JPS60204745A - Preparation of 2-(4-hydroxyphenoxy)alkanoic acid ester - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as a raw material for preparing herbicides, etc. in high yield, by reacting an alkali metal salt of hydroquinone with an alpha-haloalkanoic acid ester in a specific alcohol. CONSTITUTION:An alkali metal salt of hydroquinone is reacted with a compound expressed by formula I (X is Cl or Br; R<1> is H or lower alkyl; R<2> is lower alkyl) in an alcohol expressed by the formula R<3>OH (R<3> is CH3, C2H5, CH3OCH2CH2 or C2H5OCH2CH2) to give the aimed compound expressed by formula II. The amount of the compound expressed by formula I is usually equimolar with the hydroquinone, but may be 40-80mol% for improving particularly the selectivity. The molar amount of the alkali metal salt to be used is 1.0-2.5 times that of the hydroquinone, but preferably 1.7 times or more for improving the selectivity. The reaction is carried out at 0-100 deg.C, preferably 30-60 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 2-(4-hydroxyphenoxy)alkanoic acid esters. More specifically, 1 the present invention provides an alkali metal salt of hydroquinone and a compound having the general formula [1] ) is a compound represented by the general formula [2] R30H (2) (wherein R3 is CH3, C!l B5.CHs QC-
Indicates H2CH or C2B50CH2CH2. General formula [3] characterized in that the reaction is carried out in an alcohol represented by (wherein R1 is hydrogen or a lower alkyl group).

R3 is CHs+ C2B5, CHs 0CH2CH2
Or it shows C2B50CH2CH2. ) represented by 2
The present invention relates to a method for producing -(4-hydroxyphenoxy)alkanoic acid esters.

2-(4-hydroxyphenoxy)alkanoic acid esters are disclosed in JP-A-56-16475 and JP-A-54-22.
For example, the heterocyclic ether phenoxy fatty acid derivatives described in JP-A-56-16475, which are useful as intermediates for compounds disclosed in JP-A No. 371, JP-A-53-40767, etc., are used as active ingredients. It is useful as a raw material for producing herbicides with excellent effects.

As a method for producing 2-(4-hydroxyphenoxy)alkanoic acid esters, there is a method shown by the following reaction formula disclosed in International Application Publication No. 82100639.

There is also a method shown in the following reaction formula disclosed in European Patent No. 82413.

(In the formula, X represents a chlorine or bromine atom, and R represents a lower alkyl group.) However, the method disclosed in International Application Publication No. 82100639 has a low production rate in the step of synthesizing persulfate ester, Moreover, since the number of steps is large, it cannot be said to be industrially preferable.

Furthermore, the reaction disclosed in L'Europe Patent No. 82413 has insufficient selectivity, and unless the conversion of hydroquinone is kept within 50%, a large amount of dimer is produced. Therefore, industrially, the cost becomes high due to one recovery operation of a large amount of hydroquinone. Also, reduce the reaction rate to reduce unreacted hydroquinone.

dimer (in the formula, 2 indicates the reaction rate and R indicates a lower alkyl group).If the reaction rate is increased, the production rate of dimer increases and the yield decreases significantly.

The present inventors have conducted extensive research into an excellent method for producing 2-(4-hydroxyphenoxy)alkanoic acid, since these methods are not industrially advantageous.

Overcoming the shortcomings of the conventional method, 2-(4
-Hydroxyphenoxy)alkanoic acid esters were discovered and the present invention was completed.

That is, 9 the present invention relates to the alkali metal salt of hydroquinone and the general formula [1] 2-(4-
This is a manufacturing method for obtaining hydroxyphenoxy)alkanoic acid esters.

In the general formula [1], X is salt or bromine, but chlorine is economically preferable.The amount used is usually equimolar to that of hydroquinone, but especially when the selectivity is high (70 to 70%) It is sufficient to use 80% mole.

As the solvent, alcohols such as methanol, ethanol, isoprobanol, ethylene glycol, butanediol, and cellosolves are preferred.

