Method for synthesizing 4-methylbenzyl iodide by iodination of p-tolualdehyde through photocatalysis

Abstract

The invention belongs to the technical field of green synthetic chemistry, and particularly relates to a method for synthesizing 4-methylbenzyl iodide by iodinating p-tolualdehyde through photocatalysis. The method comprises the following steps: mixing an M-MAPbI3 photocatalyst, p-tolualdehyde, an MAPbI3 saturated HI aqueous solution and a non-water-soluble organic solvent in an irradiation type closed reaction container, and carrying out a photocatalytic reaction in an inert atmosphere under the condition of violent stirring to prepare the 4-methylbenzyl iodide, the cocatalyst is selected from any one of Pt, Pd, Au and Ru; the molar concentration of p-tolualdehyde in a mixed solvent formed by the MAPbI3 saturated HI aqueous solution and the water-insoluble organic solvent is less than or equal to 5 mmol / L; according to the method, cheap p-tolualdehyde is directly used as a reactant, the 4-methylbenzyl iodide is obtained through the catalytic reaction under the conditions of room temperature and illumination, the method has the advantages that operation is easy, the reaction condition is mild, the whole process is free of pollution, and the catalyst can be recycled, and green development of the aromatic aldehyde halogenation reaction is promoted.

Description

Technical Field

[0001] This invention belongs to the field of green synthetic chemistry technology, and specifically relates to a method for the photocatalytic iodination of p-methylbenzaldehyde to synthesize 4-methylbenzyl iodine. Background Technology

[0002] Organic conversion, a core component of modern chemistry and pharmaceutical synthesis, relies on fossil resources for its traditional preparation processes. These processes provide a toxic reaction environment and generate significant amounts of waste, exacerbating the global energy and environmental crisis. In 2024, the Ministry of Industry and Information Technology issued the "Implementation Plan for the Innovative Development of the Fine Chemical Industry (2024-2027)," emphasizing the use of renewable energy-driven green chemical technologies to promote structural reforms in traditional chemical engineering and achieve the overall goal of sustainable development in the fine chemical industry. Green photosynthesis technology based on the Honda-Fujishima effect uses solar photons as an energy source, generating photoelectrons and holes within semiconductors based on the photoelectric effect, which drive reduction and oxidation reactions respectively. This technology features mild reaction conditions, high selectivity, and zero-carbon emissions throughout the entire process, and is considered one of the ideal technologies for promoting the green transformation of the chemical industry.

[0003] Benzyl iodine, as a highly reactive intermediate in organic synthesis, can efficiently construct carbon-carbon and carbon-heterobonds through reactions such as nucleophilic substitution and transition metal-catalyzed coupling. It is widely used in the synthesis of pharmaceuticals and functional materials and is a key reagent for "benzylation" and "carbon chain extension" in organic chemistry. Currently, the industrial synthesis of benzyl iodine mainly relies on two methods: reduction and iodination of aromatic aldehydes with strong reducing agents (such as LiAlH4, NaBH4, and N2H4), and halogen exchange between benzyl chloride or benzyl bromide and iodides. The main reported methods for the synthesis of benzyl iodine are as follows: The first method involves reacting benzyl iodine and its derivatives with elemental iodine in a one-pot process at a temperature of 50-70℃, using 1,4-dioxane as a solvent and sodium borohydride as a strong reducing agent (CN111196750B). The second method involves preparing benzyl iodine and its derivatives by exchanging benzyl chloride or benzyl bromide with elemental iodine under an inert atmosphere using tetrahydrofuran as a solvent and methyllithium as a catalyst (CN111196750B). The third method involves reacting aromatic aldehydes with elemental iodine in an inert atmosphere using solvents such as acetonitrile, chloroform, and dichloromethane, and phosphorous acid as a strong reducing agent, to prepare benzyl iodine and its derivatives (CN112723982B).

