(+) -2- (4-hydroxyphenoxy) propionic acid - ...

Preparation method of R- (+) -2- (4-hydroxyphenoxy) propionic acid

Technical Field

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The invention relates to the field of compound preparation, and in particular relates to a preparation method of R- (+) -2- (4-hydroxyphenoxy) propionic acid.

Background

The R- (+) -2- (4-hydroxyphenoxy) propionic acid is an important intermediate for synthesizing aryloxy propionic acid herbicides such as thiazole diclofop-methyl, clodinafop-propargyl and high-efficiency galingale, and the appearance is white or off-white crystal powder.

The synthesis method reported in the literature and the patent at present mainly takes hydroquinone and derivatives thereof as starting materials to prepare R- (+) -2- (4-hydroxyphenoxy) propionic acid, and has the defects of excessive alkylation of hydroquinone, incomplete reaction and excessive impurities.

The preparation of R- (+) -2- (4-hydroxyphenoxy) propionic acid by reaction of an excess of hydroquinone with s-2-halopropionic acid is proposed in patent EP and has two problems: one is the over-alkylation of hydroquinone; the second is the problem of hydroquinone oxidation. A complex purification scheme is provided in EP .

In patent CN, p-hydroxyphenol sodium salt and S-2-chloropropionic acid sodium salt are adopted to react in an organic solvent, disubstituted impurities are not reduced, and meanwhile, the production difficulty is greatly increased by recycling the organic solvent. The product is distilled out by post treatment, and the production energy consumption is large.

In patent CN, a scheme of recovering excessive hydroquinone by using alkali liquor is adopted, and at the same time, the use of reducing agent sodium bisulfite is added, so that the problem of purifying hydroquinone is avoided, but excessive alkylation reaction of hydroquinone is still unavoidable.

In patent CN, R-2-phenoxypropionic acid is used as raw material, and is prepared by fermenting pseudodragonfly silk yeast-1, the method has the disadvantages of difficult yeast culture, long reaction time, much waste water and low production efficiency.

Disclosure of Invention

In order to solve the technical problems, the technical scheme of the invention is a preparation method of R- (+) -2- (4-hydroxyphenoxy) propionic acid, phenol and organic acid or organic acid salt are used as raw materials, and the purification is simple and the purity is high. The preparation method adopts the following synthetic route:

a process for preparing R- (+) -2- (4-hydroxyphenoxy) propionic acid comprises

Mixing phenol, S-2-chloropropionic acid or salt thereof, water and a first catalyst in a closed environment, and heating for alkylation reaction under the protection of inert gas to prepare 2-phenoxypropionic acid;

mixing 2-phenoxypropionic acid, a second catalyst and a halogenating reagent, and reacting at 20-30 &#; to prepare 2- (4-halogenated phenoxy) propionic acid;

2- (4-halogenated phenoxy) propionic acid, alkali solution and a third catalyst are reacted under the condition of sealing at the temperature of 150 &#; and 160 &#; under the micro pressure, and after the reaction is finished, R-2- (4-hydroxyphenoxy) propionic acid is prepared by filtration and acidification.

Preferably, the first catalyst is selected from: DMF, triethylamine, pyridine, sodium hydroxide, potassium carbonate, sodium carbonate or sodium bicarbonate.

Preferably, the phenol, the S-2-chloropropionic acid or the salt thereof and the first catalyst are in an equivalent ratio of 1 (0.8-1.2) to (0.5-3.0).

Preferably, the halogenating agent is selected from: NBS, NCS, bromine, phosphorus trichloride, phosphorus pentachloride, phosphorus oxychloride, thionyl chloride, phosgene, diphosgene or triphosgene.

Preferably, the second catalyst is selected from: DMF, triethylamine, pyridine, sodium hydroxide, potassium carbonate, sodium carbonate and sodium bicarbonate.

Preferably, the phenoxypropionic acid, the halogenating agent and the second catalyst are in an equivalent ratio of 1 (1.0-1.5) to (0.005-0.05).

Preferably, the third catalyst is a supported catalyst selected from the group consisting of a 3A (potassium A type) molecular sieve, a 4A (sodium A type) molecular sieve, a 5A (calcium A type) molecular sieve, a 10Z (calcium Z type) molecular sieve, a 13Z (sodium Z type) molecular sieve, a Y (sodium Y type) molecular sieve, a zeolite type molecular sieve, α -alumina, β -alumina, gamma-alumina, or an ion exchange resin.

Preferably, the third catalyst is a supported catalyst selected from the group consisting of: load type copper chloride, load type ferric chloride, load type magnesium chloride, load type cuprous chloride, load type ferrous chloride, load type cupric oxide, load type cuprous oxide or copper powder.

