阅读说明：本技术 反应型苯并三氮唑类紫外线吸收剂及其合成方法 (Reactive benzotriazole ultraviolet absorbent and synthetic method thereof ) 是由 田军 勾少萍 张会京 范小鹏 孙春光 李海平 于 2020-12-14 设计创作，主要内容包括：本发明提供了一种反应型苯并三氮唑类紫外线吸收剂及其合成方法。该合成方法包括：S1,将具有结构式A的醇胺类化合物、碱性催化剂和有机溶剂混合；S2,加入具有结构式B的苯并三氮唑类化合物进行酰胺化反应,得到反应型苯并三氮唑类紫外线吸收剂；R-1为-H、-Cl或-Br,R-2为-H、-CH-2CH-2OH或-CH-2CH(OH)CH-3,R-3为-CH-2CH-2OH或-CH-2CH(OH)CH-3,R为-CH-3或-C-2H-5,n为0或1。本发明以较低的反应温度较高的反应选择性及收率合成了反应型苯并三氮唑类紫外线吸收剂。(The invention provides a reactive benzotriazole ultraviolet absorbent and a synthesis method thereof. The synthesis method comprises the following steps: s1, mixing the alcohol amine compound with the structural formula A, the basic catalyst and the organic solvent; s2, adding a benzotriazole compound with a structural formula B for amidation reaction to obtain a reactive benzotriazole ultraviolet absorbent; r 1 is-H, -Cl or-Br, R 2 is-H, -CH 2 CH 2 OH or-CH 2 CH(OH)CH 3 ，R 3 is-CH 2 CH 2 OH or-CH 2 CH(OH)CH 3 R is-CH 3 or-C 2 H 5 And n is 0 or 1. The invention synthesizes the reactive benzotriazole ultraviolet absorbent with lower reaction temperature and higher reaction selectivity and yield.)

1. A synthetic method of a reactive benzotriazole ultraviolet absorbent is characterized by comprising the following steps:

s1, mixing the alcohol amine compound with the structural formula A, the basic catalyst and the organic solvent to obtain a first mixed solution;

s2, adding a benzotriazole compound with a structural formula B into the first mixed solution, and carrying out amidation reaction according to the following reaction formula to obtain the reactive benzotriazole ultraviolet absorbent with a structural formula I;

wherein, R is₁The group is-H, -Cl or-Br, the R₂The radicals being-H, -CH₂CH₂OH or-CH₂CH(OH)CH₃Said R is₃The group being-CH₂CH₂OH or-CH₂CH(OH)CH₃The R group is-CH₃or-C₂H₅And n is 0 or 1.

2. The synthesis method according to claim 1, wherein the basic catalyst is hydroxide of alkali metal, carbonate or acetate of alkali metal, preferably, the basic catalyst is one or more of NaOH, KOH, LiOH, sodium acetate, potassium acetate, lithium acetate, sodium carbonate and potassium carbonate.

3. The method of claim 1, wherein in the step S2, the reaction temperature during the amidation reaction is 60-90 ℃.

4. The synthesis method according to any one of claims 1 to 3, wherein the organic solvent is an alkane or aromatic hydrocarbon solvent having a boiling point of 60 to 138 ℃; preferably, the organic solvent is one or more of cyclohexane, petroleum ether, n-heptane, n-octane, toluene and xylene.

5. The synthesis method according to any one of claims 1 to 3, wherein the amount of the basic catalyst is 0.5 to 8% by weight of the alcohol amine compound; preferably, the molar ratio of the benzotriazole compound to the alkanolamine compound is 1 (1-5); more preferably, the weight ratio of the alcohol amine compound to the organic solvent is 1 (3-20).

6. The synthesis method according to any one of claims 1 to 5, wherein after the mixing of the alcohol amine compound, the basic catalyst and the organic solvent, the step S1 further comprises: carrying out normal-pressure or reduced-pressure reflux dehydration treatment on the first mixed solution in an inert atmosphere, wherein the time of the reflux dehydration treatment is preferably 0.5-2 h;

preferably, in the step S2, the benzotriazole compound is added to the first mixed solution in a batch manner.

7. The synthesis method according to claim 6, wherein in the step S2, the amidation reaction process obtains a crude product, and the synthesis method further comprises a step of post-treating the crude product to obtain the reactive benzotriazole ultraviolet absorber; the post-processing step comprises:

adjusting the pH value of the crude product to 5-6, and then washing the crude product to be neutral to obtain a primary treatment product;

sequentially carrying out dewatering, cooling and crystallization on the primary treatment product to obtain the reactive benzotriazole ultraviolet absorbent;

preferably, before the step of adjusting the pH of the crude product, the post-treatment step further comprises: washing the crude product with water to obtain a first neutral product, and then adjusting the pH of the first neutral product;

preferably, in the process of adjusting the pH value of the crude product, acetic acid, formic acid aqueous solution, p-toluenesulfonic acid or 1-5 wt% sulfuric acid aqueous solution is used as a pH regulator;

preferably, before subjecting the crude product to the post-treatment step, the synthesis process further comprises: evaporating the organic solvent in the crude product, and then adding toluene or xylene; more preferably, the weight ratio of the added toluene or xylene to the alcohol amine compound is (10-20): 1.