[0004] The thermochemical method for preparing benzyl iodine requires not only strong reducing agents such as LiAlH4, NaBH4, N2H4, and phosphorous acid, but also poisoning agents such as acetonitrile, chloroform, and dichloromethane to provide a solubilizing environment, causing serious environmental pollution and contradicting my country's long-term strategic goal of green development in the chemical industry. Another method, halogen exchange, uses benzyl chloride or benzyl bromide, which are difficult to prepare, as starting materials, hindering system expansion and significantly increasing preparation costs. Therefore, developing novel and green methods for preparing benzyl iodine is of great significance for promoting the iodination of aromatic aldehydes. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a photocatalytic method for the iodination of p-methylbenzyl iodide to synthesize 4-methylbenzyl iodide. This method utilizes solar-driven photocatalysis, directly using p-methylbenzyl iodide and HI solution as raw materials. An insoluble organic phase is introduced to increase the amount of p-methylbenzyl iodide fed, and an emulsion is formed under vigorous mechanical stirring to enhance the liquid / liquid two-phase mass transfer process. Ultimately, this achieves efficient iodination of p-methylbenzyl iodide to 4-methylbenzyl iodide. This reaction system features low reaction cost, simple operation, and mild reaction conditions, providing a new approach for the green preparation of benzyl iodide and the application of other halide photocatalysts based on dissolution-precipitation equilibrium.

[0006] Specifically, the technical solution adopted in this invention is as follows: A photocatalytic method for the iodination of p-methylbenzaldehyde to synthesize 4-methylbenzyl iodine includes the following steps: S1: Disperse the photocatalyst supported on lead methylamine iodide (M-MAPbI3), p-methylbenzaldehyde, saturated HI aqueous solution of lead methylamine iodide (MAPbI3), and non-water-soluble organic solvent in the photocatalytic reactor, and purge with argon or nitrogen to remove oxygen from the system, and then seal the reactor. S2: Under vigorous stirring, the sealed photocatalytic reactor is irradiated with light with external circulating water and a magnetic stirrer to drive the photocatalytic reaction. After a certain reaction time, the mixture is allowed to stand and separate to separate the M-MAPbI3 photocatalyst, the MAPbI3-saturated HI aqueous solution, and the non-water-soluble organic solvent containing the target product 4-methylbenzyl iodine.

[0007] A further improvement of the present invention is that the M-MAPbI3 photocatalyst is a nanoscale semiconductor carrier supporting a co-catalyst.

[0008] A further improvement of the present invention is that the co-catalyst is selected from any one of Pt, Pd, Au, and Ru.

[0009] A further improvement of the present invention is that the loading of the co-catalyst is 0.1 wt% to 3 wt%.

[0010] A further improvement of the present invention is that the non-water-soluble organic solvent is selected from any one of n-hexane, dimethyl carbonate, and diethyl carbonate. A further improvement of the present invention is that the volume ratio of the MAPbI3-saturated HI aqueous solution to the non-water-soluble organic solvent is 19:1 to 4:1.

[0011] A further improvement of the present invention is that the reaction occurs under an inert atmosphere in order to prevent the formation of iodide ions (I₂O₃). - Excessive oxidation forms elemental iodine (I2), which degrades the MAPbI3 photocatalyst.

[0012] A further improvement of the present invention is that the photocatalytic reaction takes more than 2 hours.

[0013] A further improvement of the present invention is that the inert atmosphere is either argon or nitrogen.

[0014] A further improvement of the present invention is that the reaction temperature is 10℃-50℃, and the temperature is controlled by adding circulating water.

[0015] A further improvement of the present invention is that, by adding external mechanical stirring, the immiscible MAPbI3-saturated HI aqueous solution and the non-water-soluble organic solvent "liquid / liquid" phases are fully mixed to form an emulsion, thereby enhancing the energy and mass transfer process between the "liquid / liquid" phases and promoting the photocatalytic reaction.

