CN102391088B - (1R, 5R)-(-)-3-arylmethylene nopinone ultraviolet absorber and preparation method thereof - Google Patents

Abstract

The invention discloses a (1R,5R)-(-)-3-arylmethylene nopinone ultraviolet absorber and a preparation method thereof. The ultraviolet absorber is (1R,5R)-(-)-3 -(4′-Hydroxybenzylidene)nopinone, (1R,5R)-(-)-3-(4′-hydroxy-3′-methoxybenzylidene)nopinone, (1R,5R )-(-)-3-(2′-Hydroxy-3′-methoxybenzylidene)nopinone, (1R,5R)-(-)-3-(4′-chlorobenzylidene)nopine Pinone or (1R,5R)-(-)-3-(furan-2'-ylmethylene)nopinone. The invention uses cheap and easy-to-obtain β-pinene as a raw material, prepares nopinone with a bicyclic structure similar to camphor through selective oxidation, and then performs aldol condensation reaction with aromatic aldehydes of different structures to synthesize an ultraviolet absorber. The method has the advantages of simple synthetic route, convenient and economical operation, high yield, less pollution, etc., and overcomes the disadvantages of long synthetic route and high price of camphor. The synthesized ultraviolet absorber has the advantages of good ultraviolet absorption effect, wide ultraviolet absorption spectrum range and good stability, and has a good application prospect in absorbing ultraviolet rays.

Description

(1R,5R)-(-)-3-arylmethylene nopinone ultraviolet absorber and preparation method thereof

technical field

The invention relates to an ultraviolet absorber and a preparation method thereof, in particular to a (1R,5R)-(-)-3-arylene nopinone ultraviolet absorber and a preparation method thereof.

Background technique

The amount of ultraviolet radiation has been increasing with the destruction of the ozone layer, and its impact on human beings has been recognized worldwide. The skin science community divides the ultraviolet rays contained in sunlight into short-wave ultraviolet rays (UVC) of 200-280nm, medium-wavelength ultraviolet rays (UVB) of 280-320nm and long-wave ultraviolet rays (UVA) of 320-400nm. Among them, ultraviolet rays below 280nm are destroyed by the ozone layer. Absorbed and cannot reach the ground. The ultraviolet rays that reach the ground will have various effects on people's skin. UVB can cause erythema or blisters on the skin, promote the formation of melanin, cause skin pigmentation, and lead to the formation of brown spots. It is the main prevention object. It was previously thought that UVA would not have a great impact on the skin, but it has been proved by electron microscopy or histochemical methods that excessive UVA irradiation will have a certain impact on the skin. UVA segment ultraviolet light is different from UVB, and its energy can be Reaching the dermis layer of the skin, it brings slow changes to the elastic fibers in the blood vessel wall or combined tissue, which causes the browning of the skin, the decrease of skin elasticity, promotes the occurrence of wrinkles, and makes people age rapidly. In addition, it can also promote erythema reaction and even trigger Phototoxicity or photosensitivity reactions. Continuous UVB and UVA radiation on sensitive skin can damage DNA, reduce immunity, and even induce skin cancer. Therefore, it is particularly important to defend against excessive UVA and UVB radiation to protect the human body from damage and delay aging. An ideal UV absorber for cosmetics should have the following properties: able to absorb ultraviolet light from 280 to 360 nm; high extinction coefficient and low dosage; not affected by solvents in cosmetics; low water solubility; non-toxic and non-phototoxic; not compatible with skin and Cosmetic components react, and have good compatibility; do not cause skin dryness, no peculiar smell, low price and so on.

There are more than 60 kinds of ultraviolet absorbers that can be used in cosmetics, but for safety reasons, countries have strict restrictions on the use of ultraviolet absorbers. Among them, there are 16 kinds of ultraviolet absorbers approved by the US FDA in 1993, 24 kinds approved by the European Union in 2000, and 27 kinds allowed by Japan in 2001. my country's 2007 "Hygienic Standards for Cosmetics" stipulates that chemical sunscreens that can be used in cosmetics include camphor, cinnamic acid esters, salicylic acids, benzoic acids, benzophenones, triazines, benzos, etc.

