阅读说明：本技术 苯并三氮唑紫外线吸收剂的制备方法 (Preparation method of benzotriazole ultraviolet absorbent ) 是由 张军华 张赣 汤国霞 郑红朝 叶强 熊昌武 孙春光 李海平 于 2020-12-15 设计创作，主要内容包括：本发明涉及一种苯并三氮唑紫外吸收剂的制备方法,在氧化镁负载金属催化剂作用下,式I所述偶氮中间体与供氢体发生转移加氢反应制得式III所述目标产物；本发明的方法催化剂用量小,原料转化率可达到100％,目标产品选择性在90％以上。(The invention relates to a preparation method of benzotriazole ultraviolet absorbent, under the action of magnesium oxide supported metal catalyst, azo intermediate and hydrogen donor in formula I are subjected to transfer hydrogenation reaction to prepare target product in formula III; the method of the invention has small catalyst consumption, 100 percent of raw material conversion rate and over 90 percent of target product selectivity.)

1. A preparation method of benzotriazole ultraviolet absorbent is characterized in that under the action of magnesium oxide supported metal catalyst, azo intermediate and hydrogen donor in formula I are subjected to transfer hydrogenation reaction to prepare target product in formula III;

the reaction formula is as follows:

in the formulae I and III, R₁Is H, Cl, C_1-4Alkyl or C_1-4One of alkoxy groups of (a);

R₂is H, C_1-12Alkyl or C_1-4One of the phenylalkyl groups of the alkyl group;

R₃is H, Cl, C_1-12Alkyl radical, C_1-12Alkoxy, phenyl, C_1-8Alkylphenyl or C_1-4One of alkoxyphenyl groups;

the magnesium oxide supported metal catalyst is magnesium oxide supported Pd or Pt.

2. The process according to claim 1, wherein R in formula I and formula III₁When it is H or Cl, R₂、R₃Each independently selected from one of H, methyl, tertiary butyl, amyl, tertiary amyl, tert-octyl, tertiary octyl and cumyl;

preferably, the loading amount of the magnesium oxide supported metal catalyst is 0.5 to 5%.

3. The preparation method according to claim 1 or 2, wherein the mass ratio of the magnesium oxide supported metal catalyst to the azo intermediate of formula I is (0.5-5): 100; preferably, the mass ratio of the azo intermediate to the hydrogen donor in the formula I is 1 (0.5-5).

4. The process according to any one of claims 1 to 3, wherein the reaction temperature is from 30 ℃ to 120 ℃, preferably from 50 ℃ to 80 ℃.

5. The process according to any one of claims 1 to 4, wherein the hydrogen donor is at least one selected from the group consisting of saturated monoalcohols, diols, triols, formic acid and its salts, and ammonia boranes.

6. The production method according to any one of claims 1 to 5, wherein the magnesium oxide-supported metal catalyst is produced by:

(1) taking a magnesium salt precursor and ammonia water as raw materials, taking sodium dodecyl sulfate as an auxiliary agent, carrying out a hydrothermal reaction to prepare magnesium hydroxide, drying and roasting to prepare a magnesium oxide carrier;

(2) dissolving a Pd or Pt precursor in an organic solvent, then adding the magnesium oxide carrier obtained in the step 1), and reducing in a hydrogen atmosphere to obtain the magnesium oxide-loaded metal catalyst.

7. The preparation method according to claim 6, wherein the magnesium salt precursor is a water-soluble magnesium salt, and the molar ratio of the magnesium salt precursor to ammonia water is 1:2-1: 8; preferably, the mass ratio of the magnesium salt precursor to the sodium dodecyl sulfate is 30: 1-10: 1.

8. the method as claimed in claim 6, wherein the reaction temperature of the hydrothermal reaction is 100-150 ℃; and/or the drying temperature is 60-110 ℃, and/or the roasting temperature is 300-600 ℃.

9. The method of claim 6, wherein the Pd or Pt precursor is a salt of Pd or Pt.

10. The magnesium oxide supported metal catalyst is characterized in that the catalyst is magnesium oxide supported Pd or Pt; preferably, the catalyst is prepared by the method of claim 7.

Technical Field

The invention relates to the field of chemical synthesis, in particular to application of a benzotriazole ultraviolet absorbent synthesized by catalytic transfer hydrogenation.

Background

The light stabilizer is an assistant which can prevent the polymer material from photo-oxidative aging and greatly prolong the service life of the polymer material. At present, light stabilizers are indispensable additives in various plastic products, fibers, rubber products, coatings, paints and adhesives. The conventional light stabilizers can be roughly classified into four groups in terms of their mechanism of action, i.e., ultraviolet light absorbers, quenchers, radical scavengers, and light-screening agents. Ultraviolet light absorbers are the main type of light stabilizers, and are a class of materials that are capable of strongly and selectively absorbing high-energy ultraviolet light and converting the energy to release or dissipate it as thermal energy or harmless low radiation. The compound type of the compound is wide, and the compound mainly comprises salicylic acids, benzophenones, benzotriazoles, hindered amines, triazines, cyanoacrylates, nickel chelates and the like.

Benzotriazole ultraviolet absorbers have the advantages of light color, low toxicity, difficult volatilization, high absorption efficiency, good oil resistance, good compatibility with polymers and the like, and are widely applied to various polymer materials and products thereof. Representative examples of benzotriazole ultraviolet light absorbers include UV-P, UV-326, UV-327, UV-328, UV-329, etc., and the general structural formula thereof is shown below.

