阅读说明：本技术 一种萘乙酸的制备方法 (Preparation method of naphthylacetic acid ) 是由 郑先福 闻东亮 许伟长 于 2019-11-26 设计创作，主要内容包括：本发明公开了一种萘乙酸的制备方法,以1-氯甲基萘为起始原料,以碘化亚铜为催化剂,在反应体系中加入三乙基苄基氯化铵作为相转移催化剂,以亚铁氰化钾为氰源制备萘乙酸。本发明利用亚铁氰化钾代替传统的氰化钾或氰化钠为氰源,避免了生产过程中氰化钾或氰化钠对操作人员的安全威胁,减少了剧毒物质对环境的污染,本发明的制备方法具有后处理简便、能耗低和三废少的优点。(The invention discloses a preparation method of naphthylacetic acid, which takes 1-chloromethyl naphthalene as an initial raw material, cuprous iodide as a catalyst, triethyl benzyl ammonium chloride as a phase transfer catalyst is added into a reaction system, and potassium ferrocyanide as a cyanide source to prepare the naphthylacetic acid. The preparation method disclosed by the invention has the advantages that potassium ferrocyanide is used for replacing the traditional potassium cyanide or sodium cyanide as a cyanogen source, the safety threat of the potassium cyanide or the sodium cyanide to operators in the production process is avoided, and the pollution of toxic substances to the environment is reduced.)

1. A preparation method of naphthylacetic acid is characterized by comprising the following steps:

(1) weighing 1-chloromethyl naphthalene and potassium ferrocyanide in a molar ratio of 1:0.3-1:0.6, taking toluene as a solvent, adding a catalyst and a phase transfer catalyst into the mixed solution, placing the mixed solution in an autoclave for closed reaction, heating the mixed solution to 140 ℃ and 180 ℃, and reacting the mixed solution for 10-12 hours under stirring to obtain a mixed solution containing naphthylacetonitrile;

(2) cooling the mixed solution containing the naphthylacetonitrile obtained in the step (1) to room temperature, filtering to remove insoluble substances, retaining the filtrate, concentrating the filtrate under negative pressure to obtain yellow oily substances, wherein the distilled substances are toluene, and recycling;

(3) heating and refluxing the yellow oily substance obtained in the step (2) by using a sodium hydroxide solution with solute mass fraction of 5% -15% for 3-6h, cooling to room temperature, washing the aqueous solution by using a recovered toluene solvent, carrying out phase separation, and drying an upper organic phase by using solid sodium hydroxide to serve as a reaction solvent;

(4) adjusting the pH of the water phase to be 2-3 by hydrochloric acid with the solute mass fraction of 30%, separating out white solid, filtering, and keeping the solid;

(5) dissolving the filter solids obtained in the step (4) with hot water, slowly cooling to separate out white crystals, and filtering to obtain a naphthylacetic acid wet product;

(6) and (4) blowing and drying the wet naphthylacetic acid product obtained in the step (5) at the temperature of 80-90 ℃ to obtain a pure naphthylacetic acid product.

2. The method for producing naphthaleneacetic acid according to claim 1, wherein in the step (1), the catalyst is cuprous iodide, and the molar ratio of 1-chloromethylnaphthalene to cuprous iodide is 1:0.05 to 1: 0.3.

3. The method of claim 1, wherein in step (1), the phase transfer catalyst is triethylbenzylammonium chloride, and the molar ratio of 1-chloromethylnaphthalene to triethylbenzylammonium chloride is 1:0.05 to 1: 0.3.

4. The method for producing naphthaleneacetic acid according to claim 1, wherein in the step (1), the mass ratio of 1-chloromethylnaphthalene to toluene is 1:10 to 1: 40.

5. The method for producing naphthaleneacetic acid according to claim 1, wherein in the step (3), the solute mass fraction of the sodium hydroxide solution is 10%.

Technical Field

The invention relates to the technical field of preparation of plant growth regulators, in particular to a preparation method of naphthylacetic acid.

