105 results about "2,4-Dichlorophenoxyacetic acid" patented technology

The invention discloses a herbicide composite. The herbicide composite comprises topramezone used as a main material and an auxiliary material which contains one or more than one of atrazine, fluroxypyr, bentazone, dicamba, nicosulfuron, mesotrione, 2,4-dichlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid butyl ester, 2,4-dichlorophenoxyacetic acid iso-octyl ester, terbuthylazine, MCPA-sodium, foramsulfuron and acetochlor. The herbicide composite is a novel herbicide composite with good weeding effect.

An herbicidal composition containing (a) aminopyralid and 2,4-D and (b) atrazine provides synergistic control of selected weeds in corn, sorghum, sugar cane and range and pasture.

The invention discloses a method for continuously producing herbicide 2,4-dichlorophenoxyacetic acid. According to the method, phenol and chlorine gas are used as raw materials; a continuous chlorination reaction is conducted through a micro-channel reactor to prepare 2,4-dichlorophenol, a condensation reaction is conducted through a tandem condensation reaction kettle to prepare 2,4-dichlorphenoxyacetic acid sodium salt, and then a continuous acidification reaction is conducted through a tandem acidification reaction kettle to prepare the 2,4-dichlorphenoxyacetic acid. Since continuous operation is realized in all the three reactions, the technological process is efficient, environmentally friendly, sustainable and suitable for industrial production; the method has the advantages that energy is saved, consumption is lowered, and emission of pollutants is reduced, and therefore safe and continuous industrial production is achieved.

An in-vitro culture method for catalpa bungei comprises 1) inducing callus, concretely, putting catalpa bungei on a callus induction medium for inducing callus, wherein the callus induction medium is obtained by adding 6-benzyladenine (6-BA) and 2,4-dichlorophenoxyacetic acid (2,4-D) on the basis of 1 / 2 MS basal medium; 2) propagating callus, concretely putting callus on a propagation medium for propagation, wherein the propagation medium is obtained by adding 6-benzyladenine (6-BA) and alpha-naphthalene acetic acid (NAA) on the basis of 1 / 2 MS basal medium; 3) inducing embryonic callus and differentiating somatic embryo, concretely putting propagated callus on an induction differentiation medium, wherein the induction differentiation medium is obtained by adding 6-benzyladenine (6-BA) and alpha-naphthalene acetic acid (NAA) on the basis of 1 / 2 MS basal medium; and 4) regenerating a plant, concretely putting somatic embryo obtained through differentiation on a regeneration medium for inducing somatic embryo to germinate, so as to obtain a catalpa bungei regeneration plant. The method aims at expanding catalpa bungei propagation coefficient and providing conditions for germplasm preservation and genetic transformation.

A method for removing contaminants from fluids comprises contacting the fluid with an expanded material selected from popped corn, puffed rice and puffed wheat. The preferred expanded material is popped corn. The method is applicable to a wide range of organic and inorganic contaminants. Examples of contaminants include aromatic compounds such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo furans (PCDFs), polychlorinated dibenzo dioxins (PCDDs), carbamates, sulphonamides, dichlorodiphenyltrichloroethane (DDT), 2,4-dichlorophenoxyacetic acid (2,4-D), other compounds such as carbon disulphide, ethylene glycol and pesticides. Other examples include inorganic compounds or organo-metallic compounds, e.g. those containing aluminum, antimony, barium, cadmium, cobalt, chromium, copper, iron, lead, mercury, molybdenum, nickel, silver, tin, titanium, vanadium and zinc.

The invention discloses a synergic herbicide composition containing cyhalofop-butyl and 2,4-dichlorophenoxyacetic acid and application thereof. The herbicide composition comprises the cyhalofop-butyl and the 2,4-dichlorophenoxyacetic acid which serve as the main active ingredients, wherein the mass ratio of the cyhalofop-butyl to the 2,4-dichlorophenoxyacetic acid is 1-60:1-60. The synergic herbicide composition can be used for preparing herbicides for controlling post-emergence weeds in paddy field. Compared with single-composition herbicide, the herbicide composition has a broad herbicide spectrum and acts for a long time on the premise of improving the herbicide effect, is safe for the paddy fields and after-reap crops and particularly has obvious effect of controlling various gramineous weeds and broadleaf weeds in the paddy fields.

