Complex, method for preparing enol from alkynol and derivative thereof

Abstract

The invention relates to a complex and a method for preparing enol from alkynol and derivatives thereof, the complex is formed by complexing a bidentate phosphorus ligand and a Lidlar catalyst, the bidentate phosphorus ligand is selected from at least one of a formula (1), a formula (2), a formula (3) and a formula (4), R1, R3, R6 and R7 are selected from C4-C9 alkyl groups and substituted or non-substituted C6-C20 aryl groups, R2 is selected from H or an electron withdrawing group, and R3 is selected from H or an electron withdrawing group. R4 and R5 are respectively and independently selected from H, halogen or C1-C6 alkyl, and X is selected from O, NH and S. The complex provided by the invention is used for catalyzing selective hydrogenation reduction of alkynol and derivatives thereof to prepare enol, has high catalytic activity and high reaction selectivity, can improve the cis-reduction selectivity of enol to 99% or above, widens the process window, and can be recycled and reused.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fine chemical synthesis, in particular to a complex and a method for preparing enol from acetylene alcohol and derivatives thereof. BACKGROUND

[0002] The key intermediate of vitamin A (VA) (such as C20 acetylene alcohol derivative) needs to be accurately reduced from acetylene bond (C≡C) to cis double bond (Z-form) through selective hydrogenation reaction to construct the all-trans conjugated polyene skeleton. The selectivity of this step directly determines the stereochemical purity and bioavailability of VA acetate. According to industry data, the global VA annual production capacity is about 35,000 tons. If the hydrogenation selectivity is improved by 1%, more than 500 tons of by-products can be reduced per year, and the energy consumption for purification can be reduced by more than 20%, which is of great significance to green manufacturing and cost control.

[0003] The commonly used method for selective reduction of acetylene to cis olefin is Lindlar reduction. Current research on Lindlar catalytic reaction mainly focuses on the preparation of catalysts. For example, patent CN101616733A uses a regular catalyst, in which palladium and zinc oxide are supported on metal fibers, and quinoline is used as a poison, to achieve good reaction conversion rate and selectivity through partial hydrogenation; patent CN101869845A uses calcium carbonate as a carrier, palladium as an active component, and Mn, Bi or Zn as a poison. After the palladium is adsorbed on the carrier, it is filtered, and then reduced to obtain the catalyst, which has high activity and selectivity (97%) for selective hydrogenation of isophytol; patent CN201380032718 controls the particle size of the calcium carbonate carrier to be more than 10 μm to reduce the specific surface area of the catalyst and thus inhibit its reaction activity; patent CN110573248A uses zinc oxide, cerium oxide, etc. as carrier materials, and the prepared catalyst shows improved activity and selectivity in partial hydrogenation reaction; patent CN110124742A discloses a method for regulating Lindlar catalyst using metal salts or metal carbonyl compounds, which effectively solves the compatibility problem of catalytic activity and selectivity. However, the use of hazardous raw material synthesis gas (hydrogen and carbon monoxide mixed gas) increases the process safety risk.

[0004] However, the traditional Lindlar hydrogenation reduction technology has the following problems: (1) the reaction activity and hydrogenation selectivity are still incompatible, resulting in low production efficiency in industrialization process; (2) in some specific catalytic systems, harsh operating conditions are usually required, such as pressure sensitivity, narrow temperature window, sensitivity to air and moisture, etc., which increases the safety risk of equipment and the difficulty of production operation; (3) in order to ensure the selectivity of the hydrogenation reaction, it is still necessary to add quinoline, pyridine, mercaptan and other organic ligand toxic substances to passivate the catalyst, but the complexing ability of the added quinoline, pyridine, mercaptan and other toxic substances with metal Pd is weak, the loss rate of toxic substances is high after each batch reaction, the catalyst needs to be regenerated and passivated again, the activity decreases significantly after multiple batches of use, which greatly increases the production cost of enterprises and affects the quality of downstream products, and these added toxic substances have the practical difficulties of large amount, difficult separation and affecting product quality, especially in the production process of vitamin A acetate, this disadvantage cannot be avoided. SUMMARY

[0005] Therefore, it is necessary to provide a complex and a method for preparing an enol from an alkyne alcohol and a derivative thereof in view of the above problems, the complex has high catalytic activity and high reaction selectivity, can increase the cis-reduction selectivity of the enol to more than 99%, and can be recycled and reused.

