Chromium compound, preparation method and application thereof, and benzyl alcohol compound catalytic oxidation method

Abstract

The invention relates to the technical field of organic synthesis, in particular to a chromium compound, a preparation method and application thereof and a benzyl alcohol compound catalytic oxidation method. The compound has a structure as shown in a formula (1): # imgabs0 #, in the formula (1), Ar is # imgabs1 # * and represents a connection site of Ar and Si; r1, R2 and R3 are independently selected from cyano, alkyl, halogen or hydrogen, and are not all hydrogen. The chromium compound disclosed by the invention has a good catalytic oxidation effect when being applied to catalytic oxidation reaction, such as catalytic oxidation of benzyl alcohol compounds.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a chromium compound and a preparation method and application thereof, and a method for catalytic oxidation of a benzyl alcohol compound. Background Art

[0002] Benzoic acid compounds are an important class of organic compounds that are widely used in medicine, pesticides and polymers.

[0003] Organic pyridinium dichromate can oxidize primary alcohols and secondary alcohols into aldehydes and ketones in organic solvents, but generally will not oxidize alcohols to carboxylic acids. However, when the reaction system contains water, the generated aldehydes and ketones will further form hydrated aldehydes or hydrated ketones, and then continue to oxidize to obtain carboxylic acids. However, organic pyridinium dichromate has the following disadvantages: (1) Organic pyridinium dichromate is weakly acidic in the reaction system and is not suitable for certain acid-sensitive compounds. Although its acidity can be weakened by adding NaOAC powder as a buffer, the effect is not very good; (2) Organic pyridinium dichromate has serious environmental pollution (Suggs E. Pyridinium chlorochromate. An efficient reagent for oxidation of primary and secondary alcohols to carbonyl compounds [J]. Tetrahedron Letters, 1975.); The oxidizing ability of pyridinium chlorochromate is stronger than that of organic pyridinium dichromate, and its oxidation is generally carried out under neutral conditions. However, whether organic pyridinium dichromate or pyridinium chlorochromate is used for the oxidation reaction, dark brown oily residue will be generated as the reaction proceeds. The product is wrapped by the residue, resulting in a decrease in yield (EJ, Corey, and, et al. Useful procedures for the oxidation of alcohols involving pyridinium dichromate in approtic media [J]. Tetrahedron Letters, 1979, 20 (5): 399-402.).

[0004] Jones oxidation reaction (Jones reagent oxidation) is a reaction in which chromic acid in acetone oxidizes primary and secondary alcohols to carboxylic acids and ketones, respectively (Ley SV, Madin A. Oxidation Adjacent to Oxygen of Alcohols by Chromium Reagents [J]. Comprehensive Organic Synthesis, 1991.). When it oxidizes secondary benzyl alcohol raw materials, it cannot obtain benzoic acid compounds in high yield. In addition, Jones reagent is an aqueous solution composed of chromium trioxide, sulfuric acid and water, and is not suitable for secondary benzyl alcohol raw materials that are not acid-resistant.

[0005] In summary, benzyl alcohol is a stable and readily available raw material, but it is currently difficult to prepare benzoic acid from benzyl alcohol. Summary of the invention

[0006] The object of the present invention is to provide a chromium compound and a preparation method thereof. The chromium compound is used in a catalytic oxidation reaction, for example, in the catalytic oxidation of benzyl alcohol compounds, and has a good catalytic oxidation effect. The prepared chromium compound can be dissolved in an organic solvent to form a homogeneous reaction with the benzyl alcohol compound, so that the reaction is more favorable, the reaction conditions are mild, and the trivalent chromium formed after the oxidation is completed has low toxicity.

[0007] The first aspect of the present invention provides a chromium compound having a structure shown in formula (1):

[0008]

[0009] Wherein, in formula (1), Ar is * represents the bonding site of Ar and Si; R1, R2 and R3 are each independently selected from cyano, alkyl, halogen or hydrogen, and not all are hydrogen.

[0010] The second aspect of the present invention provides a method for preparing a chromium compound having a structure shown in formula (1), the preparation method comprising: subjecting the compound shown in formula (2-1) to an esterification reaction with CrO3 in the presence of a solvent and an optional dehydrating agent;

[0011]

[0012] Wherein, the definitions of Ar, R1, R2 and R3 are as described above in the present invention.

[0013] The third aspect of the present invention provides the use of the chromium compound of the present invention in catalytic oxidation reaction.

[0014] A fourth aspect of the present invention provides a method for catalytic oxidation of benzyl alcohol compounds, the method comprising:

[0015] In the presence of an organic solvent, the chromium compound of the present invention is added to the benzyl alcohol compound of formula (I) to carry out a catalytic oxidation reaction;

[0016]

[0017] Wherein, R in formula (I) a Selected from H, CH3, Cl or F.

