176 results about "Nitrobenzoic acid" patented technology

The invention discloses a magnetic nano-enzyme probe and a preparation method thereof, a kit for detecting helicobacter pylori and application of the magnetic nano-enzyme probe, the core of the magnetic nano-enzyme probe is Fe3O4 nano-particles, magnetic enrichment capacity is provided, and interference of a complex matrix in a sample is eliminated; a layer of Pt nano-particles is electrostatically adsorbed through the cationic polymer to serve as a colorimetric interlayer, and a strong colorimetric signal is provided; au (at) Pt for modifying 5, 5 '-dithiobis (2-nitrobenzoic acid) is arranged on the surface layer and is used for providing strong catalytic signals and sites coupled with a large number of specific antibodies; meanwhile, the inner and outer layers of nano enzyme particles can synergistically enhance the catalytic action. The magnetic nano-enzyme probe disclosed by the invention has strong magnetic responsiveness, high colorimetric signal, strong catalytic activity and specific bacterium capturing capacity, realizes rapid enrichment and quantitative analysis of helicobacter pylori in a sample to be detected, eliminates matrix interference in practical application, and has high sensitivity and high specificity. The method has great potential in the aspects of high sensitivity and clinical monitoring of bacterial infection or pollution.

The invention discloses a high-temperature-resistant nylon composite material and a production process thereof, and belongs to the technical field of nylon composite material preparation. The high-temperature-resistant nylon composite material is prepared from the following components in parts by weight: 35-48 parts of nylon resin, 7-12 parts of a heat-resistant agent, 3-8 parts of a modified anticorrosive agent, 1-3 parts of calcium stearate, 1-3 parts of a flame retardant and 2-10 parts of glass fibers, and the heat-resistant agent is prepared from 2, 4-dinitrophenol, hydrazine hydrate, p-nitrobenzoic acid, triethylamine, polyphosphoric acid and 2, 4-dinitrophenol. The nylon composite material is prepared from 2, 2 '-bis (3, 4-dicarboxylic acid) hexafluoropropane dianhydride, and the modified anticorrosive agent is prepared from fluororubber, benzyltriethylammonium chloride, lithium aluminum hydride and isophorone diisocyanate. The nylon composite material prepared by the method has excellent high temperature resistance and corrosion resistance.

The invention discloses a preparation method of chloroprocaine hydrochloride, and belongs to the technical field of chloroprocaine hydrochloride synthesis. Comprising the following steps: (1) preparing 4-amino-2-chlorobenzoic acid: dissolving 2-chloro-4-nitrobenzoic acid in a solvent, and uniformly stirring; adding a ruthenium catalyst Ru / SNC into the system, and carrying out heat preservation reaction in a hydrogen atmosphere; the 4-amino-2-chlorobenzoic acid is obtained through a reaction; (2) preparation of chloroprocaine hydrochloride: dissolving 4-amino-2-chlorobenzoic acid, 2-chloroethyl diethylamine and a solid base catalyst K / r-GO in a reaction solvent, and carrying out an esterification reaction; the 2-(diethylamino)-2-chlorine-4-nitrobenzoic acid ethyl ester is obtained; and then salifying and drying to obtain the chloroprocaine hydrochloride. The catalyst provided by the invention realizes efficient catalytic reaction at lower temperature and pressure, can be recycled for dozens of times, and is suitable for large-scale industrial production.

The invention relates to the technical field of chemical synthesis, and particularly discloses a synthesis method of 2-fluoro-3-nitrobenzoic acid. The preparation method comprises the following steps: by taking 2-methyl-6-nitroaniline as an initial raw material, firstly preparing aromatic diazonium salt through diazotization reaction, and then carrying out Balz-Schiemann reaction on the aromatic diazonium salt and fluoboric acid under the condition of a specific catalyst, so as to prepare the 2-fluoro-3-nitrotoluene. And finally, under the condition of a specific catalyst, carrying out oxidation reaction on the 2-fluoro-3-nitrotoluene to prepare the 2-fluoro-3-nitrobenzoic acid. The white 2-fluoro-3-nitrobenzoic acid with the total yield being 85% or above and the purity being 99% or above is finally prepared, the method has the advantages of being low in production cost, high in process safety and the like, large-scale production of the 2-fluoro-3-nitrobenzoic acid is easily achieved, and the method has very important significance for widening the application range of the 2-fluoro-3-nitrobenzoic acid.