Structural general formula of benzotriazole ultraviolet light absorber

R₁Is H, Cl, C_1-4Alkyl or C_1-4One of alkoxy groups of (a); r₂Is H, C_1-12Alkyl or C_1-4One of the phenylalkyl groups of the alkyl group; r₃Is H, Cl, C_1-12Alkyl radical, C_1-12Alkoxy, phenyl, C_1-8Alkylphenyl or C_1-4One of alkoxyphenyl groups.

Benzotriazole ultraviolet light absorbers can adopt two synthetic routes.

The first route is that 2, 4-dialkyl-6-aminophenol is coupled with aniline after diazotization to generate an intermediate azo dye, 2- (2 ' -hydroxy-3 ', 5 ' -dialkyl phenyl) -5-amino-1, 2, 3-benzotriazole is obtained through oxidation cyclization, and amino is converted into chlorine or hydrogen, wherein the reaction general formula is as follows:

route one

The second route is that arylamine is coupled with alkylphenol after diazotization reaction to generate intermediate azo dye, and then the intermediate azo dye is reduced and cyclized to obtain the product, wherein the reaction general formula is shown as follows.

Route two

The two routes have respective advantages and disadvantages: the raw materials of the first route are not easy to obtain, and the operation is complex; the raw materials of the second route are easy to obtain, the operation is simple and convenient, but the yield is lower.

In the second route, the reaction process from the azo intermediate to the final product benzotriazole ultraviolet absorbent is complex, but the key step of the synthesis is. The difficulty is that the azo bond is easy to break to generate amine byproducts during the reduction of the azo intermediate, and the key of the reduction reaction is how to create conditions and avoid side reactions to the greatest extent, so that the yield and the quality of the product are improved. In the prior art, although the technology for synthesizing the benzotriazole ultraviolet light absorbers by a chemical reduction method (such as a hydrazine hydrate reduction method and a sulfide-zinc powder reduction method) is mature and the process is simple, the defects of large discharge amount of waste water and waste residue, low atom economic efficiency, expensive reducing agent, high toxicity and the like exist mostly.

The catalytic hydrogenation reduction method is a green process and has the advantages of less discharge of three wastes, high atom economy, good product quality and the like. The hydrogen is used for replacing zinc powder, glucose, hydrazine hydrate and sulfide as a reduction medium, the defects of a chemical reduction method are hopeful to be eliminated, the waste water generation amount can be reduced by more than 80%, and the method is a green technology for synthesizing the benzotriazole ultraviolet absorbent. The catalytic hydrogenation reduction method for synthesizing the benzotriazole ultraviolet absorbent is as follows: firstly, reducing the raw material azo intermediate (I) into a hydrazine compound under the action of a hydrogenation catalyst and hydrogen, performing intramolecular dehydration cyclization reaction to generate an intermediate product nitrogen oxide (II), and further hydrogenating the nitrogen oxide to finally generate a benzotriazole product (III).

Reaction path for synthesizing benzotriazole ultraviolet absorbent by catalytic hydrogenation reduction method

In recent years, research reports on the catalytic hydrogenation synthesis of benzotriazole ultraviolet absorbers include: wangli et al (orthogonal experiment optimizes the synthesis process [ J ] of UV-327. synthetic chemistry, 2007, (5): 658-. Patent EP0380840A1 reports that in a toluene-isopropanol-water-NaOH system, Raney nickel is used as a catalyst to catalyze and hydrogenate to synthesize UV-328 with the yield of 82%. However, when raney nickel is used as a hydrogenation catalyst, the selectivity and yield of the benzotriazole product are not high; and the Raney nickel has inflammability and has potential safety hazard in the use process. The synthesis of benzotriazole products using carbon-supported noble metals as hydrogenation catalysts has also been reported, for example: CIBA GEIGY (patent US5276161) adopts 5% Pt/C as catalyst to catalyze and hydrogenate to synthesize UV-P, and the yield is 92%; in the patent US5104992, 5 percent Pd/C is used as a catalyst for hydrogenation synthesis of UV-320, and the yield is 87.3 percent; patent EP0794179A1 synthesizes UV-328 by taking 4% Pd/C + 1% Pt/C as a catalyst, and the product yield can be improved by adding hypophosphorous acid or sulfuric acid into a reduction system, but a large amount of liquid acid (the molar ratio of acid/raw material is 3.0) needs to be added into a reaction system, so that more waste acid is generated to pollute the environment, and the added liquid acid is easy to remain in the product to influence the product quality. Compared with a Raney nickel catalyst, the carbon-supported noble metal catalyst has better safety.

In a word, the catalytic hydrogenation reduction method has small wastewater discharge amount and high atom economy, and hydrogen serving as a reducing agent cannot pollute the environment, but the existing catalytic hydrogenation research work has the main problems that: 1. the yield is low; the reason for this is that the hydrogenation synthesis of benzotriazole compound is a very complicated process, accompanied by many side reactions, and the product has low yield and low purity, and needs to add additional inorganic/organic base assistant. 2. Hydrogenation usually involves high pressure process, and hydrogen is flammable and explosive gas, and the safety risk is higher. The industrialization of the catalytic hydrogenation technology is restricted.

Catalytic transfer hydrogenation as a novel reduction process with H₂The fundamental differences in catalytic hydrogenation as a source of hydrogen are: it uses a hydrogen-containing polyatomic molecule as the source of hydrogen (called a hydrogen donor or hydrogen donor, such as formic acid and its salts, hydrazine, hydrocarbons, alcohols, etc.). In the reaction, hydrogen is transferred from the hydrogen donor to the reaction substrate (hydrogen acceptor). Because hydrogen is not directly used in the reaction, the reaction is mostly carried out under normal pressure, and the reaction temperature is lower, the danger of the reaction is reduced, and the requirement on equipment is not high. In addition, the diversity of hydrogen sources in the catalytic transfer hydrogenation reaction provides a new way for improving the selectivity of the reaction. Therefore, the catalytic transfer hydrogenation method becomes a synthesis method with great application prospect in both laboratories and industrial production.

