DD201445A1 - PROCESS FOR THE PREPARATION OF NEW ESTERS OF 2- (2-METHYL-4-CHLOROPHENOXY) ETHANA ACID - Google Patents

Abstract

The title compounds are esters of 2- (2-methoxy-4-chlorophenoxy) -ethanoic acid with di- or polyhydric alcohols and are potentially useful as drugs for xenobiotics. The aim and object of the invention is the development of a suitable rational process for the preparation of these new and further analogous compounds with similar utility properties. The object is achieved by bringing 2- (2-methyl-4-chlorophenoxy) -ethansÄure II with the polyhydric alcohols III under the conditions of azeotropic esterification in the presence of suitable catalysts in an opposite to the reactants inert liquid medium to implement.

Description

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Title of the invention:

Process for the preparation of new esters of 2- (2-methyl-4-chlorophenoxy) -ethanoic acid

Field of application of the invention:

The invention relates to a process for the efficient production of novel esters of 2- (2-methyl-4-chlorophenoxy) -ethanoic acid with di- (or poly) hydroxyalkanes, which can potentially be used as active ingredients in growth control agents, the Development and the Stoffvrechselprozesse of plants are suitable *

Characteristic of the known solutions:

It is known that certain aryloxyalkanoic acids have the effect of plant growth regulators. For example, the 2- (2,4-dichlorophenoxy) -ethanoic acid (2,4-D), the 2- (2,4-diethyl-4-chlorophenoxy) -ethanoic acid (MCPA) or the 4- (2-methyl-4 -chlorphenoxy) butanoic acid in the form of their salts, amides or esters as so-called growth-promoting herbicides in agricultural practices applied (R. Wegler: Chemistry of pesticides, Volume 2 and £) · ^Fu> r the production of Aryloxyalkansäureestern as potential plant growth regulators Methods have already been described (MS NEWMAN, W. FONES, M. RENOLL, J. Amer., Chem. Soc., 6, 2, 718; MUNCH-PETERSEN, Äcta Chem. Scand. £, 519; KREWSON, J. Agricult. Food Chem. 2 »118) ·

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Also, monoesters of 1,2-dihydroxyethane with aryloxyalkanoic acids are known and have been described in part as herbicidal active ingredients, bisesters of 2- (2-methyl-4-chlorophenoxy) -ethanoic acid with di-Coder poly) hydroxyalkanes have not been described * their effect as Growth regulators on plants is still unknown '·'

Object of the invention:

The invention aims to develop a process by means of which new bis-esters of 2- (2-methyl-4-chlorophenoxy) -ethanoic acid and analogous acids with di- (or poly) -hydroxyalkanes can be prepared rationally to make them to provide potential active substances for agents with growth-regulating properties in plants

Explanation of the essence of the invention:

Technical task

The object of the invention is to find a preparation process for the title compounds which ensures their efficient synthesis from easily accessible starting materials or intermediates even on a larger scale in good yield and purity.

Features of the invention:

It has been found that alkylene-bis-2- (2-methyl-Vchlorphenoxy) -ethanoate of the general formula I (see Table 1), in which χ and η are integers greater than or equal to 2, can thereby be prepared in a rational manner in that 2- (2-methyl-4-chloro-oxy) -ethanoic acid (formula II, see Table 1) is reacted with a polyhydric alcohol of general formula III (see Table 1) in which χ and η are those indicated above Possess meaning, in principle known whites under the conditions of azeotropic esterification to implement »

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The reaction is carried out in accordance with reaction equation 1 (see Table 1) as a condensation reaction with elimination of water in the presence of suitable catalysts The process according to the invention generally starts from a molar ratio of 2 mol of acid II to 1 mol of polyhydric alcohol III, but can In the context of a higher conversion rate, a larger excess of the acid II must also be used, but the reaction must be separated again in a liquid medium which is expediently made of a water-immiscible and azeotropically distillable with respect to the reaction components Solvent such as an optionally chlorinated aliphatic or aromatic hydrocarbon or a corresponding mixture, at temperatures between the ambient and the boiling temperature of the liquid reaction mixture carried out as catalysts are those for di The azeotropic esterification described substances, such as sulfuric acid and 4-toluenesulfonic acid, particularly suitable · The water formed during the reaction is most conveniently continuously removed by azeotropic distillation via a water from the reaction mixture.