Preferably, the preparation method of the supported catalyst comprises the following steps: putting the load into a catalyst aqueous solution (the mass fraction is 20-30%), heating to 50-100 &#;, carrying out heat preservation reaction for 3-10 h, cooling and filtering. Drying the obtained solid, placing the dried solid in a muffle furnace, and activating for 2-3h at the temperature of 150-.

Preferably, the pressure of the micro-pressure reaction under the sealing is controlled between 0.01 and 1 bar.

The primary improvement of the invention is to provide a novel preparation method of R- (+) -2- (4-hydroxyphenoxy) propionic acid. Under the protection of inert gas, phenol and S-2-chloropropionic acid or salt thereof are used for preparing 2-phenoxypropionic acid under the alkaline condition, a halogenating reagent is used for carrying out halogenation reaction to prepare 2- (4-halophenoxy) propionic acid, and the 2- (4-hydroxyphenoxy) propionic acid is prepared by hydrolysis under the action of a supported copper chloride catalyst. The method has the advantages of simple and easily obtained raw materials, simple synthetic route and less reaction impurities.

Compared with the preparation process adopting hydroquinone as the starting material in the traditional process, the preparation method adopts phenol as the raw material, does not generate para-alkylation reaction in the reaction, and can avoid the generation of polyphenol over-alkylation impurities.

In the invention, NBS is used as a halogenating reagent, DMF is used as a catalyst, the generation of polyhalogenated impurities in the halogenation reaction can be effectively controlled, and the yield of 2- (4-bromophenoxy) propionic acid in the reaction can reach more than 98%.

The invention provides a preparation method of a high-efficiency halohydrocarbon hydrolysis and a catalyst thereof. The gamma-alumina supported copper chloride catalyst is adopted to hydrolyze the 2- (4-bromophenoxy) propionic acid, the reaction yield is high, the by-products are few, the catalyst can be reused after being activated, and meanwhile, the reaction system is closed, thereby being beneficial to environmental protection and industrial production.

The average yield of the invention is not lower than 85%, and the product purity is more than 99.5%.

Drawings

FIG. 1 is a 2-phenoxypropionic acid nuclear magnetic hydrogen spectrum-1H NMR provided by an example of the present invention;

FIG. 2 is the nuclear magnetic spectrum-1 HNMR of 2- (4-bromophenoxy) propionic acid provided by the embodiment of the present invention;

FIG. 3 shows nuclear magnetic resonance spectrum-1 HNMR of R- (+) -2- (4-hydroxyphenoxy) propionic acid provided by the embodiment of the present invention.

Detailed Description

In order that those skilled in the art will better understand the technical solutions of the present invention, the present invention will be further described in detail with reference to the following embodiments.

The synthetic reaction path of the R- (+) -2- (4-hydroxyphenoxy) propionic acid provided by the invention is as follows:

the above route comprises the following steps:

the first step is as follows: mixing phenol and S-2-chloropropionic acid or salts thereof in a closed environment, adding water and a catalyst, and heating for alkylation reaction under the protection of inert gas to prepare 2-phenoxypropionic acid;

the second step is that: dissolving 2-phenoxy propionic acid in water, adding a catalyst, adding a halogenating reagent, and reacting at 20-30 &#; for 8h to prepare 2- (4-halogenophenoxy) propionic acid;

the third step: putting the catalyst load into a copper chloride aqueous solution (mass fraction is 20-30%), heating to 50-100 &#;, reacting for 3-10 h under heat preservation, cooling and filtering. Drying the obtained solid, placing the dried solid in a muffle furnace, and activating for 2-3h at the temperature of 150-;

the fourth step: adding 2- (4-halogenated phenoxy) propionic acid, 30% liquid alkali and a supported copper chloride catalyst into an autoclave, carrying out a micro-pressure reaction at the temperature of 150 &#; and 160 &#; in a sealed manner, and preparing the R-2- (4-hydroxyphenoxy) propionic acid by filtering and acidifying after the reaction is finished.

Preferably, the first alkylation reaction specifically comprises: mixing phenol, S-2-chloropropionic acid or salt thereof and a catalyst according to an equivalent ratio of 1 (0.8-1.2) to (0.5-3.0), preferably 1 (0.9-1.0) to (1-1.5); the reaction time is about 2-10 hours, and more preferably 4-6 hours; the heat preservation temperature is 30-100 &#;, and more preferably 50-70 &#;; the inert gas is nitrogen; the first catalyst is selected from: DMF, triethylamine, pyridine, sodium hydroxide, potassium carbonate, sodium bicarbonate, more preferablySodium hydroxide is selected; the reaction is finished when the conversion rate of the chloropropionic acid is more than 99 percent, and the reaction is finished when the conversion rate of the chloropropionic acid is more than 99.5 percent; the method for the central control analysis of the S-2-chloropropionic acid comprises the following steps: high performance liquid HPLC, Agilent C18 column (5 μm, 250X 4.6 mm); mobile phase: 0.05% H3PO4Methanol (90: 10); detection wavelength: 210 nm; flow rate: 1.0 ml/min; column temperature: 40 &#;; sample introduction amount: 10 μ l.

