Benzophenone compound as well as preparation method and application thereof

Abstract

The invention provides a benzophenone compound as well as a preparation method and application thereof, and relates to the technical field of ultraviolet absorbents. Unsaturated carbon-oxygen double bonds and aromatic acryloyl in the benzophenone compound and a benzophenone parent form a long conjugated chain, and the larger a conjugated system is, the smaller the energy difference between the highest occupied orbital and the lowest unoccupied orbital is, so that the energy required by electron transition is reduced, and the ultraviolet absorption wavelength is increased; two hydrogen bonds can be formed in the benzophenone compound, a large amount of heat can be generated when the benzophenone compound is irradiated by an external ray, so that thermal motion of molecules is caused, the hydrogen bonds are damaged, a chelate ring is opened, the structure is not stable, and redundant heat is released and removed when the benzophenone compound is recovered to an original state, so that the purpose of protecting ultraviolet rays is achieved. Therefore, the increase of the length of the conjugated chain and the increase of the number of the hydrogen bonds enhance the ultraviolet absorption capability and promote the transition of the absorption band, so that the absorption main band can be transited from UVB to UVA.

Description

Technical Field

[0001] The invention relates to the technical field of ultraviolet absorbers, and in particular to a benzophenone compound and a preparation method and application thereof. Background Art

[0002] Ultraviolet rays are divided into UVA (wavelength 320-400nm, long wave), UVB (wavelength 280-320nm, medium wave) and UVC (wavelength 100-280nm, short wave). UVC can be absorbed by the ozone layer and cannot reach the earth's surface; UVB can reach the surface of the skin and cause strong light damage, causing symptoms such as erythema, inflammation, and aging, and even leading to skin cancer; UVA can penetrate the surface of the skin and then go deep into the dermis, damaging cell DNA, accelerating skin aging, and even causing skin cancer. Therefore, comprehensive defense against both UVA and UVB bands should be strengthened.

[0003] In order to reduce or prevent the harm of UVA and UVB to human health, adding UV absorbers is the most commonly used and effective method. UV absorbers can selectively absorb ultraviolet rays in the wavelength range of 290-400nm. They are the most widely used type of light stabilizers. According to their chemical structure, they can be divided into salicylates, cinnamate, p-aminobenzoic acid, camphor, benzophenone, benzotriazole, acrylonitrile, triazine and dibenzoylmethane. Among them, benzophenone is the most widely used in industry.

[0004] In the structure of benzophenone UV absorbers, the ortho position of the carbonyl group contains a hydroxyl group to form an intramolecular hydrogen bond, thus having a stable conjugated structure that can effectively absorb ultraviolet rays. After absorbing ultraviolet rays, ultraviolet rays will destroy the intramolecular hydrogen bonds, causing the hydrogen bond ring to open, thereby forming an ionic compound. This structure is very unstable. In order to achieve a stable state, the excess energy will be released in the form of harmless heat energy, and the hydrogen bonds will return to their original state. In the cycle of opening-closing-opening the intramolecular hydrogen bonds, it can effectively absorb ultraviolet light.

[0005] The more common benzophenone UV absorbers on the market are listed in Table 1.

[0006] Table 1 Common benzophenone UV absorbers

[0007]

[0008]

[0009] However, benzophenone ultraviolet absorbers also have their own disadvantages: first, due to the relatively small molecular weight, this type of absorber has poor thermal stability and is easily decomposed and volatilized; second, due to the lack of water-soluble groups, this type of absorber has poor water solubility and compatibility, which greatly limits its application range; third, this type of absorber sold on the market is mainly concentrated in the protection of UVB band or UVA band, and there are few single products that can cover the protection of UVA and UVB bands. Summary of the invention

[0010] In view of this, the object of the present invention is to provide a benzophenone compound and a preparation method and application thereof. The benzophenone compound provided by the present invention has good water solubility, and when used as an ultraviolet absorber, the ultraviolet absorption range can cover the UVA and UVB bands, and has a wide range of applications.

[0011] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0012] The present invention provides a benzophenone compound having a structure shown in Formula I:

[0013]

[0014] The R includes H, methyl or methoxy.

[0015] Preferably, the R is located at the para position or ortho position of the phenylacryloyl group.

[0016] The present invention also provides a method for preparing the benzophenone compounds described in the above technical solution, comprising the following steps:

[0017] Mixing 2,4-dimethoxybenzophenone, acetyl chloride, Lewis acid and a first polar organic solvent for Friedel-Crafts acylation to obtain 2,4-dimethoxy-5-acetylbenzophenone;

[0018] The 2,4-dimethoxy-5-acetylbenzophenone, aromatic aldehyde, alkali solution and organic solvent are mixed to carry out aldol condensation reaction to obtain 2,4-dimethoxy-5-(aryl acryloyl)benzophenone;

[0019] The 2,4-dimethoxy-5-(aryl acryloyl) benzophenone is mixed with a catalyst and a second polar organic solvent to carry out a demethylation reaction to obtain the benzophenone compound;

[0020] The aromatic aldehyde has a structure shown in formula I-1:

[0021]

[0022] The 2,4-dimethoxy-5-(aryl acryloyl)benzophenone has a structure shown in Formula I-2:

[0023]

[0024] Preferably, the molar ratio of 2,4-dimethoxybenzophenone to acetyl chloride is 1:1-2.