[0006] A complex for catalyzing the selective hydrogenation reduction of an alkyne alcohol and a derivative thereof to prepare an enol, the complex is formed by complexing a bidentate phosphorus ligand and a Lindlar catalyst, wherein the bidentate phosphorus ligand is selected from at least one of the following formula (1), formula (2), formula (3), formula (4),

[0007] 、 、 、 ,

[0008] wherein R1, R3, R6, R7 are selected from C4-C9 alkyl, substituted or unsubstituted C6-C20 aryl, R2 is selected from H or an electron-withdrawing group, R4, R5 are independently selected from H, halogen or C1-C6 alkyl, and X is selected from O, NH, S.

[0009] In one embodiment, when R1, R3, R6, R7 are selected from substituted C6-C20 aryl, the substituents are selected from at least one of phenyl, isopropyl, cyclohexyl, cyclopentyl, adamantyl.

[0010] In one embodiment, R1, R3, R6, R7 are independently selected from phenyl, tert-butyl, 、 、 、 、 、 、 、 、 、 、 、 、 、 .

[0011] In one embodiment, R2 is selected from H, triisopropylsilyl, t-butyldiphenylsilyl, nitro, or trifluoromethyl.

[0012] In one embodiment, the mass of the bidentate phosphorus ligand in the complex is 0.01% to 0.15% of the mass of the Lindlar catalyst.

[0013] In one embodiment, the mass content of palladium in the Lindlar catalyst is 1% to 10%.

[0014] A method for preparing an enol from an alkyne alcohol and derivatives thereof, comprising the following steps:

[0015] Under a protective atmosphere, the complex as described above is added to a bottom solution containing the alkyne alcohol and derivatives thereof, and then the protective atmosphere is replaced with hydrogen for selective hydrogenation reduction reaction to prepare the enol.

[0016] In one embodiment, the mass of the complex is 0.01% to 2% of the mass of the alkyne alcohol and derivatives thereof.

[0017] In one embodiment, the bottom solution comprises the alkyne alcohol and derivatives thereof and an organic solvent, and the bottom solution satisfies at least one of the following conditions:

[0018] (1) the mass concentration of the alkyne alcohol and derivatives thereof in the bottom solution is 10% to 90%;

[0019] (2) the organic solvent comprises at least one of n-hexane, n-heptane, petroleum ether, methanol, ethanol, tetrahydrofuran, dichloromethane, dichloroethane, chloroform, toluene, ethyl acetate.

[0020] In one embodiment, the reaction process satisfies at least one of the following conditions:

[0021] (1) the hydrogen pressure is 0.1 MPa to 2 MPa;

[0022] (2) the stirring rate is 200 rpm to 500 rpm;

[0023] (3) the reaction temperature is -10°C to 25°C;

[0024] (4) the reaction time is 2-8 hours.

[0025] In one embodiment, the complex is separated from the reactants and recycled for use in the selective hydrogenation reduction reaction.

[0026] In the complex of the present application, the bidentate phosphorus ligand with a special structure forms a multidentate coordination with the Lindlar catalyst, accurately shields the over-reduction active site, while retaining the spatial channel required for cis-hydrogenation of alkyne, and the complex can maintain structural rigidity in the reaction, avoiding coordination dissociation caused by reaction fluctuations such as temperature, pressure, moisture, and oxygen, greatly enhancing the mechanical strength of the catalyst, thereby realizing the selective reduction of cis-alkenols to more than 99% without reducing the intrinsic activity of the Lindlar catalyst, and widening the process window, while not adding ligands to the complex, which can be reused more than 100 times without affecting the reaction selectivity. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present application, the present application will be described in more detail below. However, it should be understood that the present application can be realized in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the disclosure of the present application more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the specification of the present application herein is only for the purpose of describing specific embodiments or examples and is not intended to limit the present application. In the present application, numerical intervals are involved, such as without specific instructions, the above numerical intervals are considered to be continuous and include the minimum value and maximum value of the range, as well as each value between the minimum value and the maximum value. Further, when the range refers to an integer, each integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe characteristics or properties, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0029] The present application provides a complex for catalyzing the selective hydrogenation reduction of alkyne and its derivatives to prepare alkenol, the complex is formed by complexing a bidentate phosphorus ligand and a Lindlar catalyst, wherein the bidentate phosphorus ligand is selected from at least one of the following formula (1), formula (2), formula (3), formula (4),

