2-(2apos; -hydroxy-5apos,-hydroxy-5apos; preparation method and application of-tert-octyl phenyl) benzotriazole

Abstract

The invention provides a preparation method and application of 2-(2 '-hydroxy-5'-tert-octylphenyl) benzotriazole, and relates to the technical field of ultraviolet absorbers.The preparation method comprises the following steps that S1, an acid solution of ortho-nitroaniline is obtained, a sodium nitrite solution is dropwise added in several times for a diazotization reaction, and a 2-nitrodiazobenzene salt solution is obtained; s2, the 2-nitrodiazobenzene salt solution and p-tert-octylphenol are subjected to a coupling reaction in an alkali solution, and an intermediate is obtained; s3, the intermediate is subjected to a reduction reaction, and 2-(2 '-hydroxy-5'-tert-octyl phenyl) benzotriazole is obtained. In the technical scheme provided by the invention, the feeding rate of the sodium nitrite solution is controlled in a manner of adding the sodium nitrite solution for several times, and excessive or insufficient nitrous acid generated by conversion of the sodium nitrite is prevented, so that the balance between the nitrous acid generation rate and the diazotization reaction consumption rate is maintained, and the yield and purity of the product are further improved.

Description

Technical Field

[0001] The invention relates to the technical field of ultraviolet absorbers, and in particular to a preparation method and application of 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole. Background Art

[0002] Benzotriazole UV absorber is a highly efficient light stabilizer. Since the 1970s, benzotriazole has been launched by Ciba-Geigy of Switzerland. Due to its oil resistance, discoloration resistance, low volatility, and good compatibility with polymers, it has been widely used in various synthetic materials and products, especially in automotive coatings, where it is the most commonly used and most effective UV absorber.

[0003] Ultraviolet absorber 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole (commonly known as UV-329) is an efficient anti-aging agent with excellent performance. The synthesis steps of UV-329 generally include diazotization reaction, coupling reaction and reduction reaction. The diazotization reaction is mainly a diazotization reaction of o-nitroaniline and nitrite in an acidic medium to generate a diazonium salt. In the prior art, the commonly used nitrite is sodium nitrite, but sodium nitrite will decompose and fail during the reaction, thereby affecting the reaction effect of diazotization and indirectly affecting the yield and purity of the target product UV-329. Summary of the invention

[0004] The main purpose of the present invention is to provide a preparation method and application of 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, aiming to solve the problem of instability of diazotization reaction and to improve the yield and purity of the target product.

[0005] To achieve the above object, the present invention provides a method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, comprising the following steps:

[0006] S1, obtaining an acid solution of o-nitroaniline, adding a sodium nitrite solution in portions to perform a diazotization reaction, and obtaining a 2-nitrodiazonium salt solution;

[0007] S2, coupling the 2-nitrobenzenediazonium salt solution obtained above with p-tert-octylphenol in an alkaline solution to obtain 2-nitro-2'-hydroxy-5'-tert-octylazobenzene;

[0008] S3, subjecting the above-obtained 2-nitro-2'-hydroxy-5'-tert-octylazobenzene to a reduction reaction to obtain 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole.

[0009] In one embodiment, the step of adding sodium nitrite solution in batches to perform diazotization reaction comprises:

[0010] S11, obtaining an acid solution of o-nitroaniline, and adding a sodium nitrite solution dropwise at a time;

[0011] S12, adding sodium nitrite solution dropwise for a second time, and continuing the reaction to obtain a 2-nitrobenzenediazonium salt solution;

[0012] Among them, the ratio of the amount of sodium nitrite solution added in step S11 to the amount of sodium nitrite solution added in step S12 is (6-7):(3-4), and the ratio of the dropping time of step S11 to the dropping time of step S12 is (0.9-1.1):1.

[0013] In one embodiment, in step S1:

[0014] The acid solution is a hydrochloric acid solution, the concentration of the hydrochloric acid solution is 12-14 wt%, preferably 14 wt%, and the molar ratio of o-nitroaniline, hydrochloric acid and sodium nitrite is 1:(2.25-4):(1.05-1.5); and / or,

[0015] The temperature of addition is -2°C to 5°C; and / or,

[0016] The total time of addition is 1.5h to 3h; and / or,

[0017] The reaction temperature is -2°C to 5°C; and / or,

[0018] The reaction time is 4h~6h.

[0019] In one embodiment, step S2 includes:

[0020] S21, adding 4-tert-octylphenol to the first solvent to obtain a 4-tert-octylphenol solution, and then adding the first alkaline solution and the 2-nitrodiazonium salt solution to obtain a reaction solution of 2-nitro-2'-hydroxy-5'-tert-octylazobenzene after coupling reaction:

[0021] S22, post-treating the reaction solution of the 2-nitro-2'-hydroxy-5'-tert-octylazobenzene to obtain an intermediate 2-nitro-2'-hydroxy-5'-tert-octylazobenzene.

[0022] In one embodiment, step S21 includes:

[0023] Simultaneously adding the first alkaline solution and the 2-nitrodiazonium salt solution to the p-tert-octylphenol solution;

[0024] Wherein, the first solvent comprises ethanol or n-heptane; or,

[0025] The first solvent includes ethanol, and the molar volume ratio of p-tert-octylphenol to ethanol is (1.125-1.5) mol / L;

[0026] The first alkaline solution includes at least one of sodium hydroxide, potassium hydroxide and potassium carbonate; or,

[0027] The first alkaline solution includes sodium hydroxide, and the molar ratio of p-tert-octylphenol, sodium hydroxide and o-nitroaniline is (0.9-1.2):(1-2.5):1.

[0028] In one embodiment, the step of reducing 2-nitro-2'-hydroxy-5'-tert-octylazobenzene to obtain 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole comprises:

[0029] S31, a primary reduction reaction: mixing 2-nitro-2'-hydroxy-5'-tert-octylazobenzene, a second solvent and a second alkaline solution, adding a first reducing agent, and reacting to obtain 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole nitrogen oxide;

[0030] S32, secondary reduction reaction: add a second reducing agent to the 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole nitrogen oxide, react, add an acidic solution dropwise, then add a crystallization solvent, separate the layers, wash once, crystallize, filter, wash twice, and dry to obtain 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole.