According to the invention, the second step reaction is specifically:

2-phenoxypropionic acid, a halogenating agent and a catalyst are mixed according to an equivalent ratio of 1 (1.0-1.5) to 0.005-0.05, and more preferably 1 (1.1-1.2) to 0.01-0.02; the reaction time is about 4-8 hours, preferably 5-6 hours; the heat preservation temperature is 0-50 &#;, and more preferably 20-30 &#;; the reaction is ended when the conversion rate of the 2-phenoxypropionic acid is more than 95 percent, and the reaction is ended when the conversion rate of the 2-phenoxypropionic acid is more than 98 percent;

the 2-phenoxypropionic acid central control analysis method comprises the following steps: HPLC, Agilent C18 column (5 μm, 250X 4.6 mm); mobile phase: 0.05% H3PO4Methanol (90: 10); detection wavelength: 210 nm; flow rate: 1.0 ml/min; column temperature: 40 &#;; sample introduction amount: 10 μ l.

The second catalyst is selected from: DMF, triethylamine, pyridine, sodium hydroxide, potassium carbonate, sodium bicarbonate, more preferably DMF; preferably, the halogenating agent is selected from: NBS, NCS, bromine, phosphorus trichloride, phosphorus pentachloride, phosphorus oxychloride, thionyl chloride, phosgene, diphosgene, triphosgene, more preferably NBS.

According to the invention, the third step reaction is specifically as follows:

mixing the copper chloride aqueous solution and the molecular sieve according to the mass ratio of 1 (5-10), and preferably 1 (7-8); the reaction time is about 3-10 hours, preferably 5-6 hours; the heat preservation temperature is 50-100 &#;, and more preferably 70-80 &#;;

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the third catalyst is a supported catalyst, and the supported matter is selected from a 3A (potassium A type) molecular sieve, a 4A (sodium A type) molecular sieve, a 5A (calcium A type) molecular sieve, a 10Z (calcium Z type) molecular sieve, a 13Z (sodium Z type) molecular sieve, a Y (sodium Y type) molecular sieve, a zeolite type molecular sieve, α -alumina, β -alumina, gamma-alumina, ion exchange resin, and more preferably gamma-alumina.

The supported catalyst is selected from the group consisting essentially of: copper chloride, ferric chloride, magnesium chloride, cuprous chloride, ferrous chloride, cupric oxide, cuprous oxide, copper powder, and more preferably cupric chloride.

According to the invention, the fourth reaction step is specifically:

2- (4-halogenated phenoxy) propionic acid, 30% liquid alkali and a supported copper chloride catalyst are mixed according to an equivalent ratio of 1 (2-10) to (0.01-0.2), and more preferably 1 (3-5) to (0.05-0.1); the heat preservation temperature is 100-200 &#;, and more preferably 150-160 &#;; the reaction pressure is controlled between 0.05 and 1bar, and more preferably between 0.1 and 0.2 bar; the reaction is ended when the conversion rate of the 2- (4-halogenated phenoxy) propionic acid is more than 98 percent, and the reaction is ended when the conversion rate of the 2- (4-halogenated phenoxy) propionic acid is more than 99.5 percent; the central control analysis method of the 2- (4-halogenated phenoxy) propionic acid comprises the following steps: high performance liquid HPLC, Agilent C18 column (5 μm, 250X 4.6 mm); mobile phase: 0.05% H3PO4Methanol (90: 10); detection wavelength: 210 nm; flow rate: 1.0 ml/min; column temperature: 40 &#;; sample introduction amount: 10 μ l.

The following are specific examples, which illustrate specific technical solutions of the present invention in detail:

the invention relates to a preparation method of R- (+) -2- (4-hydroxyphenoxy) propionic acid, which comprises the following steps:

the first step is as follows:

adding phenol (1.0eq), S-2-chloropropionic acid (0.9-1.0 eq), sodium hydroxide (1.0-1.5 eq) and water (5.0eq) into a reaction kettle, replacing with nitrogen for three times, heating to 50-70 &#;, keeping the temperature for reaction for 4-6 hours, and monitoring the conversion rate of the S-2-chloropropionic acid by HPLC (high performance liquid chromatography) to be more than 99.5 percent to finish the reaction. Cooling, adjusting pH to less than 1 with 31% hydrochloric acid, cooling to below 10 deg.C, stirring for 30 min for crystallization, filtering to obtain 2-phenoxypropionic acid crude product, and recrystallizing with water to obtain product with purity of not less than 99%.