[0016] Compared with existing technologies, the present invention has the following advantages: 1. The photocatalytic method for synthesizing 4-methylbenzyl iodide from p-methylbenzaldehyde provided by this invention directly uses inexpensive aromatic aldehydes, namely p-methylbenzaldehyde and iodide ions (I... - Using [a specific chemical compound] as a raw material, under mild light irradiation conditions, the target product 4-methylbenzyl iodine is synthesized via M-MAPbI3 catalysis, simultaneously yielding green hydrogen energy. This method features low reaction cost, simple equipment, easy operation, no reliance on traditional fossil fuels as a driving force, and recyclable catalysts, belonging to the field of green synthetic chemistry technology. This technology fundamentally eliminates the dependence of traditional chemical engineering on poisoning reagents and the consumption of fossil fuels, providing a new approach for the green structural reform of traditional chemical engineering.

[0017] 2. This invention provides a new direction for the application of organic-inorganic hybrid perovskite photocatalytic systems based on dissolution-precipitation equilibrium. It fully utilizes the excellent photocatalytic performance of organic-inorganic hybrid perovskite photocatalysts and the abundant halide ions in the reaction system. The halogenation reaction of small organic molecules replaces the original halide ion oxidation reaction, giving full play to the strong reactivity of halide ion free radicals, and constructing a hydrogen production system coupled with high-value chemical production, while realizing the green preparation of hydrogen energy and high-value small molecules.

[0018] 3. This invention selects p-methylbenzaldehyde as a representative aromatic aldehyde, and the photosynthesis technology adopted can drive the near 100% selective preparation of 4-methylbenzyl iodide and "green hydrogen" supply from p-methylbenzaldehyde. The constructed "liquid / liquid" two-phase photocatalytic reaction system can simplify the separation and purification process, and has the advantages of strong model reaction representativeness, high product selectivity, low preparation cost and no involvement of poisoning reagents.

[0019] In summary, compared with existing technologies, this invention belongs to a type of green chemical engineering technology, which can simultaneously realize the green preparation of chemicals and the supply of "green hydrogen", thus contributing to the green structural transformation of the country's traditional chemical industry and energy. Attached Figure Description

[0020] Figure 1 The X-ray diffraction pattern of the 1 wt% Pt-MAPbI3 photocatalyst used in Example 1 of this invention is shown.

[0021] Figure 2 This is a scanning electron microscope image of the 1 wt% Pt-MAPbI3 photocatalyst used in Example 1 of the present invention.

[0022] Figure 3 This is an ultraviolet-visible diffuse reflectance image of the 1 wt% Pt-MAPbI3 photocatalyst used in Example 1 of this invention.

[0023] Figure 4a The C 1s orbital X-ray photoelectron spectrum of the 1 wt% Pt-MAPbI3 photocatalyst used in Example 1.

[0024] Figure 4b The N 1s orbital X-ray photoelectron spectrum of the 1 wt% Pt-MAPbI3 photocatalyst used in Example 1.

[0025] Figure 4c The X-ray photoelectron spectroscopy of the 1 wt% Pt-MAPbI3 photocatalyst used in Example 1 is shown as the I 3d orbital X-ray photoelectron spectrum.

[0026] Figure 4d The X-ray photoelectron spectroscopy of the Pd 4f orbital of the 1 wt% Pt-MAPbI3 photocatalyst used in Example 1 is shown.

[0027] Figure 5 This refers to the concentration change of 4-methylbenzyl iodine with photocatalytic reaction time in Example 2 of the present invention.

[0028] Figure 6 This refers to the change in the number of moles of hydrogen gas with the photocatalytic reaction time in Example 2 of the present invention.

[0029] Figure 7 This is an image of the photocatalytic reactor after the photocatalytic reaction has been terminated in Example 2 of the present invention.

[0030] Figure 8 This is the 1H NMR spectrum of the upper layer of non-water-soluble organic solvent after the reaction was terminated in Example 2 of this invention.

[0031] Figure 9a This is a gas chromatogram of 4-methylbenzyl iodine obtained by gas chromatography-mass spectrometry after column chromatography separation following the termination of the reaction in Example 2 of the present invention.

[0032] Figure 9b This is the mass spectrum of 4-methylbenzyl iodine obtained by gas chromatography-mass spectrometry after column chromatography separation following the termination of the reaction in Example 2 of this invention. Detailed Implementation

[0033] To enable those skilled in the art to better understand the present invention, the appendix in the examples of the present invention is described below. Figure 1 To be continued Figure 9b The technical solutions in the embodiments of the present invention will be clearly and completely described.