8. The method of synthesis of claim 7, wherein after removing water from the preliminary treatment product, the post-treatment step further comprises: decoloring the dewatered primary treatment product, and then performing the cooling crystallization step;

preferably, the decoloring agent adopted in the decoloring process is one or more of activated carbon, diatomite and clay;

preferably, the usage amount of the decoloring agent is 0.5-2% of the weight of the benzotriazole compound.

9. The synthesis method of claim 8, wherein the water removal step adopts an azeotropic water removal mode, and after the decolorization step, the decolorizer is removed by hot filtration, and the filtrate is cooled to 10-15 ℃ and stirred for 1-2 h to perform the cooling crystallization step;

preferably, precipitated crystals are obtained in the cooling crystallization step, and the precipitated crystals are filtered, washed and dried in sequence to obtain the reactive benzotriazole ultraviolet absorber.

10. A reactive benzotriazole ultraviolet absorber is characterized by having a structure as shown in the specification:

wherein, R is₁The group is-H, -Cl or-Br, the R₂The radicals being-H, -CH₂CH₂OH or-CH₂CH(OH)CH₃Said R is₃The group being-CH₂CH₂OH or-CH₂CH(OH)CH₃N is 0 or 1;

preferably, the reactive benzotriazole uv absorbers have a formula selected from the group consisting of:

Technical Field

The invention relates to the field of organic synthesis, and particularly relates to a reactive benzotriazole ultraviolet absorbent and a synthesis method thereof.

Background

It is well known that polymer materials such as rubber, plastic, chemical fiber, paint, adhesive, etc. are widely used in the aspects of production and life. However, these materials are easy to be aged by light, heat, oxygen and other factors during preparation, processing, transportation, storage and use, such as yellowing, brittleness, stickiness and the like, which brings great inconvenience and loss to national production and people's life. In order to delay the aging of the high polymer material and prolong the service life of the material, a proper amount of anti-aging auxiliary agent is required to be added in the preparation and processing processes of the high polymer material. It can be seen that the anti-aging auxiliaries are closely related to the production of the polymer materials.

The anti-aging aids commonly used include antioxidants, ultraviolet absorbers (UVAs), light stabilizers, and the like, and there are many kinds of such anti-aging aids that can be used for various polymer materials, but the following problems still remain. 1) The small-molecular anti-aging auxiliary agent is easily migrated out under the influence of the external environment in the using process; 2) some anti-aging additives have poor compatibility with matrix resin, and cause phase separation so as to cause poor effect of the additives; 3) the slow diffusion rate of the anti-aging auxiliary agent with higher relative molecular mass in the polymer also influences the anti-aging effect of the auxiliary agent.

The design of the synthetic reaction type anti-aging auxiliary agent can effectively solve the problems. The reactive anti-aging auxiliary agent is formed by introducing reactive groups into the structure of the traditional anti-aging auxiliary agent, and can be bonded or grafted to the main chain of a high polymer material in the preparation and processing processes of the high polymer material, so that the high polymer material has permanent anti-aging performance. A great deal of research is carried out at home and abroad aiming at the reactive anti-aging auxiliary agent, and part of products are commercialized. For example, oxalyl hydrazine type hindered amine light stabilizer HA-R100 (with the following structural formula a) developed by atropic chemistry, benzophenone type ultraviolet absorbent UV-416 (with the following structural formula b) developed by cyanotex corporation in the United states and benzotriazole type ultraviolet absorbent R-455 (with the following structural formula c) developed by Citrix corporation all exhibit good anti-aging effects.

Compared with other ultraviolet absorbers, the benzotriazole ultraviolet absorber has the characteristics of widest absorption wavelength (290-400nm), widest application range, most varieties and the like, and the reactive ultraviolet absorber formed by taking an amide structure as a bridge chain has better thermal stability, hydrolysis resistance and acid resistance. Therefore, the development of reactive benzotriazole ultraviolet absorbers having an amide structure has been the focus of research.

Ciba corporation reported in patent US4853471 a method of acylating chlorination of benzotriazole UV absorbers with carboxylic acid structure and then reacting with piperidine or bis (2-ethylhexanediamine) to obtain benzotriazole UV absorbers with amide as a bridge chain, however, this method is not suitable for synthesis of reactive UV absorbers with hydroxyl as a reactive group; meanwhile, Ciba reports a method for amidating benzotriazole ultraviolet absorbent with a methyl carboxylate structure and diamine in the patent, the reaction temperature can be up to 130 ℃, and the high reaction temperature can cause double amidation side reaction. Patent US5962683 reports that benzotriazole with methyl carboxylate structure and ethanolamine have amidation reaction at 140 ℃, and higher reaction temperature also causes transesterification side reaction, thus the product yield is lower. Basf in patent US20120058974 reports a method for synthesizing an amide bridged benzotriazole ultraviolet absorber by an amidation method, and the reaction temperature is still higher and needs 110 ℃. In order to reduce the reaction temperature, the method for amidating the benzotriazole ultraviolet absorbent with the methyl ester structure is realized at 80 ℃ by using biological enzyme as a catalyst. However, the reaction temperature of this method is low, but the use of biological enzymes undoubtedly increases the operation difficulty and the production cost (US20060110807), and thus is not suitable for industrial production. In addition, Ciba in patent US20020094320 reports that lithium amide is used as a catalyst to catalyze the benzotriazole amidation method with a methyl carboxylate structure at room temperature. However, the strong reactivity of the catalyst may activate both amino and alcoholic hydroxyl groups, and thus the catalyst is not suitable for synthesizing a reactive ultraviolet absorber having an amide as a bridge chain and an alcoholic hydroxyl group as a reactive group.

