A method for preparing benzonitrile compounds from toluene compounds

Abstract

The application discloses a method for preparing benzonitrile compounds from toluene compounds, and comprises the following steps: adding ammonium salt as a nitrogen source into an organic solvent with Ru / BiOCl as a catalyst, and then passing oxygen into the organic solvent to perform a photochemical reaction, so that the toluene compounds are directly oxidized to generate the benzonitrile compounds. In the application, no cyanide is used as a cyano source, but toluene compounds are used as raw materials, ammonium salt is used as a nitrogen source, and Ru / BiOCl is used as a catalyst, so that a C-H bond is directly converted into a cyano group through a photocatalytic reaction, and the benzonitrile compounds are obtained. The reaction condition is mild and green and environment-friendly.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of organic synthesis, and particularly relates to a method for preparing benzonitrile compounds from toluene compounds. BACKGROUND

[0002] Benzonitrile (benzonitrile) is an important intermediate in organic synthesis, and is widely used in the synthesis of benzoic acid, benzylamine, benzamide and various pesticides and dyes. It can be used as an intermediate for pesticides. Through further chemical reactions, pesticide products with insecticidal, herbicidal and other effects can be synthesized. These pesticides play an important role in agricultural production, helping to protect crops from pests and improve crop yield and quality. In addition, benzonitrile is also an important source of dye intermediates. Through specific chemical reactions, benzonitrile can be converted into various dyes, which have a wide range of applications in the textile, printing and dyeing industries. They can provide rich colors and long-lasting dyeing effects for textiles, meeting people's demand for beauty and fashion. In addition, benzonitrile can also be used as a solvent antioxidant. In chemical production, the antioxidant performance of the solvent is crucial to the stability and safety of the product. As an antioxidant, benzonitrile can effectively prevent the deterioration of the solvent due to oxidation during storage and use, thereby prolonging the service life of the solvent and improving the quality and stability of the product. Benzonitrile can also be used to synthesize other fine chemicals, such as pharmaceutical intermediates. These fine chemicals play an important role in the fields of medicine, chemical industry, etc., providing more convenience and possibility for people's production and life.

[0003] The classical methods for the synthesis of benzonitrile include halogenated benzene cyanation reaction, halogenated toluene and ammonia reaction, benzoic acid and urea reaction, and cyanation reaction of benzaldehyde. In industry, benzonitrile is prepared by amine oxidation reaction of toluene under the action of transition metal catalyst (vanadium) and high pressure and high temperature (300-500℃) conditions of ammonia and oxygen. Because the cyano group is not only a key functional group in various drugs and biologically active molecules, but also an important synthetic building block for some fine and bulk chemicals. In recent years, some new, mild, transition metal-catalyzed methods for the synthesis of cyano compounds from alcohols, amines, aldehydes or simple CH3 have been reported. However, in these methods, many cases require high temperature reaction, and even often use highly toxic cyanide as a source of cyano group. SUMMARY

[0004] In order to solve the problems of harsh reaction conditions and the use of highly toxic cyanide as a source of cyano group in the existing synthesis of benzonitrile, the purpose of the present application is to provide a method for preparing benzonitrile compounds from toluene compounds, using toluene compounds as raw materials and Ru / BiOCl as catalyst, through photocatalytic reaction to directly oxidize into benzonitrile compounds.

[0005] In order to achieve the above technical purposes, the present application adopts the following technical solutions:

[0006] A method for preparing benzonitrile compounds from toluene compounds, wherein Ru / BiOCl is used as a catalyst, ammonium salt is used as a nitrogen source, and oxygen is introduced into an organic solvent, and then a photo reaction is performed to directly oxidize toluene compounds to benzonitrile compounds, and a reaction formula is shown as formula I:

[0007]

[0008] In the formula, Ar is a phenyl group, a naphthyl group, or a substituted phenyl group, the substituted phenyl group is a phenyl group substituted with at least one substituent selected from C1-C5 alkyl, halogen, nitro, phenyl, acetylene, acetyl, methoxy, and ester, the substituent can be one or more, and the substitution position is not limited; the C1-C5 alkyl can be a linear alkyl or a branched alkyl, and is specifically propyl, isobutyl, etc.; the halogen is F, Cl, Br, or I; and the ester is specifically methyl formate, etc.