The terpene compounds currently used as UV absorbers are mainly camphor derivatives, including 3-benzylidene camphor, 4-methylbenzylidene camphor, benzylidene camphorsulfonic acid, terephthalylidene dicamphorsulfonic acid acid derivatives. (tert-butyl)benzylidene camphor derivatives can not only be used as ultraviolet absorbers, but also can be used as antioxidants and medicines for the treatment of skin allergies, anti-inflammatory, etc., and terephthalic acid is a kind of Broad-spectrum ultraviolet absorber, the absorption range is between 290-390nm, and has the highest absorption peak at 345nm. Synthetic camphor, as a terpene compound, has disadvantages such as long synthetic route and large environmental pollution in its synthesis process, while natural camphor has disadvantages such as high price and few sources. For this reason, it is particularly urgent to develop novel terpene UV absorbers.

Contents of the invention

Purpose of the invention: for the deficiencies in the prior art, the purpose of the present invention is to provide a kind of (1R, 5R)-(-)-3-aryl methylene nopine ketone ultraviolet absorber, which has the absorption ultraviolet spectrum Wide range, strong stability, simple preparation and other advantages. Another object of the present invention is to provide a method for preparing the above-mentioned (1R,5R)-(-)-3-arylmethylene nopinone UV absorber.

Technical solution: In order to realize the above-mentioned purpose of the invention, the technical solution adopted in the present invention is:

(1R, 5R)-(-)-3-arylmethylene nopinone UV absorber, the general structural formula is:

或

或

或

或

(1R，5R)-(-)-3-芳亚甲基诺蒎酮类紫外线吸收剂，具体结构和名称如下：In the formula, Ar is

or

or

or

or

(1R, 5R)-(-)-3-Arylidene nopinone UV absorber, the specific structure and name are as follows:

(1R，5R)-(-)-3-(4′-羟基亚苄基)诺蒎酮，(1)；

(1R,5R)-(-)-3-(4'-hydroxybenzylidene)nopinone, (1);

(1R，5R)-(-)-3-(4′-羟基-3′-甲氧基亚苄基)诺蒎酮，(2)；

(1R,5R)-(-)-3-(4'-hydroxy-3'-methoxybenzylidene)nopinone, (2);

(1R，5R)-(-)-3-(2′-羟基-3′-甲氧基亚苄基)诺蒎酮，(3)；

(1R,5R)-(-)-3-(2'-hydroxy-3'-methoxybenzylidene)nopinone, (3);

(1R，5R)-(-)-3-(4′-氯亚苄基)诺蒎酮，(4)；

(1R,5R)-(-)-3-(4'-chlorobenzylidene)nopinone, (4);

(1R,5R)-(-)-3-(furan-2'-ylmethylene)nopinone, (5);

A method for preparing (1R, 5R)-(-)-3-arylmethylene nopinone ultraviolet absorbers, the specific process is: β-pinene is oxidized by peracid potassium manganate to convert into nopinone ; Under the action of base catalysis, nopinone and aromatic aldehyde undergo aldol condensation to generate a series of nopinone derivatives. Nopinone is a colorless oily nopinone liquid with a yield of 83.9%, a purity of 95.04%, and a specific rotation [a]=+27.3° (c=1.0, CCl ₃ ).

The application of the above-mentioned (1R, 5R)-(-)-3-arylmethylene nopinone ultraviolet absorber in absorbing ultraviolet rays.

The application of the above-mentioned (1R, 5R)-(-)-3-arylmethylene norpinone ultraviolet absorber in absorbing ultraviolet light; wherein, (1R, 5R)-(-)-3-arylmethylene Nopinone UV absorbers are (1R,5R)-(-)-3-(4′-hydroxybenzylidene)nopineone, (1R,5R)-(-)-3-(4′-hydroxy -3'-methoxybenzylidene)nopinone, (1R,5R)-(-)-3-(2'-hydroxy-3'-methoxybenzylidene)nopinone, (1R, 5R)-(-)-3-(4'-chlorobenzylidene)nopinone, (1R,5R)-(-)-3-(furan-2'-ylmethylene)nopinone or their mixture.