Although the catalytic transfer hydrogenation reduction reaction has the above advantages, the transfer hydrogenation reduction method disclosed in the prior art has the following defects and shortcomings: (1) the catalyst is used in a large amount, which is usually 3-6% of the weight of azobenzene, and thus the industrialization of the azobenzene is hindered; (2) the product yield is generally not higher than 90%, and compared with other reduction modes, the method has no advantage; (3) and (5) the environmental pollution problem.

In view of the above, a new method for preparing benzotriazole ultraviolet absorber by transfer hydrogenation is developed to fully utilize the advantages and overcome the defects and shortcomings of the benzotriazole ultraviolet absorber.

Disclosure of Invention

In order to overcome the defect of preparing the benzotriazole ultraviolet absorbent by a transfer hydrogenation reduction method in the prior art, the invention provides a green and efficient preparation method of the benzotriazole ultraviolet absorbent.

The invention provides a preparation method of benzotriazole ultraviolet absorbent, under the action of magnesium oxide supported metal catalyst, azo intermediate and hydrogen donor of formula I are subjected to transfer hydrogenation reaction to prepare target product of formula III;

the reaction formula is as follows:

in the formulae I and III, R₁Is H, Cl, C_1-4Alkyl or C_1-4One of alkoxy groups of (a);

R₂is H, C_1-12Alkyl or C_1-4One of the phenylalkyl groups of the alkyl group;

R₃is H, Cl, C_1-12Alkyl radical, C_1-12Alkoxy, phenyl, C_1-8Alkylphenyl or C_1-4One of alkoxyphenyl groups.

The magnesium oxide supported metal catalyst is magnesium oxide supported Pd or Pt.

Preferably, in formula I and formula III, R₁When it is H or Cl, R₂、R₃Each independently selected from one of H, methyl, tertiary butyl, amyl, tertiary amyl, tert-octyl, tertiary octyl and cumyl.

Preferably, the loading amount of the magnesium oxide supported metal catalyst is 0.5 to 5%.

In the invention, the mass ratio of the magnesium oxide supported metal catalyst to the azo intermediate shown in the formula I is (0.5-5): 100. Preferably, the mass ratio of the azo intermediate to the hydrogen donor in the formula I is 1 (0.5-5).

In the present invention, the reaction temperature is 30 to 120 ℃ and preferably 50 to 80 ℃.

In the present invention, the hydrogen donor is at least one of monohydric alcohol, dihydric alcohol, trihydric alcohol, formic acid and its salt, and ammonia borane.

The invention also provides a magnesium oxide supported metal catalyst and a preparation method thereof, wherein the catalyst is magnesium oxide supported Pd or Pt.

Preferably, the magnesium oxide supported metal catalyst is prepared by the following method:

(1) taking a magnesium salt precursor and ammonia water as raw materials, taking sodium dodecyl sulfate as an auxiliary agent, carrying out a hydrothermal reaction to prepare magnesium hydroxide, drying and roasting to prepare a magnesium oxide carrier;

(2) dissolving a Pd or Pt precursor in an organic solvent, then adding the magnesium oxide carrier obtained in the step 1), and reducing in a hydrogen atmosphere to obtain the magnesium oxide-loaded metal catalyst.

The magnesium salt precursor is a water-soluble magnesium salt, and the molar ratio of the magnesium salt precursor to ammonia water is 1:2-1: 8; preferably, the mass ratio of the magnesium salt precursor to the sodium dodecyl sulfate is 30: 1-10: 1.

The reaction temperature of the hydrothermal method is 100-150 ℃; and/or the drying temperature is 60-110 ℃, and/or the roasting temperature is 300-600 ℃.

The Pd or Pt precursor is Pd or Pt salt;

the invention achieves the following positive effects: the reaction method has simple process and is green and environment-friendly. The catalyst consumption is small, the conversion rate of the raw materials can reach 100%, and the selectivity of the target product is over 90%. The waste water discharge is reduced by more than 80 percent, and the solid waste discharge is reduced by 99 percent.

Detailed Description

The present invention will be described in detail with reference to the following embodiments, but it should be understood that the scope of the present invention is not limited by these embodiments and the principle of the present invention, but is defined by the claims.

In the present invention, anything or matters not mentioned is directly applicable to those known in the art without any change except those explicitly described. Moreover, any embodiment described herein may be freely combined with one or more other embodiments described herein, and the technical solutions or ideas thus formed are considered part of the original disclosure or original description of the present invention, and should not be considered as new matters not disclosed or contemplated herein, unless a person skilled in the art would consider such combination to be clearly unreasonable.

All features disclosed in this invention may be combined in any combination and such combinations are understood to be disclosed or described herein unless a person skilled in the art would consider such combinations to be clearly unreasonable.

The numerical points disclosed in the present specification include not only the numerical points specifically disclosed in the examples but also the endpoints of each numerical range in the specification, and ranges in which any combination of the numerical points is disclosed or recited should be considered as ranges of the present invention.

Technical and scientific terms used herein are to be defined only in accordance with their definitions, and are to be understood as having ordinary meanings in the art without any definitions.

In order to solve the problems of high-pressure reaction, large catalyst dosage, high product yield and the like in a catalytic transfer hydrogenation route in the preparation process of the benzotriazole ultraviolet absorbent, the invention provides a preparation method of the benzotriazole ultraviolet absorbent.