[0025] Preferably, the Lewis acid comprises aluminum trichloride.

[0026] Preferably, the temperature of the Friedel-Crafts acylation reaction is 10-50° C. and the time is 4-8 h.

[0027] Preferably, the molar ratio of the 2,4-dimethoxy-5-acetylbenzophenone to the aromatic aldehyde is 1:1 to 1.1.

[0028] Preferably, the aldol condensation reaction is carried out at a temperature of 10 to 35° C. and for a time of 1 to 4 hours.

[0029] Preferably, the demethylation reaction is carried out at a temperature of -5 to 0°C and for a time of 0.5 to 4 hours.

[0030] The present invention also provides the use of the benzophenone compound described in the above technical solution or the benzophenone compound prepared by the preparation method described in the above technical solution as an ultraviolet absorber.

[0031] The present invention provides a benzophenone compound having a structure shown in Formula I:

[0032]

[0033] The R includes H, methyl or methoxy.

[0034] The unsaturated carbon-oxygen double bond and the aromatic acryloyl group in the benzophenone compound of the present invention form a long conjugated chain with the benzophenone parent. The larger the conjugated system, the smaller the energy difference between the highest occupied orbit and the lowest empty orbit, so the energy required for the electron transition is reduced, and the ultraviolet absorption wavelength increases; in addition, the benzophenone compound of the present invention can form two intramolecular O—H···O hydrogen bonds, and when irradiated with external rays, a large amount of heat will be generated, thereby causing the thermal motion of the molecules, destroying the hydrogen bonds and opening the chelate ring. Such a structure is not very stable, and when it returns to the original state, the excess heat is released and removed, thereby achieving the purpose of protecting ultraviolet rays. Therefore, the increase in the length of the conjugated chain and the increase in the number of hydrogen bonds both enhance the ultraviolet absorption ability, promote the transition of the absorption band, and enable the main absorption band to transition from UVB to UVA. At the same time, the increase in the number of hydrogen bonds within the molecule also strengthens the intermolecular forces, avoiding the decomposition and volatilization of benzophenone compounds; and when R is a methyl group or a methoxy group, the dipole moment of the molecule is increased, the polarity of the molecule is increased, and the water solubility of benzophenone compounds can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The UV absorption spectra of the UV absorbers obtained in Examples 1 to 5 are shown in FIG. DETAILED DESCRIPTION

[0036] The present invention provides a benzophenone compound having a structure shown in Formula I:

[0037]

[0038] The R includes H, methyl or methoxy.

[0039] In the present invention, the R is preferably located at the para position or ortho position of the phenylacryloyl group.

[0040] The present invention also provides a method for preparing the benzophenone compounds described in the above technical solution, comprising the following steps:

[0041] Mixing 2,4-dimethoxybenzophenone, acetyl chloride, Lewis acid and a first polar organic solvent for Friedel-Crafts acylation to obtain 2,4-dimethoxy-5-acetylbenzophenone;

[0042] The 2,4-dimethoxy-5-acetylbenzophenone, aromatic aldehyde, alkali solution and organic solvent are mixed to carry out aldol condensation reaction to obtain 2,4-dimethoxy-5-(aryl acryloyl)benzophenone;

[0043] The 2,4-dimethoxy-5-(aryl acryloyl) benzophenone is mixed with a catalyst and a second polar organic solvent to carry out a demethylation reaction to obtain the benzophenone compound;

[0044] The aromatic aldehyde has a structure shown in formula I-1:

[0045]

[0046] The 2,4-dimethoxy-5-(aryl acryloyl)benzophenone has a structure shown in Formula I-2:

[0047]

[0048] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known in the art.

[0049] The invention mixes 2,4-dimethoxybenzophenone, acetyl chloride, Lewis acid and a first polar organic solvent to carry out Friedel-Crafts acylation reaction to obtain 2,4-dimethoxy-5-acetylbenzophenone.

[0050] In the present invention, the preparation method of 2,4-dimethoxybenzophenone preferably comprises the following steps:

[0051] 2,4-dihydroxybenzophenone, dimethyl sulfate, an alkaline solution and an alcohol solvent are mixed to carry out an etherification reaction to obtain the 2,4-dimethoxybenzophenone.

[0052] In the present invention, the mixing preferably comprises the following steps:

[0053] 2,4-dihydroxybenzophenone is dissolved in an alcohol solvent, the obtained solution is then mixed with an alkaline solution, and then dimethyl sulfate is added dropwise to the mixed solution.