[0018] Through the above technical scheme, the present invention provides a new chromium-based compound, and uses it in a catalytic oxidation reaction, for example, in the application of catalytic oxidation of benzyl alcohol compounds, it has a good catalytic oxidation effect, the benzyl alcohol compound has a high conversion rate, and the target product benzoic acid compound has a high selectivity, and the reaction conditions of the catalytic oxidation are mild, and the trivalent chromium formed after the oxidation is completed has low toxicity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the hydrogen spectrum of the product obtained in the first step of Example 1;

[0020] Figure 2 is the carbon spectrum of the product obtained in the first step of Example 1;

[0021] Figure 3 is the infrared spectrum of the product obtained in the first step of Example 1;

[0022] Figure 4 is the hydrogen spectrum of the product obtained in the second step of Example 1;

[0023] Figure 5 is the carbon spectrum of the product obtained in the second step of Example 1;

[0024] Figure 6 is the infrared spectrum of the product obtained in the second step of Example 1;

[0025] Figure 7 is the hydrogen spectrum of the product obtained in the third step of Example 1;

[0026] Figure 8 is the carbon spectrum of the product obtained in the third step of Example 1;

[0027] Fig. 9 is the infrared spectrum of the product obtained in the third step of Example 1;

[0028] Fig.10 is the XRD crystal diffraction structure of the product obtained in the third step of Example 1;

[0029] Fig.11is the hydrogen spectrum of the product obtained in the first step of Example 2;

[0030] Fig.12 is the carbon spectrum of the product obtained in the first step of Example 2;

[0031] Fig.13 is the infrared spectrum of the product obtained in the first step in Example 2;

[0032] Fig.14 is the hydrogen spectrum of the product obtained in the second step of Example 2;

[0033] Fig.15 is the carbon spectrum of the product obtained in the second step of Example 2;

[0034] Fig.16 is the infrared spectrum of the product obtained in the second step of Example 2;

[0035] Fig.17 is the hydrogen spectrum of the product obtained in the first step of Example 3;

[0036] Fig.18 is the carbon spectrum of the product obtained in the first step of Example 3;

[0037] Fig.19 is the infrared spectrum of the product obtained in the first step in Example 3;

[0038] Fig. 20 is the hydrogen spectrum of the product obtained in the second step of Example 3;

[0039] Fig.21 is the carbon spectrum of the product obtained in the second step of Example 3;

[0040] Fig. 22 is the infrared spectrum of the product obtained in the second step of Example 3;

[0041] Fig.23 is the hydrogen spectrum of the product obtained in the third step of Example 3;

[0042] Fig.24 is the carbon spectrum of the product obtained in the third step of Example 3;

[0043] Fig.25 is the infrared spectrum of the product obtained in the third step of Example 3;

[0044] Fig.26 is the XRD crystal diffraction structure of the product obtained in the third step of Example 3;

[0045] Fig. 27 is the hydrogen spectrum of the product obtained in the first step of Example 4;

[0046] Fig.28 is the carbon spectrum of the product obtained in the first step of Example 4;

[0047] Fig.29 is the infrared spectrum of the product obtained in the first step in Example 4;

[0048] Fig.30 is the hydrogen spectrum of the product obtained in the second step of Example 4;

[0049] Fig.31 is the carbon spectrum of the product obtained in the second step of Example 4;

[0050] Fig.32 is the infrared spectrum of the product obtained in the second step of Example 4;

[0051] Fig.33 is the hydrogen spectrum of the product obtained in the first step of Example 5;

[0052] Fig.34 is the carbon spectrum of the product obtained in the first step of Example 5;

[0053] Fig.35 is the infrared spectrum of the product obtained in the first step in Example 5;

[0054] Fig.36 is the hydrogen spectrum of the product obtained in the second step of Example 5;

[0055] Fig.37 is the carbon spectrum of the product obtained in the second step of Example 5;

[0056] Fig.38 It is the infrared spectrum of the product obtained in the second step in Example 5. DETAILED DESCRIPTION

[0057] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0058] The halogen mentioned in the present invention means at least one element selected from the group consisting of fluorine, chlorine, bromine and iodine.

[0059] The alkyl group described in the present invention may be a branched alkyl group, a straight chain alkyl group, or a straight cyclic alkyl group, and the present invention has no particular limitation on this.

[0060] The alkyl C1-C 10Alkyl refers to an alkyl group having 1-10 carbon atoms, for example, a straight chain alkyl group having 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms, a branched alkyl group or a cycloalkyl group having 3, 4, 5, 6, 7, 8, 9 or 10 carbon atoms, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, cyclopropyl, methylcyclopropyl, cyclohexyl and the like; "C1-C4 alkyl" has a similar explanation, except that the number of carbon atoms is different.

[0061] As mentioned above, the first aspect of the present invention provides a chromium compound having a structure shown in formula (1):

[0062]

[0063] Wherein, in formula (1), Ar is * represents the bonding site of Ar and Si; R1, R2 and R3 are each independently selected from cyano, alkyl, halogen or hydrogen, and not all are hydrogen.

[0064] According to one embodiment of the present invention, in formula (1), R1, R2 and R3 are each independently selected from cyano, C1-C 10 Alkyl, halogen or hydrogen, and not all of them are hydrogen.

[0065] According to a preferred embodiment of the present invention, in formula (1), R1, R2 and R3 are each independently selected from C1-C4 alkyl, halogen or hydrogen, and not all are hydrogen.

[0066] According to a particularly preferred embodiment of the present invention, in formula (1), R1 and R3 are each independently selected from C1-C4 alkyl, halogen or hydrogen, and R2 is hydrogen, and not all of them are hydrogen.

[0067] According to a particularly preferred embodiment of the present invention, the compound having the structure shown in formula (1) is selected from the compounds having the structures described in formula (1-1) to formula (1-5):

[0068] Formula (1-1): R1 and R2 are hydrogen, and R3 is CH3;

[0069] Formula (1-2): R1 and R2 are hydrogen, and R3 is F;

[0070] Formula (1-3): R1 and R2 are hydrogen, and R3 is Cl;

[0071] Formula (1-4): R1 and R2 are hydrogen, and R3 is C(CH3);

[0072] Formula (1-5): R2 and R3 are hydrogen, and R1 is CH3.