The reaction formula is as follows:

in the formulae I and III, R₁Is H, Cl, C_1-4Alkyl or C_1-4One of alkoxy groups of (a);

R₂is H, C_1-12Alkyl or C_1-4One of the phenylalkyl groups of the alkyl group;

R₃is H, Cl, C_1-12Alkyl radical, C_1-12Alkoxy, phenyl, C_1-8Alkylphenyl or C_1-4One of alkoxyphenyl groups;

the magnesium oxide supported metal catalyst is magnesium oxide supported Pd or Pt.

The catalytic hydrogenation process for synthesizing the benzotriazole ultraviolet absorbent has the following side reactions: diamine bonds in HAB (namely hydroxy azobenzene derivatives) after the reduction of azo bonds are broken to form arylamine byproducts (1); excessive hydrogenation of intramolecular benzene rings to form tetrahydro side products (3, 4); if the nitrogen oxide can not be rapidly hydrogenated to obtain the target product, the ring opening is possible to generate the arylamine by-product (2) again.

Side reaction path for synthesizing benzotriazole ultraviolet absorbent by catalytic hydrogenation

In particular, hydrazine intermediates have a small N-N bond energy (167KJ/mol) and are very unstable in a hydrogen atmosphere. At present, only by adding an alkaline assistant (NaOH solution, piperidine, diethylamine and the like) into a reaction system, the main reaction of generating nitrogen oxide by intramolecular dehydration and cyclization is promoted, so that the occurrence of parallel competitive side reaction is inhibited, and the generation of arylamine by-products is reduced. The inhibition of the generation of arylamine byproducts in a reaction system without adding liquid alkali has been a problem recognized in the industry, and no relevant research report is found so far. However, the addition of the alkaline assistant also causes problems such as difficulty in separation and purification of the product and generation of alkaline waste liquid. Moreover, the post-treatment is difficult and the taste is unpleasant when an organic base is added to the reaction system, and the addition of an inorganic base causes partial deactivation and non-regeneration of the catalyst.

Researches show that in the transfer hydrogenation reaction of benzotriazole ultraviolet absorbent, the magnesium oxide supported metal catalyst provided by the invention is adopted, the catalyst takes magnesium oxide as a carrier, Pd and Pt metals as active components, the magnesium oxide has alkalinity while being taken as the carrier, an alkali active center is provided, the magnesium oxide supported metal catalyst has both a transfer hydrogenation active center and an alkali active center, a hydrogen transfer-alkali catalysis dual-catalytic active center is provided by utilizing the synergistic action of the carrier and the active components, an alkali active site on the surface of the catalyst is used for replacing an alkali auxiliary agent additionally added into a reaction system, the aim of synthesizing the benzotriazole ultraviolet absorbent in a high selectivity manner under an alkali-free system is realized, and the dual-functional catalytic synergistic system ensures that the alkali-free system meets the requirement of high selectivity. The alkali-free system realizes the simplification of the process and the emission reduction of three wastes, is an important breakthrough of the key problem in the synthesis process of the benzotriazole ultraviolet absorbent, can effectively reduce the generation of the byproducts, and efficiently and selectively synthesizes the benzotriazole ultraviolet absorbent.

In the present invention, said C_1-12The alkyl group means a linear or branched alkyl group having 1 to 12 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a tert-butyl group, an isobutyl group, a pentyl group, a tert-octyl group and isomers thereof; c_1-4The alkyl refers to a straight chain or branched chain alkyl with 1-4 carbon atoms; c_1-12The alkoxy group of (A) means a straight-chain or branched alkyl-O-group having 1 to 12 carbon atoms, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, pentyloxy, tert-octyloxy; containing C_1-4Alkoxy means a straight or branched alkyl-O-group having 1 to 4 carbon atoms.

C_1-8The alkylphenyl group is a phenyl group having a side chain to which an alkyl group having 1 to 8 carbon atoms is bonded, and examples thereof include tolyl group, ethylphenyl group, propylphenyl group, tert-butylphenyl group, cumyl group and octylphenyl group. C_1-4The alkoxyphenyl group is an alkyl-O-phenyl group having 1 to 4 carbon atoms bonded to the side chain, and examples thereof include a methoxyphenyl group, an ethoxyphenyl group, a propoxyphenyl group, an isopropoxyphenyl group, a butoxyphenyl group and an isobutoxyphenyl group.

As a preferred embodiment, in the formulae I and III, R₁When it is H or Cl, R₂、R₃Each independently selected from one of H, methyl, tertiary butyl, amyl, tertiary amyl, tert-octyl, tertiary octyl and cumyl.

According to the invention, the loading amount of the magnesium oxide supported metal catalyst is 0.5-5%. The catalyst loading calculation method comprises the following steps of: the mass of the carrier; the preferable control of the load amount within the range of 1-3 percent not only saves the cost, but also can ensure that the conversion rate of the raw materials reaches 100 percent.

In order to obtain higher reaction efficiency, the mass ratio of the magnesium oxide supported metal catalyst to the azo intermediate of the formula I is (0.5-5):100, such as 1:100, 2:10, 3:100, 4: 100.

As a preferred embodiment, the transfer hydrogenation reaction is performed in the presence of a solvent, and the solvent is selected from one or more of toluene, xylene, chlorobenzene, ethyl acetate and tetrahydrofuran. Preferably, the mass-to-volume ratio (g/ml) of the azo intermediate of formula I to the solvent is, for example, 1:5 to 1:20, preferably 1:10 to 1: 15.

