Synthesis method of 4,4'-biphenyldicarboxylate compounds

Abstract

A method for synthesizing 4,4'-biphenyldicarboxylate compounds, which belongs to the field of organic synthesis. It solves the problems of complex process route, high risk, heavy pollution and high cost in the preparation of existing 4,4'-biphenyldicarboxylate compounds. Method: First, heat and react organic titanium with 4,4'-biphenyldicarboxylic acid to obtain a crude product; Second, wash and centrifugally separate the crude product, and collect the precipitate; Third, wash and filter the precipitate, and collect the filtrate; Fourth, sequentially concentrate, crystallize, filter, wash and dry the filtrate. The invention is used for the synthesis of 4,4'-biphenyldicarboxylate compounds.

Description

Technical Field

[0001] The present invention belongs to the field of organic synthesis. Background Art

[0002] As an important fine chemical, 4,4'-biphenyldicarboxylate is a raw material for the production of 4,4-dihydroxymethylbiphenyl and 2,4,6-trimethyl iodobenzene. It has been reported in the literature that 4,4'-biphenyldicarboxylate also has electrochromic properties and can achieve the transformation from colorless to the three primary colors of red, green, and blue, and can be used to prepare liquid crystal materials.

[0003] At present, the synthesis routes of 4,4'-biphenyldicarboxylate compounds mainly include the following several:

[0004] 1. Su et al. (Su X, Fox D J, Blackwell D T, et al. Copper catalyzed oxidation of organozinc halides [J]. Chem Commun (Camb), 2006(37):3883-3885.) used p-iodobenzoate or p-bromobenzoate as raw materials, dissolved them in tetrahydrofuran (THF), added Rieke-zinc and refluxed, and then concentrated in vacuo. The obtained product was dissolved in N,N-dimethylacetamide (DMA), transferred through a cannula to a solid copper(I) bromide-dimethyl sulfide complex, an oxidant was added in DMA, and stirred at room temperature for 1 h. The reaction mixture was filtered through a silica gel plug and eluted with hexane and ethyl acetate. The filtrate was concentrated in vacuo, and the residue was purified by silica gel flash column chromatography to obtain 4,4'-biphenyldicarboxylate. This method has the disadvantages of a long synthesis route, easy spontaneous combustion and explosion of Rieke-zinc, and difficulty in obtaining oxidants.

[0005]

[0006] 2. Gribanov et al. (Gribanov P S, Golenko Y D, Topchiy M A, et al. One-pot two-step stannylation / Stille homocoupling of aryl bromides and iodides under solvent-free conditions[J]. Mendeleev Communications, 2018, 28(3): 323-325.) prepared 4,4'-biphenyldicarboxylate by a one-pot two-step stannylation / Stille homocoupling (SSHC) reaction under solvent-free conditions, using palladium acetate as a catalyst, PCy3 as a standard ligand for the Stille reaction, and in the presence of a weak base CsF at 110 °C. This method requires the use of a noble metal palladium catalyst in a large amount and at high cost. CsF is a highly toxic compound with great harm.

[0007]

[0008] 3. Huang Xuemei et al. (Huang Xuemei, Fu Xiangkai, Jia Ziyong, Wang Guoming. Electrochromic properties and devices of 4,4'-biphenyldicarboxylate compounds[J]. Journal of Functional Materials, 2012, 43(18): 2492-2495.) used biphenyl as a raw material, obtained 4,4'-biphenyldicarboxylic acid through two-step oxidation, then reacted with thionyl chloride to get 4,4'-benzoyl chloride, and finally reacted with the corresponding alcohol to obtain 4,4'-biphenyldicarboxylate. This method has a long process route, serious pollution, and involves high-risk processes such as oxidation and chlorination.

[0009]

[0010] 4. Yamamoto (Yamamoto Y. Homocoupling of Arylboronic Acids with a Catalyst System Consisting of a Palladium(II) N-Heterocyclic Carbene Complex and p-Benzoquinone[J]. Synlett, 2007, 2007(12): 1913-1916.) used palladium acetate coordinated with 1,3-bis-(2,6-diisopropylphenyl)imidazolinium chloride as a catalyst, p-benzoquinone as an oxidant, and carried out the homocoupling of (4-(ethoxycarbonyl)phenyl)boronic acid in the presence of methanol to prepare 4,4'-biphenyldicarboxylate. The catalyst used in this method is expensive and difficult to obtain, the amount of p-benzoquinone used is large, it is highly toxic, and it involves a high-risk oxidation process.