[0054] In the present invention, the mixing is preferably carried out under stirring, the stirring speed is preferably 400 rpm, and the time is preferably 0.5 h; the dripping speed of the dimethyl sulfate is preferably 30 drops / min. In the present invention, the temperature during the dripping is preferably the temperature of the etherification reaction.

[0055] In the present invention, the molar ratio of the 2,4-dihydroxybenzophenone to dimethyl sulfate is preferably 1:1-2. In a specific embodiment, the molar ratio of the 2,4-dihydroxybenzophenone to dimethyl sulfate may be 1:1, 1:1.5, 1:1.67 or 1:2.

[0056] In the present invention, the mass ratio of the 2,4-dihydroxybenzophenone to the volume ratio of the alcohol solvent is preferably 1g:8-15mL. In a specific embodiment, the mass ratio of the 2,4-dihydroxybenzophenone to the volume ratio of the alcohol solvent can be 1g:8mL, 1g:9mL, 1g:10mL, 1g:11mL, 1g:12mL, 1g:13mL, 1g:14mL or 1g:15mL. In the present invention, the alcohol solvent preferably includes anhydrous ethanol.

[0057] In the present invention, the mass ratio of the 2,4-dihydroxybenzophenone to the volume ratio of the alkaline solution is preferably 1g:1-5mL. In a specific embodiment, the mass ratio of the 2,4-dihydroxybenzophenone to the volume ratio of the alkaline solution can be 1g:1mL, 1g:2mL, 1g:3mL, 1g:4mL or 1g:5mL. In the present invention, the alkaline solution preferably includes a NaOH solution, and the mass percentage of NaOH in the NaOH solution is preferably 5-20%. In a specific embodiment, the mass percentage of NaOH in the NaOH solution can be 5%, 8%, 10%, 12%, 15%, 18% or 20%.

[0058] In the present invention, the temperature of the etherification reaction is preferably -5 to 0°C. In a specific embodiment, the temperature of the etherification reaction can be -5°C, -4°C, -3°C, -2°C, -1°C or 0°C. The time is preferably 2 to 6 hours. In a specific embodiment, the time of the etherification reaction can be 2 hours, 3 hours, 4 hours, 5 hours or 6 hours. In the present invention, the etherification reaction is preferably carried out in an ice-water bath.

[0059] After the etherification reaction, the present invention preferably further comprises: standing the product obtained from the etherification reaction for precipitation and suction filtration, and then washing and drying the obtained solid phase in sequence.

[0060] In the present invention, the washing agent preferably includes ethanol.

[0061] In the present invention, the 2,4-dimethoxybenzophenone, acetyl chloride, Lewis acid and the first polar organic solvent preferably include:

[0062] The Lewis acid is dissolved in the first polar organic solvent, the obtained solution is mixed with 2,4-dimethoxybenzophenone, and then acetyl chloride is added dropwise to the mixed solution.

[0063] In the present invention, the mixing and dropping are preferably performed at the temperature of the Friedel-Crafts acylation reaction.

[0064] In the present invention, the molar ratio of 2,4-dimethoxybenzophenone to acetyl chloride is preferably 1:1-2. In a specific embodiment, the molar ratio of 2,4-dimethoxybenzophenone to acetyl chloride can be 1:1, 1:1.3, 1:1.5, 1:1.8 or 1:2. The dropping speed of acetyl chloride is preferably 20 drops / min.

[0065] In the present invention, the molar ratio of the 2,4-dimethoxybenzophenone to the Lewis acid is preferably 1:1-2, and the molar ratio of the 2,4-dimethoxybenzophenone to the Lewis acid may be 1:1, 1:1.3, 1:1.5, 1:1.8 or 1:2; the Lewis acid preferably includes aluminum chloride.

[0066] In the present invention, the mass ratio of the 2,4-dimethoxybenzophenone to the volume ratio of the first polar organic solvent is preferably 1 g: 10 to 20 mL, and the mass ratio of the 2,4-dimethoxybenzophenone to the volume ratio of the first polar organic solvent may be 1 g: 10 mL, 1 g: 12.5 mL, 1 g: 15 mL, 1 g: 18 mL or 1 g: 20 mL. In the present invention, the first polar organic solvent preferably includes 1,2-dichloroethane.

[0067] In the present invention, the temperature of the Friedel-Crafts acylation reaction is preferably 10-50°C. In a specific embodiment, the temperature of the Friedel-Crafts acylation reaction can be 10°C, 20°C, 30°C, 40°C or 50°C. The time is preferably 4-8h. In a specific embodiment, the time of the Friedel-Crafts acylation reaction can be 4h, 5h, 6h, 7h or 8h. The time of the Friedel-Crafts acylation reaction is preferably calculated after the addition of acetyl chloride is completed.