Beneficial effect: Compared with the prior art, the (1R, 5R)-(-)-3-arylmethylene nopinone ultraviolet absorber of the present invention has the outstanding advantage that: the present invention uses cheap and easy-to-obtain β - pinene as raw material, through selective oxidation to obtain nopinone with a bicyclic structure similar to camphor, and then carry out aldol condensation reaction with aromatic aldehydes of different structures to synthesize ultraviolet absorbers, with simple synthetic route, simple and economical operation , high yield, less pollution and other advantages, it overcomes the disadvantages of long synthetic route and high price of camphor. The synthesized ultraviolet absorber has the advantages of good ultraviolet absorption effect, wide ultraviolet absorption spectrum range and the like, and has a good application prospect in absorbing ultraviolet rays.

Description of drawings

Fig. 1 is (1R, 5R)-(-)-3-aryl methylene nopinone derivative photodegradation assay result figure;

Fig. 2 is a diagram showing the results of changes in absorbance of (1R, 5R)-(-)-3-arylmethylene nopinone derivatives.

Detailed ways

The present invention will be further explained below in conjunction with specific examples.

Embodiment 1: the preparation of nopinone

The preparation method of nopinone can be disclosed in the literature [Research on the Selective Oxidation of L-β-pinene to D-Nopinene, Journal of Nanjing Forestry University: Natural Science Edition, 2010, 34 (2), 89-94] method is carried out. You can also use the following methods:

Add acetone, sulfuric acid and β-pinene into a 100mL four-neck flask equipped with a stirrer, thermometer, constant pressure addition funnel and reflux condenser, cool in an ice bath to about 15°C, add fully ground KMnO ₄ in batches, Added within 1 ~ 1.5h. The ice bath was removed, and the reaction was continued at room temperature for 5-6 h. After the reaction was finished, MnO ₂ was removed by filtration with a sand core funnel, and the solid residue was washed with acetone. Use a rotary concentrator to recover acetone, add cyclohexane to the residue, wash with saturated brine until neutral, dry the organic layer with anhydrous Na ₂ SO ₄ , distill off cyclohexane under normal pressure, and then purify under reduced pressure. Distillation, collect 100～102 ℃/2.7kPa distillate, obtain the intermediate product nopinone of colorless oily liquid, purity is 95.3%, specific rotation is

Embodiment 2: Preparation of (1R, 5R)-(-)-3-arylmethylene nopinone ultraviolet absorber

Under alkali catalysis, take (1R, 5S)-(+)-nopinone prepared in Example 1, and carry out hydroxylation with p-hydroxybenzaldehyde, vanillin, o-vanillin, p-chlorobenzaldehyde and furfural respectively. Aldehyde condensation reaction, after further dehydration, (1R, 5R)-(-)-3-(4'-hydroxybenzylidene) nopinone (1), (1R, 5R)-(-)-3-(4 '-Hydroxy-3'-methoxybenzylidene)nopinone (2), (1R,5R)-(-)-3-(2'-hydroxy-3'-methoxybenzylidene)nopine Pinone (3), (1R,5R)-(-)-3-(4′-chlorobenzylidene)nopineone (4), (1R,5R)-(-)-3-(furan-2 '-ylmethylene)nopinone (5).