[0030] , , , ,

[0031] wherein R1, R3, R6, R7 are selected from C4-C9 alkyl, substituted or unsubstituted C6-C20 aryl, R2 is selected from H or electron-withdrawing group, R4, R5 are independently selected from H, halogen or C1-C6 alkyl, X is selected from O, NH, S.

[0032] In the present application, the two sites of the bidentate phosphorus ligand are coordinated with the palladium metal in the Lindlar catalyst to form a stable complex, which on the one hand, helps to maintain the presence of the ligand during the reaction, reduces the loss during the reaction, and further prolongs the service life of the catalyst; on the other hand, as shown in the following formula (5), the space and electronic effect of the bidentate ligand can more effectively adjust the active site of the catalyst, selectively shield the over-hydrogenation active site, while retaining the required channel for cis-hydrogenation, so that the selectivity of cis-olefin is improved to more than 99%, and due to the enhanced electron-donating ability of the bidentate ligand, the passivation effect of the Lindlar catalyst is significantly improved, thereby significantly improving the selectivity of the hydrogenation reaction.

[0033]

[0034] The complex provided by the present application can also maintain structural rigidity during the reaction, avoid coordination dissociation caused by reaction fluctuations such as temperature, pressure, moisture, oxygen, etc., and greatly enhance the mechanical strength of the catalyst, thereby realizing the premise of not reducing the intrinsic activity of the Lindlar catalyst, and significantly improving the selectivity of the hydrogenation reduction. At the same time, due to the improved tolerance of the complex to conditions such as temperature, pressure, moisture, and oxygen, it is beneficial to widen the process window for preparing enol from acetylene alcohol and its derivatives, so that the selective hydrogenation reduction reaction can be stably operated under wide conditions such as -10℃ to 25℃ and 0.1MPa to 2MPa.

[0035] It should be noted that the acetylene alcohol includes but is not limited to C20 acetylene alcohol, dehydro-linalool, dehydro-isophytol, etc., and the complex provided by the present application can be applied to acetylene alcohol and its derivatives involved in the Lindlar reduction system. The Lindlar catalyst is formed by adsorbing palladium on a carrier (such as calcium carbonate or barium sulfate) and adding a small amount of inhibitor (such as lead acetate or quinoline), including but not limited to Pd / CaCO3 / PbO, Pd / CaCO3 / PbAc2, Pd / BaSO4 / quinoline, etc. The chemical bond represented by the dashed line in formula (1) represents that the bond can or can not exist, so that formula (1) contains two structural conditions: when the chemical bond represented by the dashed line exists, the structure is that two benzene rings share a side; when the chemical bond represented by the dashed line does not exist, the structure is that a cyclohexane and a benzene ring share a side.

[0036] In one embodiment of the present application, when R1, R3, R6, R7 are selected from substituted C6-C20 aryl, the substituents are selected from at least one of phenyl, isopropyl, cyclohexyl, cyclopentyl, adamantyl. It is understood that when the number of benzene rings in the aryl group is more than one, the benzene rings can share a side to form condensed ring aromatic structures such as anthracene, phenanthrene, naphthalene, pyrene, etc.

[0037] In one embodiment of the present application, as a preference, R1, R3, R6, R7 are each independently selected from phenyl, tert-butyl, , , , , , , , , , , , , , .

[0038] It is understood that Ph refers to phenyl, Cy refers to cyclohexyl, i Pr refers to isopropyl, c-Pent refers to cyclopentyl, and Ad refers to adamantyl.

[0039] Further preferably, R1, R3, R6, R7 are each independently selected from phenyl, , , , .

[0040] In one embodiment of the present application, as a preference, R2 is selected from H, triisopropylsilyl, tert-butyldiphenylsilyl, nitro, or trifluoromethyl, and further preferably, R2 is selected from H or nitro.

[0041] In one embodiment of the present application, as a preference, R4, R5 are each independently selected from H or F.