[0031] In one embodiment, in the primary reduction reaction, the first reducing agent is added in batches; and / or,

[0032] In the secondary reduction reaction, the second reducing agent is added in batches.

[0033] In one embodiment, in the primary reduction reaction, the reaction time is 2h to 2.5h; and / or,

[0034] In the primary reduction reaction, the reaction temperature is 55°C to 60°C; and / or,

[0035] In the primary reduction reaction, the reaction environment is a nitrogen atmosphere; and / or,

[0036] In the secondary reduction reaction, the reaction time is 3h to 3.5h; and / or,

[0037] In the secondary reduction reaction, the reaction temperature is 63°C to 65°C; and / or,

[0038] In the secondary reduction reaction, the crystallization temperature is -5°C to 5°C; and / or,

[0039] In the secondary reduction reaction, the crystallization time is 3h to 5h.

[0040] In one embodiment, the first reducing agent comprises glucose, and the molar ratio of glucose to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (0.8-1.2):1; and / or,

[0041] The solvent includes ethanol, and the mass ratio of ethanol to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene obtained in step S2 is (0.9-1.1):1; and / or,

[0042] The second reducing agent comprises zinc, and the molar ratio of zinc to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (1-1.2):1; and / or,

[0043] The second alkaline solution comprises sodium hydroxide and / or potassium hydroxide; or,

[0044] The second alkaline solution comprises sodium hydroxide, and the molar ratio of sodium hydroxide to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (4-5):1; and / or,

[0045] The acidic solution comprises hydrochloric acid, and the molar ratio of hydrochloric acid to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (9-11):1; and / or,

[0046] The crystallization solvent includes ethyl acetate or xylene; or,

[0047] The crystallization solvent includes ethyl acetate, and the mass ratio of ethyl acetate to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (2-3):1; and / or,

[0048] In the secondary reduction reaction, ethanol is used for the secondary washing, and the molar ratio of ethanol to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (4-6):1.

[0049] The present invention also provides an application of 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole in the preparation of 2,2'-methylenebis(4-tert-octyl-6-benzotriazolephenol) or 2-(2-2H-benzotriazole)-6-(1-methyl-1-phenyl)ethyl-4-(1,1,3,3-tetramethylbutyl)phenol, wherein the 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole includes the 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole prepared by the aforementioned preparation method.

[0050] In the technical scheme of the present invention, by adding sodium nitrite solution in batches to control its feeding rate, the molar concentration of o-nitroaniline is kept stable at a saturated state first, and then gradually reduced to promote the reaction to proceed in the forward direction, so as to ensure that the nitrous acid required for the diazotization reaction can be fully converted and generated, and to avoid excessive nitrous acid and decomposition failure, thereby maintaining the balance between the nitrous acid generation rate and the diazotization reaction consumption rate, so that nitrous acid and o-nitroaniline fully react, and then improve the yield and purity of the product. If the sodium nitrite in the reaction system is excessive, nitrous acid will be formed in large quantities, and decomposed rapidly, resulting in the inability of some raw materials to undergo diazotization reaction, and the product yield is reduced; if the sodium nitrite in the reaction system is too little, o-nitroaniline will react with the diazonium salt to generate by-products, resulting in a reduction in product purity. DETAILED DESCRIPTION

[0051] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0052] It should be noted that, in the embodiments, those without specifying specific conditions are carried out according to normal conditions or conditions recommended by the manufacturer. Those without specifying the manufacturer of reagents or instruments used are conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes, and "A and / or B" is taken as an example, including schemes A, B, or A and B that meet the same time. In addition, the technical schemes between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in the field to achieve. When the combination of the technical schemes is contradictory or cannot be achieved, it should be considered that the combination of such technical schemes does not exist, and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work, all belong to the scope of protection of the present invention.

[0053] Benzotriazole UV absorber is a highly efficient light stabilizer. Since the 1970s, benzotriazole has been launched by Ciba-Geigy of Switzerland. Due to its oil resistance, discoloration resistance, low volatility, and good compatibility with polymers, it has been widely used in various synthetic materials and products, especially in automotive coatings, where it is the most commonly used and most effective UV absorber.

[0054] The ultraviolet absorber 2-(2'-hydroxy-5'-tert-octylphenyl) benzotriazole (commonly known as UV-329) is an excellent and efficient anti-aging agent that can absorb ultraviolet light of 270-340 nanometers. It is non-flammable, non-explosive, and non-toxic. It is widely used in PE, PVC, PP, PS, PC, polypropylene fiber, ABS resin, epoxy resin, resin fiber, and ethylene vinyl acetate. It can be used in packaging materials such as plastic containers and food packaging boxes, providing them with excellent light stabilization effects, and almost does not absorb visible light. It is particularly suitable for colorless, transparent, and light-colored products. At the same time, UV-329 is also an important intermediate of UV absorbers UV-360 and UV-928. The preparation of high-purity and high-yield UV-329 products plays an important role in the synthesis of 2,2'-methylenebis(4-tert-octyl-6-benzotriazolephenol) (commonly known as UV-360) and 2-(2-2H-benzotriazole)-6-(1-methyl-1-phenyl)ethyl-4-(1,1,3,3-tetramethylbutyl)phenol (commonly known as UV-928). The synthesis steps of UV-329 usually include diazotization reaction, coupling reaction and reduction reaction. The diazotization reaction is mainly the diazotization reaction of o-nitroaniline and nitrite in an acidic medium to generate diazonium salt.

[0055] The diazotization of aromatic amines is a reaction between sodium nitrite and aromatic amines in an acidic environment. The specific reaction process is that sodium nitrite first generates nitrous acid in an acidic environment, and nitrous acid then reacts with aromatic amines to obtain diazonium salts. The reaction rate of diazotization depends on the solubility concentration of aromatic amines in an acidic environment and the reaction temperature. Nitrous acid generated by sodium nitrite is unstable in an acidic environment and easily decomposes. Therefore, the concentration of sodium nitrite solution and the feeding speed are of great significance to the effect of diazotization.