The invention discloses a synthetic method of 2-chloro-4-fluoro-5-nitrobenzoic acid. The synthetic method comprises the following steps: preparing a mixed acid of nitric acid and sulfuric acid; the method comprises the following steps: mixing 2-chloro-4-fluorotrichlorotoluene and mixed acid to carry out nitration reaction, heating the reaction system without separation after the nitration reaction is finished to carry out hydrolysis reaction, and obtaining the 2-chloro-4-fluoro-5-nitrobenzoic acid by a one-pot method. The synthesis method is high in conversion rate, good in yield, low in cost, simple in process, convenient to operate, free of separation and purification of intermediate products in the midway and easy to realize industrial production.

The invention relates to the technical field of electroplating, in particular to a nickel stripping agent, a preparation method of the nickel stripping agent and a nickel plating layer stripping method. The nickel stripping agent comprises the following raw materials: an oxidizing agent, a complexing agent, a dissolution promoter, a surfactant and a corrosion inhibitor, wherein the mass ratio of the oxidizing agent to the complexing agent to the dissolution promoter to the surfactant to the corrosion inhibitor is (4-15): (3-25): (1-11): (0.01-1): (0.01-5); wherein the oxidizing agent is nitrobenzoic acid; the complexing agent is one or more of 2-amino-2-methyl-1-propyl alcohol, acetylacetone, nitrilotriacetic acid, nitrilotriacetic acid sodium salt, acrylate, sodium gluconate and ethylenediamine hydrochloride; the dissolution promoter is an alcohol ether solvent. According to the nickel stripping agent, the oxidizing agent with relatively low toxicity and a non-toxic or low-toxicity non-volatile complexing system are adopted, nickel can be completely removed, a base material cannot be eroded, and the threat to the health of operators can be remarkably reduced.

The invention provides a 3-amino-2-fluorobenzamide compound and a preparation method thereof, and the preparation method comprises the following steps: (1) carrying out a substitution reaction on 5-chloro-2-hydroxy-3-nitrobenzoic acid to obtain 5-chloro-2-fluoro-3-nitrobenzoyl halide with a structure as shown in a formula I; (2) carrying out an amidation reaction on the 5-chloro-2-fluoro-3-nitrobenzoyl halide and an aniline compound with a structure as shown in a formula II to obtain a 3-nitro-2-fluorobenzamide compound with a structure as shown in a formula III; and (3) carrying out a reduction reaction on the 3-nitro-2-fluorobenzamide compound, so as to obtain the 3-amino-2-fluorobenzamide compound with a structure as shown in a formula IV. The preparation method is low in raw material price, almost quantitative in multi-step reaction, few in by-products, high in target product yield and mild in process condition, avoids severe reaction conditions such as deep cooling and high temperature, and is more suitable for industrial production.

The present invention provides a paroxysmal hemoglobinuria indication drug ipropam key intermediate synthesis method, and relates to the technical field of ipropam, the method comprises: taking p-bromobenzaldehyde as an initial raw material, adopting an S-configuration catalyst to obtain an intermediate 03, carrying out protection group removal on the intermediate 03, carrying out automatic ring closing to obtain an intermediate 04, and carrying out post-treatment to obtain the paroxysmal hemoglobinuria indication drug ipropam key intermediate. Reducing the intermediate 04 with sodium borohydride to obtain a single cis-configuration intermediate 05, then carrying out a chiral flip reaction and hydrolysis to remove p-nitrobenzoic acid, then carrying out an etherification reaction with diethyl sulfate to obtain an intermediate 08, reducing amide of the intermediate 08 with sodium borohydride and boron trifluoride diethyl etherate to obtain an intermediate 09, then carrying out an acetylation reaction to protect amino, and finally carrying out a reaction to obtain the chiral cis-configuration intermediate 03. Cuprous cyanide is subjected to a cyanation reaction and a hydrolytic esterification reaction to obtain the ipropam key intermediate TM. The method is low in raw material price, high in chiral control selectivity, easy in reaction condition control and low in equipment requirement, avoids column chromatography and other operations, and is more suitable for industrial production.

The invention discloses a method for synthesizing L-γ-glutamyl-3-carboxyl-4-nitroaniline ammonium salt, and relates to the technical field of organic synthesis. According to the invention, Glupa-C is synthesized by using 5-amino-2-nitrobenzoic acid and 3-nitrophthaloyl-L-glutamic anhydride as starting materials through a condensation reaction and a hydrazinolysis reaction under the catalytic action of a Lewis acid. Compared with traditional alkaline preparation conditions, the use of highly toxic reagents and the safety hazard of explosion during the preparation process are avoided, production risks are reduced, and energy consumption is lowered. In addition, the synthesis method provided by the invention can achieve a total yield of 47.8% and a purity of 99.96% for the product Glupa-C, and is suitable for industrial production.