[0042] More preferably, the bidentate phosphorus ligand is selected from at least one of the following formula (1-1), formula (1-2), formula (1-3), formula (1-4), formula (2-1), formula (2-2), formula (3-1), formula (3-2), formula (4-1), formula (4-2):

[0043] , , , , , , , , , .

[0044] It should be noted that the present application does not limit the spatial configuration of the bidentate phosphorus ligand, and the bidentate phosphorus ligand can be in R configuration or S configuration according to the configuration of the chiral center, and the bidentate phosphorus ligand can be left-handed or right-handed according to the optical rotation direction.

[0045] In an embodiment of the present application, in the complex, the mass of the bidentate phosphorus ligand is 0.01% to 0.15% of the mass of the Lindlar catalyst, and by adjusting the ratio of the Lindlar catalyst to the bidentate phosphorus ligand, the catalytic activity and the reaction selectivity can be further improved, and the recycling rate is also improved.

[0046] It can be understood that the mass percentage of the bidentate phosphorus ligand in the Lindlar catalyst includes but is not limited to any one value or a range value between any two values of 0.01%, 0.02%, 0.05%, 0.08%, 0.1%, 0.15%, and preferably 0.05% to 0.15%.

[0047] In an embodiment of the present application, the mass content of palladium in the Lindlar catalyst is 1% to 10%, including but not limited to any one value or a range value between any two values of 1%, 5%, 6%, 7%, 8%, 9%, 10%, and preferably 1% to 5%.

[0048] It should be noted that the present application does not limit the source of the Lindlar catalyst, and the commercial Lindlar catalyst or the self-made Lindlar catalyst can be used.

[0049] The present application also provides a method for preparing an enol from an alkyne alcohol and its derivative, comprising the following steps:

[0050] Under a protective atmosphere, the complex as described above is added to a bottom solution containing an alkyne alcohol and its derivative, and then the protective atmosphere is replaced by hydrogen for selective hydrogenation reduction reaction to prepare an enol.

[0051] By using the preparation method provided by the present application, the residual content of the ligand in the separated enol product in the reactant is less than 1.0 ppm, compared with the traditional process, the post-treatment purification step is not required, the practical application defects such as large amount of toxic substances such as quinoline, pyridine, and mercaptan, difficult separation, and influence on product quality are overcome, and after the reaction is completed, the complex separated from the reactant can be directly used in the hydrogenation reduction reaction of the next batch after washing, without adding ligand, and can be reused more than 100 times without affecting the reaction selectivity, thereby greatly reducing the production cost.

[0052] It should be noted that in another preparation method, the catalyst and the ligand can also be directly added to the bottom solution containing the alkyne alcohol and its derivatives for reaction, and the catalyst and the ligand can form a complex in the bottom solution.

[0053] In an embodiment of the present application, the mass of the complex is 0.01% to 2% of the mass of the alkyne alcohol and its derivatives, including but not limited to any one of 0.01%, 0.1%, 0.5%, 1%, 1.5%, 2% or a range value between any two of them, preferably 0.1% to 0.5%.

[0054] In an embodiment of the present application, the bottom solution includes the alkyne alcohol and its derivatives and an organic solvent. It can be understood that the bottom solution is an organic system, which is different from the aqueous reaction system or the water-organic two-phase reaction system suitable for traditional water-soluble ligands. Since the VA intermediate is a diol structure that is easily soluble in water, the introduction of the aqueous phase requires repeated extraction and separation, and water-soluble impurities are easily enriched in the aqueous phase, thereby affecting the selectivity control in the subsequent application process. The two-phase reaction requires higher mass transfer for the reaction device, which is also not conducive to the control of reaction selectivity. Therefore, the organic system adopted in the present application is more suitable for the industrial production of the VA intermediate.

[0055] Preferably, the mass concentration of the alkyne alcohol and its derivatives in the bottom solution is 10% to 90%, including but not limited to any one of 10%, 20%, 30%, 80%, 90% or a range value between any two of them.

[0056] Preferably, the organic solvent includes at least one of n-hexane, n-heptane, petroleum ether, methanol, ethanol, tetrahydrofuran, dichloromethane, dichloroethane, chloroform, toluene, ethyl acetate, and more preferably n-hexane.