In summary, the reactive benzotriazole ultraviolet light absorbers currently using amide as a bridge chain are mainly synthesized by the following two methods: (1) carboxylic acid is subjected to acyl chlorination and then amidation reaction with primary amine, secondary amine and the like to obtain the compound. This method is not suitable for the synthesis of reactive ultraviolet absorbers having alcoholic hydroxyl groups as reactive groups. (2) Amidating methyl carboxylate. The reaction can be carried out without a catalyst, but a higher reaction temperature is required, and when the method is used for synthesizing a reactive ultraviolet absorbent taking alcoholic hydroxyl as a reactive group, more impurities are generated, so that the quality and the yield of the product are influenced. In addition, the reaction enzyme can be used as a catalyst to catalyze the reaction mildly, but the catalyst is high in cost and harsh to the external environment, so that the method is not suitable for industrial production. The lithium amide is also used as a catalyst to catalyze amidation of methyl carboxylate under a mild condition, but the lithium amide has the problems of high price, high possibility of hydrolysis, potential safety hazards in the processes of production, storage and transportation and the like; the catalyst has high activity, can activate amino and alcoholic hydroxyl simultaneously, and undoubtedly generates more impurities when being used for synthesizing a reactive ultraviolet absorbent taking alcoholic hydroxyl as a reactive group. It can be seen that the existing synthesis process of the reactive ultraviolet absorber using amide as a bridge chain and alcoholic hydroxyl as a reactive group has the problems of expensive catalyst, harsh synthesis conditions, low selectivity, low yield and the like.

For the above reasons, there is a need for a highly selective and high-yield synthesis process which can be carried out at a relatively low reaction temperature and is suitable for a reactive ultraviolet absorber having an amide as a bridge chain and an alcoholic hydroxyl group as a reactive group.

Disclosure of Invention

The invention mainly aims to provide a reactive benzotriazole ultraviolet absorbent and a synthesis method thereof, and aims to solve the problems of high synthesis temperature, poor selectivity and low yield of the reactive ultraviolet absorbent which takes amide as a bridge chain and alcoholic hydroxyl as a reaction group in the prior art.

In order to achieve the above object, according to one aspect of the present invention, there is provided a method for synthesizing a reactive benzotriazole-based ultraviolet absorber, comprising the steps of: s1, mixing the alcohol amine compound with the structural formula A, the basic catalyst and the organic solvent to obtain a first mixed solution; s2, adding a benzotriazole compound with a structural formula B into the first mixed solution, and carrying out amidation reaction according to the following reaction formula to obtain a reactive benzotriazole ultraviolet absorbent with a structural formula I;

wherein R is₁The radicals being-H, -Cl or-Br, R₂The radicals being-H, -CH₂CH₂OH or-CH₂CH(OH)CH₃，R₃The group being-CH₂CH₂OH or-CH₂CH(OH)CH₃R is-CH₃or-C₂H₅And n is 0 or 1.

Further, the basic catalyst is hydroxide of alkali metal, carbonate or acetate of alkali metal, preferably, the basic catalyst is one or more of NaOH, KOH, LiOH, sodium acetate, potassium acetate, lithium acetate, sodium carbonate and potassium carbonate.

Further, in the step S2, the reaction temperature is 60 to 90 ℃ during the amidation reaction.

Further, the organic solvent is an alkane or aromatic hydrocarbon solvent with the boiling point of 60-138 ℃; preferably, the organic solvent is one or more of cyclohexane, petroleum ether, n-heptane, n-octane, toluene, xylene.

Further, the dosage of the alkaline catalyst is 0.5-8% of the weight of the alcohol amine compound; preferably, the molar ratio of the benzotriazole compound to the alkanolamine compound is 1 (1-5); more preferably, the weight ratio of the alcohol amine compound to the organic solvent is 1 (3-20).

Further, after mixing the alcohol amine compound, the basic catalyst and the organic solvent, step S1 further includes: carrying out normal-pressure or reduced-pressure reflux dehydration treatment on the first mixed solution in an inert atmosphere, wherein the time of the reflux dehydration treatment is preferably 0.5-2 h; preferably, in step S2, the benzotriazole compound is added to the first mixed solution in a batch manner.

