DED0007811MA - - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

Registration date : January 19, 1951. Advertised on November 8, 1956

GERMAN PATENT OFFICE

PATENT APPLICATION

CLASS 12q GROUP I4o4 INTERNAT. CLASS C 07 c -

D 7811 IVb / 12q

Edgar C. Britton and Louis E. Begin, Midland, Mich. (V. St. A.)

have been named as inventors

The Dow Chemical Company, Midland, Mich. (V. St. A.) \

Representative: Dr.-Ing. H. Ruschke, Berlin-Friedenau, and Dipl.-Ing. K. Grentzenberg, Munich 13, Ainmillerstr. 26, patent attorneys

Process for the preparation of esters of 2,4,5-trichlorophenoxyacetic acid

The priority of registration in the V. St. v. Claimed America on May 22, 1950

The invention relates to a process for the preparation of esters of 2, 4, 5-trichlorophenoxyacetic acid with following general formula

O-CH, - <

KJ )

in which η ι or 2 and R is an alkyl radical having 1 to 9 carbon atoms. These connections are e.g. B. can be used as a pesticide, as a preservative for paper, wood and for textiles made of cellulose base materials and as a plant-damaging agent.

The esters are oily liquids which are somewhat soluble in many organic solvents and which are almost insoluble in water. They are light and air resistant, are not significantly affected by carbon dioxide attacked, do not damage the skin of humans or higher animals and are only slightly volatile.

The esters are produced by reacting 2, 4, 5-trichlorophenoxyacetic acid with glycol mono-

609 706/411

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ethers of the general formula R (—O — C ₃ H ₆ ) “—OH, in which η ι or 2 and R denotes an alkyl radical with ι to 9 carbon atoms. Equimolecular amounts are preferably used. You can work with excess ether, but the reaction also takes place with a certain excess of acid. For example, 1 mole of 2,4,5-trichlorophenoxyacetic acid is reacted with a little more than 1 mole of the glycol monoether. Such glycol ethers are z. B.

Methoxypropanol, ethoxypropanol, propoxypropanol, butoxypropanol, hexoxypropanol, nonyloxypropanol, Methoxypropoxypropanol, ethoxypropoxypropanol, propoxypropoxypropanol, butoxypropoxypropanol, Hexoxypropoxypropanol and nonyloxypropoxypropanol. Good yields are obtained if one the water formed in the reaction is removed immediately after formation. The reaction . is in Presence of a dehydrating catalyst, e.g. sulfuric acid, phenol sulfonic acid, or a cation-exchanging catalyst Resin carried out with acid groups.

In a preferred mode of operation, 2, 4, 5-

Trichlorophenoxyacetic acid, a slight molecular excess of an alkyl ether of propylene glycol and the catalyst mixed and for a time at a temperature between 0, q and 160 ° heated. The heating is carried out at reduced pressure to take the water of reaction together with to remove the excess of the ether alcohol. When the reaction is almost complete, ethylene dichloride, Carbon tetrachloride or other water immiscible solvents to the mixture are added, whereupon the catalyst and unreacted 2, 4, 5-trichlorophenoxyacetic acid with alkali, e.g. dilute sodium carbonate solution or ammonium bicarbonate solution.

The resulting mixture separates into one aqueous and a solvent layer. The solvent layer containing the ester is separated and washed several times with water. The solvent is then reduced by distillation under Removed pressure and thus obtained the desired ester.

In another procedure, the reaction is carried out in a water-immiscible solvent, e.g. B. ethylene dichloride executed. The reacting substances and the catalyst are dispersed in the solvent and heated together for a time at a temperature of 90 to 150 ^0th A mixture of solvent and water of reaction is constantly distilled off from the reaction vessel, condensed and the solvent recovered therefrom. If necessary, additional solvent is introduced into the reaction zone. After the reaction is complete, the mixture can be neutralized e.g. B. with dilute sodium carbonate solution, whereupon the solvent layer, which is separated from the aqueous layer, is washed several times with water. The solvent is then removed by distillation under reduced pressure to give the ester.

The mono- and dipropylene glycol alkyl monoethers used as starting materials can be used in known Way by reaction between propylene oxide and an excess of monohydric aliphatic alcohol be won.