The second step is that:

dissolving 2-phenoxypropionic acid (1.0eq) in water, adding a catalyst (0.01-0.02 eq), adding a halogenating agent (1.1-1.2 eq) at 20-30 &#;, reacting for 8 hours at 20-30 &#; after the addition is finished, and monitoring the conversion rate of the 2-phenoxypropionic acid by HPLC to be more than 98 percent to finish the reaction. Cooling, adjusting pH to less than 1 with 31% hydrochloric acid, layering, cooling water phase to below 10 deg.C, stirring for 30 min, crystallizing, and vacuum filtering to obtain crude 2- (4-halogenated phenoxy) propionic acid product.

The third step:

adding gamma-alumina (7-8 eq) into copper chloride aqueous solution (20-25 wt%, 1.0eq), heating to 70-80 &#; under stirring, and reacting for 5-6 hours under heat preservation. After the reaction is finished, cooling to room temperature, performing suction filtration, rinsing the filter cake with a small amount of water, airing, placing the filter cake in a muffle furnace, and activating at the temperature of 150-200 &#; for 2-3h to obtain the gamma-alumina supported copper chloride catalyst.

The fourth step:

putting 1.0eq of 2- (4-halogenated phenoxy) propionic acid, 3-5 eq of 30% liquid alkali and 0.05-0.1 eq of molecular sieve-loaded copper chloride catalyst into a pressure kettle, replacing with nitrogen for three times, and sealing the equipment. Heating to 150-160 &#; under stirring, controlling the reaction pressure at 0.1-0.2 bar, and finishing the reaction when the conversion rate of the 2- (4-halogenated phenoxy) propionic acid is monitored by HPLC to be more than 99.5%. Cooling, replacing with nitrogen for three times, transferring the reaction solution to an acidification kettle, adjusting the pH to be less than 1 by using 31% hydrochloric acid, cooling to be below 10 &#;, stirring for 30 minutes for crystallization, performing suction filtration to obtain a crude product of R- (+) -2- (4-hydroxyphenoxy) propionic acid, and recrystallizing by using water, wherein the purity is more than or equal to 99.5%.

The above reaction equation is:

main reaction:

side reaction:

treatment of impurities a and B in side reactions: the impurity A and the impurity B are basically insoluble in water, when the pH is less than 1, the reaction solution is kept stand to separate an oil layer, and the impurities can be separated.

The invention will now be further illustrated with reference to the following examples.

Example 1

Preparation of 2-phenoxypropionic acid

94g (1mol, 1.0eq) of phenol, 108.5g (1mol, 1.0eq) of S-2-chloropropionic acid, 200g (1.5mol, 1.5eq) of 30% sodium hydroxide and 470g of water are added into ml of the mixture, the mixture is replaced by nitrogen for three times, the mixture is heated to 50-70 &#;, the mixture is subjected to heat preservation reaction for 4-6 hours, and the reaction is finished when the content of S-2-chloropropionic acid is less than or equal to 0.5% by HPLC monitoring. Cooling, adjusting pH to less than 1 with 31% hydrochloric acid, cooling to below 10 deg.C, stirring for 30 min, crystallizing, vacuum filtering, and recrystallizing with water to obtain 157.8g of 2-phenoxypropionic acid with yield of 95% and purity of 99.3%.

Example 2

Preparation of 2- (4-bromophenoxy) propionic acid

Dissolving 83g (0.5mol, 1.0eq) of 2-phenoxypropionic acid in water, adding 0.6g (0.mol, 0.015eq) of DMF, adding 102g (0.575mol, 1.15eq) of NBS at 20-30 &#;, reacting for 8h at 20-30 &#; after the addition is finished, and finishing the reaction when HPLC monitors that the content of 2-phenoxypropionic acid is less than or equal to 2%. Cooling, adjusting pH to less than 1 with 31% hydrochloric acid, layering, cooling water phase to below 10 deg.C, stirring for 30 min, crystallizing, and vacuum filtering to obtain 116.5g of 2- (4-bromophenoxy) propionic acid with yield of 95.1% and purity of 98.7%.

