.
[0062] In some embodiments, the diphosphine ligand is 9,9-dimethyl-4,5-bis(di-n-alkylphosphino)xanthon. Alternatively, the diphosphine ligand is 9,9-dimethyl-4,5-bis(dimethylphosphino)xanthon or 9,9-dimethyl-4,5-bis(diethylphosphino)xanthon.
[0063] 4,5-bis(di-n-alkylphosphine)xanthones can be prepared by any possible method. For example, it can be prepared by reacting 4,5-dilithiumxanthones with chloro(di-n-alkyl)phosphine.
[0064] In other embodiments, the diphosphine ligand is 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-di-n-alkylphenyl)phosphine]-butane, having the general formula:
[0065] where R is a proton (DIOP) or an alkyl group, such as methyl, ethyl or propyl.
[0066] In some embodiments, the diphosphine ligand is 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-dimethylphenyl)phosphine]butane or 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-diethylphenyl)phosphine]butane.
[0067] 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-di-n-alkylphenyl)phosphine]-butane can be prepared by any possible method. For example, it can be prepared by the reaction of 2,2-dimethyl-4,5-bis[(toluenesulfonoxymethyl)methyl]-1,3-dioxolane with lithium bis(3,5-di-n-alkylphenyl)-phosphine.
[0068] The catalyst system also includes a rhodium complex. Exemplary rhodium complexes contain rhodium linked to a ligand group. The rhodium complex is preferably soluble in methylcyclohexane. There are no particular limitations on the choice of ligands linked to the rhodium complex. For example, ligands include hydrides, carbonyl groups, substituted and unsubstituted cyclopentadienyl groups, 2,4-alkyl esters, trialkyl or triarylphosphine, diphosphine, and mixtures thereof. In some embodiments, the ligand includes carbonyl groups, acetoacetone (2,4-pentane ester), triphenylphosphine, and mixtures thereof. In other embodiments, the rhodium complex comprises (acetoacetone)dicarbonyl rhodium and tris(triphenylphosphine)carbonyl hydrogenated rhodium.
[0069] The molar ratio of the diphosphine ligand to the rhodium complex is between 0.5:1 and 5:1. In some embodiments, the molar ratio of the diphosphine ligand to the rhodium complex is in the range of 0.5:1 to 2.5:1. In some embodiments, the molar ratio of the diphosphine ligand to the rhodium complex is in the range of 0.5:1 to 1.5:1. In some embodiments, the molar ratio of the diphosphine ligand to the rhodium complex is in the range of 1:1 to 4.5:1. In some embodiments, the molar ratio of the diphosphine ligand to the rhodium complex is in the range of 1:1 to 3:1. In some embodiments, the molar ratio of the diphosphine ligand to the rhodium complex is in the range of 2:1 to 5:1. In some embodiments, the molar ratio of the diphosphine ligand to the rhodium complex is in the range of 3:1 to 5:1. The rhodium complex may be pre-associated with the diphosphine ligand prior to use in the hydromethionization reaction to form part of the rhodium complex, or it may be added separately. However, in some embodiments, it is preferred to add the rhodium complex separately from the diphosphine ligand.
[0070] Although not essential, the catalyst system may also include a monophosphine compound. The monophosphine compound complements any phosphine ligands that may be associated with the rhodium complex. The monophosphine compound is a trisubstituted phosphine represented by formula (R1)3P, wherein R1 is aryl or alkyl. Exemplary aliphatic R1 groups include methyl, ethyl, n-butyl, dibutyl, octyl, and decyl, and exemplary aromatic R1 groups include phenyl, tolyl, and naphthyl. The R1 groups may be the same or different, but are preferably the same. In some embodiments, the monophosphine is a trisubstituted arylphosphine. Alternatively, the monophosphine is triphenylphosphine or trimethylmethylphosphine.
[0071] In addition to the reaction solvent and catalyst system, the hydromethionization process also combines the ethanol matrix with carbon monoxide (CO) and hydrogen (H2). The CO:H2 molar ratio is typically about 1:1, although the molar ratio can vary considerably. The partial pressure of CO is in the range of 5 to 100 psig. The partial pressure of hydrogen is between 40 psig (~0.28 MPa) and 200 psig (~1.38 MPa). The reaction is carried out under these conditions until the major component of allyl alcohol has reacted, for example, 60% to 99.9%, and the product is mainly HBA with some branched reaction products. The reaction time is not critical, but a reaction time of 0.5 to 4 hours is usually sufficient.
