CN102775297A - Method for preparing 2-(4-methoxy phenoxy) propionic acids - Google Patents

Abstract

The invention relates to a method for preparing 2-(4-methoxy phenoxy) propionic acids. The method includes adding, by weight, 183 parts of hydroquinone and 202.5 parts of S-methyl 2-chloropropionate into a reaction kettle, adding, by weight, 100 parts of sodium hydroxide for a first batch, raising the temperature of the reaction kettle to 70 DEG C to 80 DEG C, reserving the temperature for 8 hours, and reducing the temperature of the reaction kettle to the room temperature after reaction; adding, by weight 128 parts of hydrochloric acid into the reaction kettle, keeping the pH to be about 5 to 6, and reacting the hydroquinone with the hydrochloric acid in a weak acidic environment to produce hydroquinone; adding an extracting agent 4-methyl-2-pentanone into the reaction kettle, layering the solution, wherein an organic layer is the hydroquinone and the extracting agent, and a water layer is an intermediate A/B, methanol and a salt solution; separating an organic phase mixture, reducing the pressure to distill the 4-methyl-2-pentanone, and subjecting hydroquinone crystals to centrifugal separation; and adding, by weight, 128 parts of hydrochloric acids into a dealcoholized aqueous phase, regulating the pH to be 1 to 2, reacting the intermediate under an acid precipitation condition, and precipitating the 2-(4-methoxy phenoxy) propionic acids after adding acids. The method for preparing 2-(4-methoxy phenoxy) propionic acids has the advantages of being simple to operate, low in cost, small in pollution, and suitable for industrial large scale application.

Description

The preparation method of 2-(4-oxygen phenoxyl) propionic acid

 

Technical field

The present invention relates to a kind of preparation method of herbicide intermediate, specifically relate to the preparation method of a kind of 2-(4-oxygen phenoxyl) propionic acid.

Background technology

2-(4-oxygen phenoxyl) propionic acid, molecular formula is HOC ₆H ₄OCH (CH ₃) COOH, be the Sandy oily liquids, odorless, tasteless.It is crucial middle the stopping of phenoxy propionic acid class weedicide such as quizalofopethyl, diclofop-methyl etc., and this type highy potent herbicide can selectively be prevented and kill off 1 year or perennial gramineous weeds, and consumption is few, and the person poultry harmless is so used by various countries at present widely.

This midbody compound synthetic difficulty is: one, Resorcinol oxidation by air easily in basic soln; Two, nucleophilic substitution can take place in two of Resorcinol phenolic hydroxyl groups simultaneously; Three, alpha-chloro propionic acid α-chlorine in basic soln is prone to by OH ^-Replace.At present, in the existing method of synthetic this midbody compound, relatively be typically: (1) as solvent, makes the condensation under alkaline medium calcium hydroxide of alpha-brominated propionic ester and Resorcinol with methyl-sulphoxide at low temperatures; (2) use nitrogen protection, make alpha-chloro propionic acid and Resorcinol condensation, use the diazomethane esterification, obtain product through transesterification reaction again.

The shortcoming of method (1) has been to use expensive methyl-sulphoxide and alpha-brominated propionic acid, although nucleophilic substitution takes place alpha-brominated thing easily, has also increased the disubstituted trend of Resorcinol; For preventing disubstituted generation, need with excessive Resorcinol, be 2.5:1 such as the mol ratio of Resorcinol and alpha-chloro propionic acid; So just cause a large amount of wastes of Resorcinol, the entire reaction time is about 40h, therefore; This method cost is high, and is consuming time many.

Method (2) needs to use nitrogen protection, and intermediate treatment is cumbersome, and has used severe toxicity and explosive diazomethane, and therefore, the extensive use of this method also is restricted.

Summary of the invention

Shortcoming and defect to the prior art existence; The invention provides a kind of employing 2-(4-hydroxyphenoxy) propionic acid and methyl alcohol is the method that main raw material prepares 2-(4-oxygen phenoxyl) propionic acid, and the present invention is simple to operate, and cost is low; Pollute and lack, be suitable for industry and go up large-scale application.

The present invention realizes through following technical scheme:

The preparation method of a kind of 2-(4-oxygen phenoxyl) propionic acid may further comprise the steps:

(1), gets the raw materials ready according to the Resorcinol of 183 weight parts, the S-2-methyl chloropropionate of 202.5 weight parts, the sodium hydroxide of 210 weight parts and the hydrochloric acid of 426 weight parts;

(2), once all add in the reaction kettle Resorcinol of 183 weight parts and the S-2-methyl chloropropionate of 202.5 weight parts; First batch of sodium hydroxide 100 weight parts that add; Reaction kettle is warming up to 70-81 ℃ of insulation 8h, and reaction is reduced to room temperature with the temperature of reaction kettle after accomplishing; And then in reaction kettle, add hydrochloric acid 128 weight parts, and keep pH value about 5～6, in weak acid environment, excessive Resorcinol sodium and hydrochloric acid reaction are produced Resorcinol;

(3), in reaction kettle, add the extraction agent 4-methyl-2 pentanone, the solution layering, organic layer is Resorcinol and extraction agent, water layer is intermediate A/B, methyl alcohol and salts solution;

(4), separate mixture of organic phase, underpressure distillation goes out 4-methyl-2 pentanone, spinning Resorcinol crystal;

(5), aqueous phase dripping hydrochloric acid 128 weight parts after dealcoholysis, regulate pH value 1～2, midbody reacts under the acid out condition, separates out 2-(4-oxygen phenoxyl) propionic acid after adding acid.