Further, in step S2, the amidation reaction process obtains a crude product, and the synthesis method further includes a step of performing post-treatment on the crude product to obtain a reactive benzotriazole ultraviolet absorber; the post-treatment step comprises: adjusting the pH value of the crude product to 5-6, and then washing the crude product to be neutral to obtain a primary treatment product; sequentially carrying out dewatering, cooling and crystallization on the primary treatment product to obtain a reactive benzotriazole ultraviolet absorbent; preferably, before the step of adjusting the pH of the crude product, the post-treatment step further comprises: washing the crude product with water to obtain a first neutral product, and then adjusting the pH of the first neutral product; preferably, in the process of adjusting the pH value of the crude product, acetic acid, formic acid aqueous solution, p-toluenesulfonic acid or 1-5 wt% sulfuric acid aqueous solution is used as a pH adjusting agent.

Further, before the post-treatment step of the crude product, the synthesis method further comprises: evaporating the organic solvent in the crude product, and then adding toluene or xylene; preferably, the weight ratio of the added toluene or xylene to the alcohol amine compound is (10-20): 1.

Further, after the water removal of the primary treatment product, the post-treatment step further comprises: decoloring the dewatered primary treatment product, and then cooling and crystallizing; preferably, the decoloring agent adopted in the decoloring process is one or more of activated carbon, diatomite and clay; preferably, the usage amount of the decoloring agent is 0.5-2% of the weight of the benzotriazole compound.

Further, the water removal step adopts an azeotropic water removal mode, after the decolorization step, the decolorizer is removed by hot filtration, and the filtrate is cooled to 10-15 ℃ and stirred for 1-2 hours to carry out the cooling crystallization step; preferably, the precipitated crystals are obtained in the cooling crystallization step, and the precipitated crystals are filtered, washed and dried in sequence to obtain the reactive benzotriazole ultraviolet absorbent.

According to another aspect of the present invention, there is also provided a reactive benzotriazole-type ultraviolet absorber having the structure shown below:

wherein R is₁The radicals being-H, -Cl or-Br, R₂The radicals being-H, -CH₂CH₂OH or-CH₂CH(OH)CH₃，R₃The group being-CH₂CH₂OH or-CH₂CH(OH)CH₃And n is 0 or 1.

Preferably, the reactive benzotriazole ultraviolet light absorber is selected from the following compounds:

the invention provides a synthesis method of a reactive benzotriazole ultraviolet absorbent, which comprises the step of carrying out amidation reaction on an alcohol amine compound with a structural formula A and a benzotriazole compound with a carboxylic ester structure with a structural formula B under the catalytic action of a basic catalyst to construct the reactive ultraviolet absorbent taking amide as a bridge chain and alcoholic hydroxyl as a reaction group, wherein the basic catalyst can be used for greatly reducing the reaction temperature and simultaneously improving the reaction selectivity and the product yield. Meanwhile, in the amidation reaction process, the alkaline catalyst has stable property and is not easy to inactivate, so that the production cost is saved and the benefit is increased. In addition, hydrogen chloride gas is not generated in the production process, the process is safer and more environment-friendly, and the method is an ideal method for constructing the reactive ultraviolet absorbent taking amide as a bridge chain and alcoholic hydroxyl as a reaction group.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows the nuclear magnetic spectrum of the product prepared in example 1 according to the invention; and

figure 2 shows the nuclear magnetic spectrum of the product prepared in example 5 according to the invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

As described in the background section, the current amide-bridged reactive benzotriazole uv absorbers are synthesized mainly by the following two methods. (1) Carboxylic acid is subjected to acyl chlorination and then undergoes amidation reaction with primary amine, secondary amine and the like to obtain the compound. However, when the method is used for amidation reaction of alcohol amine compounds, esterification reaction is undoubtedly associated, which undoubtedly increases purification difficulty for constructing a reactive ultraviolet absorbent taking amide as a bridge chain and alcoholic hydroxyl as a reaction group, and simultaneously reduces product yield; in addition, carboxylic acid acyl chloride requires a large amount of acyl chloride reagent and generates a large amount of hydrogen chloride gas in the reaction process, which not only increases the burden of sewage treatment but also has potential safety hazard. (2) Obtained by amidation reaction of carboxylic acid methyl ester. The reaction can be carried out without a catalyst, but a higher reaction temperature is required, and the synthesis of the reactive ultraviolet absorber with alcoholic hydroxyl as a reactive group is also accompanied with esterification reaction, so that more impurities are generated, and the quality and the yield of the product are influenced. Although the reaction enzyme can be used as a catalyst to catalyze the reaction mildly, the catalyst has high cost and severe requirements on the external environment, and is not suitable for industrial production. While lithium amide as a catalyst can mildly catalyze amidation of methyl carboxylate, the lithium amide has the problems of high price, high possibility of hydrolysis, potential safety hazards in the production, storage and transportation processes and the like; in addition, the catalyst has high activity, can activate amino and alcoholic hydroxyl simultaneously, and generates more impurities when being used for synthesizing a reactive ultraviolet absorbent taking alcoholic hydroxyl as a reactive group.