The invention discloses a micro-fluidic chip system for detecting staphylococcus aureus and escherichia coli and a detection method. The micro-fluidic chip system comprises a micro-fluidic chip, vancomycin modified iron oxide magnetic nano particles (Fe3O4-Van MNPs), silver (at) aure-4-mercaptobenzoic acid-staphylococcus aureus aptamer nano particles (Ag (at) Au-MBA-Apt NPs) and silver (at) aure-5 '5-dithiobis (2-nitrobenzoic acid)-escherichia coli aptamer nano particles (Ag (at) Au-DTNB-Apt NPs), and the micro-fluidic chip system comprises a micro-fluidic chip, a magnetic nano particle (Fe3O4-Van MNPs), a magnetic nano particle (Ag (at) Au-MBA-Apt NPs) and a magnetic nano particle (Ag (at) Au-MBA-Apt NPs), wherein the micro-fluidic chip integrates a magnetic capture unit, a composite structure construction unit and an SERS in-situ detection unit, and the micro-pipeline is provided with a plurality of necks and cylindrical baffles. When the micro-fluidic chip system is used for detecting the staphylococcus aureus and the escherichia coli in the blood, the sensitivity is high, and the limit of detection (LOD) of the staphylococcus aureus and the escherichia coli is as low as 2.01 FU / mL and 3.28 CFU / mL respectively.

The invention belongs to the technical field of chemical synthesis, and provides a method for preparing 3-methyl-4-aminobenzoic acid through catalytic hydrogenation, which comprises the following steps: mixing 3-methyl-4-nitrobenzoic acid and a solvent, and adjusting the pH value to be alkaline while stirring to obtain a 3-methyl-4-nitrobenzoic acid solution; the method comprises the following steps: pouring a 3-methyl-4-nitrobenzoic acid solution into a reaction kettle, adding a modified palladium catalyst and an auxiliary agent, sequentially replacing with nitrogen and hydrogen for 2-3 times, introducing hydrogen, controlling pressure and temperature, and carrying out hydrogenation reaction to obtain a reactant; and after the reaction kettle is cooled, filtering reactants, adjusting the pH value of filtrate to be weakly acidic, crystallizing and drying to obtain the 3-methyl-4-aminobenzoic acid. The preparation method disclosed by the invention is simple in steps, a required product can be generated by a one-step method, meanwhile, the used modified palladium catalyst can be recycled, the generation amount of three wastes is small, coordinated development of economic benefits and environmental benefits is realized, and the 3-methyl-4-aminobenzoic acid is high in yield and purity and has a relatively good application value.

The invention discloses a preparation method of isooctyl p-aminobenzoate. The preparation method comprises the following steps: carrying out esterification reaction on p-nitrobenzoic acid and isooctyl alcohol in the presence of a catalyst and a water-carrying agent to obtain an intermediate isooctyl p-nitrobenzoate; and performing catalytic hydrogenation on the intermediate isooctyl p-nitrobenzoate to obtain the target product isooctyl p-aminobenzoate. A rectifying column is arranged in a reaction device adopted by the esterification reaction. The rectifying column is arranged in the esterification reaction device, so that the water removal efficiency can be effectively improved, the reaction time can be greatly shortened, the product purity can be effectively improved, and the product quality can be improved; besides, the acidic ionic liquid is adopted as the esterification reaction catalyst, so that a better catalytic effect can be obtained, a higher reaction yield is obtained, the catalyst can be recycled and reused through liquid phase layering operation, the activity of the recycled catalyst is kept well, and the operation is simple.

A curcumin nanococrystal composition including curcumin, a coformer, and a stabilizer. The coformer may include at least one of 3,5-dinitrobenzoicacid, gentisic acid, phloroglucinol, 4,4-bipyridine, tartaric acid, citric acid, and gallic acid. The curcumin nanococrystal composition has a particle size less than 10 nm, and the curcumin has a water-solubility between 5 mg / ml and 20 mg / ml.