Preferably, the purity of said dihydroxy-benzene, S-2-methyl chloropropionate and sodium hydroxide all >=99%, hydrochloric acid purity >=30%.

The reaction equation that the esterification of 2-(4-hydroxyphenoxy) propionic acid and methyl alcohol generates 2-(4-oxygen phenoxyl) propionic acid is following:

1, building-up reactions:

The equation of S-2-methyl chloropropionate and NaOH reaction is following:

The equation of chloropropionic acid sodium and the reaction of Resorcinol sodium is following:

Main side reaction equation:

2, acid out:

3, secondary acid out:

It is the method that main raw material prepares 2-(4-oxygen phenoxyl) propionic acid that the present invention adopts 2-(4-hydroxyphenoxy) propionic acid and methyl alcohol, have simple to operate, cost is low, pollute less, be suitable for the beneficial effect that large-scale application is gone up in industry.

Description of drawings

Fig. 1 is the process flow sheet of preparation 2-(4-oxygen phenoxyl) propionic acid.

Embodiment

In order to further specify technical scheme of the present invention; Below in conjunction with embodiment the preferred embodiment of the invention is described; Describe just in order to further specify feature and advantage of the present invention but should be appreciated that these, rather than to the restriction of claim of the present invention.

The purity of Resorcinol, S-2-methyl chloropropionate and sodium hydroxide that present embodiment is used all >=99%, hydrochloric acid purity >=30%.

The preparation method of a kind of 2-(4-oxygen phenoxyl) propionic acid may further comprise the steps (as shown in Figure 1):

(1), gets the raw materials ready according to the Resorcinol of 183kg, the S-2-methyl chloropropionate of 202.5kg, the sodium hydroxide of 210kg and the hydrochloric acid of 426kg;

(2), the Resorcinol of 183kg and the S-2-methyl chloropropionate of 202.5kg are once all added in the reaction kettle, add sodium hydroxide 100kg in the first batch, reaction kettle is warming up to 70-81 ℃ of insulation 8h, reaction is reduced to room temperature with the temperature of reaction kettle after accomplishing; And then in reaction kettle, add hydrochloric acid 128 kg, and keep pH value about 5～6, in weak acid environment, excessive Resorcinol sodium and hydrochloric acid reaction are produced Resorcinol;

(3), in reaction kettle, add the extraction agent 4-methyl-2 pentanone, the solution layering, organic layer is Resorcinol and extraction agent, water layer is intermediate A/B, methyl alcohol and salts solution;

(4), separate mixture of organic phase, underpressure distillation goes out 4-methyl-2 pentanone, spinning Resorcinol crystal;

(5), aqueous phase dripping hydrochloric acid 128 kg after dealcoholysis, regulate pH value 1～2, midbody reacts under the acid out condition, separates out 2-(4-oxygen phenoxyl) propionic acid after adding acid.

Claims (2)

1. the preparation method of a 2-(4-oxygen phenoxyl) propionic acid is characterized in that said preparation method may further comprise the steps:

(1), gets the raw materials ready according to the Resorcinol of 183 weight parts, the S-2-methyl chloropropionate of 202.5 weight parts, the sodium hydroxide of 210 weight parts and the hydrochloric acid of 426 weight parts;

(2), once all add in the reaction kettle Resorcinol of 183 weight parts and the S-2-methyl chloropropionate of 202.5 weight parts; First batch of sodium hydroxide 100 weight parts that add; Reaction kettle is warming up to 70-81 ℃ of insulation 8h, and reaction is reduced to room temperature with the temperature of reaction kettle after accomplishing; And then in reaction kettle, add hydrochloric acid 128 weight parts, and keep pH value about 5～6, in weak acid environment, excessive Resorcinol sodium and hydrochloric acid reaction are produced Resorcinol;

(3), in reaction kettle, add the extraction agent 4-methyl-2 pentanone; The solution layering; Organic layer is Resorcinol and extraction agent, and water layer is midbody /

, methyl alcohol and salts solution;

(4), separate mixture of organic phase, underpressure distillation goes out 4-methyl-2 pentanone, spinning Resorcinol crystal;

(5), aqueous phase dripping hydrochloric acid 128 weight parts after dealcoholysis, regulate pH value 1～2, midbody reacts under the acid out condition, separates out 2-(4-oxygen phenoxyl) propionic acid after adding acid.

2. the preparation method of 2-according to claim 1 (4-oxygen phenoxyl) propionic acid is characterized in that, the purity of said dihydroxy-benzene, S-2-methyl chloropropionate and sodium hydroxide all >=99%, hydrochloric acid purity >=30%.

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