[0073] The second aspect of the present invention provides a method for preparing a chromium compound having a structure shown in formula (1), the preparation method comprising: subjecting the compound shown in formula (2-1) to an esterification reaction with CrO3 in the presence of a solvent and an optional dehydrating agent;

[0074]

[0075] Wherein, the definitions of Ar, R1, R2 and R3 are as described above in the present invention.

[0076] The chromium compounds of the structure shown in formula (1) involved in the second aspect of the present invention and thereafter have the same substituents as the chromium compounds described in the first aspect of the present invention. In order to avoid repetition, the present invention will not elaborate on the chromium compounds, and those skilled in the art should not understand this as a limitation of the present invention; and the R1, R2 and R3 substituents in the compounds of formula (2-1) of the present invention are all the same as the corresponding substituents in the chromium compounds of the structure shown in formula (1).

[0077] According to the present invention, as long as the purpose of the present invention can be achieved, the type of the solvent is not particularly limited. In some embodiments, the solvent is selected from non-polar solvents, preferably at least one of carbon tetrachloride, dichloromethane, benzene and hexane.

[0078] According to the present invention, the molar ratio of the compound represented by formula (2-1) to CrO3 can be 1:(2-4).

[0079] According to the present invention, there is no particular limitation on the amount of the solvent used, and it can be any conventional amount in the art, for example, the amount of the solvent used is such that the content of the compound represented by formula (2-1) in the solvent is 10-50 mg / mL.

[0080] According to the present invention, the optional dehydrating agent means that the dehydrating agent may be present or absent during the esterification reaction. During the esterification reaction, water will be generated. In order to avoid the influence of water on the esterification reaction, it is preferred to carry out the esterification reaction in the presence of a dehydrating agent. The type of dehydrating agent may be a conventional dehydrating agent in the art, for example, the dehydrating agent includes at least one of anhydrous calcium chloride, anhydrous magnesium sulfate, sodium polyacrylate, anhydrous magnesium chloride, molecular sieves and anhydrous sodium sulfate. There is no special requirement for the amount of the dehydrating agent, which may be the amount conventionally used in the art, for example, the mass of the dehydrating agent is 30-110wt% of the mass of the compound represented by formula (2-1).

[0081] According to the present invention, as long as the purpose of the present invention can be achieved, the conditions of the esterification reaction are not particularly limited. In some embodiments, the conditions of the esterification reaction include: the reaction temperature is room temperature (referring to 25±5°C).

[0082] According to a particularly preferred embodiment of the present invention, the conditions of the esterification reaction include: the reaction time is 12-36 hours.

[0083] According to the present invention, the compound represented by formula (1) obtained after the esterification reaction is first post-treated by post-treatment means conventionally used in the art, for example, filtering, drying, and recrystallization after the esterification reaction; the drying can be selected to be drying at normal pressure or vacuum drying, which is a conventional technical means in the art, and the present invention has no special limitation on this, so no further details are given; the recrystallization can be selected to be carried out in a solvent that is conducive to crystal precipitation, preferably in dichloromethane and / or n-hexane.

[0084] According to a preferred embodiment of the present invention, the method for preparing the chromium compound of the present invention further comprises: preparing the compound represented by formula (2-1) according to the following steps:

[0085] (1) In the presence of an inert atmosphere and a first solvent, coupling the compound of formula (2-2) with HSiCl3 to obtain a compound of formula (2-3);

[0086] (2) in the presence of a second solvent, subjecting the compound represented by formula (2-3) to an oxidation reaction with an oxidizing agent;

[0087]

[0088] The substituents R1, R2 and R3 in the compounds represented by formula (2-2) and formula (2-3) of the present invention are the same as the substituents in the chromium-based compound represented by formula (1).

[0089] The inert atmosphere described in the present invention is nitrogen and / or argon. Based on cost considerations, nitrogen is preferred.

[0090] According to a preferred embodiment of the present invention, the first solvent is selected from ether solvents, preferably at least one of diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether and 1,2-dimethoxypropane, and more preferably diethyl ether and / or tetrahydrofuran.

[0091] According to the present invention, when preparing the compound represented by formula (2-3), as long as the compound represented by formula (2-2) can be contacted with HSiCl3 for coupling reaction to obtain the compound represented by formula (2-3), those skilled in the art can select the order of adding materials as needed, for example, adding the material containing the first solvent and HSiCl3 dropwise to the material containing the first solvent and the compound represented by formula (2-2) for coupling reaction; preferably, the dropping time is controlled at 0.5-2 hours.

[0092] The present invention has no special limitation on the amount of the first solvent, which can be the conventional amount in the art. For example, the first solvent is used in an amount such that: the concentration of the compound described in formula (2-2) in the material containing the first solvent and the compound described in formula (2-2) is 0.5-1.5 M, and the concentration of HSiCl3 in the material containing the first solvent and HSiCl3 is 0.1-0.5 M.

[0093] According to the present invention, the molar ratio of the compound described in formula (2-2) to HSiCl3 can be greater than or equal to 3:1, preferably (3.1-3.5):1.

[0094] According to a preferred embodiment of the present invention, the conditions of the coupling reaction include: the reaction temperature is 0-100°C, preferably 0-50°C.

[0095] According to a preferred embodiment of the present invention, the conditions of the coupling reaction include: the reaction time is 2-24 hours; the reaction time refers to the time from the beginning of contact between the compound described in formula (2-2) and HSiCl3 to the end of the reaction.