Background

The naphthylacetic acid is a broad-spectrum plant growth regulator, can be used for increasing effective tillering of wheat and rice, raising earning rate, promoting grain filling and increasing yield, also can be used for increasing yield of sweet potato and cotton, can be used for solanaceous vegetables and melons, can prevent flower and fruit dropping and forming seedless fruit, and can also be used for increasing drought and waterlogging resistance, saline-alkali resistance and lodging resistance of plants.

The conventional preparation method of naphthylacetic acid comprises the following steps:

(1) adding naphthalene and chloroacetic acid into a reaction kettle, adding iron powder (or ferric oxide, aluminum powder and the like) and potassium bromide as catalysts, heating to react for about 50 hours, extracting naphthylacetic acid by using a sodium hydroxide aqueous solution, filtering, wherein insoluble substances are unreacted substances containing naphthalene, preparing a naphthylacetic acid crude product from filtrate by adjusting acid, recrystallizing with hot water to obtain a white crystal naphthylacetic acid pure product, and distilling filter residue containing naphthalene by using water vapor to recover the naphthalene for the next reaction, wherein the yield of the method is generally 30-50%, a large amount of naphthalene does not participate in the reaction and has to be recycled, and the naphthalene has a large odor and pollutes the environment and has harm to the health of operators in the recovery process;

(2) 1-chloromethyl naphthalene and potassium cyanide or sodium cyanide are refluxed and reacted in methanol-water for 2 hours, after concentrating and recovering methanol, the residual mixed solution is subjected to phase splitting, the oil phase is naphthalene acetonitrile, the naphthalene acetonitrile is refluxed and reacted in a sodium hydroxide aqueous solution, the reaction solution is washed by an organic solvent, the aqueous solution is adjusted to acid to separate out a crude naphthalene acetic acid product, and the pure naphthalene acetic acid product is obtained by filtering and recrystallization.

In recent years, K₄[Fe(CN)₆]That is, potassium ferrocyanide is successfully applied to cyanidation reaction as a cyanidation reagent, which is not only cheap (equivalent to the price of NaCN), but also very low in toxicity, and the 'dangerous chemical catalogue' of China 2015 edition shows that half of the potassium ferrocyanide is 1600-3200 mg/kg (rat oral cavity), and half of the salt is 3000mg/kg (rat oral cavity), so that the toxicity of the potassium ferrocyanide is close to that of the salt which is often eaten by people.

Similar reactions involving potassium ferrocyanide as the source of cyanide include:

(1) yunlai Ren et al reported in Tetrahedron Letters,2011,52,5107-5109 that 1-chloromethylnaphthalene reacted with potassium ferrocyanide in toluene in a reaction yield of 5% catalyzed by palladium acetate with triphenylphosphine as a ligand (Yunlai Ren et al, Pd-catalyzed cyclization of benzyl ch)lorides with nontoxic K₄[Fe(CN)₆][J]Tetrahedron Letters 52(2011)5107-5109), ligand triphenylphosphine and catalyst palladium acetate used in the reaction are expensive, and industrial application cannot be realized;

the reaction process is as follows:

(2) yunlai Ren et al report benzyl chloride to react with potassium ferrocyanide in toluene in Tetrahedron Letters,2012,53, 2825-2827 by using cuprous iodide as a catalyst at 180 ℃ for 20 hours under nitrogen protection (Yunlai Ren et al, coater-catalyzed circulation of benzyl chlorides with non-toxic K)₄[Fe(CN)₆][J]Tetrahedron Letters 53(2012) 2825-2827); in the report, no reaction is seen in which 1-chloromethyl naphthalene is used as a substrate, and experiments prove that the yield of the naphthylacetonitrile prepared by the method is less than 5%, and the yield of the reaction is too low and probably caused by larger steric hindrance of the 1-chloromethyl naphthalene.