Example 3

Preparation of gamma-alumina supported copper chloride catalyst

57g (7.5eq) of gamma-alumina is put into 50g (20 percent by mass, 1.0eq) of copper chloride aqueous solution, the temperature is raised to 70-80 &#; under stirring, and the reaction is kept for 5-6 hours. And after the reaction is finished, cooling to room temperature, performing suction filtration, rinsing a filter cake with a small amount of water, airing, placing the filter cake in a muffle furnace, and activating at 180 &#; for 3 hours to obtain 65g of the gamma-alumina supported copper chloride catalyst.

Example 4

Synthesis of R- (+) -2- (4-hydroxyphenoxy) propionic acid

122.5g (0.5mol, 1.0eq) of 2- (4-bromophenoxy) propionic acid, 67g (4.0eq) of 30% liquid alkali, 6.2g (0.05eq) of a gamma-alumina supported copper chloride catalyst, and 200g of water were put into a pressure vessel, replaced with nitrogen three times, and the apparatus was sealed. Heating to 150-160 &#; under stirring, controlling the reaction pressure at 0.1-0.2 bar, and finishing the reaction when the content of 2- (4-halogenated phenoxy) propionic acid is monitored by HPLC (high performance liquid chromatography) to be less than or equal to 0.5%. Cooling, replacing with nitrogen for three times, transferring the reaction solution to an acidification kettle, adjusting the pH to be less than 1 by using 31% hydrochloric acid, cooling to be below 10 &#;, stirring for 30 minutes for crystallization, and performing suction filtration and recrystallization by using water to obtain 89.2g of R- (+) -2- (4-hydroxyphenoxy) propionic acid, wherein the yield is 98%, and the purity is more than or equal to 99.5%.

Comparative example 1

Preparation of 3-phenoxypropionic acid (refer to the preparation process of 2-phenoxypropionic acid in example 1), the specific data are shown in table 1:

table 1: analytical data for preparing 2-phenoxypropionic acid at different feed ratios

Comparative example 2

Preparation of 2- (4-bromophenoxy) propionic acid (refer to preparation of 2- (4-bromophenoxy) propionic acid in example 1), the specific data are shown in table 2:

table 2: analytical data for preparing 2- (4-bromophenoxy) propionic acid at different feed ratios

Comparative example 3

Preparation of R- (+) -2- (4-hydroxyphenoxy) propionic acid by catalysis of molecular sieve loaded copper chloride catalyst

122.5g (0.5mol, 1.0eq) of 2- (4-bromophenoxy) propionic acid, 67g (4.0eq) of 30% liquid alkali, 6.2g (0.05eq) of 4A molecular sieve-supported copper chloride catalyst and 200g of water are put into a pressure kettle, nitrogen is replaced for three times, and the equipment is sealed. Heating to 150-160 &#; under stirring, controlling the reaction pressure at 0.1-0.2 bar, and finishing the reaction when the content of 2- (4-halogenated phenoxy) propionic acid is monitored by HPLC (high performance liquid chromatography) to be less than or equal to 0.5%. Cooling, replacing with nitrogen for three times, transferring the reaction solution to an acidification kettle, adjusting the pH to be less than 1 by using 31% hydrochloric acid, cooling to be below 10 &#;, stirring for 30 minutes for crystallization, and performing suction filtration and recrystallization by using water to obtain 81.9g of R- (+) -2- (4-hydroxyphenoxy) propionic acid, wherein the yield is 90%, and the purity is more than or equal to 97.5%.

Comparative example 4

Preparation of R- (+) -2- (4-hydroxyphenoxy) propionic acid by catalysis of gamma-alumina supported copper oxide catalyst

122.5g (0.5mol, 1.0eq) of 2- (4-bromophenoxy) propionic acid, 67g (4.0eq) of 30% liquid alkali, 6.2g (0.05eq) of a gamma-alumina-supported copper oxide catalyst, and 200g of water were put into a pressure vessel, replaced with nitrogen three times, and the apparatus was sealed. Heating to 150-160 &#; under stirring, controlling the reaction pressure at 0.1-0.2 bar, and finishing the reaction when the content of 2- (4-halogenated phenoxy) propionic acid is monitored by HPLC (high performance liquid chromatography) to be less than or equal to 0.5%. Cooling, replacing with nitrogen for three times, transferring the reaction solution to an acidification kettle, adjusting the pH to be less than 1 by using 31% hydrochloric acid, cooling to be below 10 &#;, stirring for 30 minutes for crystallization, and performing suction filtration and recrystallization by using water to obtain 68.3g of R- (+) -2- (4-hydroxyphenoxy) propionic acid, wherein the yield is 75%, and the purity is more than or equal to 92.3%.

The above is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be considered as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and these modifications and adaptations should be considered within the scope of the invention.

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