The following examples illustrate the invention.

example 1

2, 4, 5-trichlorophenoxyacetic acid 2-methoxypropyl (r) ester

Cl-

O -CH ₂ - C - O - CH ₉ - CH - O - CH,

CH,

255.5 S ( ^x mol) 2,4,5-trichlorophenoxyacetic acid, 90 g (1 mol) 2-methoxypropanol- (i) (boiling point 130 ° at 750 mm; D3JUQk) i: i; .. 2Oo: cem: ethylene dichloride ■ and 'ι ecm concentrated sulfuric acid are mixed and heated ^{I 1} Z ₂ hours at a temperature of 91 to 112 ^0. The process is carried out with the constant distillation of ethylene dichloride and water of reaction, the water being separated off and the ethylene dichloride being returned to the circuit. After the reaction has ended, the ethylene dichloride is reduced by distillation under reduced pressure - the theoretical
32.2 ° '/ ₀ .

Chlorine content for

C ₁₂ H ₁₃ O,

Example 2

2, 4, 5-trichlorophenoxyacetate isopropoxypropyl (2) ester

Cl-:

XH,

O - CH ₂ - C - O - CH - CH ₂ - O - CH

CH _S

XH,

separated, and the 2-methoxypropyl (i) ester of 2, 4, 5-trichlorophenoxyacetic acid is obtained. The product is an oily liquid with ^: a 'refractive index n ² n = 1.536 and a chlorine content of 32.6 ⁰ J ₀ .

CL is

•: 372 g, (3.15, mol) i-isopropoxypropanol- (2) .. (boiling point I39?; T> at 760 mm pressure), 765 g (3 mol) 2, 4, 5-trichlorophenoxyacetic acid ' , 200 ecm ethylene dichloride and 3 ecm sulfuric acid are 12 hours at a

705/414

D 78111Vb / 12q

Temperature between ιοί and 132 ⁰ heated. The process is carried out with the constant distillation of ethylene dichloride together with the water of reaction formed, the water being separated off and the ethylene dichloride in the. Cycle is returned. After the reaction has ended, the ethylene dichloride is removed by distillation under reduced pressure, and the i-isopropoxypropyl (2) ester of 2, 4, 5-trichlorophenoxyacetic acid is obtained as an oily liquid with a refractive index n ^z _D ^s = 1.25 and a chlorine content of 29.29 ° / _0th The theoretical one
29.6%.

Chlorine content for C ₁₄ H ₁₇ O ₄ Cl ₃ is

Example 3

2, 4, 5-trichlorophenoxyacetic acid-nonyloxypropyl- (2) -ester

ei 0,

Cl - '( ^% y - O - CH ₂ - C - O-CH-CH ₂ -OC ₉ H ₁

CH ₃

Cl

2o6 g (0.808 mol) 2, 4, 5-trichlorophenoxyacetic acid, 162.5 g (0.808 mol) i-nonyloxypropanol- (2) (boiling point 88 to 95 ° at 3 mm pressure, refractive index n% = 1.4350) and ι ecm concentrated sulfuric acid are heated together for 15 minutes at a vessel temperature of 105 to 120 °. The reaction mixture is then placed under vacuum and the temperature gradually increased, wherein a mixture of water and i-Nonyloxypropanol- (2) was distilled off from the reaction zone, until the pot temperature reached 150 ^0. The crude reaction mixture is then cooled to room temperature, diluted with 300 ecm carbon tetrachloride, and the resulting mixture is nitrated. The filtrate is washed with dilute sodium

Cl-.

5110 g (20 mol) 2, 4, 5-trichlorophenoxyacetic acid,

3800 g (20 mol) butoxypropoxypropanol (boiling point

228 ° at 760 mm pressure), 1820 ecm ethylene dichloride

, and 15 ecm of concentrated sulfuric acid are combined heated according to the procedure of Example 1 for 16 hours at a vessel temperature of 80 to 127 ° and the butoxypropoxypropyl ester of 2, 4, 5-trichlorophenoxyacetic acid. This product is an oily liquid with a refractive index «* f = 1.5072 and a chlorine content of 24.2% compared to a theoretical chlorine content of 24.7%.