[0072] The initial concentration of allyl alcohol in methylcyclohexane, the reaction solvent, is in the range of about 5% to 40% (by weight) in methylcyclohexane. Alternatively, a lower concentration of 5% to 10% (by weight) in methylcyclohexane can be used. In another alternative, the initial concentration of allyl alcohol in methylcyclohexane is in the range of 15% to 30% (by weight); or 25% to 40% (by weight) in methylcyclohexane.
[0073] The allyl alcohol is hydromethanized such that, during the hydromethanization process, the CO concentration in the liquid phase ([CO] liquid) is maintained above 4 mmol / L (0.004 M). The value of [CO] liquid is defined in U.S. Patent No. 6,225,509, the teachings of which are incorporated herein by reference. In some embodiments, the molar ratio of liquid phase hydrogen to carbon monoxide is in the range of 10:1 to about 1:2 or 5:1 to about 1:2.
[0074] After the hydromethionization process, the HBA product is separated from the solvent and catalyst system by water extraction in an extraction vessel.
[0075] Water extraction:
[0076] Water extraction methods are well known in the art and can be implemented by any suitable means, such as mixer settlers, filled or conveyed extraction towers, rotating disc contactors, or transfer to sedimentation tanks to decompose the mixture into aqueous and organic phases.
[0077] As described above, aldol products such as HBA and HMPA are insoluble in the methylcyclohexane reaction solvent. This makes it easy for the aldol products to partition into water (the aqueous phase), where they are more readily soluble. Furthermore, methylcyclohexane is immiscible in the aqueous phase, causing it to float on the surface and be separated. The combination of the immiscibility of methylcyclohexane with the aqueous phase and the immiscibility of methylcyclohexane with the aldol products facilitates a more efficient separation process.
[0078] In stark contrast to their incompatibility with methylcyclohexane, aldol products are completely compatible with other solvents, such as toluene. Similar to methylcyclohexane, toluene is insoluble in the aqueous phase and floats on top. However, the miscibility of aldol products in toluene makes their extraction more challenging. Although the extraction efficiency is sufficient to achieve this process, some toluene is entrained in the aqueous extract of the aldol product, and some water is entrained in the recovered toluene catalyst solution. This leads to catalyst loss and / or deactivation, and increases the cost of the hydromethionization process.
[0079] Hydrogenation:
[0080] An additional step is performed on the HBA (and any HMPA) reaction products: hydrogenation of 4-hydroxybutyraldehyde in the presence of a hydrogenation catalyst to produce 1,4-butanediol (BDO). Hydrogen is added to the reaction vessel for hydrogenation. Exemplary hydrogenation catalysts include any Group VIII metal, such as nickel, cobalt, ruthenium, platinum, and palladium, as well as copper, zinc, chromium, and mixtures and alloys thereof. Nickel catalysts are particularly preferred. Raney-type nickel and fixed-bed nickel catalysts are most preferred.
[0081] Any known hydrogenation conditions may be used. In some embodiments, the hydrogenation reaction conditions are in the range of 60 to 200°C and the pressure is between 200 psig (~1.38 MPa) and 1000 psig (~6.89 MPa). In other embodiments, the hydrogenation reaction conditions are in the range of 80 to 140°C and 300 psig (~2.07 MPa) to 1000 psig (~6.89 MPa). The hydrogenation reaction time is about 1 to about 10 hours.
[0082] Using the above method, the production of BDO is improved because, without being bound by theoretical constraints, the methylcyclohexane reaction solvent increases the reaction rate of the hydromethionization process while reducing the water carryover during extraction. Furthermore, compared to conventional hydromethionization reaction solvents, the immiscibility of methylcyclohexane with water improves the separation effect. This reduces the amount of water required for extraction and the amount of methylcyclohexane present in the subsequent hydrogenation process. Therefore, the use of the methylcyclohexane reaction solvent leads to a more cost-effective method for producing more BDO. Example
[0083] The following is included to illustrate embodiments using the above-described hydromethionization process as described in the appended claims. The examples are for illustrative purposes only and are not intended to unduly limit the scope of the appended claims. Those skilled in the art will understand that many changes can be made to the specific embodiments disclosed herein without departing from the spirit and scope of the disclosure, and still to obtain the same or similar results. Reading the following examples should in no way limit or define the scope of the appended claims.