In order to solve the above problems, the present invention provides a method for synthesizing a reactive benzotriazole uv absorber, which comprises the following steps: s1, mixing the alcohol amine compound with the structural formula A, the basic catalyst and the organic solvent to obtain a first mixed solution; s2, adding a benzotriazole compound with a structural formula B into the first mixed solution, and carrying out amidation reaction according to the following reaction formula to obtain a reactive benzotriazole ultraviolet absorbent with a structural formula I;

wherein R is₁The radicals being-H, -Cl or-Br, R₂The radicals being-H, -CH₂CH₂OH or-CH₂CH(OH)CH₃，R₃The group being-CH₂CH₂OH or-CH₂CH(OH)CH₃R is-CH₃or-C₂H₅And n is 0 or 1.

The method comprises the steps of carrying out amidation reaction on an alcohol amine compound with a structural formula A and a benzotriazole compound with a carboxylic ester structure with a structural formula B under the catalytic action of a basic catalyst to construct a reactive ultraviolet absorbent taking amide as a bridge chain and alcoholic hydroxyl as a reaction group, wherein the basic catalyst can be used for greatly reducing the reaction temperature and simultaneously improving the reaction selectivity and the product yield. Meanwhile, in the amidation reaction process, the alkaline catalyst has stable property and is not easy to inactivate, so that the production cost is saved and the benefit is increased. In addition, hydrogen chloride gas is not generated in the production process, the process is safer and more environment-friendly, and the method is an ideal method for constructing the reactive ultraviolet absorbent taking amide as a bridge chain and alcoholic hydroxyl as a reaction group.

In particular, the present invention provides the above synthesis method, wherein R is₁Radical, R₂Radical, R₃The group and the R group are specifically defined. The synthesis of the benzoxazole compound comprises diazotization, coupling reaction and subsequent reduction reaction, R₁The groups need to remain stable during these steps and facilitate these reactions; r₂Group and R₃The choice of the group is mainly based on the influence of steric hindrance and electronic effects on the nucleophilic ability of the amine, and when the nucleophilic ability of the amine is reduced due to the steric hindrance and the electronic effects, the reaction temperature is increased, and the reaction selectivity is reduced. According to the invention, methyl and ethyl are selected as R groups, and other groups are selected at the same time, so that the reaction activity and selectivity of amidation can be improved by adjusting the electrophilic capacity of carbonyl carbon, and the alcohol amine compounds and benzotriazole compounds carrying the groups have outstanding effects in the aspects of reduction of reaction temperature, improvement of selectivity and improvement of yield under the catalytic action of an alkaline catalyst.

For the purpose of further improving the selectivity of amidation reaction and the yield of product, in a preferred embodiment, the basic catalyst is hydroxide, carbonate or acetate of alkali metal, preferably, the basic catalyst is one or more of NaOH, KOH, LiOH, sodium acetate, potassium acetate, lithium acetate, sodium carbonate, potassium carbonate. The alkaline catalysts can improve the selectivity and the product yield of the amidation reaction, and are favorable for further reducing the reaction temperature, so that the reaction conditions are mild, and the reaction process is stable. Meanwhile, the alkaline catalysts are relatively cheaper and easily obtained, and the synthesis cost is further reduced.

In addition, aiming at different reaction substrates, the invention further preferably adopts corresponding alkaline catalysts to catalyze the amidation reaction process, and the specific steps are as follows:

when R is₁The group being-H, R₂The group being-CH₂CH₂OH，R₃The group being-CH₂CH₂OH, the R group being-CH₃When n is 1, the basic catalyst is KOH or lithium acetate;

when R is₁The radical being-Cl, R₂The group being-H, R₃The group being-CH₂CH₂OH, the R group being-C₂H₅When n is 1, the basic catalyst is LiOH;

when R is₁The radical being-Cl, R₂The group being-H, R₃The group being-CH₂CH(OH)CH₃R is-CH₃When n is 1, the alkaline catalyst is NaOH;

when R is₁The group being-H, R₂The group being-CH₂CH(OH)CH₃，R₃The group being-CH₂CH(OH)CH₃R is-CH₃When n is 1, the alkaline catalyst is sodium acetate;

when R is₁The group being-H, R₂The group being-CH₂CH(OH)CH₃，R₃The group being-CH₂CH(OH)CH₃R is-CH₃And when n is 0, the alkaline catalyst is potassium acetate, potassium carbonate or sodium carbonate.

As described above, in the present invention, an alcohol amine compound having a structural formula a and a benzotriazole compound carrying a carboxylate structure having a structural formula B are subjected to an amidation reaction under the catalytic action of a basic catalyst to construct a reactive ultraviolet absorber using an amide as a bridge chain and an alcoholic hydroxyl group as a reactive group, and the reaction temperature can be greatly reduced by using the basic catalyst. In a preferred embodiment, in the step S2, the reaction temperature is 60 to 90 ℃ and the reaction time is 3 to 12 hours during the amidation reaction. The reaction condition is mild, and the full implementation of amidation reaction is facilitated.

The reaction solvent is used for the purpose of stabilizing the amidation reaction, and may be a good solvent for the reaction substrate. In a preferred embodiment, the organic solvent is an alkane or aromatic hydrocarbon solvent with a boiling point of 60-138 ℃; preferably, the organic solvent is one or more of cyclohexane, petroleum ether, n-heptane, n-octane, toluene, xylene. The reaction process is more stable by adopting the reaction solvent.