[0057] It can be understood that the protective atmosphere includes but is not limited to a nitrogen atmosphere. The addition of the complex in the protective atmosphere is beneficial to reduce the influence of environmental conditions such as moisture and oxygen on the ligand in the complexing agent, and is beneficial to further prolong the service life of the catalyst.

[0058] In an embodiment of the present application, it is preferred to replace the protective atmosphere with hydrogen gas multiple times, so that the gas in the reaction device is mainly hydrogen.

[0059] In an embodiment of the present application, during the reaction, the hydrogen pressure is preferably 0.1 MPa to 2 MPa, including but not limited to any one of 0.1 MPa, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa or a range between any two of them; the stirring rate is preferably 200 rpm to 500 rpm, including but not limited to any one of 200 rpm, 300 rpm, 400 rpm, 500 rpm or a range between any two of them; the reaction temperature is preferably -10°C to 25°C, including but not limited to any one of -10°C, -5°C, 0°C, 10°C, 20°C, 25°C or a range between any two of them, further preferably 0°C to 10°C; the reaction time is preferably 2 h to 8 h, including but not limited to any one of 2 h, 4 h, 6 h, 8 h or a range between any two of them.

[0060] In an embodiment of the present application, the complex is separated from the reactants and recycled for use in the selective hydrogenation reduction reaction. After repeated tests, it is found that the conversion rate is still not less than 99.2% after 100 consecutive uses, and the hydrogenation reaction selectivity does not decrease significantly, which is conducive to improving the downstream VA crystallization rate and product quality.

[0061] Hereinafter, the complex and the method for preparing an enol from an acetylene alcohol and derivatives thereof will be further described through the following specific examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. If no specific conditions are specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be obtained by purchase on the market.

[0062] Example 1

[0063] 302 g of C20 acetylene alcohol and 600 g of n-hexane solvent were added to a reaction kettle, 300 mg of Pd / CaCO3 (Xinhecheng, palladium content 1%, inhibitor lead acetate), 0.3 mg of the ligand shown as formula (1-1) were added under a nitrogen atmosphere, hydrogen was introduced to replace nitrogen for 3 times, the hydrogen pressure was maintained at 0.1 MPa, the temperature of the reaction system was controlled at 0°C, the stirring rate was controlled at 100 rpm, and the reaction time was 6 h.

[0064]

[0065] Example 2

[0066] The difference between Example 2 and Example 1 is only that an equal amount of the ligand shown as formula (1-2) is used.

[0067]

[0068] Example 3

[0069] Example 3 differs from Example 1 only in that an equal amount of ligand shown as formula (2-1) is used.

[0070]

[0071] Example 4

[0072] Example 4 differs from Example 1 only in that an equal amount of ligand shown as formula (3-1) is used.

[0073]

[0074] Example 5

[0075] Example 5 differs from Example 1 only in that the amount of ligand is increased to 0.36 mg.

[0076] Example 6

[0077] Example 6 differs from Example 1 only in that the amount of ligand is increased to 0.45 mg.

[0078] Example 7

[0079] Example 7 differs from Example 1 only in that an equal amount of Pd / CaCO3 (BETOL, palladium content 5%, inhibitor lead) is used.

[0080] Example 8

[0081] Example 8 differs from Example 1 only in that an equal amount of Pd / BaSO4 (BETOL, palladium content 5%, non-poisoned) is used.

[0082] Example 9

[0083] Into a reaction kettle, 302 g of C20 alkyne alcohol and 600 g of n-heptane solvent were added, 300 mg of commercial Lindlar catalyst and 0.3 mg of ligand shown as formula (1-1) were added under a nitrogen atmosphere, hydrogen was introduced to replace nitrogen 3 times, the hydrogen pressure was maintained at 0.1 MPa, the reaction system temperature was controlled at 0°C, the stirring rate was controlled at 100 rpm, and the reaction time was 5.5 h.

[0084] Example 10

[0085] Into a reaction kettle, 302 g of C20 alkyne alcohol and 600 g of n-hexane solvent were added, 300 mg of commercial Lindlar catalyst and 0.3 mg of ligand shown as formula (1-1) were added under a nitrogen atmosphere, hydrogen was introduced to replace nitrogen 3 times, the hydrogen pressure was maintained at 1.0 MPa, the reaction system temperature was controlled at 0°C, the stirring rate was controlled at 100 rpm, and the reaction time was 2 h.