[0096] In the present invention, the compound represented by the formula (2-3) obtained by coupling reaction of the compound represented by the formula (2-2) with HSiCl3 is first subjected to post-treatment means conventionally used in the art for post-treatment, and then introduced into the next step for oxidation reaction with o-chloroperoxybenzoic acid; for example, post-treatment is performed by separation, organic phase concentration, drying, recrystallization, washing and drying, etc.; in order to neutralize the base that has not been completely reacted as the base of the reaction alkane, and at the same time, it is more conducive to separation and extraction of the product, preferably, the post-treatment also includes an acidification step, and more preferably, hydrochloric acid or acetic acid is used for acidification; in order to remove water in the layers obtained after separation, preferably, the separation is followed by The organic layer is dried using a water absorbent (such as anhydrous magnesium sulfate); preferably ethanol and isopropyl ether are used for recrystallization; preferably anhydrous ethanol is used for washing; specifically, 0.5-2M hydrochloric acid is used to acidify and neutralize the material obtained after the coupling reaction, and then isopropyl ether is added for liquid separation, the organic layer is washed with 25mL of 0.5-2M hydrochloric acid and then separated, and the organic layer is dried with anhydrous magnesium sulfate, and then filtered, and rotary evaporated at 30-40°C to obtain a crude product, and then the crude product is dissolved in a mixed solution of ethanol and isopropyl ether, concentrated under reduced pressure, cooled for crystallization, and finally the precipitated crystals are washed with anhydrous ethanol and vacuum dried to obtain the compound shown in formula (2-3).

[0097] According to a preferred embodiment of the present invention, the second solvent is selected from at least one of dichloromethane, carbon tetrachloride, chloroform and 1,2-dichloroethane.

[0098] According to a preferred embodiment of the present invention, the oxidant is selected from at least one of hydrogen peroxide, meta-chloroperbenzoic acid, tert-butyl peroxide and peracetic acid, preferably meta-chloroperbenzoic acid.

[0099] According to the present invention, there is no particular limitation on the amount of the second solvent, which can be a conventional amount in the art. For example, the amount of the second solvent is such that the content of the compound represented by formula (2-3) in the second solvent is 0.02-0.15 mg / mL.

[0100] According to a preferred embodiment of the present invention, the molar ratio of the compound represented by formula (2-3) to the oxidant is 1:(1.5-3).

[0101] According to a preferred embodiment of the present invention, the conditions of the oxidation reaction include: the reaction temperature is 0-80°C.

[0102] According to a preferred embodiment of the present invention, the conditions of the oxidation reaction include: the reaction time is 5-100 hours.

[0103] In the present invention, the compound represented by formula (2-3) is subjected to an oxidation reaction with o-chloroperoxybenzoic acid and then subjected to post-treatment by post-treatment means conventionally used in the art to obtain the compound represented by formula (2-1). For example, the material obtained by the oxidation reaction is washed with a saturated sodium bicarbonate solution and a saturated saline solution, and the organic phase is concentrated and dried, and then separated by column chromatography to obtain the compound represented by formula (2-1); preferably, the eluent during column chromatography separation is a mixture of petroleum ether (PE) and ethyl acetate (EA) in a volume ratio of (8-12):1.

[0104] The third aspect of the present invention provides the use of the chromium compound of the present invention in catalytic oxidation reaction.

[0105] The chromium compound in the present invention has excellent catalytic oxidation performance.

[0106] According to a preferred embodiment of the present invention, the chromium compound is used in the catalytic oxidation of benzyl alcohol compounds.

[0107] In the present invention, when the chromium compound of the present invention is used in the catalytic oxidation of benzyl alcohol compounds, the purpose of directly catalytically oxidizing benzyl alcohol compounds to obtain benzoic acid compounds can be well achieved, and the raw materials have a high conversion rate and the target product has a high selectivity.

[0108] A fourth aspect of the present invention provides a method for catalytic oxidation of benzyl alcohol compounds, the method comprising:

[0109] In the presence of an organic solvent, the chromium compound of the present invention is added to the benzyl alcohol compound of formula (I) to carry out a catalytic oxidation reaction;

[0110]

[0111] Wherein, R in formula (I) a Selected from H, CH3, Cl or F.

[0112] In the present invention, the chromium-based compounds of the present invention are used in the catalytic oxidation reaction of benzyl alcohol compounds, so that benzoic acid compounds can be obtained in the absence of water and additional acidic additives, and can be applied to the catalytic oxidation of different types of benzyl alcohol compounds to obtain benzoic acid compounds with high selectivity.

[0113] According to a preferred embodiment of the present invention, the molar ratio of the chromium compound to the benzyl alcohol compound is 0.5-3.0.

[0114] According to a preferred embodiment of the present invention, the conditions of the catalytic oxidation reaction include: the reaction temperature is 10-80°C.

[0115] According to a preferred embodiment of the present invention, the conditions of the catalytic oxidation reaction include: the reaction time is 3-24 hours.