[0034] A photocatalytic method for the iodination of p-methylbenzaldehyde to synthesize 4-methylbenzyl iodine includes the following steps: S1: Add a reaction solution to the top-irradiated photocatalytic reactor. The reaction solution is a saturated HI aqueous solution of MAPbI3 and a non-water-soluble organic solvent with a volume ratio of 19:1 to 4:1. Then add p-tolualdehyde and M-MAPbI3 to the aforementioned reaction solution. After addition, the molar concentration of p-tolualdehyde is ≤5 mmol / L, and the ratio of M-MAPbI3 to the reaction solution is ≤3 g:1 L. Inert gas is introduced to remove oxygen from the reactor. Then the photocatalytic reactor is sealed. S2: Under vigorous stirring and at 10-50°C, the sealed photocatalytic reactor was irradiated with a xenon lamp for more than 2 hours. Then, the xenon lamp was turned off to obtain a non-water-soluble organic solvent containing the target product 4-methylbenzyl iodine.

[0035] After the reaction was completed, the product in the reactor was allowed to stand and separated to separate the M-MAPbI3 photocatalyst, the MAPbI3-saturated HI aqueous solution, and the non-water-soluble organic solvent containing the target product 4-methylbenzyl iodine.

[0036] The process of introducing the co-catalyst into M-MAPbI3 in step S1, i.e. the preparation process of M-MAPbI3 photocatalyst, is prepared by the following steps: dispersing the metal salt of the co-catalyst and nano-sized MAPbI3 in a saturated HI aqueous solution of MAPbI3, and then photochemically reducing and depositing the co-catalyst in situ onto the surface of MAPbI3 to prepare the M-MAPbI3 photocatalyst.

[0037] The photocatalytic method for synthesizing 4-methylbenzyl iodide from p-methylbenzaldehyde can simultaneously achieve the green preparation of hydrogen energy and 4-methylbenzyl iodide. The p-methylbenzaldehyde and the product 4-methylbenzyl iodide are hydrophobic and are mainly dispersed in non-water-soluble organic solvents.

[0038] Among them, when 1 wt% Pt was deposited as a co-catalyst, it exhibited excellent photocatalytic performance in producing hydrogen and 4-methylbenzyl iodine, with the highest hydrogen and 4-methylbenzyl iodine production rates of 0.76 mmol / h, respectively. -1 and 0.54 mmol L -1 h -1 .

[0039] The present invention will be further illustrated by the following Examples 1 to 8, and the present invention can be better understood by referring to the following examples.

[0040] Example 1 S1: Add 10 mL of reaction solution to the top-irradiated photocatalytic reactor. The volume ratio of MAPbI3-saturated HI aqueous solution to n-hexane in the reaction solution is 9:1. Then add 20 μmol of p-methylbenzaldehyde and 30 mg of 1wt% Pt-MAPbI3 to the aforementioned reaction solution, and purge with argon gas for 10 min to remove oxygen from the reactor and reaction solution. After that, seal the photocatalytic reactor. S2: Under vigorous stirring and at 25°C, the sealed photocatalytic reactor was irradiated for 2 hours with a 300W xenon lamp as the light source. The xenon lamp light source was then turned off, and the reactor was allowed to stand and separate the contents to separate 1 wt% Pt-MAPbI3 photocatalyst, MAPbI3-saturated HI aqueous solution, and n-hexane containing the target product 4-methylbenzyl iodide.

[0041] like Figure 1 The X-ray diffraction pattern of the photocatalyst used in Example 1 is shown, indicating that MAPbI3 has a tetragonal crystal structure. The absence of the characteristic diffraction peaks of metallic Pt can be attributed to the low loading.

[0042] like Figure 2 The image shown is a scanning electron microscope image of the photocatalyst used in Example 1, indicating that 1 wt% Pt-MAPbI3 has a layered structure with uneven particle size.

[0043] like Figure 3 The image shown is a UV-Vis diffuse reflectance spectrum of the photocatalyst used in Example 1, indicating that its absorption edge is about 850 nm and the corresponding optical band gap is 1.46 eV.