[0009] Preferably, the Ru / BiOCl catalyst is obtained by loading Ru metal on BiOCl through a photo deposition method.

[0010] Further preferably, a specific preparation process of the Ru / BiOCl catalyst is as follows: BiOCl, CH3OH, and RuCl3·3H2O are added into deionized water, and stirring is performed in a glass reactor with a quartz window, a vacuum chamber is extracted, then 1 atm of Ar is filled, and a 300 W UV-Xe lamp is irradiated at 3 Wcm-2 for 1 hour, after solid-liquid separation, the precipitate is washed several times with distilled water, and then dried in a vacuum at 333 K overnight to obtain the Ru / BiOCl catalyst; wherein the amount of BiOCl and RuCl3·3H2O is 1 g: 0.4-0.8 mmol. -2

[0011] Preferably, the ammonium salt is selected from one of ammonium bromide, hydroxylamine hydrochloride, ammonium carbonate, and ammonium carbamate; and further preferably, the ammonium salt is ammonium bromide.

[0012] Preferably, the organic solvent is acetonitrile.

[0013] Preferably, the light source of the photo reaction is light with a wavelength of 200-400 nm, for example, a 300 W xenon lamp; the light irradiation time is not less than 6 hours; and further preferably, the light irradiation time is 10-24 hours.

[0014] Further, the amount of the catalyst is not less than 20 mg of catalyst per 10 μL of toluene compound; and further preferably, the amount of the catalyst is 50-100 mg of catalyst per 10 μL of toluene compound.

[0015] The present application has the following beneficial effects:​​

[0016] The application does not need cyanide as a cyanide source, but uses toluene compounds as raw materials, ammonium salt as a nitrogen source, and Ru / BiOCl as a catalyst to directly convert C-H bond into cyanide through photocatalytic reaction to obtain benzonitrile compounds, and the reaction condition is mild and green and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 XRD spectra of BiOCl and Ru / BiOCl with different Ru loadings.

[0018] Figure 2 NMR spectra of the product after the light irradiation reaction in Example 1. 13 C-NMR). DETAILED DESCRIPTION

[0019] In order to better understand the essence of the application, the content of the application will be further described below in combination with examples, but it should not be regarded as a limitation on the application. The following description is only used to explain the application, and any modification, replacement or improvement made without departing from the spirit and principles of the application shall fall within the scope of the application.

[0020] In the application, BiOCl can be commercially available or self-made, and the self-made one belongs to a conventional preparation process, for example, Bi(NO3)3·5H2O and KCl are treated by hydrothermal treatment, specifically:

[0021] 70mmol HOAc is dispersed in 30mL ammonia solution (containing 27mmol NH3·H2O), the mixture is stirred, then 0.5mmol Bi(NO3)3·5H2O and 1.3mmol KCl are added to the above mixture solution respectively, and the obtained solution is transferred to a 100mL Teflon-lined stainless steel autoclave and heated at 100℃ for 24 hours. After solid-liquid separation, the obtained precipitate is washed with deionized water and ethanol, and dried at 65℃ overnight to obtain BiOCl.

[0022] Example 1

[0023] Ru metal is loaded into BiOCl by a photo-deposition method, specifically:

[0024] 1g BiOCl, 10mL CH3OH and 0.6mmol RuCl3·3H2O are added to 50mL deionized water and stirred in a glass reactor (250mL) with a quartz window. The chamber is vacuumed, then filled with 1atm Ar, and a 300Wjing UV-Xe lamp is used to irradiate at 3Wcm-2 for 2h. The obtained product is separated by centrifugation and dried at 60℃ for 12h. -2After irradiation for 1 hour, the precipitate was separated from the solid and washed several times with distilled water and then dried overnight in a vacuum at 333 K to obtain Ru / BiOCl-6.