[0068] After the Friedel-Crafts acylation reaction, the present invention preferably further comprises: removing impurities and separating the product obtained from the Friedel-Crafts acylation reaction, and then washing, removing moisture, concentrating and purifying the crude 2,4-dimethoxy-5-acetylbenzophenone obtained by separation.

[0069] In the present invention, the impurity removal preferably comprises: mixing the product obtained by Friedel-Crafts acylation reaction with ice water and concentrated hydrochloric acid; the volume ratio of the ice water to the concentrated hydrochloric acid is preferably 200:1; the concentration of the concentrated hydrochloric acid is preferably 12 mol / L. The impurity removal removes impurities insoluble in the organic phase from the crude 2,4-dimethoxy-5-acetylbenzophenone.

[0070] In the present invention, the washing preferably comprises washing with a saturated sodium bicarbonate solution, water and saturated saline in sequence.

[0071] In the present invention, the dehydration preferably comprises: mixing with a desiccant, and then separating the desiccant except for the absorbed moisture. The desiccant preferably comprises anhydrous sodium sulfate.

[0072] In the present invention, the purification is preferably mobile phase column chromatography. In the present invention, the eluent for purification is preferably a mixture of petroleum ether and ethyl acetate; the volume ratio of petroleum ether to ethyl acetate in the eluent is preferably 6:1.

[0073] After obtaining 2,4-dimethoxy-5-acetylbenzophenone, the present invention mixes the 2,4-dimethoxy-5-acetylbenzophenone, aromatic aldehyde, alkali solution and organic solvent to carry out aldol condensation reaction to obtain 2,4-dimethoxy-5-(aryl acryloyl)benzophenone.

[0074] In the present invention, the mixing preferably comprises the following steps:

[0075] After 2,4-dimethoxy-5-acetylbenzophenone, alkali solution and an organic solvent are mixed, aromatic aldehyde is added dropwise to the mixed solution.

[0076] In the present invention, the molar ratio of the 2,4-dimethoxy-5-acetylbenzophenone to the aromatic aldehyde is preferably 1:1 to 1.1; the aromatic aldehyde preferably includes benzaldehyde, p-methylbenzaldehyde, o-methylbenzaldehyde, p-methoxybenzaldehyde or o-methoxybenzaldehyde.

[0077] In the present invention, the molar ratio of the 2,4-dimethoxy-5-acetylbenzophenone to the alkali in the alkali solution is preferably 1:0.5-3. In a specific embodiment, the molar ratio of the 2,4-dimethoxy-5-acetylbenzophenone to the alkali in the alkali solution can be 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.5 or 1:3. In the present invention, the alkali solution preferably includes a sodium hydroxide solution, and the mass fraction of the sodium hydroxide solution is preferably 9-10%.

[0078] In the present invention, the volume ratio of the organic solvent to the water in the alkali solution is preferably 1:1 to 1.25; the organic solvent preferably includes ethanol.

[0079] In the present invention, the mass ratio of the 2,4-dimethoxy-5-(aromatic acyl)benzophenone to the volume ratio of the organic solvent is preferably 1 g:2 to 10 mL, and the mass ratio of the 2,4-dimethoxy-5-(aromatic acyl)benzophenone to the volume ratio of the organic solvent may be 1 g:2 mL, 1 g:5 mL, 1 g:8 mL or 1 g:10 mL.

[0080] In the present invention, the dropping speed of the aromatic aldehyde is preferably 30 drops / min.

[0081] In the present invention, the temperature of the aldol condensation reaction is preferably 10-35°C. In a specific embodiment, the temperature of the aldol condensation reaction can be 10°C, 15°C, 20°C, 25°C, 30°C or 35°C. The time is preferably 1-4h. In a specific embodiment, the time of the aldol condensation reaction can be 1h, 2h, 3h or 4h. The time of the aldol condensation reaction is preferably counted from the end of the dropwise addition of the aromatic aldehyde.

[0082] After the aldol condensation reaction, the present invention preferably further comprises: filtering the product obtained from the aldol condensation reaction, and sequentially washing and recrystallizing the obtained solid phase.

[0083] In the present invention, the washing and recrystallization solvent preferably comprises ethanol.

[0084] The present invention has no particular limitation on the washing, and washing until neutrality is sufficient.

[0085] After obtaining 2,4-dimethoxy-5-(aryl acryloyl) benzophenone, the present invention mixes the 2,4-dimethoxy-5-(aryl acryloyl) benzophenone with a catalyst and a second polar organic solvent to carry out a demethylation reaction to obtain the benzophenone compound.

[0086] In the present invention, the mixing preferably comprises: dissolving the 2,4-dimethoxy-5-(aryl acryloyl)benzophenone in a second polar organic solvent, and then mixing the obtained solution with a catalyst.