This invention provides a method for preparing and applying a highly insecticidal diamide compound, relating to the chemical and pesticide fields. The method includes: reacting 2-fluoro-3-nitrobenzoic acid with thionyl chloride (a chlorinating agent) and dimethylformamide (a catalyst) to obtain compound A; condensing compound A with 2-trifluoromethyl-4-heptafluoroisopropyl-6-bromoaniline amide to obtain compound B; reducing compound B to obtain compound C; and, during the reaction under a hydrogen atmosphere, determining the reaction temperature and hydrogen flow rate in each hydrogenation reaction zone based on the concentration of compound B; reacting compound C with paraformaldehyde to obtain compound D; chlorinating 3-chloro-4-fluorobenzoic acid with thionyl chloride (a chlorinating agent) and dimethylformamide (a catalyst) to obtain compound E; and amide condensing compound E with compound D to obtain the novel diamide compound of this invention. The diamide compound of this invention exhibits excellent insecticidal effects when used in pesticide compositions.

This invention belongs to the field of environmental chemistry and relates to a method for quantitatively analyzing the concentrations of cystine and cysteine ​​in a mixed solution. Based on the theoretical characteristics of the reaction between the disulfide bond in cystine, a representative amino acid, and the thiol group in cysteine, and persulfate, this invention expands the detection capability of the traditional 5,5-dithio-bis-(2-nitrobenzoic acid) (DTNB), providing support for the quantitative analysis of cystine and cysteine ​​concentrations and the study of their transformation processes.

The present invention relates to a method of adding an isocitrate lyase specific inhibitor to a lactic acid fermentation process to block the production of succinic acid as a byproduct of fermentation. The specific inhibitor includes a combination of one or more of glycolic acid methyl ester, malonic acid dimethyl ester, hydroxymalonic acid diethyl ester, 3-nitropropionic acid ethyl ester, mercuric chloride, or 5,5'-dithiobis(2-nitrobenzoic acid) to effectively reduce the amount of succinic acid in the lactic acid.

The application discloses 4-nitrobenzoic acid imidazole quaternary ammonium salt and a preparation method and application thereof. The 4-nitrobenzoic acid imidazole quaternary ammonium salt provided by the application has a structure as shown in formula (I), is in a single crystal form, is in a triclinic crystal system, and belongs to a P-1 space group. The 4-nitrobenzoic acid imidazole quaternary ammonium salt has a significant bacteriostatic effect, good thermal stability, and can be applied to preparation of antibacterial materials as an antibacterial agent.

This invention belongs to the field of insecticide technology, specifically relating to a diamide compound, its preparation method, intermediate preparation equipment, and applications. The preparation method includes: reacting 2-fluoro-3-nitrobenzoic acid with thionyl chloride in the presence of dimethylformamide to generate compound A; condensing compound A with 2-trifluoromethyl-4-heptafluoroisopropyl-6-bromoaniline amide to obtain compound B; reducing compound B to obtain compound C; substituting compound C with formaldehyde to obtain compound D; and condensing compound D with 3,5-dichloro-4-fluorobenzoyl chloride to obtain the diamide compound. The beneficial effects of this invention are: the diamide compound solves the problem of insecticide resistance and possesses high insecticidal activity, exhibiting good insecticidal effect at low doses. Furthermore, the preparation method uses mild reaction conditions, produces few byproducts, and has a high reaction yield, reducing raw material loss and thus lowering production costs.

The invention discloses a soybean meal quality evaluation method based on protein oxidation, which comprises the following steps: sampling a soybean meal sample, determining the protein carbonyl content of the soybean meal by adopting a 2, 4-dinitrophenylhydrazine (DNPH) method and / or determining the protein carbonyl content of the soybean meal by adopting 5, 4-dinitrophenylhydrazine (DNPH) method. According to the method, the content of free sulfydryl in the soybean meal protein is measured by a 5, 5 '-dithio-2-nitrobenzoic acid (DTNB) method, the oxidation degree of the soybean meal protein is evaluated, the quality of the soybean meal is graded and evaluated, and the evaluation result can be verified by adopting the in-vitro digestibility of the protein. The evaluation method disclosed by the invention is simple and convenient to operate and high in result repeatability, can effectively evaluate the quality of the soybean meal, and can be applied to quality control, storage management and feed formula optimization of the soybean meal.