[0056] In the prior art, when the sodium nitrite is added too fast or the concentration is too high, the generation rate of nitrous acid exceeds the reaction rate of the diazotization reaction, thereby causing part of the sodium nitrite to decompose and fail, and cannot fully participate in the diazotization reaction; when the sodium nitrite is added too slow or the concentration is too low, o-nitroaniline will react with the diazonium salt obtained by the diazotization reaction to generate a by-product, thereby generating impurities, affecting the yield and purity of the final product.

[0057] In view of this, the present invention provides a method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, comprising the following steps:

[0058] S1, obtaining an acid solution of o-nitroaniline, adding a sodium nitrite solution in portions to perform a diazotization reaction, and obtaining a 2-nitrodiazonium salt solution;

[0059] S2, coupling the 2-nitrobenzenediazonium salt solution obtained above with p-tert-octylphenol in an alkaline solution to obtain 2-nitro-2'-hydroxy-5'-tert-octylazobenzene;

[0060] S3, subjecting the above-obtained 2-nitro-2'-hydroxy-5'-tert-octylazobenzene to a reduction reaction to obtain 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole.

[0061] In the technical scheme of the present invention, the feeding rate of the sodium nitrite solution is controlled by adding in batches to prevent the nitrous acid generated by the conversion of sodium nitrite from being excessive or insufficient, thereby maintaining a balance between the nitrous acid generation rate and the diazotization reaction consumption rate, so that the nitrous acid and o-nitroaniline react fully, thereby improving the yield and purity of the product; by adding in batches, different dropping speeds can be used in different dropping stages, thereby more finely adjusting the reaction process, reducing the decomposition reaction of nitrous acid, and further improving the yield and purity of the product.

[0062] It should be noted that the acid solution of o-nitroaniline in step S1 may be an organic acid solution of o-nitroaniline or an inorganic acid solution of o-nitroaniline, which is not limited herein.

[0063] In one embodiment, the step of adding sodium nitrite solution dropwise to carry out diazotization reaction comprises:

[0064] S11, obtaining an acid solution of o-nitroaniline, and adding a sodium nitrite solution dropwise at a time;

[0065] S12, adding sodium nitrite solution dropwise for a second time, and continuing the reaction to obtain a 2-nitrobenzenediazonium salt solution;

[0066] Among them, the ratio of the amount of sodium nitrite solution added in step S11 to the amount of sodium nitrite solution added in step S12 is (6-7):(3-4), and the ratio of the dropping time of step S11 to the dropping time of step S12 is (0.9-1.1):1.

[0067] In the technical scheme of the present invention, the dropping speed can be controlled by adjusting the dropping time, thereby controlling the reaction process; the decomposition of the diazonium salt generated by the reaction due to excessively high temperature can be avoided by adjusting the dropping temperature to -2°C to 5°C; the amount of sodium nitrite added in the first half of the dropping time is adjusted to be greater than the amount of sodium nitrite added in the second half of the dropping time, so that in the diazotization reaction occurring during the dropping process, the dropping speed of sodium nitrite in the first half of the reaction is slightly higher than that in the second half of the reaction, thereby further preventing the excess or insufficient nitrous acid generated by the conversion of sodium nitrite.

[0068] It should be noted that the dripping can be performed at a uniform speed or at a variable speed, first fast and then slow. The specific dripping method is not limited here. Specifically, in some embodiments of the present invention, a uniform dripping method is used.

[0069] In one embodiment, in step S1:

[0070] The acid solution is a hydrochloric acid solution, the concentration of the hydrochloric acid solution is 12-14 wt%, preferably 14 wt%, and the molar ratio of o-nitroaniline, hydrochloric acid and sodium nitrite is 1:(2.25-4):(1.05-1.5); and / or,

[0071] The temperature of addition is -2°C to 5°C; and / or,

[0072] The total time of addition is 1.5h to 3h; and / or,

[0073] The reaction temperature is -2°C to 5°C; and / or,

[0074] The reaction time is 4h~6h.

[0075] In the technical scheme of the present invention, by selecting a hydrochloric acid solution with a mass concentration of 12% to 14%, the dissolution of o-nitroaniline can be promoted, and at the same time, sodium nitrite can be acidified to produce nitrous acid for reaction; by adjusting the molar ratio of o-nitroaniline, hydrochloric acid and sodium nitrite, the amount of raw materials is adjusted in proportion, so that most of the raw materials can react completely, thereby improving the yield of the product; by adjusting the dropping temperature and / or the reaction temperature to around 0°C, the side reaction of the raw materials can be slowed down, the side reaction products can be reduced, thereby improving the purity of 2-nitro-2'-hydroxy-5'-tert-octyl azobenzene; by controlling the reaction time to 4 to 5 hours, the raw materials can have a sufficiently long reaction time after mixing to react completely, thereby further improving the yield of the product.

[0076] Preferably, the concentration of the sodium nitrite solution is 20-25wt%; the molar ratio of o-nitroaniline: hydrochloric acid: sodium nitrite is 1:2.5:1.1; more preferably, the mass concentration of the sodium nitrite solution is 20wt%; if the concentration is too high, the sodium nitrite generates nitrous acid too quickly during the addition process, and the nitrous acid concentration is too high, which is prone to decomposition reaction; if the concentration is too low, too much water is added, which affects the concentration of each reactant and causes a decrease in the reaction rate.

[0077] In one embodiment, step S2 includes:

[0078] S21, adding 4-tert-octylphenol to the first solvent to obtain a 4-tert-octylphenol solution, and then adding the first alkaline solution and the 2-nitrodiazonium salt solution to obtain a reaction solution of 2-nitro-2'-hydroxy-5'-tert-octylazobenzene after coupling reaction:

[0079] S22, post-treating the reaction solution of the 2-nitro-2'-hydroxy-5'-tert-octylazobenzene to obtain an intermediate 2-nitro-2'-hydroxy-5'-tert-octylazobenzene.