[0025] Take 20 mg of the prepared photocatalyst material, 2 mL of acetonitrile, 10 μL of toluene, and 1 g of NH₄Br. Stir for 30 minutes with oxygen, then irradiate for 12 hours using a 300 W xenon lamp. After irradiation, transfer to a centrifuge tube, centrifuge, and separate the catalyst. Qualitative and quantitative analysis of the product was performed using NMR, HPLC, and GC. The yield of benzonitrile was 87%, and the selectivity was greater than 96%. The NMR spectrum of the obtained product is shown below. 13 C-NMR (such as) Figure 2 As shown, from the NMR spectrum of the product

[0026] ( 13 As can be seen from the C-NMR, a peak belonging to benzonitrile can be clearly seen at 118.6 ppm.

[0027] Examples 2-3

[0028] Same as Example 1, except that the proportions of BiOCl and RuCl3·3H2O added are different. The results are shown in Table 1.

[0029] Table 1. Results of catalytic reactions at different dosage ratios

[0030]

[0031] Examples 4-7

[0032] Same as Example 1, except for the different illumination time, the results are shown in Table 2.

[0033] Table 2. Results of catalytic reactions under different light exposure times.

[0034]

[0035] Examples 8-10

[0036] Same as Example 1, except for the nitrogen source. The results are shown in Table 3.

[0037] Table 3. Catalytic reaction results with different nitrogen sources

[0038]

[0039] Examples 11-14

[0040] Same as Example 1, except for the amount of catalyst used. The results are shown in Table 4.

[0041] Table 4. Results of catalytic reactions under different light exposure times.

[0042]

[0043] Examples 15 to 33

[0044] The same procedure as in Example 1 was followed except that the reaction substrates were different. The results are shown in Table 5.

[0045] Table 5. Results of catalytic reactions with different substrates

[0046]

[0047]

Claims

1. A method for preparing benzonitrile compounds from toluene compounds, characterized in that: Using Ru / BiOCl as a catalyst and ammonium salt as a nitrogen source, oxygen is introduced into an organic solvent, and the reaction is carried out under light irradiation to directly oxidize toluene compounds to benzonitrile compounds. The reaction formula is shown in Formula I: ； Formula I Wherein, Ar is a phenyl or a substituted phenyl, and the substituted phenyl is a phenyl containing at least one substituent selected from C1 to C5 alkyl, halogen, nitro, phenyl, ethynyl, acetyl, methoxy, and ester groups; The specific preparation process of the Ru / BiOCl catalyst is as follows: BiOCl, CH3OH, and RuCl3·3H2O are added to deionized water and stirred in a glass reactor with a quartz window. The chamber is then evacuated, filled with 1 atm Ar, and heated by a 300 W UV-Xe lamp at 3 W cm⁻¹. -2 After irradiation for 1 hour, the precipitate was washed several times with distilled water after solid-liquid separation, and then dried overnight in a vacuum at 333 K to obtain the Ru / BiOCl catalyst; wherein the amount of BiOCl and RuCl3·3H2O was 1 g: 0.4~0.8 mmol. The ammonium salt is selected from one of ammonium bromide, hydroxylamine hydrochloride, ammonium carbonate, and ammonium carbamate; The organic solvent is acetonitrile.

2. The method according to claim 1, characterized in that: The ammonium salt is ammonium bromide.

3. The method according to claim 1, characterized in that: The light source for the photoreaction is light with a wavelength ƛ>400 nanometers, and the illumination time is not less than 6 hours.

4. The method according to claim 3, characterized in that: The illumination time is 10~24h.

5. The method according to claim 1, characterized in that: The amount of catalyst used is not less than 20 mg catalyst / 10 µL toluene compound.

6. The method according to claim 5, characterized in that: The amount of catalyst used is 50~100 mg catalyst / 10 µL toluene compound.

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