The invention discloses a method for simultaneously determining multiple plant growth regulators in exported vegetables. The method comprises the following steps: extraction, purification, concentration, ultrahigh-performance liquid chromatography-triple quadrupole / composite linear ion hydrazine mass spectrometer (UHPLC-QTRAP) determination and the like. The method can simultaneously determine the 17 plant growth regulators, including gibberellin, indolyl-3-butyric acid, p-chlorophenoxyacetic acid, abamectin, diethyl aminoethyl hexanoate, atrazine, simazine, 6-benzyl aminopurine, 2,4-dichlorphenoxyacetic acid, forchlorfenuron, mepiquat chloride, chlormequat chloride, paclobutrazol, uniconazole, abscisic acid, thidiazuron and p-fluorophenoxyacetic acid. The method disclosed by the invention has the advantages of simple steps, short time consumption, high accuracy and high precision.

The invention relates to a synthesis method of herbicide 2, 4-dichlorphenoxyacetic acid, which comprises the following steps that: under the existence of weak base and the effect of sodium iodide and phase transfer catalyst, 2, 4-dichlorophenol is condensed with monochloroacetone through Williamson to obtain 2, 4-dichlorophenoxy acetone; the obtained 2, 4-dichlorophenoxy acetone is reacted and acidified in sodium hypochlorite solution to finally obtain 2, 4-D. With the method, the free phenol content in the product can be effectively controlled below the national standard, the discharge of the phenol-contained waste water can be reduced, and the synthesis method is simple and convenient to operate and has good product quality and small environmental pollution.

The invention relates to a process for preparing 2,4-dichlorphenoxyacetic acid with high quality; and the process comprises the following steps of: using phenol as a raw material; first chlorinating the phenol so as to prepare 2-chlorophenol, 4-chlorophenol and 2,4-chlorophenol; separating out the 2-chlorophenol through rectifying; further chlorinating the 4-chlorophenol to obtain 2,4-dichlorophenol immediate with mass percentage of not less than 98%; and under an alkaline condition, reacting the 2,4-dichlorophenol immediate with chloroacetic acid, so as to obtain 2,4-dichlorphenoxyacetic acid with mass percentage of not less than 98%. Compared with the prior art, the process for preparing 2,4-dichlorphenoxyacetic acid with the high quality, provided by the invention, has the advantages as follows: the 2,4-dichlorphenoxyacetic acid (98%) with high quality is obtained; meanwhile, untransformed 2,4-dichlorophenol is recycled through solvent extraction and is recycled as reaction raw material for the next reaction through being neutralized and alkalified; therefore, the environment friendly process for preparing the 2,4-dichlorphenoxyacetic acid with high quality and high yield is provided.

The invention provides a preparation method and device of 2,4-dichlorphenoxyacetic acid. The preparation method provided by the invention is used for solving the technical problems of heavy pollution, low yield, low content and high cost of the existing synthetic method of 2,4-dichlorphenoxyacetic acid; in the process of synthesizing the 2,4-dichlorphenoxyacetic acid, a special dropwise adding reactor is employed to dropwise add chloroacetic acid and caustic soda liquid simultaneously so that sodium chloroacetate generated through a reaction reacts with sodium phenate before hydrolysis; as lots of heat is released by the reaction between the chloroacetic acid and the caustic soda liquid, the reaction heat needed by condensing the sodium chloroacetate and the sodium phenate is just guaranteed; and independent preparation of brine ice which needs to be consumed to keep the sodium chloroacetate at a low temperature and heating required by a condensation reaction are also avoided. According to the invention, non-reacting phenol is recovered and wastewater is recovered to reduce the amount of the wastewater; and the wastewater contains no phenol and thus is easier to treat; and the preparation method provided by the invention can be applied to synthesis of 2,4-dichlorphenoxyacetic acid and analogues.

The invention discloses a method for preparing a paper mulberry somatic embryo and application thereof to paper mulberry expanding propagation. The provided method for preparing the paper mulberry somatic embryo includes the following steps that 1, embryonic callus of paper mulberry is added into a second culture medium to be cultured, and the second culture medium is a 1 / 2MS culture medium containing 0.5 mg / L 2,4-dichlorphenoxyacetic acid and 30 g / L saccharose; 2, after the step 1 is finished, the culture system is transferred to a third culture medium to be cultured, and the third culture medium is a 1 / 2MS culture medium containing 0.5 mg / L NAA, 0.2 mM TDZ, 0.4 mg / L IBA, 0.4 mg / L 6-BA and 30 g / L saccharose. The whole technological system of efficiently inducing somatic cells of the paper mulberry from explants and culturing the somatic cells in fluid in a suspension mode is completed for the first time, the technology is provided for large-scale industrialized production, and the problems that it is tedious to manufacture paper mulberry germchit, and the paper mulberry germchit is highly demanded in the market are solved.