[0086] Example 11

[0087] Into a reaction kettle, 152 g of dehydro-linalool, 600 g of n-hexane solvent were added, 300 mg of commercial Lindlar catalyst, 0.3 mg of ligand shown in formula (1-1) were added under nitrogen atmosphere, hydrogen was introduced to replace nitrogen for 3 times, the hydrogen pressure was maintained at 0.1 MPa, the reaction system temperature was controlled at 0°C, the stirring rate was controlled at 100 rpm, and the reaction time was 8 h.

[0088] Example 12

[0089] Into a reaction kettle, 294 g of dehydro-isolinalool, 600 g of n-hexane solvent were added, 300 mg of commercial Lindlar catalyst, 0.3 mg of ligand shown in formula (1-1) were added under nitrogen atmosphere, hydrogen was introduced to replace nitrogen for 3 times, the hydrogen pressure was maintained at 0.1 MPa, the reaction system temperature was controlled at 0°C, the stirring rate was controlled at 100 rpm, and the reaction time was 8 h.

[0090] Example 13

[0091] Into a reaction kettle, 302 g of C20 alkyne alcohol, 600 g of n-hexane solvent were added, 500 mg of Pd / CaCO3 (Xinhecheng, palladium content is 4%, inhibitor is lead acetate), 0.15 mg of ligand shown in formula (4-1) were added under nitrogen atmosphere, hydrogen was introduced to replace nitrogen for 3 times, the hydrogen pressure was maintained at 0.2 MPa, the reaction system temperature was controlled at 10°C, the stirring rate was controlled at 150 rpm, and the reaction time was 10 h.

[0092]

[0093] Example 14

[0094] The difference between Example 14 and Example 1 is only that an equal amount of ligand shown in formula (1-3) is used.

[0095]

[0096] Example 15

[0097] The difference between Example 15 and Example 1 is only that an equal amount of ligand shown in formula (2-2) is used.

[0098]

[0099] Example 16

[0100] The difference between Example 16 and Example 1 is only that an equal amount of ligand shown in formula (3-2) is used.

[0101]

[0102] Example 17

[0103] Example 17 differs from Example 1 only in that an equal amount of ligand as shown in formula (4-2) is used.

[0104]

[0105] Example 18

[0106] Example 18 differs from Example 1 only in that an equal amount of ligand as shown in formula (1-4) is used.

[0107]

[0108] Comparative Example 1

[0109] Comparative Example 1 differs from Example 1 only in that an equal amount of triphenylphosphine is used as ligand.

[0110] Comparative Example 2

[0111] Comparative Example 2 differs from Example 1 only in that an equal amount of PdCl2 (PdCl2) is used as catalyst.

[0112] Comparative Example 3

[0113] Comparative Example 3 differs from Example 1 only in that an equal amount of ligand as shown in formula (6) is used.

[0114]

[0115] Comparative Example 4

[0116] Comparative Example 4 differs from Example 1 only in that an equal amount of tri-(2,4-dimethyl-5-sulfonate sodium phenyl) phosphine is used as ligand.

[0117] The preparation processes of all examples and comparative examples are monitored by GC to determine the conversion rate of alkyne alcohol, the selectivity of cis-alkenol and the selectivity of perhydrogenation, and the results are shown in Table 1.

[0118] Table 1

[0119]

[0120] According to Table 1, the complex provided by the application has high catalytic activity and high reaction selectivity when used for catalyzing the selective hydrogenation reduction of alkyne alcohol and its derivatives to prepare alkenol, and can increase the selectivity of cis-reduction of alkenol to more than 99%.

[0121] The reaction product of Example 1 was intercepted by a 1 μm precision filter under air environment, and GC-MS detection showed that phosphorus impurities were not detected (detection limit 0.1 ppm), and the intercepted complex was directly put into the next batch reaction after being washed with n-hexane. The changes of the conversion rate of acetylene alcohol, the selectivity of cis-alkenol and the yield of alkenol in the recycling process are shown in Table 2.