[0011]

[0012] 5. Chen et al. (Chen Z, Wen Y, Fu Y, et al. Graphene Oxide: An Efficient Acid Catalyst for the Construction of Esters from Acids and Alcohols [J]. Synlett, 2017, 28(08): 981-985.) prepared the catalyst graphene oxide by completely oxidizing graphite with permanganate and hydrogen peroxide under strong acid conditions. Using 1,2-dichloroethane (DCE) as the solvent, 4,4'-biphenyldicarboxylic acid and alcohol as raw materials to prepare 4,4'-biphenyldicarboxylate. This method has a large amount of catalyst used (50 wt%), the strong acid used in the catalyst preparation process is easy to corrode equipment, and the reaction of permanganate and hydrogen peroxide is extremely prone to explosion, and the production process is dangerous.

[0013] SUMMARY OF THE INVENTION

[0014] The present invention aims to solve the problems of complex process route, high danger, heavy pollution and high cost in the preparation process of existing 4,4'-biphenyldicarboxylate compounds, and provides a synthesis method of 4,4'-biphenyldicarboxylate compounds.

[0015] A synthesis method of 4,4'-biphenyldicarboxylate compounds is carried out according to the following steps:

[0016] I. Heating and reacting organic titanium with 4,4'-biphenyldicarboxylic acid to obtain a crude product;

[0017] The molar ratio of the organic titanium to 4,4'-biphenyldicarboxylic acid is 1: (0.1-2.0);

[0018] II. Washing and centrifuging the crude product to collect the precipitate;

[0019] III. Washing and filtering the precipitate to collect the filtrate;

[0020] IV. Concentrating, crystallizing, filtering, washing and drying the filtrate in sequence to obtain 4,4'-biphenyldicarboxylate compounds.

[0021] The beneficial effects of the present invention are:

[0022] 1. In terms of the synthesis route, the present invention can realize the one-step synthesis of 4,4'-biphenyldicarboxylate compounds, with simple operation. The titanium-containing compounds in the crude product are insoluble in organic reagents and are easy to separate and purify.

[0023] 2. In terms of safety and environmental protection, the organotitanium and dimethyl sulfoxide used in the present invention are of low toxicity, and 4,4'-biphenyldicarboxylic acid is of medium toxicity. The reaction process is mild, without involving high-risk chemical processes, and the harm to humans and the environment is small.

[0024] 3. In terms of material economy, the chemical reagents used in the present invention are cheap and easily available, and the production cost is low.

[0025] 4. In terms of product quality, the purity of the 4,4'-biphenyldicarboxylic acid ester compound prepared by the present invention can reach more than 99%.

[0026] The present invention relates to a method for synthesizing a 4,4'-biphenyldicarboxylic acid ester compound. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 XRD pattern of the diethyl 4,4'-biphenyldicarboxylate crystal prepared in Example 1;

[0028] Figure 2 Optical micrograph of the diethyl 4,4'-biphenyldicarboxylate crystal prepared in Example 1;

[0029] Figure 3 SEM image of the diethyl 4,4'-biphenyldicarboxylate crystal prepared in Example 1;

[0030] Figure 4 Molecular structure diagram of the diethyl 4,4'-biphenyldicarboxylate crystal analyzed by single crystal X-ray diffraction prepared in Example 1;

[0031] Figure 5 1H NMR spectrum of the diethyl 4,4'-biphenyldicarboxylate crystal prepared in Example 1;

[0032] Figure 6 EDS spectrum of the diethyl 4,4'-biphenyldicarboxylate crystal prepared in Example 1;

[0033] Figure 7 XRD patterns of the precipitates prepared in Step 2 of Examples 1 to 3, 1 is Example 1, 2 is Example 2, and 3 is Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0034] DETAILED DESCRIPTION OF THE INVENTION I: A method for synthesizing a 4,4'-biphenyldicarboxylic acid ester compound according to this embodiment is carried out according to the following steps:

[0035] I. Heat and react organotitanium with 4,4'-biphenyldicarboxylic acid to obtain a crude product;

[0036] The molar ratio of the organotitanium to 4,4'-biphenyldicarboxylic acid is 1:(0.1 - 2.0);

[0037] II. Wash the crude product and centrifuge it to collect the precipitate.

[0038] III. Wash the precipitate and filter it to collect the filtrate.

[0039] IV. Concentrate, crystallize, filter, wash, and dry the filtrate in sequence to obtain 4,4'-biphenyldicarboxylate compounds.