Preparation of (1R, 5R)-(-)-3-(4'-hydroxybenzylidene)nopinone (1):

(c＝0.6，CCl₃)；FT-IR(KBr)n(cm^-1)：3378(n_O-H)，2962～2911(n_C-H)，1669(n_C＝O)，1607～1469(苯环，n_asC＝C)，987～647(单取代苯环，t_C-H)；EI-MS m/z(％)：242(M⁺，100)，227(M⁺-15，31)，199(227-C₂H₄，42)，186(22)，171(47)，132(56)，107(54)，83(35)，55(53)，41(34)。Add 1.38g (0.01mol) nopinone, 30ml of potassium tert-butoxide tert-butanol solution with a concentration of 10% and 1.83g (0.015mol) p-hydroxybenzaldehyde into a 100mL three port equipped with stirrer, thermometer and reflux condenser In the flask, reflux under nitrogen protection for 7-8 hours until the conversion rate of nopinone reaches more than 95% (GC tracking detection). The reaction solution was extracted 3 times with ethyl acetate, the combined organic phase was washed with water and saturated brine until neutral, dried over anhydrous Na ₂ SO ₄ , filtered, and concentrated to obtain a yellow solid crude product, which was then dissolved in acetone and refluxed to the solution Transparent, after filtration, the filtrate was placed for several days for recrystallization, and a colorless and transparent (1R, 5R)-(-)-3-(4-hydroxybenzylidene)nopineone crystal was obtained, with a yield of 38.8%, GC Purity 97.4%; mp199.6～200.6℃;

(c=0.6, CCl ₃ ); FT-IR(KBr)n(cm ^-1 ): 3378(n _OH ), 2962～2911(n _CH ), 1669(n _C=O ), 1607～1469(benzene , n _asC=C ), 987～647 (monosubstituted benzene ring, t _CH ); EI-MS m/z (%): 242 (M ⁺ , 100), 227 (M ⁺ -15, 31), 199 ( 227- _C2H4 , ₄₂ ), 186(22), 171(47), 132(56), 107(54), 83(35), 55(53), 41(34).

Preparation of (1R, 5R)-(-)-3-(4'-hydroxy-3'-methoxybenzylidene)nopinone (2):

Add 1.38g (0.01mol) nopinone, 30ml of 10% potassium tert-butoxide toluene solution and 1.824g (0.012mol) vanillin (3-methoxy-4-hydroxybenzaldehyde) with stirring In a 100mL three-necked flask with a thermometer, a thermometer and a reflux condenser, the reflux reaction was carried out under nitrogen protection for 10-12 hours, and the conversion rate of nopinone reached 70-80%, and there were about 10-15% of by-products and 70-75% of the main product. The reaction solution was extracted three times with ethyl acetate, and the combined organic phase was washed with water and saturated brine until neutral, dried over anhydrous Na ₂ SO ₄ , filtered, and concentrated to obtain a yellow solid crude product, which was dissolved in acetone and added a little ethanol And reflux until the solution is transparent, and after filtration, the filtrate is placed for several days for recrystallization to obtain colorless and transparent (1R, 5R)-(-)-3-(4-hydroxyl-3-methoxybenzylidene)nopine Ketone crystals, yield 19.2%, GC purity 95.3%, mp173.5～1742℃, (c=0.32, CCl3). FT-IR (KBr) v (cm ^-1 ): 3238 (v _OH ), 2966~2901 (v _CH ), 1674 (v _C=O ), 1593~1440 (benzene ring, v _asC=C ), 1307~ 1130 (v _O-CH3 ), 856～619 (τ _CH ); EI-MS m/z (%): 272 (M ⁺ , 100), 257 (19), 229 (18), 203 (30), 162 (26), 137(24), 115(21), 91(20), 83(16), 55(33), 41(19).

Preparation of (1R, 5R)-(-)-3-(2'-hydroxy-3'-methoxybenzylidene)nopinone (3):