This utility model relates to the field of nitrobenzoic acid storage technology, and more particularly to a p-nitrobenzoic acid storage tank, including a tank body and a tank cover detachably connected to the upper end of the tank body, as well as a screw and a drive mechanism. One end of the screw is rotatably connected to the inside of the tank body, and a scraping element for scraping the inner wall of the tank body is threadedly connected to the screw. The scraping element is slidably connected to the inner wall of the tank body. The drive mechanism is located on the tank cover and is used to drive the screw to rotate, thereby scraping the inner wall of the tank body by the scraping element. In this utility model, when the tank cover is connected to the tank body, the drive mechanism drives the screw to rotate, and the screw rotation simultaneously drives the scraping element to slide up and down on the inner wall of the tank body, dynamically scraping off the material adhering to the inner wall of the tank body. At this time, the cleaning process in the closed state of the tank body can reduce the damage caused by manual cleaning of the inner wall of the tank body.

The invention relates to the technical field of organic synthesis, in particular to a method for preparing 4-nitro-N-phenylbenzamide by a one-pot process, which comprises the following steps: under the protection of inert gas, adding an inert solvent, p-nitrobenzoic acid and a composite catalyst into a reactor, and heating to dissolve, the composite catalyst comprising NFM and TPPO; slowly adding thionyl chloride into a reaction system for acylation reaction; then slowly adding aniline into the reaction system to carry out condensation reaction; and after the reaction is finished, carrying out post-treatment to obtain the 4-nitro-N-phenylbenzamide. According to the method, one-pot reaction can be realized, and high-risk intermediates do not need to be separated. In the composite catalyst, NFM efficiently catalyzes acylating chlorination, and TPPO stabilizes an acyl chloride intermediate and promotes condensation, so that the reaction is performed efficiently, stably and highly selectively, and the product is high in yield and purity. And the catalyst is easy to recycle, and the process is green, safe, economical and suitable for industrial production.

The invention provides a black direct dye as well as a preparation method and application thereof. The preparation method of the black direct dye disclosed by the invention comprises the following steps: acquiring polyaniline: performing oxidative polymerization on aniline hydrochloride by using an oxidizing agent to obtain polyaniline; obtaining a condensation product: carrying out condensation reaction on polyaniline and p-nitrotoluene o-sulfonic acid and / or 2-methyl-5-nitrobenzoic acid to obtain the condensation product; and a post-treatment step: carrying out post-treatment on the condensation product to obtain the black direct dye. The preparation method of the black direct dye is simple and easy to implement, few in three wastes in the production process and environmentally friendly. The black direct dye prepared by the preparation method is bright in color, good in water solubility, high in dye-uptake and excellent in dyeing performance.

The present invention discloses a pomalidomide feed additive and a preparation method and application thereof, and belongs to the technical field of functional feed additive synthesis. The technical scheme of the present invention is as follows: the pomalidomide feed additive molecule has a structure #imgabs0# wherein n is 1 or 2; R is an alkyl group or a halogen group or a methoxy group or #imgabs1#. The present invention uses 2-nitrobenzoic acid as a starting material, first reacts to obtain 2-(2,6-dioxopiperidin-3-yl)-4-nitroisoindoline-1,3-dione, then reacts to obtain pomalidomide, then introduces an azide group, and finally obtains a target molecule with a novel structure through a click reaction, which has a certain inhibitory effect on urease and can be used as a potential feed additive.

The utility model discloses continuous production equipment for p-nitrobenzoic acid, which belongs to the technical field of continuous production equipment for p-nitrobenzoic acid and comprises an equipment body and a stabilizing seat. Before the equipment body is opened, the threaded rod is promoted to extend into the upper base through the fixing block, the reinforcing plate extends into the clamping groove through continuous extension of the threaded rod, the clamping effect on the equipment body is achieved, and the equipment body is more stable in the operation period; the main gravity block is located in the center of the upper base and plays a basic main stabilizing role, the auxiliary weighting mechanism, the first auxiliary gravity block and the second auxiliary gravity block are arranged, four corners of the upper base and four corners of the lower base are further reinforced in an auxiliary mode, and therefore through a series of weighting, the stabilizing effect on the equipment body in the running period is achieved, and the stability of the equipment body is improved. And therefore, the production effect of the equipment body is improved, and the production efficiency of the equipment body is improved.

This invention relates to the field of lithium-ion battery technology, and in particular to a positive electrode lithium replenishment agent, its preparation method, and a positive electrode sheet, comprising lithium-rich lithium iron phosphate and lithium nitrobenzene. The positive electrode lithium replenishment agent provided by this invention uses LFO as the main lithium source and combines it with lithium nitrobenzene to form a protective layer in situ on the surface of lithium-rich lithium iron phosphate particles, reducing interfacial side reactions and gas generation, achieving efficient active lithium compensation, and thus improving the overall performance of the battery.