[0040] The beneficial effects of this specific embodiment are as follows:

[0041] 1. In terms of the synthetic route, this specific embodiment can achieve the one-step synthesis of 4,4'-biphenyldicarboxylate compounds. The operation is simple. The titanium-containing compounds in the crude product are insoluble in organic reagents and are easy to separate and purify.

[0042] 2. In terms of safety and environmental protection, the organotitanium and dimethyl sulfoxide used in this specific embodiment are of low toxicity, and 4,4'-biphenyldicarboxylic acid is of medium toxicity. The reaction process is mild and does not involve high-risk chemical processes, posing little harm to humans and the environment.

[0043] 3. In terms of material economy, the chemical reagents used in this specific embodiment are cheap and easily available, and the production cost is low.

[0044] 4. In terms of product quality, the purity of the 4,4'-biphenyldicarboxylate compounds prepared by this specific embodiment can reach over 99%.

[0045] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that the organotitanium described in Step I is one or a combination of tetraethyl titanate, tetramethyl titanate, tetra-n-propyl titanate, tetra-isopropyl titanate, and tetrabutyl titanate. Others are the same as Specific Embodiment 1.

[0046] Specific Embodiment 3: The difference between this embodiment and either Specific Embodiment 1 or 2 is that the heating reaction described in Step I is specifically carried out at a temperature of 50°C to 180°C for 2 h to 24 h. Others are the same as Specific Embodiment 1 or 2.

[0047] Specific Embodiment 4: The difference between this embodiment and any one of Specific Embodiments 1 to 3 is that at room temperature, the crude product is washed with absolute ethanol 1 to 5 times; the mass ratio of the crude product to absolute ethanol is 1:(10 - 100). Others are the same as Specific Embodiments 1 to 3.

[0048] Specific Embodiment 5: The difference between this embodiment and any one of Specific Embodiments 1 to 4 is that the centrifugation separation described in Step II is specifically carried out at a rotation speed of 1000 r / min to 20000 r / min for 1 min to 20 min. Others are the same as Specific Embodiments 1 to 4.

[0049] Specific Embodiment Six: The difference between this embodiment and any one of Specific Embodiments One to Five is that: in Step Three, under the condition that the washing temperature is 20°C to 120°C, the precipitate is washed with dimethyl sulfoxide for 1 to 3 times; the mass ratio of the precipitate to dimethyl sulfoxide is 1:(10 to 200). Others are the same as in Specific Embodiments One to Five.

[0050] Specific Embodiment Seven: The difference between this embodiment and any one of Specific Embodiments One to Six is that: in Step Four, the concentration and crystallization specifically refer to concentrating and crystallizing for 12 h to 144 h under the conditions of a temperature of 50°C to 150°C and a pressure of -0.02 MPa to -0.20 MPa. Others are the same as in Specific Embodiments One to Six.

[0051] Specific Embodiment Eight: The difference between this embodiment and any one of Specific Embodiments One to Seven is that: in Step Four, the washing specifically refers to washing with absolute ethanol for 1 to 3 times at room temperature. Others are the same as in Specific Embodiments One to Seven.

[0052] Specific Embodiment Nine: The difference between this embodiment and any one of Specific Embodiments One to Eight is that: in Step Four, the drying specifically refers to drying under the condition of a temperature of 25°C to 100°C. Others are the same as in Specific Embodiments One to Eight.

[0053] Specific Embodiment Ten: The difference between this embodiment and any one of Specific Embodiments One to Nine is that: when the organotitanium in Step One is tetraethyl titanate, diethyl 4,4'-biphenyldicarboxylate is obtained in Step Four. Others are the same as in Specific Embodiments One to Nine.

[0054] The following examples are used to verify the beneficial effects of the present invention:

[0055] Example One:

[0056] A method for synthesizing a 4,4'-biphenyldicarboxylate compound, which is carried out according to the following steps:

[0057] I. At room temperature, add 20 mmol of organotitanium to a stainless-steel reaction kettle with a polytetrafluoroethylene inner liner, then add 10 mmol of 4,4'-biphenyldicarboxylic acid, and react at a temperature of 150°C for 12 h, and naturally cool to room temperature to obtain a crude product;

[0058] II. Wash the crude product and centrifuge to separate, and collect the precipitate;

[0059] III. Wash the precipitate and filter, and collect the filtrate;

[0060] IV. Concentrate, crystallize, filter, wash and dry the filtrate in sequence to obtain diethyl 4,4'-biphenyldicarboxylate crystals.

[0061] The organotitanium described in Step 1 is tetraethyl titanate.