In a preferred embodiment, the amount of the basic catalyst is 0.5-8%, preferably 0.5-2% by weight of the alkanolamine compound, which is favorable for further improving the efficiency of the amidation reaction. Preferably, the molar ratio of the benzotriazole compound to the alkanolamine compound is 1 (1-5); more preferably, the weight ratio of the alcohol amine compound to the organic solvent is 1 (3-20). The relation of the use amount of each raw material is controlled in the range, so that the reaction process is more stable, the normal reaction is promoted, and the product conversion rate and the yield are higher.

In step S1, the alcohol amine compound, the reaction solvent, and the basic catalyst are directly mixed, and then the benzotriazole compound is added to react. Of course, in order to further reduce the generation of impurities in the reaction, in a preferred embodiment, after the mixing the alcohol amine compound, the basic catalyst and the organic solvent, the step S1 further comprises: and carrying out normal pressure or reduced pressure reflux dehydration treatment on the first mixed solution in an inert atmosphere. The impurity water is removed, so that the occurrence of side reactions can be further reduced, for example, the hydrolysis reaction of carboxylic ester caused by the impurity water can be effectively inhibited. The time for the reflux dehydration treatment is preferably 2 hours.

Preferably, in step S2, the benzotriazole compound is added to the first mixed solution in a batch manner. The batch adding mode is adopted, the reaction process is more stable, and the safety is higher. Meanwhile, batch addition is also beneficial to reducing the occurrence of side reactions.

In a preferred embodiment, in step S2, the amidation reaction process obtains a crude product, and the synthesis method further includes a step of post-treating the crude product to obtain a reactive benzotriazole-type ultraviolet absorber; the post-treatment step comprises: adjusting the pH value of the crude product to 5-6, and then washing the crude product to be neutral to obtain a primary treatment product; and (4) sequentially carrying out dewatering, cooling and crystallization on the primary treatment product to obtain the reactive benzotriazole ultraviolet absorbent. The pH regulation step is beneficial to ensuring the thermal stability of the product and preventing the product from yellowing under an alkaline condition. The water washing is to remove the added acid, alcohol amine compound and catalyst to improve the purity of the product.

Preferably, before the step of adjusting the pH of the crude product, the post-treatment step further comprises: washing the crude product with water to obtain a first neutral product, and then adjusting the pH of the first neutral product;

preferably, in the process of adjusting the pH value of the crude product, acetic acid, formic acid aqueous solution, p-toluenesulfonic acid or 1-5 wt% sulfuric acid aqueous solution is used as a pH adjusting agent. The pH is adjusted by adopting the acids, so that the aim of adjusting the pH can be fulfilled, new impurities can not be introduced, and a target product can be separated out and separated more easily in the subsequent cooling crystallization process.

For further purification of the product, in a preferred embodiment, the synthesis process further comprises, before the work-up step of the crude product: the organic solvent in the crude product was distilled off, followed by addition of toluene or xylene. Preferably, the weight ratio of the added toluene or xylene to the alcohol amine compound is (10-20): 1. Thus being beneficial to the follow-up cooling crystallization process to be carried out more efficiently and simultaneously leading the target product to be separated more fully.

In a preferred embodiment, after the water removal of the primary treatment product, the post-treatment step further comprises: and (4) decoloring the dewatered primary treatment product, and then cooling and crystallizing. The decolorization step facilitates the removal of transesterification and hydrolysis impurities from the crude product. Preferably, the decoloring agent adopted in the decoloring process is one or more of activated carbon, diatomite and clay; preferably, the usage amount of the decoloring agent is 0.5-2% of the weight of the benzotriazole compound.

In a preferred embodiment, the water removal step adopts an azeotropic water removal mode, after the decolorization step, the decolorizer is removed by hot filtration, and the filtrate is cooled to 10-15 ℃ and stirred for 1-2 h to carry out the cooling crystallization step. The filtrate is crystallized at the temperature, and the target product can be better separated from other impurities. The azeotropic water removal process may be carried out under normal pressure or under reduced pressure. Preferably, the precipitated crystals are obtained in the cooling crystallization step, and the precipitated crystals are filtered, washed and dried in sequence to obtain the reactive benzotriazole ultraviolet absorbent. In the actual operation process, the precipitated crystals are preferably washed by adopting a reaction solvent, and the drying condition is preferably air-blast drying for 6-12 h at 40-60 ℃.

In the present invention, the raw material a can be commercially available or prepared by a method known in the art, and the raw material B can be prepared by a method known in the art, for example, the following preparation method can be adopted:

diazotizing o-nitroaniline with sodium nitrite under acidic condition to obtain diazotized product, then coupling reacting with o-tert-butylphenol compound under alkaline condition, and further reducing the coupled product to obtain benzotriazole compound shown in structure B.