[0116] The present invention will be described in detail below through examples. In the following examples, the sources of raw materials are shown in Table 1, and unless otherwise specified, other raw materials can be obtained commercially:

[0117] Table 1 Sources of raw materials

[0118]

[0119] The prepared compounds were subjected to FTIR, 1 H NMR, XRD and other characterization and analysis, using element analyzer for quantification, melting point using melting point instrument for determination, the characterization and analysis methods involved are shown in Table 2:

[0120] Table 2 Evaluation and analysis methods

[0121]

[0122] Example 1

[0123] Synthesis of bis(tri-p-tolylsilyl)chromate:

[0124] first step:

[0125]

[0126] 100mL of 1.0M p-tolylmagnesium bromide solution was pressed into a 500mL three-necked flask in which the internal gas was replaced with nitrogen in advance using a double-ended needle, and then 100mL of a tetrahydrofuran solution of 4.20g trichlorosilane (31mmol) was slowly added dropwise over 1 hour, and the temperature was controlled below 35°C. After the addition was completed, stirring was continued at room temperature for 3 hours. After the reaction was completed, 25mL of 1.0M hydrochloric acid was used for neutralization, and 200mL of isopropyl ether was used for separation. The organic layer was washed with 25mL of 1.0M hydrochloric acid and then separated. The organic layer was dried with 20g of anhydrous magnesium sulfate, filtered, and rotary evaporated at 35°C to obtain a crude product. The crude product was then dissolved in 15mL of ethanol and 15mL of isopropyl ether, concentrated under reduced pressure, cooled and crystallized, and finally the precipitated crystals were washed with 20mL of anhydrous ethanol and vacuum dried to obtain the product, obtaining 5.60g of the product with a yield of 60.3% and a melting point of 75-76°C.

[0127] Figure 1 is the hydrogen spectrum of the product obtained in the first step, Figure 2 is the carbon spectrum of the product obtained in the first step, Figure 3 is the infrared spectrum of the product obtained in the first step. Figure 1-3 The product obtained in the first step is tri(p-tolyl)silane.

[0128] Step 2:

[0129]

[0130] 2.50 g of tri(p-tolyl)silane (8.25 mmol) was dissolved in 30 mL of dichloromethane in a 50 mL three-necked flask. After cooling to 0°C, 2.84 g (16.50 mmol) of mCPBA was added. The ice bath was removed and stirred at room temperature for 48 hours, followed by dilution with 370 mL of dichloromethane. The liquid was transferred to a 1000 mL separatory funnel and washed three times with 150 mL of saturated sodium bicarbonate solution and 100 mL of saturated sodium chloride solution in sequence. The organic phase was dried over 20 g of anhydrous magnesium sulfate, and the crude product was obtained by spin drying at 35°C. The product was eluted by column chromatography (PE:EA in the eluent = 9:1) to obtain 700 mg of the product with a yield of 26.6% and a melting point of 108-109°C.

[0131] Figure 4 is the hydrogen spectrum of the product obtained in the second step, Figure 5 is the carbon spectrum of the product obtained in the second step, Figure 6 is the infrared spectrum of the product obtained in the second step. Figure 4-6 The product obtained in the second step is tri(p-tolyl)silanol.

[0132] Step 3:

[0133]

[0134] 500 mg of tri(p-tolyl)silanol (1.57 mmol), 450 mg of chromium trioxide (4.50 mmol) and 0.5 g of anhydrous magnesium sulfate were placed in a 100 mL round-bottom flask, with 30 mL of carbon tetrachloride as solvent, stirred at room temperature for 24 h, then filtered and dried under vacuum to obtain an orange-red crude product, which was recrystallized from n-hexane at room temperature to obtain the product, and the obtained product was subjected to X-ray crystal diffraction test.

[0135] Figure 7 is the hydrogen spectrum of the product obtained in the third step, Figure 8 is the carbon spectrum of the product obtained in the third step, Fig. 9 is the infrared spectrum of the product obtained in the third step; Fig.10 is the XRD crystal diffraction structure of the product obtained in the third step, Figure 7-10 The product obtained in the third step is bis(tri-p-tolylsilyl) chromate.

[0136] Embodiment 2:

[0137] Synthesis of bis(tri-p-fluorophenylsilyl)chromate:

[0138] first step:

[0139]

[0140] 100 mL of 1.0 M p-fluorophenylmagnesium bromide was added to a 500 mL three-necked flask in which the internal gas had been replaced with nitrogen in advance. Then, 100 mL of a tetrahydrofuran solution of 4.20 g of trichlorosilane (31 mmol) was slowly added dropwise over 1 hour. The temperature was controlled below 35° C. After the addition was completed, stirring was continued at room temperature for 3 hours. After the reaction was completed, 25 mL of 1.0 M hydrochloric acid was used for neutralization, and 200 mL of isopropyl ether was used for separation. The organic layer was washed with 25 mL of 1.0 M hydrochloric acid and then separated. The organic layer was dried with 20 g of anhydrous magnesium sulfate, filtered, and rotary evaporated at 35° C. to obtain a crude product. The crude product was then dissolved in 15 mL of n-pentane, filtered with slow filter paper at normal pressure to remove the precipitated colored product, and the filtrate was rotary evaporated at 35° C. and recrystallized with 10 mL of methanol to obtain 4.50 g of the product with a yield of 46.2% and a melting point of 44-45° C.

[0141] Fig.11 is the hydrogen spectrum of the product obtained in the first step, Fig.12 is the carbon spectrum of the product obtained in the first step, Fig.13 is the infrared spectrum of the product obtained in the first step. Figure 11-13 The product obtained in the first step is tri(p-fluorophenyl)silane.