[0084] In this example, different reaction solvents were combined with catalyst systems for the hydromethionization of allyl alcohol. Each batch of reactions was carried out using a catalyst system with Rh ligand A, which is trans-1,2-bis(bis(3,5-di-n-methylphenyl)phosphinomethyl)-cyclobutane, at 65°C and 200 psig. The molar composition of the catalyst system was [Rh]:[ligand A] = 1:2. The amount of rhodium in each reaction solvent was [Rh] = 4.3 x 10⁻⁵ mol. For each reaction, HBA and HMPA were analyzed using gas chromatography (GC). No hydrogenation step was performed because the conversion from the aldol product to the diol was readily achieved, with a conversion and selectivity greater than 99%. Therefore, the ratio of HBA to HMPA generated during the hydromethionization process was used to predict the amount of BDO and MPD formed after the hydrogenation process. Table 1 shows the results for each reaction.
[0085] Table 1: Comparison of Solvents Table 1: Comparison of Solvents reaction solvent BDO MPD C3 L:B Ratio comparison Toluene 89.6 9.3 0.12 9.64 Methylcyclohexane 89.7 9.4 0.08 9.57 1.36 times the rate in toluene. Ethylcyclohexane 89.4 9.5 0.09 9.6 1.03 times the rate in toluene Cyclohexane 90.2 9.1 0.08 9.88 1.2 times the rate in toluene Ethylbenzene 89.5 9.0 0.11 9.89 ~0.93 times the rate in toluene Cyclohexene 70 29 0.32 2.4 0.66 times the rate in toluene m-xylene 88.6 9.3 0.14 9.5 Similar rates in toluene Oxyxylene 89.7 9.3 0.11 9.7 Similar rates in toluene P-xylene 90.1 9.3 0.12 9.7 Similar rates in toluene L:B = Ratio of linear HBA to branched HMPA
[0086] Baseline comparison of reaction rates using toluene as another reaction solvent. Many of these solvents have been previously used in the hydromethionization process, and their rates are similar to toluene. However, changing the reaction solvent to methylcyclohexane unexpectedly resulted in a significant increase in reaction rate, as shown in Table 1. Methylcyclohexane increased the reaction rate by 36%, indicating that less rhodium metal can be used in the catalyst system. This will greatly improve the cost savings of the HBA production process.
[0087] Compared to toluene, cyclohexane also increases the rate by approximately 20%, but it is worth noting that separating this solvent in the water extraction step is more difficult than with methylcyclohexane. Cyclohexane has a certain degree of miscibility in the aqueous phase, making it difficult to separate from water. This results in water being carried into the cyclohexane catalyst system, and the catalyst solution being carried into the water extract, leading to catalyst loss and / or deactivation.
[0088] In contrast, the aldol products are insoluble in methylcyclohexane. In fact, during subsequent gas chromatography (GC) analysis of each reaction product, ethanol must be added to the methylcyclohexane reaction product sample to form a single-phase solution for accurate analysis. This step is not required with other reaction solvents. This insolubility allows the aldol products to be readily partitioned into the aqueous phase during the water extraction step. Furthermore, methylcyclohexane is immiscible with the aqueous phase, causing it to separate and float on the water surface. This separation is more effective than with other reaction solvents in Table 1, meaning less water is required for the extraction step. Moreover, almost no water remains in the catalyst system, further reducing the cost of the hydromethionization process.
[0089] In addition to increasing the reaction rate and improving separation, the use of methylcyclohexane also reduces the formation of unwanted C3 byproducts. The formation of C3 byproducts effectively represents another yield loss in this method, which can have a seriously adverse impact on the economics of the method. The use of methylcyclohexane provides one of the lowest C3 selectivity.
[0090] The quantities of BDO and MPD in Table 1 are predicted based on the ratio (L:B) of linear HBA to branched HMPA. The use of methylcyclohexane does not substantially affect the high yield of HBA compared to HMPA, and therefore does not negatively impact the predicted quantities of BDO and MPD. As shown in Table 1, the predicted values are similar to those for other reaction solvents; therefore, there is no efficiency loss in the hydromethionization reaction when methylcyclohexane is used instead of other known reaction solvents.
[0091] Therefore, the use of methylcyclohexane as a reaction solvent in the catalyst system provides a more economically attractive method for the hydromethionization of allyl alcohol. The use of methylcyclohexane unexpectedly increases the reaction rate, thereby reducing the amount of rhodium required in the catalyst and thus lowering process costs. Furthermore, the insoluble reaction products in methylcyclohexane and the immiscibility of methylcyclohexane with the aqueous phase improve the separation process. This not only reduces the amount of water entering the hydromethionization reactor along the recovered solvent / catalyst system but also increases the recovery rate of the desired reaction products.