(c＝0.24，CCl₃)；FT-IR(KBr)v(cm^-1)：3246(v_O-H)，2959～2935(v_C-H)，1673(v_C＝O)，1597～1440(苯环，v_asC＝C)，1301～1201(v_O-CH3)，795～726(τ_C-H)；EI-MS m/z(％)：272(M⁺，30)，231(100)，213(14)，197(13)，161(24)，137(21)，128(12)，115(21)，91(21)，55(33)，41(19)。Add 2.76g (0.02mol) nopinone, 20% potassium tert-butoxide toluene solution 30ml and 3.65g (0.024mol) o-vanillin (3-methoxy-2-hydroxybenzaldehyde) In a 100mL three-necked flask with a stirrer, a thermometer and a reflux condenser, the reflux reaction was carried out under nitrogen protection for 20-22 hours, and the conversion rate of nopinone was 50%. The reaction solution was extracted 3 times with toluene, the combined organic phase was washed with water and saturated brine until neutral, dried over anhydrous Na ₂ SO ₄ , filtered, and concentrated to obtain a yellow solid crude product, which was dissolved in acetone, added a little ethanol and refluxed After the solution is transparent, after filtration, the filtrate is left for several days for recrystallization, and a colorless and transparent crystal of (1R, 5R)-(-)-3-(2-hydroxy-3-methoxybenzylidene)nopinone is obtained , yield 47.1%, GC purity 96.8%, mp195.2～195.6℃,

(c=0.24, CCl ₃ ); FT-IR(KBr)v(cm ^-1 ): 3246(v _OH ), 2959～2935(v _CH ), 1673(v _C=O ), 1597～1440(benzene ring , v _asC=C ), 1301～1201(v _O-CH3 ), 795～726(τ _CH ); EI-MS m/z(%): 272(M ⁺ , 30), 231(100), 213( 14), 197(13), 161(24), 137(21), 128(12), 115(21), 91(21), 55(33), 41(19).

Preparation of (1R, 5R)-(-)-3-(4'-chlorobenzylidene)nopinone (4):

(c＝0.31，CCl₃)；FT-IR(KBr)v(cm^-1)：2984～2874(v_C-H)，1686(v_C＝O)，1686～1407(苯环，v_asC＝C)，979～686(苯环对取代)；EI-MSm/z(％)：260(M⁺，97)，245(54)，217(54)，204(21)，189(39)，165(31)，150(48)，141(47)，125(48)，115(100)，83(78)，55(89)。Add 1.38g (0.01mol) nopinone, 30ml of 10% sodium methoxide tert-butanol solution and 1.68g (0.012mol) p-chlorobenzaldehyde into a 100mL three-necked flask equipped with a stirrer, thermometer and reflux condenser , reflux reaction under the protection of nitrogen for 5-8 hours, and the conversion rate of nopinone reached 100%. The reaction solution was added with saturated brine and extracted three times with ethyl acetate, the combined organic phase was washed with water and saturated brine until neutral, dried over anhydrous Na ₂ SO ₄ , filtered and concentrated to obtain a yellow solid crude product, which was then dissolved in acetone , add a little ethanol and reflux until the solution is transparent, after filtration, the filtrate is placed for several days for recrystallization, and yellow transparent (1R, 5R)-(-)-3-(4-chlorobenzylidene)nopineone crystals are obtained. Yield is 85.5%, GC purity is 97.8%, mp109.7～110.7℃,

(c=0.31, CCl ₃ ); FT-IR(KBr)v(cm ^-1 ): 2984~2874 (v _CH ), 1686(v _C=O ), 1686~1407 (benzene ring, v _asC=C ) , 979～686 (para-substituted benzene ring); EI-MSm/z(%): 260(M ⁺ , 97), 245(54), 217(54), 204(21), 189(39), 165( 31), 150(48), 141(47), 125(48), 115(100), 83(78), 55(89).

Preparation of (1R, 5R)-(-)-3-(furan-2'-ylmethylene)nopinone (5):

