CS232333B1 - Method of decreasing of content of 3-methyl-4-nitrophenol in 0,0-dimethyl-0-/3-methyl-4-nitrophenyl/tiophosphate - Google Patents

Description

The invention relates to reducing the content of 3-methyl-4-nitrophenol in technical O, O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate by extraction.

Q, O-Dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate is used as an effective insecticide, particularly in semi-agricultural applications. It is less toxic to warm-blooded animals than 0,0-dimethyl-O- (4-nitrophenyl) thiophosphate. Most commonly, O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate is prepared by reacting O, O-dimethylchlorothiophosphate with 3-methyl-4-nitrophenol.

Preparation in the presence of an acid binding agent or in the presence of a medium is described e.g. v brit. pat * č. 670,030 and in German Pat. no. 814 297. Franc. pat. no. No. 1,266,417 discloses the preparation of O, O-(O-3-methyl-4-nitrophenyl) thiophosphate by adding O, O-dimethyl chlorothiophosphate to a mixture of 3-methyl-4-nitrophenol, KgCO3 and a powder medium in toluene. . Franc. pat. no. 1,272,685 uses chlorobenzane as the reaction medium. Condensation of O, O-diethylchlorothiophosphate with 3-methyl-4-nitrophenol in anhydrous acetone, methyl ketane in the presence of NagCO2 at reflux temperature is described in U.S. Pat. no. 2,520,393, brit. pat. no. 644 610, franepat. no. 957 803. The preparation of O, O-dialkyl- (4-nitrophenyl) thiophosphate by reaction of O, O-dialkyl chlorothiophosphate with sodium 4-nitrophenolate in chlorobenzene, ethanol, or an aqueous medium is described by Fletcher J. Aa. Chem. Soc. 70, 3943 (1948).

The preparation of O, Q-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate by reaction of O, O-dimethyl chlorothiophosphate with 3-methyl-4-nitrophenol is described in the Schutz Beriohte der deutschen chem. Gesellschaft, 40 4322. Production of O, O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate by reaction of O, O-dimethylthiothiophosphate with an alkali metal 3-methyl-4-nitrophenolate or 3-methyl-4-nitrophenol in the presence of acid-retarding agents is described in U.S. Pat. pat. no. 89 124.

The inecticidal preparation of O, O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate and a process for its preparation by reacting O, O-dimethyl chlorothiophosphate with 3-methyl-4-nitrophenol or its alkali salt is described in Japan. patentooh č. 28 075 (1959) and no. 30,541 (1959), and in U.S. Pat. no.

U.S. Pat. 3,091,565.

purification of organophosphorus pesticides of the general formula

X wherein R 1, and fig is C 1 -C 4 alkyl, X is O, or S and R 1 is aryl, optionally aryl substituted with alkyl, halogens or nitro, the impurities being distilled off with water, see U.S. Pat. AO č. 21, 804. Preparation of O, O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate by reacting 3-methyl-4-nitrophenyl with Q, Q-dimethylchlorothiophosphate in the presence of KgCO2 in methyl ethyl ketone, cooling the reaction mixture and the precipitated salt is suctioned off, described by G. Sehrader, Die Entwieklung neuer Insectizider Phosphorsaiire Ester, Verlag Chemie GMBH Weinheim sty.

293 (1963).

Extraction of 3-methyl-4-nitrophenol from technical O, O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate is most often done with an aqueous solution of NagCO3, which is a risk that the sodium salt may not be present. 3-methyl-4-nitrophenol, or NaHCO 3 crystallizes. Extractions can be described by chemical equation 1

OH ONa

no ₂ no ₂

The rate of extraction depends on the diffusion of 3-methyl-4-nitrophenol at the interface of 0,0-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate and the aqueous layer, the size of the interface, the rate of chemical reaction (1) and other factors. The rate of chemical reaction (1) is directly proportional to the concentration of NagCO 3, as the concentration of NagCO 3 in solution decreases, the reaction rate of the chemical reaction (1) also decreases until equilibrium is established.

At low reaction rates and chemical reaction equilibrium (1), extraction is economically unbearable. For this reason, extraction is carried out in several extraction stages using fresh NagCO-1 solutions or in the countercurrent arrangement of aqueous solution and O, O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate in the individual extraction stages. Countercurrent extraction is performed to obtain a more concentrated aqueous solution of sodium 3-methyl-4-nitrophenolate. When using 1.5 wt. It is not economically feasible to obtain aqueous solutions having a content of 1.5 wt. 3-methyl-4-nitrophenol, which is a disadvantage mainly because large volumes of vdd are formed which are worse processed to yield the individual components from these vdd.

The above drawbacks are overcome by the purification of O, O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate, which consists in extracting 3-methyl-4-nitrophenol from technical 0,0-dimethyl-O. - (3-methyl-4-nitrophenyl) thiophosphate with aqueous sodium hydroxide and carbonate solution. The molar ratio of NaOH: NagCO 3 is 0.1: 1 to 100: 1, the molar ratio of 3-methyl-4-nitrophenol to hydroxide and sodium carbonate is 1: 1. 0.5 to 1: 5.

The extraction is performed with sodium carbonate with the gradual addition of an aqueous NaOH solution to the extraction mixture during extraction.

The extraction is carried out in at least two extraction steps. Proceed in a countercurrent manner, the aqueous solution from the second extraction stage being used for subsequent extraction in the first extraction stage.

The aqueous solution from the second extraction step is enriched for subsequent use by the addition of aqueous sodium hydroxide solution. Molar ratio of 3-methyl-4-nitrophenol from aqueous solution. The second extraction step to the added sodium hydroxide is 0.2: 1 to 2: 1.