According to another aspect of the present invention, there is also provided a reactive benzotriazole-type ultraviolet absorber having the structure shown below:

wherein R is₁The radicals being-H, -Cl or-Br, R₂The radicals being-H, -CH₂CH₂OH or-CH₂CH(OH)CH₃，R₃The group being-CH₂CH₂OH or-CH₂CH(OH)CH₃And n is 0 or 1. The compound is a reactive ultraviolet absorbent which takes amide as a bridge chain and alcoholic hydroxyl as a reactive group, and has outstanding performance in the aspect of aging resistance.

Preferably, the reactive benzotriazole uv absorbers have a formula selected from the group consisting of:

the present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.

Example 1

1) 10.00g (0.095mol) of diethanolamine, 256mL of cyclohexane and 0.05g of KOH are added into a four-mouth bottle, and reflux dehydration is carried out for 2 h; cooling to 50 ℃, adding 13.25g of 2- [3 ' -tert-butyl-2 ' -hydroxy-5 ' - (2-methoxycarbonylethyl) phenyl ] benzotriazole, refluxing and stirring for 1h, and adding the rest 13.25g of benzotriazole; the reaction was stopped after stirring at reflux for 8 h.

2) After cyclohexane is evaporated, 116mL of toluene is added into the reaction system, and the temperature is raised to 45-50 ℃; dropwise adding glacial acetic acid until the pH value of the reaction solution is 5-6; washing with 30mL of water for 3 times, performing reduced pressure azeotropic dehydration, adding 0.13g of activated carbon into the reaction solution, stirring at 60 ℃ for 1h, filtering while hot, cooling the filtrate to room temperature while stirring, cooling with an ice water bath to 10-15 ℃, preserving heat at the temperature, stirring for 1h, filtering, washing the filter cake with cold toluene, and drying the filter cake to obtain a white solid product with the yield of 85.2% and the purity of 99.0%.

The nuclear magnetic spectrum of the white solid is shown in figure 1, and the testing process takes deuterated chloroform as a solvent and is 400 Hz.

Example 2

1) 10.00g (0.095mol) of diethanolamine, 153mL of petroleum ether and 0.20g of lithium acetate are charged into a four-necked flask, and 7.37g of 2- [3 ' -tert-butyl-2 ' -hydroxy-5 ' - (2-methoxycarbonylethyl) phenyl ] -5-chloro-benzotriazole are added; the reaction was stopped after stirring at reflux for 12 h.

2) After the reaction is finished, cooling to 40-45 ℃, and adjusting the pH of the reaction solution to 5-6 by using 1 wt% sulfuric acid aqueous solution; washing with 30mL of water for 3 times, performing azeotropic dehydration on the reaction solution, then adding 0.14g of diatomite into the reaction solution, refluxing and stirring for 2 hours, filtering while hot, cooling the filtrate to room temperature, cooling with an ice water bath to 10-15 ℃, preserving heat and stirring for 1 hour at the temperature, filtering, washing a filter cake with petroleum ether, and drying the filter cake to obtain a white solid product, wherein the yield is 88.7%, and the purity is 99.5%.

Example 3

1) 10.00g (0.164mol) ethanolamine, 35mL toluene and 0.50g LiOH were added to a four-necked flask, 43.94g 2- [3 ' -tert-butyl-2 ' -hydroxy-5 ' - (2-ethoxycarbonylethyl) phenyl ] -5-chloro-benzotriazole was added; the reaction was stopped after introducing nitrogen and stirring at 90 ℃ for 3 h.

2) Adding 197mL of toluene after the reaction is finished, cooling to 40-45 ℃, and then dropwise adding glacial acetic acid until the pH value of the reaction solution is 5-6; washing with 30mL of water for 3 times, performing azeotropic dehydration under reduced pressure, cooling to room temperature, cooling to 10-15 ℃ with an ice water bath, preserving heat at the temperature, stirring for 1h, filtering, washing a filter cake with toluene, and drying the filter cake to obtain a white solid product, wherein the yield is 89.2% and the purity is 99.3%.

Example 4

1) 10.00g (0.133mol) of isopropanolamine, 40mL of xylene and 0.10g of NaOH are added to a four-necked flask, and 25.82g of 2- [3 ' -tert-butyl-2 ' -hydroxy-5 ' - (2-methoxycarbonylethyl) phenyl ] -5-chloro-benzotriazole are added; the reaction was stopped after nitrogen was bubbled through and stirred at 60 ℃ for 10 h.

2) After the reaction is finished, adding 76mL of dimethylbenzene, cooling to 40-45 ℃, and adding a proper amount of p-toluenesulfonic acid until the pH of the reaction solution is 5-6; washing with 30mL of water for 3 times, performing reduced pressure azeotropic dehydration, adding 0.13g of argil into the reaction solution, performing reduced pressure azeotropic dehydration at 80 ℃, cooling to room temperature after dehydration is finished, cooling to 10-15 ℃ with an ice water bath, preserving heat and stirring at the temperature for 1h, filtering, washing a filter cake with cold dimethylbenzene, and drying the filter cake to obtain a white solid product, wherein the yield is 86.9% and the purity is 98.9%.