[0092] The following references are all incorporated by way of citation. US7612241 US7279606 US7271295 Additional disclosures
[0093] The embodiments disclosed herein include:
[0094] A: A method for producing 4-hydroxybutyraldehyde, comprising reacting allyl alcohol with carbon monoxide and hydrogen in the presence of a methylcyclohexane reaction solvent and a catalyst system, said catalyst system comprising a rhodium complex and a substituted or unsubstituted diphosphine ligand.
[0095] Embodiment A may include one or more of the following additional elements:
[0096] Element 1: The diphosphine complex is trans-1,2-bis(bis(3,5-di-n-alkylphenyl)phosphinomethyl)-cyclobutane, trans-1,2-bis(bis(3,4,5-di-n-alkylphenyl)phosphinomethyl)-cyclobutane, 4,5-bis(di-n-alkylphosphine)-butane, or 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-di-n-alkylphenyl)phosphine]-butane, wherein the n-alkyl group is methyl, ethyl, or propyl. Element 2: The trans-1,2-bis(bis(3,5-di-n-alkylphenyl)phosphinomethyl)-cyclobutane is trans-1,2-bis(bis(3,5-dimethylphenyl)phosphinomethyl)-cyclobutane. Element 3: The trans-1,2-bis(bis(3,5-di-n-alkylphenyl)phosphinomethyl)-cyclobutane is a trans-1,2-bis(bis(3,5-dihexylphenyl)phosphinomethyl)-cyclobutane. Element 4: The 4,5-bis(di-n-alkylphosphino) is a 9,9-dimethyl-4,5-bis(dimethylphosphino) or 9,9-dimethyl-4,5-bis(diethylphosphino) Element 5: The 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-di-n-alkylphenyl)phosphine]-butane is a 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-dimethylphenyl)phosphine]butane or a 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-diethylphenyl)phosphine]butane. Element 6: The rhodium complex comprises rhodium and one or more ligands selected from the group consisting of hydrides, carbonyl groups, trialkyl or triarylphosphines, diphosphines, cyclopentadienyl groups, 2,4-alkanoates, and mixtures thereof. Element 7: The reaction is carried out at a temperature of about 45°C to about 85°C and a pressure of about 30 psig (~0.21 MPa) to about 400 psig (~2.76 MPa). Element 8: The reaction is carried out at a temperature of about 65°C to about 85°C and a pressure of about 200 psig (~1.37 MPa). Element 9: The catalyst system further comprises a monophosphine compound. Element 10: The monophosphine compound is triphenylphosphine. Element 11: The concentration of carbon monoxide in the liquid phase is maintained at or above 4 mmol / L (0.004 M). Element 12: The reaction further includes hydrogenation of 4-hydroxybutyraldehyde in the presence of a hydrogenation catalyst to form 1,4-butanediol. Element 13: The hydrogenation catalyst is a nickel catalyst. Element 14: The concentration of carbon monoxide in the liquid phase is maintained in the range of about 2 mmol / L (0.002 M) to about 10 mmol / L (0.010 M). Element 15: The concentration of carbon monoxide in the liquid phase is maintained in the range of about 3 mmol / L (0.003 M) to about 6 mmol / L (0.006 M).Element 16: The concentration of carbon monoxide in the liquid phase is maintained in the range of about 4 mmol / L (0.004 M) to about 8 mmol / L (0.008 M). Element 17: The concentration of carbon monoxide in the liquid phase is maintained in the range of about 4 mmol / L (0.004 M) to about 25 mmol / L (0.025 M). Element 18: The concentration of carbon monoxide in the liquid phase is maintained in the range of about 4 mmol / L (0.004 M) to about 50 mmol / L (0.050 M). Element 19: The concentration of carbon monoxide in the liquid phase is maintained in the range of about 4 mmol / L (0.004 M) to about 100 mmol / L (0.100 M).
[0097] The specific embodiments disclosed above are merely illustrative, as the invention can be modified and practiced in different but equivalent ways, as will be apparent to those skilled in the art who benefit from the teachings herein. Furthermore, the construction or design details shown herein are not limited except as described in the following claims. Therefore, it is apparent that the specific illustrative embodiments disclosed above can be changed or modified, and such changes are contemplated within the scope and spirit of the invention. Alternative embodiments resulting from combining, integrating, and / or omitting features of the embodiments are also within the scope of the invention. Although compositions and methods are described in the broader terms as “having,” “comprising,” “including,” or “comprising” various components or steps, compositions and methods may also “substantially comprise” or “comprising” various components and steps. The use of the term “optional” for any element of the claim means that the element is present or not present, both alternatives being within the scope of the claims. In the claims, the method plus function clause is intended to cover structures described herein as performing the stated function, including not only structural equivalents but also equivalent structures. The applicant expressly states that it does not invoke any limitation under Section 112, paragraph 6 of Title 35 of the United States Code for any claim in this application, except for limitations that are expressly used in the scope of the patent application to refer to the “method” and related functions.