The invention discloses a composition containing glyphosate and 2,4-dichlorophenoxyacetic acid, and a use thereof. The composition is characterized in that crop accepted auxiliary materials contain glyphosate and 2,4-dichlorophenoxyacetic acid. The composition has an obvious synergistic effect on gramineous weeds represented by crabgrass and an addition effect on broad leaf weeds represented by chenopodium album thus can be utilized as a non-selective herbicide. The composition has the advantages that 1, the composition is compounded from novel drugs and has the characteristics of strong efficacy and low usage amount; the composition has weed control effects concretely comprising an obvious synergistic effect on gramineous weeds and an addition effect on broad leaf weeds; and the composition realizes that when a dosage of each drug is reduced, good weed control effects are still obtained thus a weed control cost is reduced and adverse influences caused by large dose drugs on the environment are avoided; and 2, the composition has good control effects, a fast weed eliminating speed and a strong adaptability.

The invention discloses a method for preparing a magnetic halloysite molecularly imprinted polymer with specific adsorption to 2,4-dichlorophenoxyacetic acid. The preparation method comprises the following steps: preparing magnetic halloysite nano-tubes by using corroded halloysite nano-tubes by a coprecipitation method; reacting the magnetic halloysite nano-tubes and methacrylate in methylbenzene to obtain magnetic halloysite nano-tubes with double-bond-modified surfaces; after polymerizing the magnetic halloysite nano-tubes with double-bond-modified surfaces, the polymerized monomers and a crosslinker by taking the 2,4-dichlorophenoxyacetic acid as a template, then removing the 2,4-dichlorophenoxyacetic acid to obtain the magnetic halloysite molecularly imprinted polymer with specific adsorption to the 2,4-dichlorophenoxyacetic acid. The raw materials used in the preparation method are low in cost; the preparation method is easy to operate and easy to implement; the prepared magnetic halloysite molecularly imprinted polymer is stable in structure, has specific adsorption to the 2,4-dichlorophenoxyacetic acid, and can effectively separate and remove the 2,4-dichlorophenoxyacetic acid from a complex system.

The invention provides a Chuanminshen violaceum tissue culture method. According to the method, the stem tip, tender leaves and fresh tender leaf stalks of the Chuanminshen violaceum plant with good characters in the vigorous growth period are utilized as explants, and the method comprises the following steps of: performing disinfection treatment and inoculation induction to form callus; performing callus multiplication, bud induction culture and rooting culture to obtain complete Chuanminshen violaceum plant seedling; and transplanting the complete seedling into a seedling culture medium, and culturing to obtain a Chuanminshen violaceum annual seedling. All the culture media are based on an MS culture medium in combination with components such as 6-benzyladenine, naphthylacetic acid, 2,4-dichlorphenoxyacetic acid, indolebutyric acid, sucrose an agar. The method provided by the invention can be used for realizing the tissue rapid propagation of Chuanminshen violaceum by use of a plant tissue culture technology, and has important application values in terms of annual seedling supply and improved-variety rapid expanding propagation of the industrialized cultivation of Chuanminshen violaceum.

The invention discloses a method for producing 2,4-dichlorphenoxyacetic acid. The method comprises the following steps of: etherifying, dehydrogenating and oxidizing phenol and epoxy ethane in the presence of an oxidation catalyst to generate phenoxy acetic acid; dissolving the phenoxy acetic acid in a mixed solvent; making the solution react with chlorine in the presence of a chlorination catalyst; and cooling, crystallizing, filtering and drying to obtain the 2,4-dichlorphenoxyacetic acid. The method has the advantages of easiness for operation, avoidance of dioxin which is an extremely toxic substance and chlorinated phenol which is a smelly substance during production, high environmental friendliness, small amount of waste water and small treating amount of three wastes; the product has high yield and good quality; and the content of active ingredients is over 98.6 percent.