[0044] like Figures 4a to 4d The X-ray photoelectron spectra of the C 1s, N 1s, I 3d, and Pd 4f orbitals of the photocatalyst used in Example 1 are shown.

[0045] As shown in Example 1, compared with existing technologies such as CN111196750B, CN111196750B, and CN112723982B, this invention has the following two advantages: 1) It does not use poisoning reagents such as sodium borohydride, tetrahydrofuran, methyllithium, acetonitrile, chloroform, and dichloromethane, and does not rely on fossil fuels for additional energy supply, thus belonging to green photosynthesis technology; 2) The Pt-MAPbI3 catalyst is reusable, which helps to reduce the preparation cost of benzyl iodine. Figure 1 -Figure 4).

[0046] Example 2 S1: Add 20 mL of reaction solution to the top-irradiated photocatalytic reactor. The volume ratio of MAPbI3-saturated HI aqueous solution to n-hexane in the reaction solution is 9:1. Then add 20 μmol of p-methylbenzaldehyde and 20 mg of 1wt% Pt-MAPbI3 to the aforementioned reaction solution, and purge with argon gas for 10 min to remove oxygen from the reactor and reaction solution. After that, seal the photocatalytic reactor. S2: Under vigorous stirring and at 25°C, the sealed photocatalytic reactor was irradiated for 2 hours with a 300W xenon lamp as the light source. The xenon lamp light source was then turned off, and the reactor was allowed to stand and separate the contents to separate 1 wt% Pt-MAPbI3 photocatalyst, MAPbI3-saturated HI aqueous solution, and n-hexane containing the target product 4-methylbenzyl iodide.

[0047] Under the conditions of Example 2, the formation rates of the reaction products hydrogen and 4-methylbenzyl iodide were 0.76 mmol / h, respectively. -1 and 0.54 mmol L -1 h -1 The 1H NMR spectrum and gas-mass spectrum showed that the selectivity of the 4-methylbenzyl iodine was approximately 100%.

[0048] like Figure 5 The figure shows the concentration change of 4-methylbenzyl iodine with photocatalytic reaction time, indicating that the formation rate of 4-methylbenzyl iodine is 0.54 mmol / L. -1 h -1 .

[0049] like Figure 6The figure shows the change in the number of moles of hydrogen gas over time in the photocatalytic reaction, indicating that the hydrogen production rate is 0.76 mmol / h. -1 .

[0050] like Figure 7 The image shown is inside the photocatalytic reactor after the reaction has been terminated. Since 4-methylbenzyl iodine has low solubility in n-hexane, suspended powder can be observed.

[0051] like Figure 8 The image shows the 1H NMR spectrum of the non-water-soluble organic layer. The single-headed peak at 2.19 ppm belongs to methyl hydrogen, the single-headed peak at 4.19 ppm belongs to iodomethylene hydrogen, and the double-headed peaks at 7.09 and 7.23 ppm belong to hydrogen on the benzene ring.

[0052] like Figure 9a , Figure 9b The image shows the chromatogram obtained by gas chromatography-mass spectrometry (GC-MS). First, the water-insoluble organic solvent layer containing the target product 4-methylbenzyl iodide was separated by column chromatography using ethyl acetate and petroleum ether as the mobile phase. Second, ethyl acetate and petroleum ether were removed by rotary evaporation at 60 °C to obtain 4-methylbenzyl iodide powder. Finally, the 4-methylbenzyl iodide powder was dispersed in ethyl acetate for GC-MS analysis. Figure 9a The image shows a gas chromatogram, where 14.6628 min represents the signal for 4-methylbenzyl iodine. Figure 9b The mass spectrum at 14.6628 min provides direct evidence that the iodinated product of p-methylbenzaldehyde is 4-methylbenzyl iodide.