[0122] Table 2

[0123]

[0124] According to Table 2, the complex provided by the application is used for catalyzing the selective hydrogenation reduction of acetylene alcohol and its derivatives to prepare alkenol, which not only does not need to supplement ligands, but also can be reused for 100 times without affecting the reaction selectivity. In the recycling process, the conversion rate of acetylene alcohol can still be maintained at more than 99.2%, the selectivity of cis-alkenol can still reach more than 98.7%, and the yield of alkenol can reach more than 98.5%.

[0125] The precision filter was detected, and no small catalyst particles were intercepted, indicating that the introduction of the bidentate phosphorus ligand significantly improves the mechanical strength of the Lindlar catalyst. In the recycling process, only the water content in the solvent needs to be controlled below 0.5% to meet the production requirements. In addition, during the filtration operation, the complex is in contact with air, but during the test of 1 to 100 batches, the catalytic activity does not decrease significantly, proving that the tolerance of the complex provided by the application to water and oxygen is significantly improved.

[0126] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0127] The above-described embodiments only express several embodiments of the present application, which are described in detail and specifically, but should not be construed as limiting the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, some modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of the patent of the present application should be subject to the appended claims.

Claims

1. A complex for catalyzing the selective hydrogenation reduction of alkynols and their derivatives to prepare enols, characterized in that, The complex is formed by the complexation of a bidentate phosphorus ligand and a Lindlar catalyst, wherein the bidentate phosphorus ligand is selected from at least one of the following formulas (1), (2), (3), and (4). 、 、 、 ， R1, R3, R6, and R7 are selected from C4-C9 alkyl groups, substituted or unsubstituted C6-C20 aryl groups, R2 is selected from H or an electron-withdrawing group, R4 and R5 are independently selected from H, halogens, or C1-C6 alkyl groups, and X is selected from O, NH, and S.

2. The complex according to claim 1, characterized in that, When R1, R3, R6, and R7 are selected from substituted C6-C20 aryl groups, the substituents are selected from at least one of phenyl, isopropyl, cyclohexyl, cyclopentyl, and adamantyl.

3. The complex according to claim 1, characterized in that, R1, R3, R6, and R7 are independently selected from phenyl, tert-butyl, and other organic compounds, respectively. , , , , , , , , , , , , , .

4. The complex according to claim 1, characterized in that, R2 is selected from H, triisopropylsilyl, tert-butyldiphenylsilyl, nitro, or trifluoromethyl.

5. The complex according to claim 1, characterized in that, In the complex, the bidentate phosphorus ligand has a mass of 0.01% to 0.15% of the mass of the Lindlar catalyst; And / or, the palladium content in the Lindlar catalyst is 1% to 10% by mass.

6. A method for preparing enols from alkynols and their derivatives, characterized in that, Includes the following steps: Under a protective atmosphere, the complex as described in any one of claims 1 to 5 is added to a base liquid containing alkynols and their derivatives, and then the protective atmosphere is replaced with hydrogen to carry out a selective hydrogenation reduction reaction to obtain an enol.

7. The method for preparing enols from alkynols and their derivatives according to claim 6, characterized in that, The mass of the complex is 0.01% to 2% of the mass of the alkynol and its derivatives.

8. The method for preparing enols from alkynols and their derivatives according to claim 6, characterized in that, The underlying liquid comprises alkynyl alcohols and their derivatives and an organic solvent, and the underlying liquid satisfies at least one of the following conditions: (1) The mass concentration of alkynols and their derivatives in the bottom liquid is 10% to 90%; (2) The organic solvent includes at least one of n-hexane, n-heptane, petroleum ether, methanol, ethanol, tetrahydrofuran, dichloromethane, dichloroethane, chloroform, toluene, and ethyl acetate.

9. The method for preparing enols from alkynols and their derivatives according to claim 6, characterized in that, The reaction process satisfies at least one of the following conditions: (1) The hydrogen pressure is 0.1 MPa to 2 MPa; (2) The stirring speed is 200 rpm to 500 rpm; (3) The reaction temperature is -10℃ to 25℃; (4) The reaction time is 2h to 8h.

10. The method for preparing enols from alkynols and their derivatives according to claim 6, characterized in that, The complex is separated from the reactants and recycled in the selective hydrogenation reduction reaction.

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