Example 5

486 g (3.17 mol) of a mixed Polypropylenglykolbutyläthers (average molecular weight 153 containing 72% i-Butoxypropanol- (2), 20% butoxy propoxy propanol and ^8% Butyläthern of 3-propylene glycols and higher polypropylene glycols), 766.5 g (3 moles ) 2, 4, 5-trichlorophenoxyacetic acid and 15 g of phenolsulfonic acid are heated ^{5 x} / ₂ hours at vessel temperatures of 121 to 179 ^0. The reaction mixture is then placed under reduced pressure and the temperature gradually increased, creating a mixture

egg o.

- O - CH ₂ - C - O - C ₃ H ₆ - O - C ₃ H ₆ - O - C ₄ H ₉

washed carbonate solution, filtered and washed with dilute sodium carbonate solution and water. The carbon tetrachloride is then removed by distillation until a vessel temperature of 170 ° at ι mm pressure has been reached and the i-nonyloxypropyl (2) ester of 2, 4, 5-trichlorophenoxyacetic acid is obtained. The latter is an oily liquid with a refractive index w | ⁵ = 1.511 and a chlorine content of 24.77%> while the theoretical chlorine content is 24 ° / ₀ .

Example 4, ^::

2, 4, 5-trichlorophenoxyacetic acid butoxypropoxypropyl ester

distilled off from water and propylene glycol butyl ethers from the reaction zone until the vessel temperature reaches 149 ⁰ . The crude reaction mixture is then filtered and the filtrate is diluted with dilute aqueous ammonium bicarbonate solution and a small amount of carbon tetrachloride. The resulting mixture is filtered again and the filtrate washed with dilute aqueous sodium carbonate solution. The carbon tetrachloride is removed from the mixture by distillation up to a vessel temperature of 130 ° at 35 to 45 mm pressure and an ester mixture is obtained, which mainly consists of the i-butoxypropyl (2) and the butoxypropoxypropyl esters of 2,4, 5- Trichlorophenoxyacetic acid consists. This product is an oily liquid with a refractive index nf = 1.5132 and a specific gravity of 1.2184 at 25 ⁰ .

Example 6

118 kg (657 mol) of a mixed methyl polypropylene glycol ether (having an average molecular weight of 180, containing 60% methoxypropoxypropanol, 26 ° / ₀ ^ Methoxypropoxypropöxyprop

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D 7811 IYbIUq

anol and 14% of the methyl ethers of tetrapropylenuhd higher propylene glycols), 88 kg (598 mol) 2, 4, 5-trichlorophenoxyacetic acid and 13.5 kg of a cation exchange resin (mixed polymer of styrene and divinylbenzene) are sulfonated together for hours at a vessel temperature of 130 ⁰ and Heated 12.7 to 15.2 mm pressure. The reaction mixture is then filtered and the mixed esters, which mainly consist of the methoxypropoxypropyl and methoxypropoxypropoxypropyl esters of the 2,4,5-tri

chlorophenoxyacetic acid, separated. This product is an oily liquid with a refractive index »| ⁵ = 1.5101 and a chlorine content of 25.93%

Claims (5)

PATENT CLAIMS: i. Process for the preparation of esters of 2, 4, 5-trichlorophenoxyacetic acid of the general formula ^ - O - CH ₂ - C - O - (C ₃ H ₆ - O -) "R in which η ι or 2 and R denotes an alkyl radical having 1 to 9 carbon atoms, characterized in that 2, 4, 5-trichlorophenoxyacetic acid with glycol monoethers of the general formula R (_0 - C ₃ H ₆ ) "- OH, in which η and R have the above meaning is implemented. 2. The method according to claim 1, characterized in that that the reaction mixture is heated under reduced pressure to the at the Reaction to remove water formed immediately after its formation. 3. The method according to claim 1, characterized in that the reaction in one is carried out with water-immiscible solvent and that the reaction mixture is heated in order to continuously distill off this solvent and the water formed during the reaction, with additional solvent being added to the reaction mixture as needed can. 4. The method according to claim 1 to 3, characterized in that the reaction is in the presence a dehydrating catalyst is carried out. 5. The method according to claim 1 to 4, characterized in that the glycol monoether butoxypropanol or butoxypropoxypropanol is used. 706/411 10.56