The amount used varies depending on the type of each solvent and the reaction temperature and is not limited. As an alkali metal salt of hydroquinone,
Lithium, sodium, and potassium salts are used, but sodium is most preferred in view of monoselectivity and economy.

The sodium salt of hydroquinone is produced by reacting hydroquinone with 1 to 2 times the mole of sodium hydroxide in water or alcohol.

It may be isolated and used after sufficient water has been distilled off.

Depending on the solvent, it may be produced by adding 1 to 2 times the mole of metallic sodium. Alternatively, it may be manufactured using commercially available sodium alcoholade. In this step, sufficient care must be taken to avoid contamination of water, and the amount of alkali metal used is 1.0 to 2.5 times the mole of hydroquinone. However, if the amount of alkali metal is small, the selectivity will be poor, so it is preferable to use 1.7 times the mole or more of hydroquinone.

The reaction temperature varies depending on the raw materials used, the alkali metal, the type of solvent, etc., but is preferably 0-100'C. Considering the reaction rate 2 selectivity, the temperature is most preferably 30 to 60°C. Since some of the hydroxyl groups in the reaction product are sodium salts, it is necessary to convert them into hydroxyl groups using hydrogen chloride gas or an organic acid such as acetic acid for isolation. After making it acidic, the solvent is distilled off to remove inorganic salts and unreacted hydroquinone.

2-(4-hydroxyphenoxy) is obtained by washing with water and rectification.
Isolate the alkanoic acid esters.

This will be explained in more detail below with reference to Examples.

The present invention is not limited to these.

1 lid 1 1 g of hydroquinone, 110 g of ethanol,
After purging with nitrogen, 4.6 g of sodium metal was added to produce sodium salt of hydroquinone. After raising the temperature to 60°C, 13.7 g of ethyl α-chloropropionate was added and the mixture was stirred for 2 hours at a *60” c. After neutralization with hydrogen chloride gas and distilling off the solvent, it was washed with water and rectified to give 2-( 15.7 g of ethyl 4-hydroxyphenoxy)propionate was obtained.The boiling point was 1
40t/lmmHg Add 1g of hydroquinone and 110g of ethanol.
After purging with nitrogen, 8 g of sodium hydroxide was added, the solution was made homogeneous at 60°C, and the ethanol was distilled off. Furthermore, 50 g of toluene was added and azeotropic dehydration was performed to remove water, then the toluene was distilled off, 110 g of ethanol was added, and the mixture was heated to 60°C.
- 13.7 g of ethyl chloropropionate was added. 60
The mixture was stirred at ℃ for 2 hours. After neutralization with hydrogen chloride gas and distillation of the solvent, the mixture was washed with water and rectified to obtain 13.5 g of ethyl 2-(4-hydroxyphenoxy)propionate.

Prepared with 11g of refreshing lhl hydroquinone and 110g of ethanol,
After purging with nitrogen, 4.6 g of sodium metal was added to produce sodium salt of hydroquinone. After raising the temperature to 60°C, 16.5 g of butyl α-chloropropionate was added. After the completion of the reaction, which was stirred at 60°C for 2 hours, 6.5 g of acetic acid was added at 20-25°C for neutralization, and then ethanol was distilled off, washed with water, and purified to obtain ethyl 2-(4-hydroxyphenoxy)propionate 13 .6g was obtained.

Boiling point is 140℃/lmmHg Patent applicant: Nissan Chemical Industries, Ltd.

Claims (2)

[Claims] (1) Alkali metal salt of hydroquinone and general formula [1] The compound represented by the general formula [2] R30H (2) (wherein R3 is CHs, C2I5, CH30-CHx
General formula [3] characterized in that the reaction is carried out in an alcohol represented by C2I50CH2c) I2 is represented by 2
- A method for producing (4-hydroxyphenoxy)alkanoic acid esters. (2) The manufacturing method according to claim 1, wherein R2 and R3 are the same and are CH3 or C2H5.