The hydrogen donor can be selected from conventional hydrogen donors in the field, such as monohydric alcohol, dihydric alcohol, trihydric alcohol, formic acid and its salt, ammonia borane, etc., and the monohydric alcohol, the dihydric alcohol, the trihydric alcohol, the polyhydric alcohol, preferably C_1-10Monohydric alcohol, dihydric alcohol and trihydric alcohol. Examples of the monohydric alcohol include n-butanol, isobutanol, n-propanol, and isopropanol, and examples of the dihydric alcohol include ethylene glycol and propylene glycol; such as glycerol. The formic acid and its salts are selected, for example, from formic acid, sodium formate. Research shows that when the hydrogen donor is ammonia borane, the hydrogen donor is matched with a magnesium oxide supported metal catalyst for use, and compared with other common hydrogen donors such as isopropanol, formate and the like, the in-situ hydrogen donor has strong in-situ hydrogen supplying capability and high transfer hydrogenation efficiency. In the transfer hydrogenation reaction, the mass ratio of the azo intermediate and the hydrogen donor in the formula I is 1 (0.5-5), preferably 1:1-1: 2.

In the transfer hydrogenation reaction, incomplete reaction or long reaction time can be caused by too low temperature, and by-products in products can be generated by too high temperature, so that the selectivity and yield of the products are influenced. The reaction temperature is controlled to be 30-120 ℃, preferably 50-80 ℃, so that the reaction is fully carried out, and the selectivity and the yield of the product are improved. In the reaction system of the present invention, in the transfer hydrogenation reaction, the reaction time is 1 to 10 hours, preferably 2 to 5 hours.

The preparation method also comprises a post-treatment step, and the pure product of the target product in the formula III is obtained by washing and drying deionized water and methanol.

In the method, the magnesium oxide supported metal catalyst can be recycled, and experiments prove that after 10 times of recycling, the conversion rate of the raw material is 100 percent, and the selectivity of the product is more than 95 percent. Preferably, the catalyst is washed with water and methanol after recovery.

The reaction solvent can be recycled, and the solvent evaporated under reduced pressure after the reaction can be directly recycled.

The invention also provides a magnesium oxide supported metal catalyst and a preparation method thereof, wherein the catalyst is magnesium oxide supported Pd or Pt.

Preferably, the preparation method comprises the following steps:

(1) taking a magnesium salt precursor and ammonia water as raw materials, taking sodium dodecyl sulfate as an auxiliary agent, carrying out a hydrothermal reaction to prepare magnesium hydroxide, drying, and roasting to prepare a magnesium oxide carrier;

(2) dissolving a Pd or Pt precursor in an organic solvent, then adding the magnesium oxide carrier obtained in the step 1), and reducing in a hydrogen atmosphere to obtain the magnesium oxide-loaded metal catalyst.

The magnesium oxide loaded metal catalyst prepared by the method has higher specific surface area, can ensure the double catalytic activity of hydrogen transfer-alkali catalysis, ensures the high dispersion degree of active metal by the magnesium oxide carrier with high specific surface area, and improves the activity of the catalyst.

In the method for preparing the catalyst:

step 1) the magnesium salt precursor is a water-soluble magnesium salt, such as: magnesium chloride, magnesium nitrate and magnesium sulfate, wherein in a specific embodiment, the magnesium salt precursor is Mg (NO)₃)₂·6H₂O。

The magnesium salt precursor participates in the reaction in the form of aqueous solution, and is specifically prepared by dissolving the magnesium salt precursor in deionized water, wherein the dosage of the deionized water is 10-30 times, preferably 25 times of the mass of the magnesium salt precursor.

In the invention, in order to ensure that the magnesium salt precursor is successfully converted into the porous magnesium hydroxide, the molar ratio of the magnesium salt precursor to the ammonia water is 1:2-1:8, preferably 1: 5; the concentration of the ammonia water is not particularly limited, and the ammonia water is the concentration commonly used in the field, and in a specific embodiment, the mass percentage concentration of the ammonia water is 25-28%. And (2) adding an auxiliary agent sodium dodecyl sulfate in the reaction, wherein the mass ratio of the magnesium salt precursor to the sodium dodecyl sulfate is 30: 1-10: 1, preferably 25: 1.

the reaction temperature of the hydrothermal method is 100-150 ℃, and in specific embodiments, the reaction temperature can be 110 ℃, 120 ℃, 130 ℃ and 140 ℃.

In order to ensure the drying efficiency, the drying temperature is 60-110 ℃, and in a specific embodiment, the drying temperature can be 70 ℃, 80 ℃, 90 ℃ and 100 ℃; preferably, the drying time is 12-48h, such as 20h, 24 h. Preferably, the product is isolated after the reaction is complete, washed with water 1-10 times and dried.

In order to obtain the magnesia carrier with high specific surface area, the roasting temperature is 300-600 ℃, preferably 400 ℃ or 500 ℃; in a specific embodiment, the heating rate in the roasting process is 2 ℃/min; heating to a predetermined temperature and then roasting for 10-50 h.

The specific surface area of the magnesium oxide carrier prepared by the method is 300-400m²In one embodiment, the specific surface area is 350m²/g。

Step 2), the Pd or Pt precursor is Pd or Pt salt, preferably, the Pd or Pt precursor is at least one of palladium acetate, tetraaminopalladium acetate and tetraaminoplatinum acetate;

the organic solvent is toluene or acetone or a mixed solvent thereof; when the organic solvent is a mixed solvent of toluene and acetone, the mass/volume ratio of the Pd or Pt precursor to the toluene and acetone is 1: (20-100): (20-100), preferably 1: (50-60): (50-60).