[0087] In the present invention, the mixing is preferably performed at a temperature of the demethylation reaction.

[0088] In the present invention, the molar ratio of the 2,4-dimethoxy-5-(aromatic acyl) benzophenone to the catalyst is preferably 1:1.5-4. In a specific embodiment, the molar ratio of the 2,4-dimethoxy-5-(aromatic acyl) benzophenone to the catalyst may be 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5 or 1:4. More preferably, it is 1:2.5. In the present invention, the catalyst preferably includes aluminum chloride.

[0089] In the present invention, the mass ratio of the 2,4-dimethoxy-5-(aromatic acyl) benzophenone to the volume ratio of the second polar organic solvent is preferably 1 g: 15 to 25 mL. In a specific embodiment, the mass ratio of the 2,4-dimethoxy-5-(aromatic acyl) benzophenone to the volume ratio of the second polar organic solvent may be 1 g: 15 mL, 1 g: 20 mL or 1 g: 25 mL. In the present invention, the second polar organic solvent preferably includes 1,2-dichloroethane.

[0090] In the present invention, the temperature of the demethylation reaction is preferably -5 to 0°C. In a specific embodiment, the temperature of the demethylation reaction can be -5°C, -4°C, -3°C, -2°C, -1°C or 0°C; the time is preferably 0.5 to 4h. In a specific embodiment, the time of the demethylation reaction can be 0.5h, 1h, 2h, 3h or 4h.

[0091] After the demethylation reaction, the present invention preferably further comprises: mixing the product obtained from the demethylation reaction with ice water and concentrated hydrochloric acid, then extracting the mixture with an extractant, and then drying and purifying the obtained organic phase.

[0092] In the present invention, the extractant preferably includes 1,2-dichloroethane; the drying preferably includes: mixing with a desiccant, and then separating the desiccant that absorbs moisture. The desiccant preferably includes anhydrous magnesium sulfate.

[0093] In the present invention, the purification is preferably mobile phase column chromatography. In the present invention, the eluent for purification is preferably a mixture of petroleum ether and ethyl acetate; the volume ratio of petroleum ether to ethyl acetate in the eluent is preferably 10:1.

[0094] The present invention also provides the use of the benzophenone compound described in the above technical solution or the benzophenone compound prepared by the preparation method described in the above technical solution as an ultraviolet absorber.

[0095] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0096] Example 1

[0097] In a 1L round-bottom flask, 50.0g (0.24mol) of 2,4-dihydroxybenzophenone was dissolved in 500mL of anhydrous ethanol, and 100.0mL (0.4mol) of a 10% NaOH solution was added under an ice-water bath. After stirring at 400rpm for 0.5h, 38.0mL (0.4mol) of dimethyl sulfate was added dropwise. After etherification reaction for 4h, a large amount of white solid precipitated in the bottle, which was filtered, washed with a small amount of ethanol, and dried to obtain 48.7g of a white powder solid, i.e. 2,4-dimethoxybenzophenone.

[0098] The yield of the white solid is 86.1%, the melting point is 80-82°C, and the H-NMR spectrum information is: 1 HNMR (CDCl3, 300MHz), δ: 7.78-7.763 (m, 6H), 6.56-6.51 (m, 2H), 3.90 (s, 3H), 3.83 (s, 3H).

[0099] In a 250 mL round-bottom flask, 4.0 g (30 mmol) of aluminum chloride was dissolved in 60.0 mL of 1,2-dichloroethane. 5.0 g (20.6 mmol) of 2,4-dimethoxybenzophenone was added under ice-water bath. After stirring for 30 min, 2.1 mL (30.0 mmol) of acetyl chloride was slowly added dropwise. The reaction solution turned from colorless to red. After the addition was completed, the temperature was slowly returned to room temperature and the reaction was continued for 6 h to obtain a reddish-brown liquid. 50.0 mL of ice water and concentrated hydrochloric acid (the volume ratio of ice water to concentrated hydrochloric acid is 200:1; the concentration of concentrated hydrochloric acid is 12 mol / L) were added, and the solution was separated after stratification, and then the obtained organic phase was washed with saturated sodium bicarbonate solution until weak alkalinity, then washed with water until neutral, washed three times with 10.0 mL of saturated brine, and the organic phase was dried over anhydrous sodium sulfate, and column chromatography was performed using petroleum ether: ethyl acetate = 6:1 (V / V) as the mobile phase to obtain 3.8 g of white powder solid, i.e. 2,4-dimethoxy-5-acetylbenzophenone.

[0100] The yield of the white solid is 64.9%, the melting point is 110-112°C, and the H-NMR spectrum information is: 1 H NMR (CDCl3, 300MHz), δ: 7.95 (s, 1H), 7.75-7.25 (m, 5H), 6.51 (s, 1H), 4.01 (s, 3H), 3.80 (s, 3H), 2.58 (s, 3H).