[0053] As can be seen from Example 2, compared with existing technologies such as CN111196750B, CN111196750B and CN112723982B, the present invention has the following advantages: 1) Fast conversion rate (2h > 80%); Figure 5 At the same time, it achieves "green hydrogen" supply (hydrogen generation rate: 0.76 mmol / h). -1 ; Figure 6 ); 2) The reaction is a two-phase "liquid / liquid" reaction and the target product is insoluble in either phase, making the separation and purification process simple. Figure 7 ); 3) The reaction process is controllable, enabling the controllable conversion of p-methylbenzaldehyde to 4-methylbenzyl iodine, with high reaction selectivity (selectivity ≥ 99%; product purity ≥ 98%). Figure 8 (and Figure 9).

[0054] Example 3 S1: Add 20 mL of reaction solution to the top-irradiated photocatalytic reactor. The volume ratio of MAPbI3-saturated HI aqueous solution to n-hexane in the reaction solution is 19:1. Then add 20 μmol of p-methylbenzaldehyde and 20 mg of 0.1wt% Pt-MAPbI3 to the aforementioned reaction solution, and purge with argon gas for 10 min to remove oxygen from the reactor and reaction solution. After that, seal the photocatalytic reactor. S2: Under vigorous stirring and at 25°C, the sealed photocatalytic reactor was irradiated for 4 hours with a 300W xenon lamp as the light source. Then, the xenon lamp was turned off, and the reactor was allowed to stand and separate the contents to separate 0.1 wt% Pt-MAPbI3 photocatalyst, MAPbI3-saturated HI aqueous solution, and n-hexane containing the target product 4-methylbenzyl iodide.

[0055] Example 4 S1: Add 20 mL of reaction solution to the top-irradiated photocatalytic reactor. The volume ratio of MAPbI3-saturated HI aqueous solution to n-hexane in the reaction solution is 4:1. Then add 20 μmol of p-methylbenzaldehyde and 20 mg of 2wt% Pt-MAPbI3 to the aforementioned reaction solution, and purge with argon gas for 10 min to remove oxygen from the reactor and reaction solution. After that, seal the photocatalytic reactor. S2: Under vigorous stirring and at 25°C, the sealed photocatalytic reactor was irradiated for 6 hours with a 300W xenon lamp as the light source. The xenon lamp was then turned off, and the reactor was allowed to stand and separate the contents to separate 2 wt% Pt-MAPbI3 photocatalyst, MAPbI3-saturated HI aqueous solution, and n-hexane containing the target product 4-methylbenzyl iodide.

[0056] Example 5 S1: Add 20 mL of reaction solution to the top-irradiated photocatalytic reactor. The volume ratio of MAPbI3-saturated HI aqueous solution to n-hexane in the reaction solution is 9:1. Then add 20 μmol of p-methylbenzaldehyde and 20 mg of 3wt% Pt-MAPbI3 to the aforementioned reaction solution, and purge with nitrogen for 10 min to remove oxygen from the reactor and reaction solution. After that, seal the photocatalytic reactor. S2: Under severe conditions at 10°C, the sealed photocatalytic reactor was irradiated for 4 hours with a 300W xenon lamp as the light source. The xenon lamp light source was then turned off, and the reactor was allowed to stand and separate the contents to separate 3 wt% Pt-MAPbI3 photocatalyst, MAPbI3-saturated HI aqueous solution, and n-hexane containing the target product 4-methylbenzyl iodide.

[0057] Example 6 S1: Add 20 mL of reaction solution to the top-irradiated photocatalytic reactor. The volume ratio of MAPbI3-saturated HI aqueous solution to n-hexane in the reaction solution is 9:1. Then add 20 μmol of p-methylbenzaldehyde and 20 mg of 1wt% Pd-MAPbI3 to the aforementioned reaction solution, and purge with argon gas for 10 min to remove oxygen from the reactor and reaction solution. After that, seal the photocatalytic reactor. S2: Under vigorous stirring and at 50°C, the sealed photocatalytic reactor was irradiated for 6 hours with a 300W xenon lamp as the light source. The xenon lamp light source was then turned off, and the reactor was allowed to stand and separate the contents to separate 1 wt% Pd-MAPbI3 photocatalyst, MAPbI3-saturated HI aqueous solution, and n-hexane containing the target product 4-methylbenzyl iodide.