1.38g (0.01mol) nopinone, 10% NaOH ethanol solution 30ml and 1152g (0.012mol) furfural were added in the 100mL three-necked flask equipped with stirrer, thermometer and reflux condenser, and reflux reaction under nitrogen protection 4 After ~4.5h, the conversion rate of nopinone reached 93.6%. The reaction solution was added with saturated brine and extracted 3 times with ethyl acetate, the combined organic phase was washed with water and saturated brine until neutral, dried over anhydrous Na ₂ SO ₄ , filtered and concentrated to obtain a yellow solid crude product, which was subjected to silica gel column chromatography After separation [V _{petroleum ether} : V _{ethyl acetate} = 6:1], a yellow liquid (1R, 5R)-(-)-3-(furan-2-ylmethylene)nopinone was obtained with a yield of 85.5 %, GC purity 97.1%, (c=0.5, CCl ₃ ); FT-IR(KBr)v(cm ^-1 ): 3435(v= _CH ), 2935(v _CH ), 1691(v _C=O ), 1610～1548(furan ring, v _C=C ), 1297～1195 (v _COC ), 744 (δ _c=c out-of-plane bending vibration); EI-MS m/z(%): 216(M ⁺ , 86), 201(27), 173 (100), 145(35), 131(15), 115(21), 106(37), 91(31), 78(24), 65(14), 55(38), 41(16), 39 (18).

The physical properties of five kinds of (1R, 5R)-(-)-3-arylene nopinone derivatives prepared were compared, and the results are shown in Table 1.

The physical properties of table 1 (1R, 5R)-(-)-3-aryl methylene nopinone derivatives

It can be seen from Table 1 that the five (1R, 5R)-(-)-3-arylmethylene nopinone derivatives obtained by synthesis all have high optical activity, but the aryl structure is different and the same aryl group has different The optical activity of the products obtained by the substituents is different, and the specific optical rotation of (1R, 5R)-(-)-3-(2-hydroxyl-3-methoxybenzylidene)nopinone is the highest, followed by ( 1R,5R)-(-)-3-(4-hydroxybenzylidene)nopinone, while (1R,5R)-(-)-3-(furan-2-ylmethylene)nopinone is the least .

The light-absorbing capacity of embodiment 3 (1R, 5R)-(-)-3-aryl methylene nopinone derivatives is measured

The 5 compounds synthesized in Example 2 were dissolved in 55% ethanol to form a solution with a mass fraction of about 0.0015%, and full-ultraviolet scanning was performed in the range of 200-700nm to measure the absorbance range and maximum absorption wavelength. The molar absorptivity ε of each compound was calculated according to the following formula, and the results are shown in Table 2.

ε=A/CL

A-absorbance

ε-molar absorptivity, L/mol.cm

C-sample concentration, mol/L,

L-length of optical path, cm

Table 2 (1R, 5R)-(-)-3-aryl methylene nopinone derivatives UV absorption range and maximum absorption wavelength

compound UV absorption range Maximum absorption wavelength λ _max (nm) Molar absorptivity ε(L/mol cm) 1 240～360 322.5 29400 2 200～390 335.0 23430 3 280～390 306.0 24780 4 240～350 295.0 34110 5 270～370 322.5 22290

It can be seen from Table 2 that compounds 1-5 all have strong UV absorption. The ultraviolet absorption ranges of compounds 3 and 5 are 280-390nm and 270-370nm, respectively, and the maximum absorption wavelength λ _max and absorbance values are 306nm, 24780L/mol cm and 322.5nm, 22290L/mol cm, respectively. The condition of type A ultraviolet absorber; Compound 2 then has the widest ultraviolet absorption range, and maximum absorption wavelength λ _max reaches 335nm, has the function that can absorb UV-A and UV-B simultaneously; From molar absorptivity as can be known, each compound The order of ability to absorb ultraviolet rays is: (4)>(1)>(3)>(2)>(5).

Photodegradation Determination of Embodiment 4 (1R, 5R)-(-)-3-aryl methylene nopinone derivatives

50 ml of the 5 solutions prepared in Example 3 were respectively injected into 3 conical flasks with stoppers of the same specification, 1 was kept in the dark, 1 was placed indoors, and 1 was placed under sunlight. Taking the aqueous solution with the same mass fraction of ethanol as a reference, measure its absorbance at the maximum absorption wavelength every day, calculate the degradation rate of each compound under different conditions, and compare the photostability of each ultraviolet absorber.