[0101] In a 100 mL round-bottom flask, 2.5 g of NaOH was dissolved in 25 mL of water, and then 20 mL of ethanol and 10.0 g (35.0 mmol) of 2,4-dimethoxy-5-acetylbenzophenone were added respectively. 4.3 mL (35.0 mmol) of benzaldehyde was added dropwise at room temperature. After addition, the reaction was continued with stirring for 2 h. A large amount of solid precipitated. The solid was filtered and washed three times with 15.0 mL of ethanol until neutral, and then recrystallized with ethanol to obtain 10.6 g of light yellow solid, which is 2,4-dimethoxy-5-(phenylacryloyl)benzophenone.

[0102] Yield 81.2%, mp 132-134℃, 1 HNMR (CDCl3, 300MHz), δ: 8.07 (d, J = 14.2Hz, 1H), 7.85-7.40 (m, 12H), 6.71 (s, 1H), 4.01 (s, 3H), 3.80 (s, 3H).

[0103] In a 50 mL round-bottom flask, 1.0 g (2.7 mmol) of 2,4-dimethoxy-5-(phenylacryloyl)benzophenone was dissolved in 20 mL of 1,2-dichloroethane, and 0.8 g (6.0 mmol) of aluminum chloride was slowly added in an ice-water bath. After reacting for 2 h, 100 mL of a mixture of ice water and hydrochloric acid (the volume ratio of ice water to concentrated hydrochloric acid was 200:1; the concentration of concentrated hydrochloric acid was 12 mol / L) was poured into the mixture and stirred for 10 min. 1,2-dichloroethane was added for layered extraction, and the organic layers were combined, dried over anhydrous magnesium sulfate, and subjected to column chromatography using petroleum ether: ethyl acetate = 10:1 (V / V) as the mobile phase to obtain 0.6 g of a yellow solid, i.e., 2,4-dihydroxy-5-(phenylacryloyl)benzophenone.

[0104] Yield 64.5%, mp 144-146℃, 1 H NMR (CDCl3, 300MHz), δ: 16.41 (s, 1H), 12.22 (s, 1H), 8.02 (d, J = 14.4Hz, 1H), 7.85-7.35 (m, 12H), 6.66 (s, 1H).

[0105] Example 2

[0106] In a 100mL round-bottom flask, dissolve 2.5g of NaOH in 25mL of water, then add 20mL of ethanol and 10.0g (35.0mmol) of 2,4-dimethoxy-5-acetylbenzophenone respectively, and add 4.1mL (35.0mmol) of p-tolualdehyde dropwise at room temperature. After addition, continue stirring and react for 2h. A large amount of solid precipitates. Filter the solid, wash it three times with 15.0mL of ethanol until it is neutral, and then recrystallize it with ethanol to obtain 10.1g of light yellow solid, which is 2,4-dimethoxy-5-(p-methylphenyl)benzophenone.

[0107] Yield 74.6%, mp 137-139℃, 1 HNMR (CDCl3, 300MHz), δ: 8.12 (d, J = 13.6Hz, 1H), 7.85-7.45 (m, 9H), 7.40 (d, J = 7.6Hz, 2H), 6.64 (s, 1H), 3.90 (s, 3H), 3.82 (s, 3H), 2.41 (s, 3H).

[0108] In a 50 mL round-bottom flask, 1.0 g (2.6 mmol) of 2,4-dimethoxy-5-(p-methylphenyl acryloyl) benzophenone was dissolved in 20 mL of 1,2-dichloroethane, and 0.8 g (6.0 mmol) of aluminum chloride was slowly added in an ice-water bath. After reacting for 2 h, 100 mL of a mixture of ice water and hydrochloric acid (the volume ratio of ice water to concentrated hydrochloric acid was 200:1; the concentration of concentrated hydrochloric acid was 12 mol / L) was poured into the mixture and stirred for 10 min. 1,2-dichloroethane was added for layered extraction, and the organic layers were combined, dried over anhydrous magnesium sulfate, and subjected to column chromatography using petroleum ether: ethyl acetate = 10:1 (V / V) as the mobile phase to obtain 0.6 g of a yellow solid, i.e., 2,4-dihydroxy-5-(p-methylphenyl acryloyl) benzophenone.

[0109] Yield 64.4%, mp 160-162℃, 1 H NMR (CDCl3, 300MHz), δ: 15.80 (s, 1H), 12.41 (s, 1H), 8.08 (d, J = 13.8Hz, 1H), 7.85-7.45 (m, 9H), 7.38 (d, J = 7.6Hz, 2H), 6.62 (s, 1H), 2.46 (s, 3H).