The application provides a preparation method of bumetanide, taking p-chlorobenzoic acid as a starting material, performing chlorosulfonation, nitration, and ammonolysis to obtain a key intermediate of 3-(N-(tert-butyl) sulfamoyl)-4-chloro-5-nitrobenzoic acid, then performing phenoxylation, nitro reduction, n-butylation, and tert-butyl removal, and finally obtaining the bumetanide. Compared with the synthesis process of the prior art, the method has less side reactions, low cost, high yield, high safety, and is beneficial to industrial production.

The invention belongs to the technical field of biological pharmacy, and particularly relates to olpicopone and a preparation method thereof.The preparation method comprises the following steps that 2, 5-dichloro-4, 6-dimethyl nicotinonitrile is oxidized and then subjected to an addition reaction with hydroxylamine, and a compound 2 is obtained; carrying out condensation reaction on the compound 2 and 3-methoxy-4-hydroxy-5-nitrobenzoic acid to obtain a compound 3; and the compound 3 is subjected to methoxy removal to obtain the final product opiapone. The method provided by the invention avoids the problem that excessive intermediate products are left and are not easy to remove in the oxidation step, and avoids yield loss caused by multiple refinement at the same time.

The invention provides a preparation method of 2, 6-diaminobenzene, and relates to the technical field of organic synthesis. The preparation method comprises the following steps: taking 2-amino-4-nitrobenzoic acid as an initial raw material, carrying out diazotization reaction on the initial raw material and nitrite ester under an acidic condition, then carrying out cyclization reaction, and reducing by using a reducing agent to obtain the 2, 6-diaminobenzene. The preparation method provided by the invention is short in reaction route, high in atom conversion rate, high in product yield, high in production efficiency, simple to operate, cheap and easily available in raw material 2-amino-4-nitrobenzoic acid, low in production cost, green and environment-friendly, and suitable for industrial production. The preparation method provided by the invention has important significance on organic synthesis, medicinal chemistry and material chemistry of the biphenyl alkene derivative. The test result of the embodiment shows that the total yield of the 2, 6-diaminobenzene prepared by the preparation method provided by the invention is more than 43.9%.

The invention discloses a strongly-bundled high-insulation glass fiber cloth and a preparation method thereof, and relates to the technical field of glass fiber cloth preparation, the glass fiber cloth is obtained by dipping a fiber cloth obtained by crushing, melting, drawing, yarn preparation, sizing and weaving of a glass raw material in a surface treating agent, after the yarn is subjected to sizing treatment, the strong bundling property meets the requirement, and the surface treating agent is obtained by mixing waterborne polyurethane emulsion prepared from functional diisocyanate and the like with a reinforcing agent and the like. The functional diisocyanate is obtained by carrying out a reaction on 1, 3-dihydroxyethyl adamantane, 3-amino-5-nitrobenzoic acid methyl ester, 4-amino-3-methyl benzonitrile, oleanolic acid and the like; the reinforcing agent is obtained by loading a product e containing aza-adamantane, phosphamide, cyano, hydroxyl and castor oil-based alkane long chains on halloysite nanotubes. The glass fiber cloth disclosed by the invention has relatively high insulativity, mechanical strength, high temperature resistance and flame retardance.

The invention relates to the technical field of organic acids, and particularly discloses a preparation method of 2-fluoro-4-nitrobenzoic acid. The invention relates to a preparation method of 2-fluoro-4-nitrobenzoic acid, which comprises the following steps: by taking polystyrene waste as a raw material, heating concentrated sulfuric acid and concentrated nitric acid to nitrate the polystyrene waste to obtain 4-nitropolystyrene, and oxidizing the 4-nitropolystyrene by taking sodium chlorate as an oxidant, zinc nitrate as a catalyst and concentrated nitric acid as a solvent to obtain 4-nitrobenzoic acid. And finally, by taking iridium acetate as a catalyst and N-fluorobisbenzenesulfonamide as a fluorinating agent, adding potassium fluoride, nitrite and the self-made ligand, and carrying out fluorination reaction to prepare the 2-fluoro-4-nitrobenzoic acid. According to the preparation method disclosed by the invention, efficient utilization of polystyrene waste is realized, the way of recycling polystyrene resources is expanded, and the yield of the prepared 2-fluoro-4-nitrobenzoic acid is high.