The invention provides a 2,4-dichlorophenoxyacetic acid preparation method including the following steps: A) providing phenoxyacetic acid; B) mixing hydrochloric acid, an oxidizing agent and the phenoxyacetic acid of the step A), carrying out a chlorination reaction in the presence of a chlorination catalyst, to obtain 2,4-dichlorophenoxyacetic acid, wherein the molar ratio of the phenoxyacetic acid to the hydrochloric acid to the oxidizing agent is 1 to (2-200) to (2-200), and the molar ratio of the hydrochloric acid to the oxidizing agent is 1 to (0.1-10). The 2,4-dichlorophenoxyacetic acid preparation method provided by the invention only needs one-step chlorination reaction, and then the 2,4-dichlorophenoxyacetic acid can be obtained; while the purity and yield of the 2,4-dichlorophenoxyacetic acid are ensured, the production process of the 2,4-dichlorophenoxyacetic acid is simplified. Moreover, the preparation method provided by the invention has no 'three wastes' emissions and achieves greenization of synthesis of the product.

The invention relates to a strain of degrading herbicide 2,4-dichlorophenoxyacetic acid and an application thereof, belonging to the technical fields of environmental engineering and microbial engineering. The strain cupriavidus campinensis of degrading herbicide 2,4-dichlorophenoxyacetic acid is named BJ71, with collection number of CCTCC (China Center for Type Culture Collection) M2014006. The strain has the capacity of growing with 2,4-dichlorophenoxyacetic acid as the unique carbon source and energy, and can obviously reduce the concentration of 2,4-dichlorophenoxyacetic acid in the environment. Experiments prove that the strain has more than 92% of 2,4-dichlorophenoxyacetic acid degradation rate in 21 days, and the experiments show that the strain can be applied to bioremediation of 2,4-dichlorophenoxyacetic acid polluted soil.

The invention provides a continuous preparation method of herbicide intermediate 2, 4-dichlorphenoxyacetic acid, which comprises the steps of subjecting 2, 4-dichlorphenoxyacetic acid with a mole ratio of 1: (1.2-1.5) and chloroacetic acid to consecutive reaction through a multistage condensation reaction tower at a temperature of 80-110 DEG C, controlling the PH value of the reaction to be 8-12 through addition of alkali liquor, and finally cooling the liquid material after reaction, subjecting the liquid material to suction filtration and obtaining the 2, 4- dichlorphenoxyacetic acid. Existing interval methods are replaced with the continuous preparation method for preparing the herbicide 2, 4-D acid intermediate 2, 4-dichlorphenoxyacetic acid, the preparation method is easy to operate, the production is safe and can be controlled, the labor intensity of workers is reduced greatly, the production field environment is improved, the safety of the reaction is improved, the discharge of the three wastes is reduced and the production during unit time is increased.

The invention discloses a rapid propagation method of kudzu roots, and relates to the technical field of plant tissue culture. Kudzu root tips are selected as the explant, an MS culture medium serves as the basic culture medium for a shoot induction medium, and 2,4-dichlorophenoxyacetic acid with concentration of 0.25-0.35 mg / L is added; a 1 / 2 MS culture medium serves as the basic culture medium for a rooting culture medium, and naphthylacetic acid with concentration of 0.25-0.3 mg / L and gibberellin with concentration of0.1-0.2 mg / L are added; a 2 / 3 MS culture medium serves as a basic culture medium for a seedling strengthening culture medium, and naphthylacetic acid with concentration of 0.3-0.5 mg / L is added; the germination rates of stem tips all reach 92% or above, and the rooting rates can reach 91% or above.

The invention provides a preparation method for 2,4-dichlorophenoxyacetic acid, belonging to the technical field of organic synthesis. The preparation method comprises the following steps: a) reactinghalogenated acetate with 2,4-dichlorophenolate in the presence of a phase-transfer catalyst so as to obtain 2,4-dichlorophenoxyacetate; and b) hydrolyzing 2,4-dichlorophenoxyacetate so as to obtain 2,4-dichlorophenoxyacetic acid. According to the invention, oil-phase halogenated acetate reacts with 2,4-dichlorophenolate under the action of the phase-transfer catalyst to prepare 2,4-dichlorophenoxyacetate, and then 2,4-dichlorophenoxyacetate is hydrolyzed to obtain 2,4-dichlorophenoxyacetic acid and corresponding alcohols. Under the action of the phase-transfer catalyst, few hydrolysis by-products are produced during a reaction, fast reaction speed and high conversion rate and yield are obtained, and the amount of produced waste water is low; so industrial application of the preparation method can be easily implemented.