[0080] In the technical scheme of the present invention, the coupling reaction between tert-octylphenol and diazonium salt can be promoted by providing an alkaline environment, wherein sodium hydroxide solution and potassium hydroxide as strong bases can convert phenolic hydroxyl groups into phenolic oxygen anions, which is beneficial to the attack of weak electrophilic reagents, that is, the diazonium salt as a weak electrophilic reagent is promoted to undergo an electrophilic substitution reaction with tert-octylphenol, thereby ensuring that the coupling reaction proceeds normally; and by post-treating the reaction solution of the 2-nitro-2'-hydroxy-5'-tert-octylazobenzene, most of the reaction raw materials and side reaction products can be removed.

[0081] It should be noted that in step S22, the post-treatment step is used to wash away impurities in the reaction solution of 2-nitro-2'-hydroxy-5'-tert-octylazobenzene and dry it; in some embodiments of the present invention, the reaction solution of 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is a slurry, which needs to be dispersed at high speed while washing to remove most of the impurities and further improve the purity of the product; specifically, in some embodiments of the present invention, the post-treatment step includes suction filtration, pulping, rinsing, and drying. In the pulping step, an organic solvent is used to mix and pulp the precipitate obtained by filtration, and the organic solvent is used for rinsing after filtering again; wherein, the pulping temperature is 55°C to 65°C, the pulping time is 2h to 2.5h, and the organic solvent includes n-heptane.

[0082] In the technical solution of the present invention, by using organic solvent for pulping and eluting, and adjusting the pulping temperature to 55°C to 65°C and the pulping time to 2h to 2.5h, most of the unreacted raw materials and side reaction products can be dissolved and washed away, further improving the purity of the product.

[0083] In one embodiment, the steps of step S21 include:

[0084] Simultaneously adding the first alkaline solution and the 2-nitrodiazonium salt solution to the p-tert-octylphenol solution;

[0085] Wherein, the first solvent comprises ethanol or n-heptane; or,

[0086] The first solvent includes ethanol, and the molar volume ratio of p-tert-octylphenol to ethanol is (1.125-1.5) mol / L;

[0087] The first alkaline solution includes at least one of sodium hydroxide, potassium hydroxide and potassium carbonate; or,

[0088] The first alkaline solution includes sodium hydroxide, and the molar ratio of p-tert-octylphenol, sodium hydroxide and o-nitroaniline is (0.9-1.2):(1-2.5):1.

[0089] In the technical scheme of the present invention, when the sodium hydroxide solution is added in a dropwise manner, the sodium hydroxide solution and the 2-nitrodiazonium benzene salt solution can be co-dropped, thereby controlling the coupling reaction environment to be weakly alkaline, reducing the decomposition of the diazonium salt or the occurrence of other side reactions in a strong alkaline environment; when the sodium hydroxide solution is added in a direct mixing manner, most of the tert-octylphenol can be converted into sodium phenolate, thereby increasing the reaction rate; by controlling the molar ratio of tert-octylphenol, sodium hydroxide and o-nitroaniline, the amount of raw materials is adjusted in proportion, so that most of the raw materials can react completely, thereby increasing the yield of the product.

[0090] Preferably, in step S21, the first alkaline solution is a sodium hydroxide solution, the mass concentration of the sodium hydroxide solution is 30% to 35%, and the molar ratio of tert-octylphenol, sodium hydroxide and o-nitroaniline is 0.95:1.5:1; more preferably, the mass concentration of the sodium hydroxide solution is 30%.

[0091] In one embodiment, the step of reducing 2-nitro-2'-hydroxy-5'-tert-octylazobenzene to obtain 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole comprises:

[0092] S31, a primary reduction reaction: mixing 2-nitro-2'-hydroxy-5'-tert-octylazobenzene, a second solvent and a second alkaline solution, adding a first reducing agent, and reacting to obtain 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole nitrogen oxide;

[0093] S32, secondary reduction reaction: add a second reducing agent to the 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole nitrogen oxide, react, add an acidic solution dropwise, then add a crystallization solvent, separate the layers, wash once, crystallize, filter, wash twice, and dry to obtain 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole.

[0094] In the technical solution of the present invention, by adopting two reduction reactions, 2-nitro-2'-hydroxy-5'-tert-octylazobenzene can be gradually reduced to 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, thereby reducing the situation in which side reactions are caused by the excessive reducing property of the reducing agent when using a one-step reduction reaction; by adopting the second alkaline solution, an alkaline environment can be adjusted to provide the alkaline conditions required for a single reduction reaction.

[0095] It should be noted that the primary washing and the secondary washing are used to wash away impurities that are easily soluble in polar solvents, and the primary washing and the secondary washing can use the same washing liquid or different washing liquids, which is not limited here. Specifically, in some embodiments of the present invention, the primary washing uses water as the washing liquid, and the secondary washing uses ethanol as the washing liquid.

[0096] In one embodiment, in the primary reduction reaction, the first reducing agent is added in batches; and / or,

[0097] In the secondary reduction reaction, the second reducing agent is added in batches.

[0098] In the technical solution of the present invention, the first reducing agent and / or the second reducing agent are added in batches to ensure smooth reaction, prevent the reducing agent from being added all at once resulting in too fast a reaction rate, and reduce the situation in which the local temperature in the reaction system is too high and causes boiling.

[0099] It should be noted that the specific number of batches can be two or three, which is not limited here; specifically, in some embodiments of the present invention, the first reducing agent is added in two batches, half of the total amount of the first reducing agent is added before the reaction starts, and the remaining amount of the first reducing agent is added after the reaction is carried out for 0.5h to 1h.

[0100] In one embodiment, in the primary reduction reaction, the reaction time is 2h to 2.5h; and / or,

[0101] In the primary reduction reaction, the reaction temperature is 55°C to 60°C; and / or,

[0102] In the primary reduction reaction, the reaction environment is a nitrogen atmosphere; and / or,

[0103] In the secondary reduction reaction, the reaction time is 3h to 3.5h; and / or,

[0104] In the secondary reduction reaction, the reaction temperature is 63°C to 65°C; and / or,

[0105] In the secondary reduction reaction, the crystallization temperature is -5°C to 5°C; and / or,

[0106] In the secondary reduction reaction, the crystallization time is 3h to 5h.