[0110] Example 3

[0111] In a 100mL round-bottom flask, 2.5g NaOH was dissolved in 25mL water, and then 20mL ethanol and 10.0g (35.0mmol) 2,4-dimethoxy-5-acetylbenzophenone were added respectively. 4.0mL (35.0mmol) o-methylbenzaldehyde was added dropwise at room temperature. After addition, the reaction was continued with stirring for 2h. A large amount of solid precipitated. The solid was filtered and washed three times with 15.0mL ethanol until neutral, and then recrystallized with ethanol to obtain 9.8g yellow solid, which is 2,4-dimethoxy-5-(o-methylpropenoyl)benzophenone.

[0112] Yield 72.3%, mp 134-135℃, 1 HNMR (CDCl3, 300MHz), δ: 8.04 (d, J = 13.8Hz, 1H), 7.88-7.40 (m, 11H), 6.72 (s, 1H), 3.92 (s, 3H), 3.80 (s, 3H), 2.50 (s, 3H).

[0113] In a 50 mL round-bottom flask, 1.0 g (2.6 mmol) of 2,4-dimethoxy-5-(o-methyl acryloyl) benzophenone was dissolved in 20 mL of 1,2-dichloroethane, and 0.8 g (6.0 mmol) of aluminum chloride was slowly added in an ice-water bath. After reacting for 2 h, 100 mL of a mixture of ice water and hydrochloric acid (the volume ratio of ice water to concentrated hydrochloric acid was 200:1; the concentration of concentrated hydrochloric acid was 12 mol / L) was poured into the mixture and stirred for 10 min. 1,2-dichloroethane was added for layered extraction, and the organic layers were combined, dried over anhydrous magnesium sulfate, and subjected to column chromatography using petroleum ether: ethyl acetate = 10:1 (V / V) as the mobile phase to obtain 0.5 g of a yellow solid, i.e., 2,4-dihydroxy-5-(o-methyl acryloyl) benzophenone.

[0114] Yield 53.8%, mp 152-153℃, 1 H NMR (CDCl3, 300MHz), δ: 15.94 (s, 1H), 12.21 (s, 1H), 8.11 (d, J = 13.9Hz, 1H), 7.85-7.45 (m, 11H), 6.64 (s, 1H), 2.51 (s, 3H).

[0115] Example 4

[0116] In a 100 mL round-bottom flask, 2.5 g of NaOH was dissolved in 25 mL of water, and then 20 mL of ethanol and 10.0 g (35.0 mmol) of 2,4-dimethoxy-5-acetylbenzophenone were added respectively. 4.3 mL (35.0 mmol) of p-methoxybenzaldehyde was added dropwise at room temperature. After addition, the reaction was continued with stirring for 2 h. A large amount of solid precipitated. The solid was filtered and washed three times with 15.0 mL of ethanol until neutral, and then recrystallized with ethanol to obtain 9.6 g of light yellow solid, which is 2,4-dimethoxy-5-(p-methoxyphenylacryloyl)benzophenone.

[0117] Yield 67.8%, mp 139-140℃, 1 HNMR (CDCl3, 300MHz), δ: 8.08 (d, J = 13.8Hz, 1H), 7.70-7.50 (m, 9H), 7.06 (d, J = 7.6Hz, 2H), 6.86 (s, 1H), 3.91 (s, 3H), 3.82 (s, 3H), 3.74 (s, 3H).

[0118] In a 50 mL round-bottom flask, 1.0 g (2.5 mmol) of 2,4-dimethoxy-5-(p-methoxyphenyl acryloyl) benzophenone was dissolved in 20 mL of 1,2-dichloroethane, and 0.8 g (6.0 mmol) of aluminum chloride was slowly added in an ice-water bath. After reacting for 2 h, 100 mL of a mixture of ice water and hydrochloric acid (the volume ratio of ice water to concentrated hydrochloric acid was 200:1; the concentration of concentrated hydrochloric acid was 12 mol / L) was poured into the mixture and stirred for 10 min. 1,2-dichloroethane was added for layered extraction, and the organic layers were combined, dried over anhydrous magnesium sulfate, and subjected to column chromatography using petroleum ether: ethyl acetate = 10:1 (V / V) as the mobile phase to obtain 0.6 g of a yellow solid, i.e., 2,4-dihydroxy-5-(p-methoxyphenyl acryloyl) benzophenone.

[0119] Yield 54.0%, mp 165-166℃, 1 H NMR (CDCl3, 300MHz), δ: 15.94 (s, 1H), 12.48 (s, 1H), 8.14 (d, J = 13.6Hz, 1H), 7. 70-7.50(m,8H),7.24(s,1H),7.08(d,J=7.8Hz,2H),6.59(s,1H),3.81(s,3H).

[0120] Example 5

[0121] In a 100 mL round-bottom flask, 2.5 g of NaOH was dissolved in 25 mL of water, and then 20 mL of ethanol and 10.0 g (35.0 mmol) of 2,4-dimethoxy-5-acetylbenzophenone were added respectively. 4.3 mL (35.0 mmol) of o-anisaldehyde was added dropwise at room temperature. After addition, the reaction was continued with stirring for 2 h. A large amount of solid precipitated. The solid was filtered and washed three times with 15.0 mL of ethanol until neutral, and then recrystallized with ethanol to obtain 9.9 g of yellow solid, which is 2,4-dimethoxy-5-(o-anisyl)benzophenone.