The reduction reaction temperature is 200-400 ℃, preferably 250-300 ℃; preferably, the rate of temperature rise of the reduction reaction is 5 ℃/min.

In the preparation process of the magnesium oxide supported metal catalyst, the magnesium oxide supported metal catalyst is fully stirred before reaction, and the stirring speed is 200rpm-1500rpm, preferably 500rpm-1000 rpm.

The invention is illustrated by taking the preparation of UV-P, UV-326, UV-327 and UV-328 as examples, and the structural formulas of the azo intermediate (I) of the formula (III) are respectively shown as follows:

example 1

1.1 magnesium oxide Supported Metal catalysts

10.26g of Mg (NO)₃)₂·6H₂Dissolving O in 250mL of deionized water, adding 31.2 mL of 25 wt% ammonia water and 0.4g of Sodium Dodecyl Sulfate (SDS), stirring at 1000rpm for 5-10min, placing in a hydrothermal kettle, heating to 120 ℃ for reaction for 12h, centrifuging after the reaction is finished, washing with deionized water for 5 times, drying at 90 ℃ for 24h, and roasting at 400 ℃ for 12 h.

0.21g of Pd (O)₂CCH₃)₂Dissolving in 10mL of toluene and 10mL of acetone, adding 10g of the MgO carrier prepared in the previous step into the precursor solution, stirring at 500rpm for 4-8h, and reducing at 250 ℃ for 4h in a hydrogen atmosphere to obtain the magnesium oxide supported metal catalyst (1% Pd/MgO) with the load of 1 wt% Pd.

1.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 2

2.1 magnesium oxide Supported Metal catalysts

10.26g of Mg (NO)₃)₂·6H₂Dissolving O in 250mL of deionized water, adding 31.2 mL of 25 wt% ammonia water and 0.4g of Sodium Dodecyl Sulfate (SDS), stirring at 1000rpm for 5-10min, placing in a hydrothermal kettle, heating to 120 ℃ for reaction for 12h, performing centrifugal separation after the reaction is finished, andwashing with deionized water for 5 times, drying at 90 deg.C for 24 hr, and calcining at 400 deg.C for 12 hr.

0.42g of Pd (O)₂CCH₃)₂Dissolving the mixture in 10mL of toluene and 10mL of acetone, adding 10g of the MgO carrier prepared in the step (1) into the precursor solution, stirring at 500rpm for 4-8h, and reducing at 250 ℃ for 4h in a hydrogen atmosphere to obtain the magnesium oxide supported metal catalyst (2% Pd/MgO) with the load of 2 wt% Pd.

2.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 2% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 3

3.1 magnesium oxide Supported Metal catalysts

10.26g of Mg (NO)₃)2·6H₂Dissolving O in 250mL of deionized water, adding 31.2 mL of 25 wt% ammonia water and 0.4g of Sodium Dodecyl Sulfate (SDS), stirring at 1000rpm for 5-10min, placing in a hydrothermal kettle, heating to 120 ℃ for reaction for 12h, centrifuging after the reaction is finished, washing with deionized water for 5 times, drying at 90 ℃ for 24h, and roasting at 400 ℃ for 12 h.

0.63g of Pd (O)₂CCH₃)₂Dissolving the mixture in 10mL of toluene and 10mL of acetone, adding 10g of the MgO carrier prepared in the step (1) into the precursor solution, stirring at 500rpm for 4-8h, and reducing at 250 ℃ for 4h in a hydrogen atmosphere to obtain the magnesium oxide supported metal catalyst (3% Pd/MgO) with the load of 3 wt% Pd.

3.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 3% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 4

4.1 magnesium oxide Supported Metal catalysts

10.26g of Mg (NO)₃)₂·6H₂Dissolving O in 250mL of deionized water, adding 31.2 mL of 25 wt% ammonia water and 0.4g of Sodium Dodecyl Sulfate (SDS), stirring at 1000rpm for 5-10min, placing in a hydrothermal kettle, heating to 120 ℃ for reaction for 12h, centrifuging after the reaction is finished, washing with deionized water for 5 times, drying at 90 ℃ for 24h, and roasting at 400 ℃ for 12 h.

0.105g of Pd (O)₂CCH₃)₂Dissolving the mixture in 10mL of toluene and 10mL of acetone, adding 10g of the MgO carrier prepared in the step (1) into the precursor solution, stirring at 500rpm for 4-8h, and reducing at 250 ℃ for 4h in a hydrogen atmosphere to obtain the magnesium oxide supported metal catalyst (0.5% Pd/MgO) with the load of 0.5 wt% Pd.

4.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 0.5% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 10g of ammonia borane were charged, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 5

5.1 magnesium oxide Supported Metal catalysts

10.26g of Mg (NO)₃)₂·6H₂Dissolving O in 250mL of deionized water, adding 31.2 mL of 25 wt% ammonia water and 0.4g of Sodium Dodecyl Sulfate (SDS), stirring at 1000rpm for 5-10min, placing in a hydrothermal kettle, heating to 120 ℃ for reaction for 12h, centrifuging after the reaction is finished, washing with deionized water for 5 times, drying at 90 ℃ for 24h, and roasting at 400 ℃ for 12 h.

0.2g of Pt (NH) was taken₃)₄(CH₃COO)₂Dissolved in 10mL of tolueneAnd+ 10mL of acetone, adding 10g of the MgO carrier prepared in the step (1) into the precursor solution, stirring at 500rpm for 4-8h, and reducing at 250 ℃ for 4h in a hydrogen atmosphere to obtain the magnesium oxide supported metal catalyst (1% Pt/MgO) with the Pt loading of 1 wt%.