Example 5

1) 10.00g (0.075mol) of diisopropanolamine, 150mL of cyclohexane and 0.20g of sodium acetate are added into a four-neck bottle, and the mixture is refluxed and dehydrated for 2 hours; cooling to 50 ℃, adding 13.25g of 2- [3 ' -tert-butyl-2 ' -hydroxy-5 ' - (2-methoxycarbonylethyl) phenyl ] benzotriazole, refluxing and stirring for 1h, and adding the rest 13.25g of benzotriazole; the reaction was stopped after stirring at reflux for 8 h.

2) After cyclohexane is evaporated, 116mL of toluene is added into the reaction system, and the temperature is raised to 45-50 ℃; dropwise adding glacial acetic acid until the pH value of the reaction solution is 5-6; washing with 30mL of water for 3 times, performing azeotropic dehydration under reduced pressure, cooling to room temperature, cooling to 10-15 ℃ with an ice water bath, preserving heat at the temperature, stirring for 1h, filtering, washing a filter cake with cold toluene, and drying the filter cake to obtain a white solid product, wherein the yield is 85.2%, and the purity is 99.0%.

The nuclear magnetic spectrum of the white solid is shown in figure 2, and the testing process takes deuterated chloroform as a solvent and is 400 Hz.

Example 6

1) 10.00g (0.075mol) of diisopropanolamine, 150mL of n-heptane and 0.50g of potassium acetate were placed in a four-necked flask, 17.67g of 2- [3 ' -tert-butyl-2 ' -hydroxy-5 ' - (2-methoxycarbonyl) phenyl ] benzotriazole were added, and the reaction was stopped after stirring at 90 ℃ for 10 hours under nitrogen protection.

2) Cooling to 45-50 ℃, washing with 30mL of water for 3 times, then dropwise adding a 5 wt% sulfuric acid aqueous solution to adjust the pH to 5-6, then washing with 30mL of water until the water washing solution is neutral, reducing the pressure, performing azeotropic dehydration, then cooling to room temperature, cooling to 10-15 ℃ with an ice water bath, preserving the temperature, stirring for 1h, filtering, washing a filter cake with cold toluene, and drying the filter cake to obtain a white solid product, wherein the yield is 87.3% and the purity is 99.5%.

Example 7

1) 10.00g (0.075mol) of diisopropanolamine, 160mL of n-octane and 0.50g of potassium carbonate were put into a four-necked flask, 17.67g of 2- [3 ' -tert-butyl-2 ' -hydroxy-5 ' - (2-methoxycarbonyl) phenyl ] benzotriazole was added, and the mixture was stirred at 90 ℃ for 10 hours under nitrogen protection to stop the reaction.

2) Cooling to 45-50 ℃, washing with 30mL of water for 3 times, then dropwise adding glacial acetic acid to adjust the pH value to 5-6, then washing with 30mL of water until the water washing liquid is neutral, reducing the pressure for azeotropic dehydration, cooling to room temperature, cooling to 10-15 ℃ with an ice water bath, preserving the temperature, stirring for 1h at the temperature, filtering, washing a filter cake with cold toluene, and drying the filter cake to obtain a white solid product with the yield of 88.1% and the purity of 99.0%.

Example 8

1) 10.00g (0.075mol) of diisopropanolamine, 160mL of cyclohexane and 0.50g of sodium carbonate were placed in a four-necked flask, 19.39g of 2- [3 ' -tert-butyl-2 ' -hydroxy-5 ' - (2-methoxycarbonylethyl) phenyl ] -5-chloro-benzotriazole were added, and the reaction was stopped after stirring at 90 ℃ for 10 hours under nitrogen protection.

2) Cooling to 45-50 ℃, dropwise adding glacial acetic acid to adjust the pH value to 5-6, then washing with 30mL of water until the water washing liquid is neutral, carrying out azeotropic dehydration, cooling to room temperature, cooling to 10-15 ℃ with an ice water bath, preserving heat at the temperature, stirring for 1h, filtering, washing a filter cake with cold toluene, and drying the filter cake to obtain a white solid product with the yield of 89.7% and the purity of 99.2%.

Comparative example 1

According to the method reported in the patent US5459222A, 50.0g of 2- [3 ' -tert-butyl-2 ' -hydroxy-5 ' - (2-methoxycarbonylethyl) phenyl ] benzotriazole and 22.3g of diethanolamine are added into a 250mL four-neck flask, the temperature is raised to 130 ℃ under the protection of nitrogen, the temperature is kept at the temperature for reaction for 8 hours, the content of a product in a sampling analysis reaction liquid is 80.50%, the product contains a transesterification byproduct and a hydrolysis byproduct, and the content is more than 18%. Cooling to 65 ℃, gradually adding toluene into the reaction system, washing the reaction solution into a 1000mL four-neck bottle, wherein the adding amount of the toluene is 500mL totally, cooling to 45-50 ℃, dropwise adding glacial acetic acid until the pH value of the reaction solution is 5-6, washing with 30mL of water for 3 times, then performing reduced pressure azeotropic dehydration, then cooling to room temperature under stirring, cooling to 10-15 ℃ with an ice water bath, filtering, washing a filter cake with cold toluene, and drying the filter cake to obtain a white solid product, wherein the yield is 75.25%, and the purity is 94.10%.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.