[0107] In the technical scheme of the present invention, by controlling the time of the primary reduction reaction to be 2h-2.5h, the reaction time is extended to promote the complete reaction of the first reduction reaction and improve the yield and purity of the product; by adjusting the temperature of the primary reduction reaction to be 55°C-60°C, the reaction rate of the reduction reaction can be accelerated; by setting the primary reduction reaction environment to be a nitrogen atmosphere, the influence of the oxidizing atmosphere on the reduction reaction can be reduced, thereby reducing the amount of reducing agent added to improve the yield of the product; by controlling the time of the secondary reduction reaction to be 3h-3.5h, the reaction time is extended to promote the complete reaction of the second reduction reaction and improve the yield and purity of the product; by adjusting the temperature of the secondary reduction reaction to be 63°C-65°C, the reaction speed of the second reduction reaction is accelerated; by adjusting the crystallization temperature in the secondary reduction reaction to -5°C-5°C, the solubility of the product can be reduced and the precipitation amount of the product can be increased; by adjusting the crystallization time in the secondary reduction reaction to be 3h-5h, the crystallization time is extended so that the 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole can be precipitated as much as possible, thereby improving the yield of the product.

[0108] In one embodiment, the first reducing agent comprises glucose, and the molar ratio of glucose to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (0.8-1.2):1; and / or,

[0109] The second solvent comprises ethanol, and the mass ratio of ethanol to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene obtained in step S2 is (0.9-1.1):1; and / or,

[0110] The second reducing agent comprises zinc, and the molar ratio of zinc to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (1-1.2):1; and / or,

[0111] The second alkaline solution comprises sodium hydroxide and / or potassium hydroxide; or,

[0112] The second alkaline solution comprises sodium hydroxide, and the molar ratio of sodium hydroxide to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (4-5):1; and / or,

[0113] The acidic solution comprises hydrochloric acid, and the molar ratio of hydrochloric acid to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (9-11):1; and / or,

[0114] The crystallization solvent includes ethyl acetate or xylene; or,

[0115] The crystallization solvent includes ethyl acetate, and the mass ratio of ethyl acetate to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (2-3):1; and / or,

[0116] In the secondary reduction reaction, ethanol is used for the secondary washing, and the molar ratio of ethanol to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (4-6):1.

[0117] In the technical solution of the present invention, by setting the molar ratio of the sodium hydroxide solution, the glucose and the 2-nitro-2'-hydroxy-5'-tert-octylazobenzene, the amount of the raw materials is adjusted in proportion so that most of the raw materials can react completely, thereby improving the yield of the product; by using ethyl acetate as the crystallization solvent, it is beneficial to separate the water layer and has an excellent impurity removal effect, thereby further improving the yield and purity of the product.

[0118] Preferably, in step S31, the second alkaline solution is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 20-25wt%; the second solvent includes ethanol, and the molar ratio of the sodium hydroxide solution, the glucose, the ethanol and the 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is 4.6:1:1:1; more preferably, the concentration of the sodium hydroxide solution is 20wt%.

[0119] Preferably, in step S32, the acidic solution includes hydrochloric acid, and the concentration of the hydrochloric acid solution is 20-25wt%; the second reducing agent includes zinc, and the molar ratio of zinc, hydrochloric acid and 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is 1.1:10.1:1; the crystallization solvent includes ethyl acetate, and the mass ratio of ethyl acetate to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is 4:1; more preferably, the concentration of the hydrochloric acid solution is 20wt%.

[0120] The present invention also provides an application of 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole in the preparation of 2,2'-methylenebis(4-tert-octyl-6-benzotriazolephenol) or 2-(2-2H-benzotriazole)-6-(1-methyl-1-phenyl)ethyl-4-(1,1,3,3-tetramethylbutyl)phenol, wherein the 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole includes the 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole prepared by the aforementioned preparation method.

[0121] In the technical solution of the present invention, UV-329 is an important intermediate of ultraviolet absorbers UV-360 and UV-928. High-purity and high-yield UV-329 is applied to the synthesis of UV-360 or UV-928, which can simplify the process flow and improve the purity and yield of the prepared UV-360 or UV-928.

[0122] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0123] Example 1

[0124] This embodiment provides a method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and the specific steps are as follows:

[0125] S1. Diazotization reaction: 65.34 g of 14 wt% hydrochloric acid solution (0.25 mol) and 13.81 g of o-nitroaniline (0.1 mol) were mixed and dissolved, cooled to about 0 ° C, and 37.95 g of 20% sodium nitrite (0.11 mol) was added dropwise. During the addition, the internal temperature was kept below 5 ° C. The addition was completed in about 2 hours (about 25.3 g was added in the first 1 hour, and about 12.65 g was added in the last 1 hour). After the addition was completed, the reaction was continued to stir at 0 ° C for 4 hours, and the reaction solution was filtered for standby use;

[0126] S2. Coupling reaction: 19.60 g of p-tert-octylphenol (0.095 mol) was mixed with 62.85 g of ethanol (about 80 ml), 6.00 g of sodium hydroxide (0.15 mol) and 14.00 g of water (or a sodium hydroxide solution with a concentration of 30 wt%), cooled to 0°C, and the filtered reaction solution (diazonium salt) was added dropwise to the reaction system. The internal temperature was ensured to be below 5°C during the addition process. After the addition was completed, the mixture was kept at 0°C for 3 h, filtered, and the filter cake was slurried with 50 g of n-heptane at 60°C for 2 h, cooled to about 0°C, filtered, and the filter cake was rinsed with 20 g of n-heptane and dried to obtain 31.04 g of 2-nitro-2'-hydroxy-5'-tert-octyl azobenzene (referred to as intermediate) (0.087 mol), with a yield of 91.93% and a purity of 99.25%;

[0127] S31. A reduction reaction: 31.04 g of ethanol, 80.00 g of a 20% sodium hydroxide solution (0.4 mol) and the intermediate obtained above were put into a three-necked flask, replaced with nitrogen three times, heated to 55 ° C, and an equal amount of glucose was added twice at an interval of 0.5 h for 2 h. The total amount of glucose added twice was 15.74 g (about 0.087 mol) (with a molar ratio of 1:1 to the intermediate);

[0128] S32. Secondary reduction reaction: heat to 65°C, add equal amount of zinc powder twice with an interval of 0.5h and react for 3h (internal temperature is 63°C), the total amount of zinc powder added twice is 6.28g (0.096mol) (the molar ratio with the intermediate is 1.1:1), slowly add 160g of 20% hydrochloric acid solution (about 0.87mol), stir for 0.5h and then add 62.08g of ethyl acetate, stir again for 0.5h, let stand to separate the water layer, wash the organic phase twice with 60.00g of water, then stir and crystallize at 0°C for 4h, filter, rinse the filter cake with 20.00g of anhydrous ethanol, dry at 60°C to obtain 26.48g of finished product.