5.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 1% Pt/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 6

6.1 magnesium oxide Supported Metal catalysts

10.26g of Mg (NO)₃)₂·6H₂Dissolving O in 250mL of deionized water, adding 49.92 mL of 25 wt% ammonia water and 0.4g of Sodium Dodecyl Sulfate (SDS), stirring at 1000rpm for 5-10min, placing in a hydrothermal kettle, heating to 120 ℃ for reaction for 12h, centrifuging after the reaction is finished, washing with deionized water for 5 times, drying at 90 ℃ for 24h, and roasting at 400 ℃ for 12 h.

0.21g of Pd (O)₂CCH₃)₂Dissolving in 10mL of toluene and 10mL of acetone, adding 10g of the MgO carrier prepared in the previous step into the precursor solution, stirring at 500rpm for 4-8h, and reducing at 250 ℃ for 4h in a hydrogen atmosphere to obtain the magnesium oxide supported metal catalyst (1% Pd/MgO) with the load of 1 wt% Pd.

6.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 7

7.1 magnesium oxide Supported Metal catalysts

10.26g of Mg (NO)₃)₂·6H₂Dissolving O in 250mL of deionized water, adding 31.2 mL of 25 wt% ammonia water and 0.342g of Sodium Dodecyl Sulfate (SDS), stirring at 1000rpm for 5-10min, placing in a hydrothermal kettle, heating to 120 ℃ for reaction for 12h, centrifuging after the reaction is finished, washing with deionized water for 5 times, drying at 90 ℃ for 24h, and roasting at 400 ℃ for 12 h.

0.21g of Pd (O)₂CCH₃)₂Dissolving in 10mL of toluene and 10mL of acetone, adding 10g of the MgO carrier prepared in the previous step into the precursor solution, stirring at 500rpm for 4-8h, and reducing at 250 ℃ for 4h in a hydrogen atmosphere to obtain the magnesium oxide supported metal catalyst (1% Pd/MgO) with the load of 1 wt% Pd.

7.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 8

8.1 magnesium oxide Supported Metal catalysts

10.26g of Mg (NO)₃)₂·6H₂Dissolving O in 250mL of deionized water, adding 31.2 mL of 25 wt% ammonia water and 0.4g of Sodium Dodecyl Sulfate (SDS), stirring at 1000rpm for 5-10min, placing in a hydrothermal kettle, heating to 120 ℃ for reaction for 12h, centrifuging after the reaction is finished, washing with deionized water for 5 times, drying at 90 ℃ for 24h, and roasting at 400 ℃ for 12 h.

0.21g of Pd (O)₂CCH₃)₂Dissolving the mixture in 10mL of toluene and 10mL of acetone, adding 10g of MgO carrier prepared in the step (1) into the precursor solution, stirring at 500rpm for 4-8h, and reducing at 250 ℃ for 4h in hydrogen atmosphere to obtain the magnesium oxide load with 1 wt% Pd loadMetal catalyst (1% Pd/MgO).

8.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 20g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 9

9.1 magnesium oxide Supported Metal catalysts

10.26g of Mg (NO)₃)₂·6H₂Dissolving O in 250mL of deionized water, adding 31.2 mL of 25 wt% ammonia water and 0.4g of Sodium Dodecyl Sulfate (SDS), stirring at 1000rpm for 5-10min, placing in a hydrothermal kettle, heating to 120 ℃ for reaction for 12h, centrifuging after the reaction is finished, washing with deionized water for 5 times, drying at 90 ℃ for 24h, and roasting at 400 ℃ for 12 h.

0.21g of Pd (O)₂CCH₃)₂Dissolving the mixture in 10mL of toluene and 10mL of acetone, adding 10g of the MgO carrier prepared in the step (1) into the precursor solution, stirring at 500rpm for 4-8h, and reducing at 250 ℃ for 4h in a hydrogen atmosphere to obtain the magnesium oxide supported metal catalyst (1% Pd/MgO) with the load of 1 wt% Pd.

9.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 5g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 10

10.1 high specific surface area magnesium oxide-supported Metal catalysts

10.26g of Mg (NO)₃)₂·6H₂O dissolves in 2Adding 31.2 mL of 25 wt% ammonia water and 0.4g of Sodium Dodecyl Sulfate (SDS) into 50mL of ionized water, stirring at 1000rpm for 5-10min, placing into a hydrothermal kettle, heating to 120 ℃ for reaction for 12h, centrifuging after the reaction is finished, washing with deionized water for 5 times, drying at 90 ℃ for 24h, and roasting at 400 ℃ for 12 h.

0.21g of Pd (O)₂CCH₃)₂Dissolving the mixture in 10mL of toluene and 10mL of acetone, adding 10g of the MgO carrier prepared in the step (1) into the precursor solution, stirring at 500rpm for 4-8h, and reducing at 250 ℃ for 4h in a hydrogen atmosphere to obtain the magnesium oxide supported metal catalyst (1% Pd/MgO) with the load of 1 wt% Pd.

10.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 60 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 11

11.1 high specific surface area magnesium oxide-supported Metal catalysts

10.26g of Mg (NO)₃)₂·6H₂Dissolving O in 250mL of deionized water, adding 31.2 mL of 25 wt% ammonia water and 0.4g of Sodium Dodecyl Sulfate (SDS), stirring at 1000rpm for 5-10min, placing in a hydrothermal kettle, heating to 120 ℃ for reaction for 12h, centrifuging after the reaction is finished, washing with deionized water for 5 times, drying at 90 ℃ for 24h, and roasting at 400 ℃ for 12 h.