[0142] Step 2:

[0143]

[0144] 2.59 g of tri(p-fluorophenyl)silane (8.25 mmol) was dissolved in 30 mL of dichloromethane in a 50 mL three-necked flask. After cooling to 0°C, 2.84 g (16.50 mmol) of mCPBA was added. The ice bath was removed and stirred at room temperature for 96 hours, followed by dilution with 370 mL of dichloromethane. The liquid was transferred to a 1000 mL separatory funnel and washed three times with 150 mL of saturated sodium bicarbonate solution and 100 mL of saturated sodium chloride solution in sequence. The organic phase was dried over 20 g of anhydrous magnesium sulfate, and the crude product was obtained by spin drying at 35°C. The product was eluted by column chromatography (PE:EA in the eluent = 19:1) to obtain 1.80 g of the product with a yield of 66.2% and a melting point of 81-82°C.

[0145] Fig.14 is the hydrogen spectrum of the product obtained in the second step, Fig.15 is the carbon spectrum of the product obtained in the second step, Fig.16 is the infrared spectrum of the product obtained in the second step. Figure 14-16 The product obtained in the second step is tri(p-fluorophenyl)silanol.

[0146] Step 3:

[0147]

[0148] 517 mg of tri(p-fluorophenyl)silanol (1.57 mmol), 450 mg of chromium trioxide (4.50 mmol) and 0.5 g of anhydrous magnesium sulfate were placed in a 100 mL round-bottom flask, with 30 mL of carbon tetrachloride as solvent, stirred at room temperature for 24 h, then filtered, and dried under vacuum to obtain an orange-red crude product, which was recrystallized from n-hexane at room temperature to obtain the product, which was bis(tri(p-fluorophenylsilyl)chromate).

[0149] Embodiment 3:

[0150] Synthesis of bis(tri-p-chlorophenylsilyl)chromate:

[0151] first step:

[0152]

[0153] 100 mL of 1.0 M p-chlorophenylmagnesium bromide solution was added to a 500 mL three-necked flask in which the internal gas was replaced with nitrogen in advance, and then 100 mL of a tetrahydrofuran solution of 4.20 g of trichlorosilane (31 mmol) was slowly added dropwise over 1 hour, and the temperature was controlled below 35° C. After the addition was completed, stirring was continued at room temperature for 3 hours. After the reaction was completed, 25 mL of 1.0 M hydrochloric acid was used for neutralization, and 200 mL of isopropyl ether was used for separation. The organic layer was washed with 25 mL of 1.0 M hydrochloric acid and then separated. The organic layer was dried with 20 g of anhydrous magnesium sulfate, filtered, and rotary evaporated at 35° C. to obtain a crude product, which was then recrystallized in 15 mL of anhydrous ethanol, filtered, and vacuum dried to obtain a white solid to obtain 9.00 g of the product with a yield of 79.8% and a melting point of 75-77° C.

[0154] Fig.17 is the hydrogen spectrum of the product obtained in the first step, Fig.18 is the carbon spectrum of the product obtained in the first step, Fig.19 is the infrared spectrum of the product obtained in the first step. Figure 17-19 The product obtained in the first step is tri(p-chlorophenyl)silanol.

[0155] Step 2:

[0156]

[0157] 3.00 g of tri(p-chlorophenyl)silane (8.25 mmol) was dissolved in 30 mL of dichloromethane in a 50 mL three-necked flask. After cooling to 0°C, 2.84 g (16.50 mmol) of mCPBA was added. The ice bath was removed and stirred at room temperature for 48 hours, followed by dilution with 370 mL of dichloromethane. The liquid was transferred to a 1000 mL separatory funnel and washed three times with 150 mL of saturated sodium bicarbonate solution and 100 mL of saturated sodium chloride solution in sequence. The organic phase was dried over 20 g of anhydrous magnesium sulfate, and the crude product was dried at 35°C and washed with 50 mL of n-hexane to obtain 2.30 g of pure product with a yield of 73.5% and a melting point of 115-116°C.

[0158] Fig. 20 is the hydrogen spectrum of the product obtained in the second step, Fig.21 is the carbon spectrum of the product obtained in the second step, Fig. 22 is the infrared spectrum of the product obtained in the second step. Figure 20-22 The product obtained in the second step is tri(p-chlorophenyl)silanol.

[0159] Step 3:

[0160]

[0161] 1 g of tri(p-chlorophenyl)silanol (2.70 mmol), 720 mg of chromium trioxide (7.20 mmol) and 0.5 g of anhydrous magnesium sulfate were placed in a 100 mL round-bottom flask, with 30 mL of carbon tetrachloride as solvent, stirred at room temperature for 24 h, then filtered, and dried under vacuum to obtain an orange-red crude product, which was recrystallized from a mixed solvent of dichloromethane / n-hexane in a volume ratio of 1:1 at room temperature to obtain the product, and the obtained product was subjected to X-ray crystal diffraction test.

[0162] Fig.23 is the hydrogen spectrum of the product obtained in the third step, Fig.24 is the carbon spectrum of the product obtained in the third step, Fig.25 is the infrared spectrum of the product obtained in the third step; Fig.26 is the XRD crystal diffraction structure of the product obtained in the third step, Figure 23-26 The product obtained in the third step is bis(tri-p-chlorophenylsilyl)chromate.