[0062] In Step 2, at room temperature, the crude product was washed twice with absolute ethanol; the mass ratio of the crude product to absolute ethanol was 1:40.

[0063] The centrifugal separation described in Step 2 was specifically carried out at a rotation speed of 8000 r / min for 2 min.

[0064] In Step 3, at a washing temperature of 50 °C, the precipitate was washed once with dimethyl sulfoxide; the mass ratio of the precipitate to dimethyl sulfoxide was 1:80.

[0065] The concentration and crystallization described in Step 4 were specifically carried out using a rotary evaporator at a temperature of 95 °C and a pressure of -0.10 MPa for 72 h.

[0066] The washing described in Step 4 was specifically carried out at room temperature with absolute ethanol twice.

[0067] The drying described in Step 4 was specifically carried out at a temperature of 60 °C for 12 h.

[0068] The 4,4'-diphenyldicarboxylic acid diethyl ester crystals prepared in Example 1 were colorless and transparent with a purity of 99%.

[0069] Example 2: The difference between this example and Example 1 is that 13.3 mmol of 4,4'-diphenyldicarboxylic acid was added in Step 1. Others were the same as in Example 1.

[0070] The purity of the 4,4'-diphenyldicarboxylic acid diethyl ester crystals prepared in Example 2 was 99%.

[0071] Example 3: The difference between this example and Example 1 is that 5 mmol of 4,4'-diphenyldicarboxylic acid was added in Step 1. Others were the same as in Example 1.

[0072] The purity of the 4,4'-diphenyldicarboxylic acid diethyl ester crystals prepared in Example 3 was 99%.

[0073] The synthesis routes of the 4,4'-diphenyldicarboxylic acid diethyl ester crystals in Examples 1 to 3 are as follows:

[0074]

[0075] The reaction mechanism is speculated as follows:

[0076] The organotitanium acts both as a catalyst and as a raw material to react with 4,4'-diphenyldicarboxylic acid. The alkoxy group in the organotitanium replaces the position of the hydroxyl group in 4,4'-diphenyldicarboxylic acid to form 4,4'-diphenyldicarboxylic acid diethyl ester crystals.

[0077] Figure 1 XRD pattern of the diethyl 4,4'-biphenyldicarboxylate crystal prepared in Example 1; As can be seen from the figure, sharp diffraction peaks appear at 2θ angles of 9.28°, 15.27°, 18.49°, 21.43°, 24.89°, 25.42°, 27.83° and 37.37°, indicating that the substance is a crystalline material. Further analysis shows that these are the characteristic diffraction peaks of diethyl 4,4'-biphenyldicarboxylate.

[0078] Figure 2 Optical microscopic image of the diethyl 4,4'-biphenyldicarboxylate crystal prepared in Example 1; As can be seen from the figure, the diethyl 4,4'-biphenyldicarboxylate crystal is a colorless and transparent crystal with long strip-like textures on the surface. The crystal is 3.84 mm long, 1.04 mm wide and 0.08 mm thick.

[0079] Figure 3 SEM image of the diethyl 4,4'-biphenyldicarboxylate crystal prepared in Example 1; As can be seen from the figure, the diethyl 4,4'-biphenyldicarboxylate crystal is a flaky solid with a dense surface and distinct edges and corners.

[0080] Figure 4 Molecular structure diagram of the diethyl 4,4'-biphenyldicarboxylate crystal prepared in Example 1 analyzed by single crystal X-ray diffraction; As can be seen from the figure, the analyzed structure is diethyl 4,4'-biphenyldicarboxylate. The detailed information of the crystal structure is shown in Tables 1 to 5.

[0081] Figure 5 1H NMR spectrum of the diethyl 4,4'-biphenyldicarboxylate crystal prepared in Example 1; The solvent is deuterated dimethyl sulfoxide. As can be seen from the figure, the peak at a chemical shift of 2.50 ppm is the solvent peak, the peak at a chemical shift of 3.32 ppm is the water peak. The integration results at chemical shifts of 8.07 ppm and 8.05 ppm indicate the presence of 4 hydrogens, corresponding to the hydrogens labeled as a in the molecular structure in the figure. The integration results at chemical shifts of 7.90 ppm and 7.88 ppm indicate the presence of 4 hydrogens, corresponding to the hydrogens labeled as b in the molecular structure in the figure. The integration results at chemical shifts of 4.37 ppm, 4.35 ppm, 4.34 ppm and 4.32 ppm indicate the presence of 4 hydrogens, corresponding to the hydrogens labeled as c in the molecular structure in the figure. The integration results at chemical shifts of 1.36 ppm, 1.34 ppm and 1.33 ppm indicate the presence of 6 hydrogens, corresponding to the hydrogens labeled as d in the molecular structure in the figure.