The invention discloses an imprinted sensor based on gold nanoparticles, a preparation method and an application thereof. The method comprises the following steps: 1)placing a target electrode in a first mixing solution containing Na2SO4 and HAuCl4 and performing electrochemical deposition to prepare the gold nanoparticles for modifying the electrode; 2)under existence of a buffer solution, placing the electrode modified by the gold nanoparticles in a second mixing solution containing o-phenylenediamine and 2,4-dichlorphenoxyacetic acid, employing a cyclic voltammetry method for scanning to prepare a polymer membrane for modifying the electrode; and 3)placing the electrode modified by the polymer membrane in ethanol or an ethanol solution for eluting to prepare the imprinted sensor based on gold nanoparticles; wherein the target electrode is glassy carbon electrode or ITO electrode. The imprinted sensor can detect the 2,4-dichlorophenoxyacetic acid in a sensitive mode.

The invention relates to a method for controlling a continuous reaction crystal size of a herbicide 2,4-dichlorphenoxyacetic acid. The method comprises the following steps: (1) preparing a 80-100 DEG C saturated or nearly saturated solution of a 2,4-dichlorphenoxyacetic acid salt, and 10-38% hydrochloric acid respectively; (2) in a crystallizer, continuously adding the 2,4-dichlorphenoxyacetic acid salt solution and the hydrochloric acid prepared in the step (1), wherein a molar ratio of the 2,4-dichlorphenoxyacetic acid salt to hydrochloric acid is 1 to (1-1.2), controlling the crystallization temperature at 20-60 DEG C, controlling the retention time to 2-10 hours, continuously discharging the material to an after-treatment process to obtain the 2,4-dichlorphenoxyacetic acid product. According to the crystal size control method disclosed by the invention, the 2,4-dichlorphenoxyacetic acid salt is dissolved at a high temperature, the 2,4-dichlorphenoxyacetic acid salt solution and hydrochloric acid are subjected to a continuous reaction crystallization process in the crystallizer at a low temperature, so that the problems that the 2,4-dichlorphenoxyacetic acid product produced by the process of performing acidification reaction at a high temperature and then cooling for crystallizing is low in purity and small in crystal size and easily causes equipment corrosion are solved. The method has the advantages that the prepared produce has a great crystal size and a high purity, energy consumption is low, equipment corrosion is hardly caused, the operation is simplified and the process is easily controlled automatically.

The invention relates to a method of inducing and culturing plant callus tissue and especially discloses a method of quickly inducing and breeding halogeton glomeratus radicle callus tissue. The method includes following steps: (1) obtaining sterilized explants; (2) performing callus tissue induction; and (3) performing callus tissue proliferation cultivation. Through subculture, a large amount of excellent callus tissue materials, which are white in color and crisp in structure, are obtained, and a problem of lignifications of root system is solved as well. The invention provides technical base for tissue culture of halogeton glomeratus radicle and cell suspension culture. The culture mediums used in induction and subculture of the callus tissue are all prepared with 2,4-D (2,4-dichlorophenoxyacetic acid) as an exogenous hormone, so that seedling culture, radicle callus induction and callus proliferation are all carried out under the same environment, thereby achieving a good effect. The halogeton glomeratus radicle callus tissue can be obtained simply, easily and high-effectively.

The invention discloses a method for producing ester of 2, 4-dichlorphenoxyacetic acid, wherein the finished product of the ester of the 2, 4-dichlorphenoxyacetic acid is prepared by reacting phenoxyacetic acid with chlorine introduced into an alcohol solvent in the presences of phenothiazine and dimethylamino pyridine as catalysts. The finished product of the ester of the 2, 4-dichlorphenoxyacetic acid can be directly produced from phenoxyacetic acid in one reaction kettle, without separating the intermediate 2, 4-dichlorphenoxyacetic acid by using the method. The total yield of the finishedproduct of the ester of the 2, 4-dichlorphenoxyacetic acid can be increased to more than 95%, and the content of effective ingredients can be increased to more than 95%.

The invention provides a ginseng medium for increasing the content of panaxoside, and belongs to the technical field of ginseng tissue culture. A medium B5 is used as a basic medium, and naphthylacetic acid (NAA), 2,4-D(2,4-dichlorphenoxyacetic acid), lanthanum nitrate, agar powder and white granulated sugar are added. The medium has the advantages of being capable of increasing the content of panaxoside in callus and promoting callus proliferation.