[0163] Embodiment 4:

[0164] Synthesis of bis(tri-p-tert-butylphenylsilyl)chromate:

[0165] first step:

[0166]

[0167] 100 mL of 1.0 M p-tert-butylphenylmagnesium bromide solution was added to a three-necked flask in which the internal gas was replaced with nitrogen in advance, and then 100 mL of a tetrahydrofuran solution of 4.20 g of trichlorosilane (31 mmol) was slowly added dropwise over 1 hour, and the temperature was controlled below 35° C. After the addition was completed, stirring was continued at room temperature for 3 hours. After the reaction was completed, 25 mL of 1.0 M hydrochloric acid was used for neutralization, and 200 mL of isopropyl ether was used for separation. The organic layer was washed with 25 mL of 1.0 M hydrochloric acid and then separated. The organic layer was dried with 20 g of anhydrous magnesium sulfate, filtered, and rotary evaporated at 35° C. to obtain a crude product, which was then recrystallized in anhydrous ethanol, filtered, and vacuum dried to obtain a white solid to obtain 10.80 g of the product with a yield of 81.2% and a melting point of 109-112° C.

[0168] Fig. 27 is the hydrogen spectrum of the product obtained in the first step, Fig.28 is the carbon spectrum of the product obtained in the first step, Fig.29 is the infrared spectrum of the product obtained in the first step. Figure 27-29 The product obtained in the first step is tri(p-tert-butylphenyl)silane.

[0169] Step 2:

[0170]

[0171] 3.54 g of tri(p-tert-butylphenyl)silane (8.16 mmol) was dissolved in 30 mL of dichloromethane in a 50 mL three-necked flask. After cooling to 0°C, 2.81 g (16.32 mmol) of mCPBA was added. The ice bath was removed and stirred at room temperature for 24 hours, followed by dilution with 370 mL of dichloromethane. The liquid was transferred to a 1000 mL separatory funnel and washed three times with 150 mL of saturated sodium bicarbonate solution and 100 mL of saturated sodium chloride solution in sequence. The organic phase was dried over 20 g of anhydrous magnesium sulfate, and the crude product was dried at 35°C and washed with 50 mL of n-hexane to obtain 1.90 g of product with a yield of 52.3% and a melting point of 192-194°C.

[0172] Fig.30 is the hydrogen spectrum of the product obtained in the second step, Fig.31 is the carbon spectrum of the product obtained in the second step, Fig.32 is the infrared spectrum of the product obtained in the second step. Figure 30-32 The product obtained in the second step is tri(p-tert-butylphenyl)silanol.

[0173] Step 3:

[0174]

[0175] 1.20 g of tri(p-tert-butylphenyl)silanol (2.70 mmol), 720 mg of chromium trioxide (7.20 mmol) and 0.5 g of anhydrous magnesium sulfate were placed in a 100 mL round-bottom flask, with 30 mL of carbon tetrachloride as solvent, stirred at room temperature for 24 h, then filtered, and dried under vacuum to obtain an orange-red crude product, which was recrystallized from a mixed solvent of dichloromethane / n-hexane in a volume ratio of 1:1 at room temperature to obtain the product, and the obtained product was bis(tri-p-tert-butylphenylsilyl) chromate.

[0176] Embodiment 5:

[0177] Synthesis of bis(tri-o-tolylsilyl)chromate:

[0178] first step:

[0179]

[0180] 100 mL of 1.0 M o-tolylmagnesium bromide was added to a three-necked flask in which the internal gas was replaced with nitrogen in advance, and then 100 mL of a tetrahydrofuran solution of 4.20 g of trichlorosilane (31 mmol) was slowly added dropwise over 1 hour, and the temperature was controlled below 35° C. After the addition was completed, stirring was continued at room temperature for 3 hours. After the reaction was completed, 25 mL of 1.0 M hydrochloric acid was used for neutralization, and 200 mL of isopropyl ether was used for separation. The organic layer was washed with 25 mL of 1.0 M hydrochloric acid and then separated. The organic layer was dried with 20 g of anhydrous magnesium sulfate, filtered, and rotary evaporated at 35° C. to obtain a crude product. Dark impurities were removed with petroleum ether by column chromatography. Finally, the crude product was washed with 15 mL of methanol and dried to obtain a white solid to obtain 3.95 g of the product with a yield of 42.0% and a melting point of 71-72° C.

[0181] Fig.33 is the hydrogen spectrum of the product obtained in the first step, Fig.34 is the carbon spectrum of the product obtained in the first step, Fig.35 is the infrared spectrum of the product obtained in the first step. Figure 33-35 The product obtained in the first step is tri(o-tolyl)silane.

[0182] Step 2:

[0183]

[0184] 1.25 g of tri(o-tolyl)silane (4.13 mmol) was dissolved in 30 mL of dichloromethane in a 50 mL three-necked flask. After cooling to 0°C, 1.42 g (8.25 mmol) of mCPBA was added. The ice bath was removed and stirred at room temperature for 5 hours, then diluted with 200 mL of dichloromethane. The liquid was transferred to a 1000 mL separatory funnel and washed three times with 100 mL of saturated sodium bicarbonate solution and 50 mL of saturated sodium chloride solution in sequence. The organic phase was dried over 10 g of anhydrous magnesium sulfate, and the crude product was dried at 35°C and washed with 50 mL of n-hexane to obtain a white solid product with a yield of 860 mg and a yield of 45.5%. The melting point was 87-88°C.

[0185] Fig.36 is the hydrogen spectrum of the product obtained in the second step, Fig.37 is the carbon spectrum of the product obtained in the second step, Fig.38 is the infrared spectrum of the product obtained in the second step. Figure 36-38 The product obtained in the second step is tri(o-tolyl)silanol.