The inventive method provides in a manner known in principle, new bis-esters of 2- (2-methyl-4-chlorophenoxy) -ethanoic acid with dihydric and polyhydric alcohols. The starting components are available on an industrial scale, the acid component is produced in the form of its sodium salt as a herbicidal active ingredient (MCPA). In basically the same way, corresponding esters of analogous aryloxyalkanoic acids can also be prepared by the process according to the invention, so that this opens up the possibility of synthesizing a broad range of novel chemical compounds with potential suitability as plant growth regulators. The process according to the invention is illustrated by the following examples of execution:

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embodiments

Example 1:

Ethylene-1,2-bis-2- (2-methyl-4-chloro-1-phenoxy) -ethanbate In a reaction vessel equipped with a mechanical stirrer and a water separator, 6 to 5 g (3.4 mol) of 2- (2-methyl-4-one) chlorophenoxy) -ethanoic acid with 78.2 g (1.7 mol) of 1,2-dihydroxyethane, 12.6 ml of concentrated sulfuric acid and 2.8 1 of tetrachloromethane. Under constant stirring, this mixture is refluxed for 27 hours, during which Separate 61 ml of water. The cooled reaction solution is filtered and extracted successively with 200 ml of water, sodium bicarbonate solution and once more with water. The organic phase is dried over calcium chloride and then the solvent is distilled off in vacuo. The viscous residue is taken up in 300 ml of ethanol and stored in the refrigerator for crystallization. The solid crude product is filtered off with suction and recrystallised from ethanol. This gives 530 g (73% of theory..) Ethylene-1,2-bis-2- (2-methyl-4-chlorophenoxy) ethanoate, mp 81-83 ⁰ C.

Example 2:

Propylene-1,2-bis-2 ~ (2-methyl-4-chlorophenoxy) -ethanoate 80 g (0.4 mol) of 2- (2-methyl-4-chlorophenoxy) -ethanoic acid are mixed with 15.2 g ( 0.2 mol) of 1,2-dihydroxypropane and 3 ml of conc. Sulfuric acid mixed in 300 ml of benzene and boiled under stirring for 24 h at reflux, with 7.2 ml of water deposited. The workup. is carried out analogously to Example 1. After recrystallization from ethanol, 33 g (37 % d. Th.) Of propylene-1,2-bis-2- (2-methyl-4-chlorophenoxy) -ethanoat, F · 40-41 ⁰ C.

Further compounds of the general formula I which can be prepared by the process according to the invention in accordance with the above examples are given in Table 2 · r

To this 1 page formulas here! Page Tobellen

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Table 1

CH "-C00-

^C _X ^H ₂ x ₊ 2-n ^(0H) n-2

Cl-Ct J) -O-CH ₂ -COOH

'CH.

II

CH ". · (OH) χ 2x + 2-n ^v 'n

III

Cat. 2 II + III - ». ι

Eq. 1

Table 2 Numerical value χ η 2 Structure of the group ^C x ^H 2x ₊ 2-n < ^0H) n-2 F. ( ⁰ o No. 2 2 -CH ₂ CH ₂ - 81  - 83 1 3 2 -CH ₂ CH (CH ₃ ) - 40 - 41 2 2 -CH ₂ CH ₂ CH (CH ₃ ) - 34 - 36 3 8th 3 - (CH ₂ ) Q- oil 4 3 -CH ₀ CH (OH) CH - 2 2 63 - 65 5

- * - ii6 ι / y ζ

Cl-Cf) Vo-CH ₀ -COO-

CH, ^C x ^H 2x _{+ 2} -n ^(0H) n-2

Claims (1)

Invention claim: A process for the preparation of novel alkylene-bis-2- (2-methyl-4-chlorophenoxy) ethanoates of the general formula I, in which χ and η are integers greater than or equal to 2, characterized in that in a manner known in principle 2 - (2-methyl-4-chlorophenoxy) -ethanoic acid (formula II) with a polyhydric alcohol of the general formula III in which χ and η have the abovementioned meaning, in a liquid medium which is inert to the reaction components and not with water is miscible, in the presence of a catalyst under the conditions of azeotropic esterification to the reaction brings.