[0098] The numbers and ranges disclosed above may vary. Whenever a range of numbers with a lower and upper limit is disclosed, any numbers within that range and any included ranges are specifically disclosed. Specifically, each range of values disclosed herein (in the form of “from about a to about b,” or equivalently, “from about a to b,” or equivalently, “from about a to b”) should be understood to describe every number and range included within a broader range of values. Furthermore, unless the patentee expressly and obviously defines otherwise, the terms in the claims have simple, general meanings. If there is any conflict between the use of a word or term in this specification and in one or more patents or other documents, the definition consistent with this specification shall prevail.
[0099] Therefore, the scope of protection is not limited by the above description, but only by the following scope of the patent application, which includes the equivalent of the object of the patent application. [Simplified Explanation of the Diagram]
[0044] None.
Claims
1. A method for producing 4-hydroxybutyraldehyde, the method comprising reacting allyl alcohol with carbon monoxide and hydrogen in the presence of a methylcyclohexane reaction solvent and a catalyst system, said catalyst system comprising a rhodium complex and a substituted or unsubstituted diphosphine ligand.
2. The method of claim 1, wherein the diphosphine complex is trans-1,2-bis(bis(3,5-di-n-alkylphenyl)phosphinemethyl)-cyclobutane, trans-1,2-bis(bis(3,4,5-di-n-alkylphenyl)phosphinemethyl)-cyclobutane, 4,5-bis(di-n-alkylphosphine)xanthan or 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-di-n-alkylphenyl)phosphine]-butane, wherein the n-alkyl group is a methyl, ethyl or propyl group.
3. The method of claim 2, wherein the trans-1,2-bis(bis(3,5-di-n-alkylphenyl)phosphinomethyl)-cyclobutane is a trans-1,2-bis(bis(3,5-dimethylphenyl)phosphinomethyl)-cyclobutane.
4. The method of claim 2, wherein the trans-1,2-bis(bis(3,5-di-n-alkylphenyl)phosphinomethyl)-cyclobutane is a trans-1,2-bis(bis(3,5-dihexylphenyl)phosphinomethyl)-cyclobutane.
5. The method of claim 2, wherein the 4,5-bis(di-n-alkylphosphine) saxon is 9,9-dimethyl-4,5-bis(dimethylphosphine) saxon or 9,9-dimethyl-4,5-bis(diethylphosphine) saxon.
6. The method of claim 2, wherein the 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-di-n-alkylphenyl)phosphine]-butane is a 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-dimethylphenyl)phosphine]butane or a 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis[bis(3,5-diethylphenyl)phosphine]butane.
7. The method of claim 1, wherein the rhodium complex comprises rhodium and one or more ligands selected from the group consisting of hydrides, carbonyl groups, trialkyl or triarylphosphine, diphosphine, cyclopentadienyl groups, 2,4-alkanoates and mixtures thereof.
8. The method of claim 1, wherein the reaction is carried out at a temperature ranging from about 20°C to about 120°C and at a pressure ranging from about 20 psig (~0.14 MPa) to about 600 psig (~4.14 MPa).
9. The method of claim 1, wherein the reaction is carried out at a temperature in the range of about 65°C to about 85°C and at a pressure of about 200 psig (~1.37 MPa).
10. The method of claim 1, wherein the catalyst system further comprises a monophosphine compound.
11. The method of claim 10, wherein the monophosphine compound further comprises triphenylphosphine.
12. The method of claim 1, wherein the concentration of carbon monoxide in the liquid phase is maintained above 4 mmol / L (0.004 M).
13. The method of claim 1, further comprising hydrogenating the 4-hydroxybutyraldehyde in the presence of a hydrogenation catalyst to form 1,4-butanediol.
14. The method of claim 13, wherein the hydrogenation catalyst is a nickel catalyst.
15. The method of claim 1, wherein the concentration of carbon monoxide in the liquid phase is maintained in the range of about 4 mmol / L (0.004 M) to about 100 mmol / L (0.100 M).