[0186] Step 3:

[0187]

[0188] 8.6 g of tri(o-tolyl)silane (2.70 mmol), 720 mg of chromium trioxide (7.20 mmol) and 0.5 g of anhydrous magnesium sulfate were placed in a 100 mL round-bottom flask, with 30 mL of carbon tetrachloride as solvent, stirred at room temperature for 24 h, then filtered, and dried under vacuum to obtain an orange-red crude product, which was recrystallized from a mixed solvent of dichloromethane / n-hexane at room temperature to obtain the product, which was bis(tri-p-o-tolylsilyl) chromate.

[0189] Application Examples

[0190] 1 molar amount of benzyl alcohol was dissolved in dichloromethane, and the chromium compounds prepared in Examples 1-5 were added at 0°C, stirred for 3 hours, and then heated to room temperature to continue the reaction for 3 hours. After liquid chromatography analysis, the conversion rate of benzyl alcohol and the selectivity of benzoic acid are shown in Table 3.

[0191] Table 3 Conversion rate of benzyl alcohol and selectivity of benzoic acid

[0192] Chromium compounds Conversion rate of benzyl alcohol (%) Selectivity of benzoic acid (%) Example 1 98％ 92％ Example 2 99％ 93％ Example 3 99％ 96％ Example 4 97％ 95％ Example 5 98％ 96％

[0193] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A chromium compound, characterized in that: The compound has a structure shown in formula (1): Wherein, in formula (1), Ar is * indicates the bonding site between Ar and Si; R1, R2 and R3 are each independently selected from cyano, alkyl, halogen or hydrogen, and not all are hydrogen.

2. The compound according to claim 1, wherein In formula (1), R1, R2 and R3 are each independently selected from cyano, C1-C 10 Alkyl, halogen or hydrogen, not all of which are hydrogen; Preferably, R1, R2 and R3 are each independently selected from C1-C4 alkyl, halogen or hydrogen, and not all are hydrogen; More preferably, R1 and R3 are each independently selected from C1-C4 alkyl, halogen or hydrogen, and R2 is hydrogen, and not all of them are hydrogen.

3. The compound according to claim 1 or 2, wherein The compound having the structure shown in formula (1) is selected from the compounds having the structures described in formula (1-1) to formula (1-5): Formula (1-1): R1 and R2 are hydrogen, and R3 is CH3; Formula (1-2): R1 and R2 are hydrogen, and R3 is F; Formula (1-3): R1 and R2 are hydrogen, and R3 is Cl; Formula (1-4): R1 and R2 are hydrogen, and R3 is C(CH3); Formula (1-5): R2 and R3 are hydrogen, and R1 is CH3.

4. A method for preparing a chromium compound, characterized in that: The chromium compound has a structure shown in formula (1), and the preparation method comprises: subjecting the compound shown in formula (2-1) to an esterification reaction with CrO3 in the presence of a solvent and an optional dehydrating agent; Wherein, Ar, R1, R2 and R3 are defined as in any one of claims 1-3.

5. The preparation method according to claim 4, wherein The solvent is selected from at least one of carbon tetrachloride, dichloromethane, benzene and hexane; and / or The dehydrating agent comprises at least one of anhydrous calcium chloride, anhydrous magnesium sulfate, sodium polyacrylate, anhydrous magnesium chloride, molecular sieves and anhydrous sodium sulfate; and / or The conditions of the esterification reaction include: the reaction temperature is room temperature; and / or the reaction time is 12-36 hours.

6. The preparation method according to claim 4 or 5, wherein: The preparation method also includes preparing the compound described in formula (2-1) according to the following steps: (1) In the presence of an inert atmosphere and a first solvent, coupling the compound of formula (2-2) with HSiCl3 to obtain a compound of formula (2-3); (2) in the presence of a second solvent, subjecting the compound represented by formula (2-3) to an oxidation reaction with an oxidizing agent; Wherein, R1, R2 and R3 are defined as any one of claims 1 to 3, and X is a halogen.

7. The preparation method according to claim 6, wherein: The first solvent is selected from ether solvents, preferably at least one of diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether and 1,2-dimethoxypropane, more preferably diethyl ether and / or tetrahydrofuran; and / or The conditions of the coupling reaction include: a reaction temperature of 0-100° C.; and / or a reaction time of 2-24 hours; and / or The second solvent is selected from at least one of dichloromethane, carbon tetrachloride, chloroform and 1,2-dichloroethane; and / or The oxidant is selected from at least one of hydrogen peroxide, meta-chloroperbenzoic acid, tert-butyl peroxide and peracetic acid, preferably meta-chloroperbenzoic acid; and / or The molar ratio of the compound represented by formula (2-3) to the oxidant is 1:(1.5-3); and / or The conditions of the oxidation reaction include: a reaction temperature of 0-80° C.; and / or a reaction time of 5-100 hours.

8. Use of the chromium compound according to any one of claims 1 to 3 in a catalytic oxidation reaction, preferably in the catalytic oxidation of benzyl alcohol compounds.

9. A method for catalytic oxidation of benzyl alcohol compounds, characterized in that: The method includes: In the presence of an organic solvent, adding the chromium compound described in any one of claims 1 to 3 to the benzyl alcohol compound described in formula (I) to carry out a catalytic oxidation reaction; Wherein, R in formula (I) a is selected from H, CH3, Cl or F.

10. The method according to claim 9, wherein: The molar ratio of the chromium compound to the benzyl alcohol compound is 0.5-3.0; and / or The conditions of the catalytic oxidation reaction include: a reaction temperature of 10-80° C.; and / or a reaction time of 3-24 hours.

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