[0129] Finally, the purity of the finished product UV-329 was 99.63%, the reduction reaction yield was 94.10%, and the total synthesis yield was 86.18%.

[0130] Example 2

[0131] This embodiment provides a method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and the specific steps are as follows:

[0132] S1. Diazotization reaction: 68.61 g of 12 wt% hydrochloric acid solution (0.225 mol) and 13.81 g of o-nitroaniline (0.1 mol) were mixed and dissolved, cooled to about 0 ° C, and 28.98 g of 25% sodium nitrite (0.105 mol) was added dropwise. During the addition, the internal temperature was kept below 5 ° C. The addition was completed in about 3 hours (about 19.32 g was added dropwise in the first 1.45 hours, and about 9.66 g was added dropwise in the last 1.55 hours). After the addition was completed, the reaction was continued to stir at 0 ° C for 5 hours, and the reaction solution was filtered for standby use;

[0133] S2. Coupling reaction: 18.57 g of p-tert-octylphenol (0.09 mol) was mixed with 62.85 g of ethanol (about 80 ml), 4.00 g of sodium hydroxide (0.1 mol) and 8.50 g of water (or a sodium hydroxide solution with a concentration of 32 wt%), cooled to 0°C, and the filtered reaction solution (diazonium salt) was added dropwise to the reaction system. The internal temperature was kept below 5°C during the addition process. After the addition was completed, the mixture was kept at 0°C for 3 h, filtered, and the filter cake was slurried with 50 g of n-heptane at 60°C for 2 h, cooled to about 0°C, filtered, and the filter cake was rinsed with 20 g of n-heptane and dried to obtain 29.15 g of 2-nitro-2'-hydroxy-5'-tert-octyl azobenzene (referred to as intermediate) (0.082 mol), with a yield of 91.1300% and a purity of 99.31%;

[0134] S31. A reduction reaction: 29.15 g of ethanol, 52.48 g of a 25% sodium hydroxide solution (0.328 mol) and the intermediate obtained above were put into a three-necked flask, replaced with nitrogen three times, heated to 55 ° C, and an equal amount of glucose was added twice at an interval of 0.5 h for 2 h. The total amount of glucose added twice was 11.81 g (about 0.0656 mol) (with a molar ratio of 0.8: 1 to the intermediate);

[0135] S32. Secondary reduction reaction: heat to 65°C, add equal amount of zinc powder twice with an interval of 0.5h and react for 3h (internal temperature is 63°C), the total amount of zinc powder added twice is 5.36g (0.082mol) (the molar ratio with the intermediate is 1:1), slowly add 134.9g of 20% hydrochloric acid solution (about 0.74mol), stir for 0.5h and then add 116.6g of ethyl acetate, stir again for 0.5h, let stand to separate the water layer, wash the organic phase twice with 60.00g of water, then stir and crystallize at 0°C for 4h, filter, rinse the filter cake with 20.00g of anhydrous ethanol, dry at 60°C to obtain 24.82g of finished product.

[0136] Finally, the purity of the finished product UV-329 was 99.76%, the reduction reaction yield was 93.59%, and the total synthesis yield was 85.27%.

[0137] Example 3

[0138] This embodiment provides a method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and the specific steps are as follows:

[0139] S1. Diazotization reaction: 104.54 g of 14 wt% hydrochloric acid solution (0.4 mol) and 13.81 g of o-nitroaniline (0.1 mol) were mixed and dissolved, cooled to about 0 ° C, and 51.74 g of 20% sodium nitrite (0.15 mol) was added dropwise. During the addition, the internal temperature was kept below 5 ° C. The addition was completed in about 1.5 h (about 31.04 g was added dropwise in the first 0.75 h, and about 20.70 g was added dropwise in the last 0.75 h). After the addition was completed, the reaction was continued to stir at 0 ° C for 6 h, and the reaction solution was filtered for standby use;

[0140] S2. Coupling reaction: 24.76 g of p-tert-octylphenol (0.12 mol) was mixed with 62.85 g of ethanol (about 80 ml), 10.00 g of sodium hydroxide (0.25 mol) and 18.57 g of water (or a sodium hydroxide solution with a concentration of 35 wt%), cooled to 0°C, and the filtered reaction solution (diazonium salt) was added dropwise to the reaction system. The internal temperature was kept below 5°C during the addition process. After the addition was completed, the mixture was kept at 0°C for 3 h, filtered, and the filter cake was slurried with 50 g of n-heptane at 60°C for 2 h, cooled to about 0°C, filtered, and the filter cake was rinsed with 20 g of n-heptane and dried to obtain 31.28 g of 2-nitro-2'-hydroxy-5'-tert-octyl azobenzene (referred to as intermediate) (0.088 mol), with a yield of 88.00% and a purity of 99.13%;

[0141] S31. Primary reduction reaction: 31.28 g of ethanol, 88.00 g of 20% sodium hydroxide solution (0.44 mol) and the intermediate obtained above were put into a three-necked flask, replaced with nitrogen three times, heated to 55 ° C, and an equal amount of glucose was added three times at intervals of 0.5 h for 2 h. The total amount of glucose added three times was 18.90 g (about 0.105 mol) (with a molar ratio of 1:1.2 to the intermediate);

[0142] S32. Secondary reduction reaction: heat to 65°C, add equal amount of zinc powder three times at intervals of 0.5h and react for 3h (internal temperature is 63°C), the total amount of zinc powder added three times is 6.9g (0.106mol) (molar ratio with intermediate is 1.2:1), slowly add dropwise 141.17g of 25% hydrochloric acid solution (about 0.97mol), stir for 0.5h and then add 125.12g of ethyl acetate, stir again for 0.5h, let stand to separate the water layer, wash the organic phase with 60.00g of water twice, then stir and crystallize at 0°C for 4h, filter, rinse the filter cake with 20.00g of anhydrous ethanol, dry at 60°C to obtain 26.15g of finished product.