[0082] Figure 6 EDS spectrum of the diethyl 4,4'-biphenyldicarboxylate crystal prepared in Example 1; As can be seen from the figure, the compound does not contain titanium. The integration results show that the atomic ratio of carbon to oxygen is 3.83, close to the theoretical value of 4.50.

[0083] Figure 7 XRD patterns of the precipitates prepared in Step 2 of Examples 1 to 3. 1 represents Example 1, 2 represents Example 2, and 3 represents Example 3. As can be seen from the figure, the diffraction peaks at 2θ angles of 9.28°, 15.27°, 18.49°, 21.43°, 24.89°, 25.42°, 27.83° and 37.37° are the diffraction peaks of diethyl 4,4'-biphenyldicarboxylate, and the diffraction peaks at 2θ angles of 6.21°, 6.38° and 17.01° are the diffraction peaks of titanium oxide.

[0084] The crystal data of diethyl 4,4'-biphenyldicarboxylate prepared in Example 1 are as follows:

[0085] Table 1 Crystal data and structure refinement of diethyl 4,4'-biphenyldicarboxylate in Example 1

[0086]

[0087] Table 2 Fractional atomic coordinates (×10 4 ) and equivalent isotropic displacement parameters of diethyl 4,4'-biphenyldicarboxylate crystal in Example 1

[0088]

[0089] Table 3 Typical bond lengths of diethyl 4,4'-biphenyldicarboxylate crystal in Example 1

[0090]

[0091] Table 4 Typical bond angles of diethyl 4,4'-biphenyldicarboxylate crystal in Example 1

[0092]

[0093] Table 5 Typical torsion angles of diethyl 4,4'-biphenyldicarboxylate crystal in Example 1

[0094]

Claims

1. A method for synthesizing 4,4'-biphenyldicarboxylate compounds, characterized in that It is carried out according to the following steps:

1. Heat and react organotitanium with 4,4'-biphenyldicarboxylic acid to obtain a crude product; The molar ratio of the organotitanium to the 4,4'-biphenyldicarboxylic acid is 1:(0.1 - 2.0); the organotitanium is tetraethyl titanate; 2. Wash and centrifuge the crude product, and collect the precipitate; 3. Wash and filter the precipitate, and collect the filtrate; 4. Concentrate, crystallize, filter, wash and dry the filtrate in sequence to obtain a 4,4'-biphenyldicarboxylic acid ester compound; The 4,4'-biphenyldicarboxylic acid ester compound is diethyl 4,4'-biphenyldicarboxylate.

2. The synthesis method of a 4,4'-biphenyldicarboxylate compound according to claim 1, characterized in that The heating reaction described in step 1 is specifically carried out at a temperature of 50°C - 180°C for 2h - 24h.

3. The synthesis method of a 4,4'-biphenyldicarboxylate compound according to claim 1, characterized in that In step 2, at room temperature, wash the crude product with absolute ethanol 1 - 5 times; the mass ratio of the crude product to the absolute ethanol is 1:(10 - 100).

4. The synthesis method of a 4,4'-biphenyldicarboxylate compound according to claim 3, characterized in that The centrifugation separation described in step 2 is specifically carried out at a rotational speed of 1000r / min - 20000r / min for 1min - 20min.

5. The synthesis method of a 4,4'-biphenyldicarboxylate compound according to claim 1, wherein In step 3, at a washing temperature of 20°C - 120°C, wash the precipitate with dimethyl sulfoxide 1 - 3 times; the mass ratio of the precipitate to the dimethyl sulfoxide is 1:(10 - 200).

6. The synthesis method of a 4,4'-biphenyldicarboxylate compound according to claim 1, characterized in that The concentration and crystallization described in step 4 are specifically carried out at a temperature of 50°C - 150°C and a pressure of -0.02MPa - -0.20MPa for 12h - 144h.

7. The synthesis method of a 4,4'-biphenyldicarboxylate compound according to claim 1, characterized in that The washing described in step 4 is specifically carried out at room temperature with absolute ethanol 1 - 3 times.

8. The synthesis method of a 4,4'-biphenyldicarboxylate compound according to claim 1, characterized in that The drying described in step 4 is specifically carried out at a temperature of 25°C - 100°C.

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