The reaction process is as follows:

disclosure of Invention

The invention provides a preparation method of naphthylacetic acid, aiming at improving the defects of low utilization rate of naphthalene, complex recovery process and use of a highly toxic cyanide in the existing method.

The purpose of the invention is realized as follows:

a preparation method of naphthylacetic acid comprises the following steps:

(1) weighing 1-chloromethyl naphthalene and potassium ferrocyanide in a molar ratio of 1:0.3-1:0.6, taking toluene as a solvent, adding a catalyst and a phase transfer catalyst into the mixed solution, placing the mixed solution in an autoclave for closed reaction, heating the mixed solution to 140 ℃ and 180 ℃, and reacting the mixed solution for 10-12 hours under stirring to obtain a mixed solution containing naphthylacetonitrile;

(2) cooling the mixed solution containing the naphthylacetonitrile obtained in the step (1) to room temperature, filtering to remove insoluble substances, retaining the filtrate, concentrating the filtrate under negative pressure to obtain yellow oily substances, wherein the distilled substances are toluene, and recycling;

(3) heating and refluxing the yellow oily substance obtained in the step (2) by using a sodium hydroxide solution with solute mass fraction of 5% -15% for 3-6h, cooling to room temperature, washing the aqueous solution by using a recovered toluene solvent, carrying out phase separation, and drying an upper organic phase by using solid sodium hydroxide to serve as a reaction solvent;

(4) adjusting the pH of the water phase to 2-3 by hydrochloric acid with the solute mass fraction of 30%, separating out white solid, filtering, and keeping the filtered solid;

(5) dissolving the filter solids obtained in the step (4) with hot water, slowly cooling to separate out white crystals, and filtering to obtain a naphthylacetic acid wet product;

(6) and (4) blowing and drying the wet naphthylacetic acid product obtained in the step (5) at the temperature of 80-90 ℃ to obtain a pure naphthylacetic acid product.

In the step (1), the catalyst is cuprous iodide, and the molar ratio of the 1-chloromethyl naphthalene to the cuprous iodide is 1:0.05-1: 0.3.

In the step (1), the phase transfer catalyst is triethylbenzylammonium chloride, and the molar ratio of the 1-chloromethylnaphthalene to the triethylbenzylammonium chloride is 1:0.05-1: 0.3.

In the step (1), the mass ratio of the 1-chloromethyl naphthalene to the toluene is 1:10-1: 40.

In the step (3), the solute mass fraction of the sodium hydroxide solution is 10%.

The invention has the following beneficial effects:

(1) the invention takes the intermediate 1-chloromethyl naphthalene which is easy to prepare as the initial raw material, and the method does not need to consider the problem of naphthalene recovery, thereby reducing the pollution of the smell of naphthalene to the environment;

(2) the potassium ferrocyanide is used for replacing the traditional potassium cyanide and sodium cyanide which are cyanogen sources, so that the requirement on equipment is reduced, the environmental pollution caused by toxic substances is reduced, and the safety of operators is improved;

(3) in the preparation process, a catalyst cuprous iodide and a phase transfer catalyst triethylbenzylammonium chloride are added, so that the reaction conversion rate is improved, the reaction time is shortened to 10-12h, and the production efficiency is improved;

(4) the solvent is concentrated and recovered, and the unreacted 1-chloromethyl naphthalene in the sodium hydroxide aqueous solution is washed and then continuously used, so that the utilization rate of the raw materials is improved.

Drawings

FIG. 1 is a process flow diagram of a process for preparing naphthylacetic acid in accordance with the present invention.

FIG. 2 shows nuclear magnetic hydrogen spectra of naphthaleneacetonitrile in yellow oil prepared in example 1.

FIG. 3 shows nuclear magnetic hydrogen spectra of the pure naphthylacetic acid prepared in example 1.

FIG. 4 is a liquid phase diagram of naphthaleneacetonitrile in yellow oil prepared in example 2.

FIG. 5 is a liquid phase diagram of a purified naphthylacetic acid prepared in example 2.

Detailed Description