[0143] Finally, the purity of the finished product UV-329 was 99.51%, the reduction reaction yield was 91.88%, and the total synthesis yield was 80.85%.

[0144] Example 4

[0145] This embodiment provides a method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and the steps are similar to those of Example 1, except that the coupling reaction in step S2 of this embodiment includes:

[0146] 19.60 g of p-tert-octylphenol (0.095 mol) and 62.85 g of ethanol (about 80 ml) were mixed to obtain a p-tert-octylphenol solution, 6.00 g of sodium hydroxide (0.15 mol) and 14.00 g of water were mixed to obtain a 30 wt % sodium hydroxide solution, the temperature was lowered to 0° C., the reaction solution (diazonium salt) filtered in step S1 and the 30 wt % sodium hydroxide solution were respectively and simultaneously added dropwise to the p-tert-octylphenol solution, To ensure that the reaction system is weakly alkaline, the internal temperature is kept below 5°C during the dropwise addition process, and the mixture is kept at 0°C for 3h after addition. The filter cake is slurried with 50g of n-heptane at 60°C for 2h, cooled to about 0°C, and filtered. The filter cake is rinsed with 20g of n-heptane and dried to obtain 31.28g (referred to as intermediate) (0.088mol) of 2-nitro-2'-hydroxy-5'-tert-octyl azobenzene, with a yield of 92.64% and a purity of 99.29%.

[0147] Finally, 26.67 g of UV-329 product was obtained with a purity of 99.65%, a reduction reaction yield of 93.7%, and a total synthesis yield of 86.80%.

[0148] Example 5

[0149] This embodiment provides a method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and its steps are similar to those of Example 1, except that 124.16 g of xylene is used instead of ethyl acetate in step S32 of this embodiment.

[0150] Finally, 24.8 g of the finished product was obtained with a purity of 91.83%, a reduction reaction yield of 88.14%, and a total synthesis yield of 81.05%.

[0151] Example 6

[0152] This embodiment provides a method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and its steps are similar to those of Example 1, except that the amount of sodium hydroxide used in step S31 of this embodiment is: 138g of 20% sodium hydroxide solution (about 0.69mol).

[0153] Finally, 25.8 g of the finished product was obtained with a purity of 92.1%, a reduction reaction yield of 91.69%, and a total synthesis yield of 83.97%.

[0154] Comparative Example 1

[0155] This comparative example proposes a method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and its steps are similar to those of Example 1, except that the diazotization reaction in step S1 of this comparative example comprises:

[0156] Mix and dissolve 65.34 g of 14 wt% hydrochloric acid solution (0.25 mol) and 13.81 g of o-nitroaniline (0.1 mol), cool to about 0°C, add 37.95 g of 20% sodium nitrite solution (0.11 mol) at once, continue stirring at 0°C for 6 h, and filter the reaction solution for later use.

[0157] In step S2 of this comparative example, 26.3 g (0.074 mol) of the intermediate was obtained with a yield of 77.89% and a purity of 98.96%.

[0158] Finally, 22.14 g of the finished product was obtained with a purity of 99.60%, a reduction reaction yield of 92.50%, and a total synthesis yield of 72.05%.

[0159] Comparative Example 2

[0160] This comparative example proposes a method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and its steps are similar to those of Example 1, except that the diazotization reaction in step S1 of this comparative example comprises:

[0161] Mix and dissolve 65.34 g of 14 wt% hydrochloric acid solution (0.25 mol) and 13.81 g of o-nitroaniline (0.1 mol), cool to about 0°C, and then add 37.95 g of 20% sodium nitrite solution (0.11 mol) dropwise at a uniform rate for 1 hour. After the addition is completed, stir at 0°C for 6 hours. Filter the reaction solution for later use.

[0162] In step S2 of this comparative example, 26.9 g (0.076 mol) of the intermediate was obtained with a yield of 79.66% and a purity of 98.43%.

[0163] Finally, 22.76 g of the finished product was obtained with a purity of 99.56%, a reduction reaction yield of 92.1%, and a total synthesis yield of 73.68%.

[0164] Comparative Example 3

[0165] This comparative example proposes a method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and its steps are similar to those of Example 1, except that the diazotization reaction in step S1 of this comparative example comprises:

[0166] Mix and dissolve 65.34 g of 14 wt% hydrochloric acid solution (0.25 mol) and 13.81 g of o-nitroaniline (0.1 mol), cool to about 0°C, and then add 37.95 g of 20% sodium nitrite solution (0.11 mol) dropwise at a uniform rate for 4 hours. After the addition is completed, continue stirring at 0°C for 6 hours. Filter the reaction solution for later use.

[0167] In step S2 of this comparative example, 28.1 g (0.079 mol) of the intermediate was obtained with a yield of 83.16% and a purity of 98.75%.

[0168] Finally, 23.97 g of the finished product was obtained with a purity of 99.61%, a reduction reaction yield of 93.67%, and a total synthesis yield of 77.89%.

[0169] Comparative Example 4

[0170] This comparative example proposes a method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and its steps are similar to those of Example 1, except that the diazotization reaction in step S1 of this comparative example comprises:

[0171] 65.34 g of 14 wt% hydrochloric acid solution (0.25 mol) and 13.81 g of o-nitroaniline (0.1 mol) were mixed and dissolved, and the temperature was lowered to about 0°C. 7.59 g of sodium nitrite and 30.36 g of water were added at once, and stirring was continued at 0°C for 6 h. The reaction solution was filtered and set aside.