The invention discloses a herbicidal composition containing bentazone and 2,4-dichlorophenoxyacetic acid. The herbicidal composition uses bentazone and 2,4-dichlorophenoxyacetic acid as main active ingredients. The mass ratio of pine to 2,4-dichlorophenoxyacetic acid is 1-80:1-80. The herbicidal composition of the present invention is applied to post-emergence weeding in wheat and paddy fields, especially for controlling broad-leaved weeds in wheat and paddy fields, and has remarkable effects. Compared with a single dose, the herbicidal composition of the present invention delays weed resistance, has a wide herbicidal spectrum, long duration of action and is safe to wheat and subsequent crops on the premise of improving the efficacy of a single agent.

The invention discloses a method for adding 2,4-dichlorphenoxyacetic acid to improve the yield of DHA (Docosahexaenoic Acid) in schizochytrium limacinum and promote the oil accumulation of schizochytrium limacinum in a schizochytrium limacinum growth process, and belongs to the technical field of microalgae biology. The method specifically comprises the following operating steps: (1) adding 2,4-dichlorphenoxyacetic acid at different concentrations in a regulation period of the growth of the schizochytrium limacinum; (2) analyzing the influence of the addition of the 2,4-dichlorphenoxyacetic acid at different concentrations on oil accumulation and DHA content. According to the method, the addition of the 2,4-dichlorphenoxyacetic acid for improving the oil accumulation of the schizochytrium limacinum and increasing the DHA content in the schizochytrium limacinum growth process is put forward for the first time, and a new idea is provided for promoting the oil accumulation of the schizochytrium limacinum and increasing the DHA content by virtue of a chemical method.

The invention provides a one step method for micropropagation of tea plants from leaf explants via callus phase, wherein the explants are maintained in basal Murashige and Skoog medium (Murashige T. and Skoog F. A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiol. Plant. 15: 473-497; 1962) supplemented with vitamins like thiamine-HCl (0.05 to 2.0 mg / l), pyridoxine-HCl (0.25 to 1.5 mg / l) and nicotinic acid (0.25 to 1.5 mg / l) together with glycine (1.0 to 3.0 mg / l) and either 2.5, 5.0 or 7.5 mg / l 2,4-Dichlorophenoxy acetic acid for a period of 14-16 weeks, from the stage of induction of callus to rhizogenesis and shoot formation.

The invention relates to an piezoelectric immuno-sensing method for detecting 2,4-dichlorphenoxyacetic acid (2,4-D) content in agricultural products, mainly comprising the following steps: 1) coupling 2,4-dichlorphenoxyacetic acid with BSA; 2) preparing an electrode modification immunosensor; 3) preparing a Goat anti Mouse IgG antibody marked with nanogold; 4) preparing a standard curve; and 5) detecting a sample. The invention has the beneficial effect: during detection, the Goat anti Mouse IgG antibody marked with nanogold magnifies a signal to improve detection sensitivity so as to realize the high-sensitivity quantitative detection of 2,4-D. The invention is in linear relation when 2,4-D concentration is 13.3 ng.mL<-1>-666 ng.mL<-1> and has the lower limit of detection of 13 ng.mL<-1>. Meanwhile, the method has the advantages of simple method, reliable result, low cost and the like.

The invention provides a preparation method for 2,4-dichlorophenoxyacetic acid. The preparation method comprises the following steps: a) reacting halogenated acetate with 2,4-dichlorophenolate so as to obtain 2,4-dichlorophenoxyacetate; and B) hydrolyzing 2,4-dichlorophenoxyacetate under the action of a catalyst so as to obtain 2,4-dichlorophenoxyacetic acid, wherein the catalyst is one or more selected from the group consisting of polyether, crown ether, quaternary ammonium salt, tertiary amine, quaternary phosphonium salt, pyridine, titanate, inorganic acid and organic acid. According to theinvention, halogenated acetate reacts with 2,4-dichlorophenolate to obtain 2,4-dichlorophenoxyacetate, and then 2,4-dichlorophenoxyacetate is hydrolyzed to obtain 2,4-dichlorophenoxyacetic acid. Through usage of a specific reaction route and the specific catalyst of the invention, the finally prepared 2,4-dichlorophenoxyacetic acid has high purity and yield, few by-products are produced, the reaction route is simple, and the application of the preparation method is facilitated.