0.21g of Pd (O)₂CCH₃)₂Dissolving the mixture in 10mL of toluene and 10mL of acetone, adding 10g of the MgO carrier prepared in the step (1) into the precursor solution, stirring at 500rpm for 4-8h, and reducing at 250 ℃ for 4h in a hydrogen atmosphere to obtain the magnesium oxide supported metal catalyst (1% Pd/MgO) with the load of 1 wt% Pd.

11.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 70 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 12

12.1 high specific surface area magnesium oxide-supported Metal catalysts

10.26g of Mg (NO)₃)₂·6H₂Dissolving O in 250mL of deionized water, adding 31.2 mL of 25 wt% ammonia water and 0.4g of Sodium Dodecyl Sulfate (SDS), stirring at 1000rpm for 5-10min, placing in a hydrothermal kettle, heating to 120 ℃ for reaction for 12h, centrifuging after the reaction is finished, washing with deionized water for 5 times, drying at 90 ℃ for 24h, and roasting at 400 ℃ for 12 h.

0.21g of Pd (O)₂CCH₃)₂Dissolving the mixture in 10mL of toluene and 10mL of acetone, adding 10g of the MgO carrier prepared in the step (1) into the precursor solution, stirring at 500rpm for 4-8h, and reducing at 250 ℃ for 4h in a hydrogen atmosphere to obtain the magnesium oxide supported metal catalyst (1% Pd/MgO) with the load of 1 wt% Pd.

12.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 80 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 13

13.1 magnesium oxide Supported Metal catalysts

The same as example 1.1.

13.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of toluene, and 10g of isopropanol were added, and after heating to 50 ℃, stirring was started (stirring rate about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 14

14.1 magnesium oxide Supported Metal catalysts

The same as example 1.1.

14.2 preparation of UV-P

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the UV-P azo intermediate, about 60mL of chlorobenzene, and 10g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 15

15.1 magnesium oxide Supported Metal catalysts

The same as example 1.1.

15.2 preparation of UV-326

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the UV-326 azo intermediate, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 16

16.1 magnesium oxide Supported Metal catalysts

The same as example 1.1.

16.2 preparation of UV-327

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the azo intermediate UV-327, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Example 17

17.1 magnesium oxide Supported Metal catalysts

The same as example 1.1.

17.2 preparation of UV-328

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/MgO catalyst, 10g of the UV-328 azo intermediate, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Comparative example

Weigh 0.154g K₂PdCl₄Adding the mixture into 7.5g of deionized water, and stirring and dissolving the mixture uniformly to prepare a precursor solution; adding 5g of activated carbon into the prepared precursor solution, and soaking for 12 hours at room temperature; after completion of the impregnation, it was dried under vacuum at 80 ℃ for about 8 hours. And (3) putting the dried catalyst into a tubular furnace, and reducing for 5 hours at 250 ℃ in a hydrogen atmosphere to obtain the 1% Pd/C catalyst.

In a 250mL three-necked flask, 0.2g of the prepared 1% Pd/C catalyst, 10gUV-P azo intermediate, about 60mL of toluene, and 10g of ammonia borane were added, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, filtering the catalyst, separating an organic layer, and analyzing the composition of a hydrogenation product in the filtrate by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product.

Table 1 catalyst performance results for specific examples 1-17 and comparative examples

Examples	Catalyst and process for preparing same	Conversion ratio of raw Material (%)	Product selectivity (%)	Product yield (%)
					1	1％Pd/MgO	100	99.3	98.6
2	2％Pd/MgO	100	98.3	97.9
					3	3％Pd/MgO	100	96.7	95.3
4	0.5％Pd/MgO	97.8	97.5	97.1
					5	1％Pt/MgO	100	95.3	94.3
6	1％Pd/MgO	100	98.6	98.0
					7	1％Pd/MgO	100	97.3	96.6
8	1％Pd/MgO	100	97.1	96.8
					9	1％Pd/MgO	98.9	96.8	95.5
10	1％Pd/MgO	100	95.1	94.6
					11	1％Pd/MgO	100	93.9	93.1
12	1％Pd/MgO	100	92.2	91.6
					13	1％Pd/MgO	92.6	91.2	84.1
14	1％Pd/MgO	100	97.2	96.7
					15	1％Pd/MgO	100	98.5	97.4
16	1％Pd/MgO	100	96.3	95.6
					17	1％Pd/MgO	100	97.1	96.4
Comparative example	1％Pd/C	100	42.1	40.5

As can be seen from Table 1, the selectivity of the conventional Pd/C catalyst without adding alkali is very poor, only 42.1%, which is much worse than that of the Pd/MgO catalyst provided by the present invention. Therefore, the common Pd/C catalyst can obtain high selectivity and yield only by additionally adding an alkali assistant, but the Pd/MgO catalyst of the invention can have high selectivity and yield without adding the alkali assistant, and reduce the discharge of waste water and waste solids.

Use examples 1 to 10:

in a 1L three-necked flask, 0.8g of the prepared 1% Pd/MgO catalyst, 40gUV-P azo intermediate, about 240mL of toluene, and 40g of ammonia borane were charged, and after heating to 50 ℃, stirring was started (stirring rate: about 600rpm), and the reaction was carried out for 5 hours; after the reaction is finished, the filtered catalyst and the catalyst filter cake are washed by deionized water and methanol and then applied to the next mechanical experiment, an organic layer is separated out, and the composition of a hydrogenation product in the filtrate is analyzed by adopting high performance liquid chromatography; and (4) decompressing and evaporating the solvent, washing with deionized water and methanol, and drying to obtain a target product. The results of the application experiments are shown in table 2:

TABLE 2 set of catalyst performance results for examples 1-10

Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.