[0172] In step S2 of this comparative example, 25.9 g (0.073 mol) of the intermediate was obtained with a yield of 76.70% and a purity of 98.12%.

[0173] Finally, 21.99 g of the finished product was obtained with a purity of 99.56%, a reduction reaction yield of 93.14%, and a total synthesis yield of 71.57%.

[0174] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, characterized in that: The following steps are involved: S1, obtaining an acid solution of o-nitroaniline, adding a sodium nitrite solution in portions to perform a diazotization reaction, and obtaining a 2-nitrodiazonium salt solution; S2, coupling the 2-nitrobenzenediazonium salt solution obtained above with p-tert-octylphenol in an alkaline solution to obtain 2-nitro-2'-hydroxy-5'-tert-octylazobenzene; S3, subjecting the above-obtained 2-nitro-2'-hydroxy-5'-tert-octylazobenzene to a reduction reaction to obtain 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole.

2. The method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole according to claim 1, characterized in that: Step S1 includes: S11, obtaining an acid solution of o-nitroaniline, and adding a sodium nitrite solution dropwise at a time; S12, adding sodium nitrite solution dropwise for a second time, and continuing the reaction to obtain a 2-nitrobenzenediazonium salt solution; Among them, the ratio of the amount of sodium nitrite solution added in step S11 to the amount of sodium nitrite solution added in step S12 is (6-7):(3-4), and the ratio of the dropping time of step S11 to the dropping time of step S12 is (0.9-1.1):

1.

3. The method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole according to claim 1, characterized in that: In step S1: The acid solution is a hydrochloric acid solution, the concentration of the hydrochloric acid solution is 12-14 wt%, preferably 14 wt%, and the molar ratio of o-nitroaniline, hydrochloric acid and sodium nitrite is 1:(2.25-4):(1.05-1.5); and / or, The temperature of addition is -2°C to 5°C; and / or, The total time of addition is 1.5h to 3h; and / or, The reaction temperature is -2°C to 5°C; and / or, The reaction time is 4h~6h.

4. The method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole according to claim 1, characterized in that: Step S2 includes: S21, adding 4-tert-octylphenol to the first solvent to obtain a 4-tert-octylphenol solution, and then adding the first alkaline solution and the 2-nitrodiazonium salt solution to obtain a reaction solution of 2-nitro-2'-hydroxy-5'-tert-octylazobenzene after coupling reaction: S22, post-treating the reaction solution of the 2-nitro-2'-hydroxy-5'-tert-octylazobenzene to obtain an intermediate 2-nitro-2'-hydroxy-5'-tert-octylazobenzene.

5. The method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole according to claim 4, characterized in that: Step S21 includes: Simultaneously adding the first alkaline solution and the 2-nitrodiazonium salt solution to the p-tert-octylphenol solution; Wherein, the first solvent comprises ethanol or n-heptane; or, The first solvent includes ethanol, and the molar volume ratio of p-tert-octylphenol to ethanol is (1.125-1.5) mol / L; The first alkaline solution includes at least one of sodium hydroxide, potassium hydroxide and potassium carbonate; or, The first alkaline solution includes sodium hydroxide, and the molar ratio of p-tert-octylphenol, sodium hydroxide and o-nitroaniline is (0.9-1.2):(1-2.5):

1.

6. The method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole according to claim 1, characterized in that: The step of reducing 2-nitro-2'-hydroxy-5'-tert-octylazobenzene to obtain 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole comprises: S31, a primary reduction reaction: mixing 2-nitro-2'-hydroxy-5'-tert-octylazobenzene, a second solvent and a second alkaline solution, adding a first reducing agent, and reacting to obtain 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole nitrogen oxide; S32, secondary reduction reaction: add a second reducing agent to the 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole nitrogen oxide, react, add an acidic solution dropwise, then add a crystallization solvent, separate the layers, wash once, crystallize, filter, wash twice, and dry to obtain 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole.

7. The method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole according to claim 6, characterized in that: In the primary reduction reaction, the first reducing agent is added in batches; and / or, In the secondary reduction reaction, the second reducing agent is added in batches.

8. The method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole according to claim 6, characterized in that: In the primary reduction reaction, the reaction time is 2h to 2.5h; and / or, In the primary reduction reaction, the reaction temperature is 55°C to 60°C; and / or, In the primary reduction reaction, the reaction environment is a nitrogen atmosphere; and / or, In the secondary reduction reaction, the reaction time is 3h to 3.5h; and / or, In the secondary reduction reaction, the reaction temperature is 63°C to 65°C; and / or, In the secondary reduction reaction, the crystallization temperature is -5°C to 5°C; and / or, In the secondary reduction reaction, the crystallization time is 3h to 5h.

9. The method for preparing 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole according to claim 6, characterized in that: The first reducing agent comprises glucose, and the molar ratio of glucose to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (0.8-1.2):1; and / or, The second solvent comprises ethanol, and the mass ratio of ethanol to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene obtained in step S2 is (0.9-1.1):1; and / or, The second reducing agent comprises zinc, and the molar ratio of zinc to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (1-1.2):1; and / or, The second alkaline solution comprises sodium hydroxide and / or potassium hydroxide; or, The second alkaline solution comprises sodium hydroxide, and the molar ratio of sodium hydroxide to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (4-5):1; and / or, The acidic solution comprises hydrochloric acid, and the molar ratio of hydrochloric acid to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (9-11):1; and / or, The crystallization solvent includes ethyl acetate or xylene; or, The crystallization solvent includes ethyl acetate, and the mass ratio of ethyl acetate to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (2-3):1; and / or, In the secondary reduction reaction, ethanol is used for the secondary washing, and the molar ratio of ethanol to 2-nitro-2'-hydroxy-5'-tert-octylazobenzene is (4-6):

1.

10. Use of 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole in the preparation of 2,2'-methylenebis(4-tert-octyl-6-benzotriazolephenol) or 2-(2-2H-benzotriazole)-6-(1-methyl-1-phenyl)ethyl-4-(1,1,3,3-tetramethylbutyl)phenol, characterized in that: The 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole includes the 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole prepared by the aforementioned preparation method.