Test result as shown in Figure 1, the change of its absorbance of 5 kinds of (1R, 5R)-(-)-3-aryl methylene nopinone derivatives prepared in embodiment 2 are different under illumination, the compound The absorbance of 1 and 2 changed significantly in the first two days. Compared with the first day, the absorbance decreased by 6.2% and 7.0% respectively on the second day, and their absorbance basically did not change after the second day, both at 0.35%. Within; the absorbance of compounds 3 and 4 changed slightly in the first two days, being 1.7% and 1.0% respectively; while the absorbance of compound 5 had almost no change, and the second day only decreased by 0.1% compared with the first day. Absorbance of all 5 compounds hardly changed after the third day. This shows that the order of stability of the compounds is 5>4>3>1>2. Overall, these five compounds all have good photostability.

In the same way, the absorbance changes of the synthesized 5 kinds of arylmethylene nopinone derivatives were also measured indoors and under light-shielding conditions. Compared with direct sunlight irradiation, under indoor and light-shielding conditions, The photodegradation phenomenon of these compounds is weakened and the photostability is enhanced. Under indoor and dark conditions, the photodegradation tendency of the UV absorber slowed down, and the absorbance of the UV absorber p-tolualdehyde also showed a tendency to increase. It can be seen that its photostability is better indoors and under dark conditions. Comparing the photostability under indoor and dark conditions, it can be seen that the photostability is better under dark conditions.

The five synthetic (1R, 5R)-(-)-3-arylmethylene nopinone derivatives were compounded in equal mass ratios, and 55% ethanol was used as a solvent to form a solution, and at 200-400nm Carry out a full scan under the same conditions, measure its ultraviolet absorption range, and determine its maximum absorption wavelength; place the compound under three conditions of light, indoor and dark, and measure the change of its absorbance value at the maximum absorption wavelength every day , so as to determine the photostability of the compound.

Five kinds of UV absorbers were formulated into solvents in equal proportions, and a full scan was performed under the condition of 200-400nm. It was found that the UV absorption wavelength range of the compound solvent became wider, and at different wavelength positions, its UV absorption intensity vary. The maximum absorption peak of a single UV absorber is between 289.5 and 322.5. After compounding, the full scan of UV absorption shows that its strongest UV absorption peak is at 307nm, so the photostability at 307nm is selected to investigate the compound The characteristics of photostability changes.

Place the prepared compound solution in the same way under light, indoor, and light-proof conditions, and detect the change of its absorbance value every day. The results are shown in Figure 2. The absorbance of the compound under different conditions ranges from From the third day to the fourth day, the decline gradually decreased and began to stabilize. Therefore, the comparison of photostability of the compound was investigated from the fourth day. Select the change value of the absorbance in the last four days, calculate its decline rate, and compare the photostability of the compound under different conditions. According to the experimental data, under the three conditions, the photostability of the compound is higher than that of a single product, and it still satisfies the fastest degradation rate under light, the slowest degradation rate in a closed environment, and the stability most.

To sum up, for different substituents, this series of products have a wide range of ultraviolet absorption, high extinction coefficient, good stability, low degradation rate of hydroalcoholic solution, and good ultraviolet absorption curve. And this series of products have a wider range of UV absorption and better stability under compounding conditions. At the same time, as a UV absorber, it is best to keep it away from light.

Claims (3)

1. (1R, 5R)-(-)-3-arylmethylene nopinone ultraviolet absorbent, is characterized in that, general structure is:

In formula, Ar is

.

2. a method of preparing (1R, 5R) claimed in claim 1-(-)-3-arylmethylene nopinone ultraviolet absorbent, is characterized in that, comprising: beta-pinene is oxidized through acid potassium permanganate, changes into nopinone; Under base catalysis, nopinone and aromatic aldehyde carry out aldol condensation generation (1R, 5R)-(-)-3-arylmethylene nopinone ultraviolet absorbent; Reaction formula is:

。

3. the application of (1R, 5R) claimed in claim 1-(-)-3-arylmethylene nopinone ultraviolet absorbent in absorbing ultraviolet ray.

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