[0122] Yield 70.4%, mp 145-146℃, 1 HNMR (CDCl3, 300MHz), δ: 8.33 (d, J = 14.2Hz, 1H), 7.70-7.50 (m, 9H), 7.10-7.00 (m, 2H), 6.84 (s, 1H), 3.91 (s, 6H), 3.82 (s, 3H).

[0123] In a 50 mL round-bottom flask, 1.0 g (2.5 mmol) of 2,4-dimethoxy-5-(o-methoxyphenyl acryloyl) benzophenone was dissolved in 20 mL of 1,2-dichloroethane, and 0.8 g (6.0 mmol) of aluminum chloride was slowly added in an ice-water bath. After reacting for 2 h, 100 mL of a mixture of ice water and hydrochloric acid (the volume ratio of ice water to concentrated hydrochloric acid was 200:1; the concentration of concentrated hydrochloric acid was 12 mol / L) was poured into the mixture and stirred for 10 min. 1,2-dichloroethane was added for layered extraction, and the organic layers were combined, dried over anhydrous magnesium sulfate, and subjected to column chromatography using petroleum ether: ethyl acetate = 10:1 (V / V) as the mobile phase to obtain 0.5 g of a yellow solid, i.e., 2,4-dihydroxy-5-(o-methoxyphenyl acryloyl) benzophenone.

[0124] Yield 53.8%, mp 162-164℃, 1 H NMR (CDCl3, 300MHz), δ: 16.44 (s, 1H), 12.40 (s, 1H), 8.33 (d, J = 14.4Hz, 1H), 7.65-7.45(m,8H),7.24(s,1H),7.10-7.00(m,2H),6.56(s,1H),3.81(s,3H).

[0125] The ultraviolet absorption spectra of the ultraviolet absorbers obtained in Examples 1 to 5 were tested, with 2,4-dihydroxybenzophenone (BP-1) as a control. The results are as follows: Figure 1 shown.

[0126] according to Figure 1It can be seen that the ultraviolet absorber provided by the present invention has excellent absorption performance in the wavelength range of 280-400nm, indicating that the ultraviolet absorber provided by the present invention can absorb UVA and UVB at the same time, while BP-1 has good absorption performance only in the range of 280-330nm (UVB) and cannot absorb UVA.

[0127] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A benzophenone compound, characterized in that: It has the structure shown in formula I: The R includes H, methyl or methoxy.

2. The benzophenone compound according to claim 1, characterized in that The R is located at the para position or ortho position of the phenylacryloyl group.

3. The method for preparing the benzophenone compound according to claim 1 or 2, characterized in that: The following steps are involved: Mixing 2,4-dimethoxybenzophenone, acetyl chloride, Lewis acid and a first polar organic solvent for Friedel-Crafts acylation to obtain 2,4-dimethoxy-5-acetylbenzophenone; The 2,4-dimethoxy-5-acetylbenzophenone, aromatic aldehyde, alkali solution and organic solvent are mixed to carry out aldol condensation reaction to obtain 2,4-dimethoxy-5-(aryl acryloyl)benzophenone; The 2,4-dimethoxy-5-(aryl acryloyl) benzophenone is mixed with a catalyst and a second polar organic solvent to carry out a demethylation reaction to obtain the benzophenone compound; The aromatic aldehyde has a structure shown in formula I-1: The 2,4-dimethoxy-5-(aryl acryloyl)benzophenone has a structure shown in Formula I-2:

4. The preparation method according to claim 3, characterized in that: The molar ratio of the 2,4-dimethoxybenzophenone to acetyl chloride is 1:1-2.

5. The preparation method according to claim 3, characterized in that: The Lewis acid includes aluminum trichloride.

6. The preparation method according to any one of claims 3 to 5, characterized in that: The temperature of the Friedel-Crafts acylation reaction is 10-50° C. and the time is 4-8 hours.

7. The preparation method according to claim 3, characterized in that: The molar ratio of the 2,4-dimethoxy-5-acetylbenzophenone to the aromatic aldehyde is 1:1 to 1.

1.

8. The preparation method according to claim 3 or 7, characterized in that: The temperature of the aldol condensation reaction is 10 to 35° C., and the time is 1 to 4 hours.

9. The preparation method according to claim 3, characterized in that: The temperature of the demethylation reaction is -5 to 0°C, and the time is 0.5 to 4 hours.

10. Use of the benzophenone compound according to claim 1 or 2 or the benzophenone compound prepared by the preparation method according to any one of claims 3 to 9 as an ultraviolet absorber.

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