[0058] Example 7 S1: Add 20 mL of reaction solution to the top-irradiated photocatalytic reactor. The volume ratio of MAPbI3-saturated HI aqueous solution to dimethyl carbonate in the reaction solution is 9:1. Then add 60 μmol of p-methylbenzaldehyde, 20 mg of 1 wt% Au-MAPbI3 and 0.35 mg of chloroauric acid (1 wt% Au) to the aforementioned reaction solution. Argon gas is then introduced for 10 min to remove oxygen from the reactor and reaction solution. After that, the photocatalytic reactor is sealed. S2: Under vigorous stirring and at 25°C, the sealed photocatalytic reactor was irradiated for 6 hours with a 300W xenon lamp as the light source. The xenon lamp was then turned off, and the reactor was allowed to stand and separate the contents to separate 1 wt% Au-MAPbI3 photocatalyst, MAPbI3-saturated HI aqueous solution, and dimethyl carbonate containing the target product 4-methylbenzyl iodide.

[0059] Example 8 S1: Add 20 mL of reaction solution to the top-irradiated photocatalytic reactor. The volume ratio of MAPbI3-saturated HI aqueous solution to diethyl carbonate in the reaction solution is 9:1. Then add 100 μmol of p-methylbenzaldehyde and 20 mg of 1 wt% Rh-MAPbI3 to the aforementioned reaction solution, and purge with argon gas for 10 min to remove oxygen from the reactor and reaction solution. After that, seal the photocatalytic reactor. S2: Under vigorous stirring and at 25°C, the sealed photocatalytic reactor was irradiated for 6 hours with a 300W xenon lamp as the light source. The xenon lamp light source was then turned off, and the reactor was allowed to stand and separate the contents to separate 1 wt% Rh-MAPbI3 photocatalyst, MAPbI3-saturated HI aqueous solution, and diethyl carbonate containing the target product 4-methylbenzyl iodide.

Claims

1. A method for the photocatalytic iodination of p-methylbenzaldehyde to synthesize 4-methylbenzyl iodine, characterized in that, Includes the following steps: 4-Methylbenzyl iodide was prepared by photocatalysis in an irradiated closed reaction vessel by mixing a lead methyl iodide photocatalyst supported on a co-catalyst, p-methylbenzaldehyde, a HI aqueous solution saturated with lead methyl iodide and a non-water-soluble organic solvent, under inert atmosphere, light irradiation and stirring. The co-catalyst is selected from any one of Pt, Pd, Au, and Ru, and the loading of the co-catalyst is 0.1 wt% to 3 wt%. The non-water-soluble organic solvent is selected from any one of n-hexane, dimethyl carbonate, and diethyl carbonate; The molar concentration of p-methylbenzaldehyde in a mixed solvent consisting of methylamine lead saturated HI aqueous solution and non-water-soluble organic solvent is ≤5 mmol / L.

2. The method according to claim 1, characterized in that, The stirring process thoroughly mixes the immiscible methylamine lead-saturated HI aqueous solution and the insoluble organic solvent "liquid / liquid" two phases to form an emulsion.

3. The method according to claim 1, characterized in that, The volume ratio of the methylamine lead-saturated HI aqueous solution to the non-water-soluble organic solvent is 19:1 to 4:

1.

4. The method according to claim 1, characterized in that, The ratio of the supported methylamine lead photocatalyst to a mixture of methylamine lead iodide-saturated HI aqueous solution and an insoluble organic solvent is ≤3 g:1 L.

5. The method according to claim 1, characterized in that, The inert atmosphere is argon or nitrogen.

6. The method according to claim 1, characterized in that, The reaction temperature is 10℃-50℃.

7. The method according to claim 1, characterized in that, The photocatalytic reaction takes more than 2 hours.

8. The method according to claim 1, characterized in that, The co-catalyst is Pt, the loading of Pt is 1 wt%, the non-water-soluble organic solvent is n-hexane, the volume ratio of the methylamine lead-saturated HI aqueous solution to the non-water-soluble organic solvent is 9:1, and the reaction temperature is 25°C.

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