«<

When using an aqueous solution of NaOH added to the extraction mixture, the chemical equations of 2.3 ° C

·· © NaHCO ₃ + NaOH j = ± Na ₂ CO ₃ ♦ HjO * / 2 /,

OH ONa

In equation (2), Na ₂ CO ₃ is formed, while at the same time the reaction rate of equation (1) is increased, thereby accelerating extraction. By conducting the reaction (1,2,3), it is possible to achieve such extraction conditions that the extraction mixture contains NaHCO ₃ and NagCO ₃ , which are buffer-like.

An advantage of the method of reducing 3-methyl-4-nitrophenol in the 0,0-dimethylamino-O (3-methyl-4-nitrophenyl) / thiophosphate according to the invention is to obtain a solution of sodium 3-methyl-4-nitrophenol containing 2.5 to 3 %, 5 wt. 3-methyl-4-nitrophenol, from which 3-methyl-4-nitrophenol, or its sodium salt, can be obtained in an economic manner. In countercurrent two-stage extraction! aa consumes half the amount of water and NagCO ₃ as in extraction! two-stage and Na ₂ CO ₃ under the same conditions.

The obtained 0,0-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate has a 0.05 to 0.25 wt. 3-methyl-4-nitrophenol less. The preparation of a NaOH solution is unpretentious and easier than the preparation of a Na ₂ CO ₃ solution prepared from solid Na 2 SO 4. In an alternative manner, half the amount of waste water is produced which is more concentrated and from which 3-methyl-3-nitrophenol can be obtained. Since the extraction mixture contains Nb 3 CO 3 and NaHCO 3, which form a buffer, the pH of the aqueous solution can be controlled.

The extraction takes place at a pH of preferably 8 to 10. At higher pH, there is a certain risk of decomposition of O, O-(O-3-methyl-4-nitrophenyl) thiophosphate, or of the concomitant impurities, in particular the hydrolysis of the chloro derivatives. The addition of NaOH to the reaction mixture improved its separation after the extraction was complete, especially in the first extraction stage.

Example 1

An Erlenmeyer flask was charged with 200 ml of 91.3 wt. % Of O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate containing 3.2 wt. 3-methyl-4-nitrophenol and 400 g of 1.5 wt. % Na ₂ CO ₃ solution and 0.25 wt. NaOH. The mixture was stirred for 4 hours on an electromagnetic stirrer. The mixture was then allowed to stand for one hour. The aqueous layer was separated from the O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate layer. The aqueous layer contained 1.87 wt. 3-methyl-4-nitrophenol; O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate contained 0.42 wt. 3-methyl-4-nitrophenol.

To the obtained O, O-dimethyl-3- (3-methyl-4-nitrophenyl) thiophosphate, 400 g of 1.5 wt. solution of Na ₂ CO ₃ . The mixture was stirred for three hours. 3 ml of 41.2 wt. aqueous NaOH solution. After stirring, the extraction mixture was left to sediment for one hour and then the aqueous layer was separated from O, O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate. The aqueous solution contained 0.16 wt. 3-methyl-4-nitrophenol; 0.0-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate contained 0.16 wt. 3-methyl-4-nitrophenol. The obtained O, O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate was washed with 400 ml of water, which was used after separation to prepare an extraction solution of Na 2 CO 4 and NaOH for subsequent extraction. in the second extraction stage.

Example 2

The procedure of Example 1 was followed except that an aqueous solution was used for the first extraction step after the second extraction step of Example 1. While stirring, 2 ml of 43 wt. aqueous NaOH solution. The aqueous solution after the first extraction step contained 1.95 wt. 3-methyl-4-nitrophenol; 0.0-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate contained 0.46 wt. 3-methyl-4-nitrophenol.

After the second extraction step, the aqueous solution contained 0.14 wt. 3-methyl-4-nitrophenol; O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate was washed with 300 mL of water.

Example 3

The procedure was as described in Example 2 except that 300 ml of Rostok were used for extraction in both extraction steps. The aqueous solution after the first extraction step contained 2.61 wt. % Of 3-methyl-4-nitrophenol and O, O-dimethyl-O (3-methyl-4-nitrophenyl) thiophoaphate contained 0.43 wt. 3-Methyl-4-nitrophenol. The aqueous solution after the second extraction step contained 0.23 wt. 3-methyl-4-nitrophenol; 0.0-dimethyl-O- (3-methyl-4-nitrophenyl) triphosphate contained 0.17 wt. 3-methyl-4-nitrophenol. The obtained O, O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate was washed with 300 ml of water.

Example 4

The procedure of Example 1 was followed except that technical 0,0-dimethyl-0- / 35

of methyl 4-nitrophenyl / thiophosphate was added 300 mL of 0.3% NaOH and 0.01% wt. After the first extraction step, the O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate contained 0.84 wt. 3-methyl-4-nitrophenol.

Example 5

The procedure of Example 1 was followed except that 500 g of 5 wt.% Was added to technical 0,0-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate. Na 2 GO 3 During stirring for 3 h, 200 ml of 0.5% NaOH was added to the mixture, and the obtained 0 ', O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate contained 0.24 wt. 3-methyl-4-nitrophenol.

Example 6

The procedure of Example 2 was followed except that, in the first extraction step, 20 ml of 0.45 wt. aqueous NaOH solution. After the first extraction step, the O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate contained 0.48 wt. % Of 3-ethyl-4-nitrophenol and after a second extraction step 0.15 wt. 3-methyl-4-nitrophenol.

The invention can be used in the purification of O, O-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate to obtain a higher quality product than in the prior art and aqueous solutions of the extender are more concentrated to 3-methyl-4-nitrophenol than hitherto and 3-Methyl-4-nitrophenol can be obtained therefrom. The stock can be operated on the existing production facility.

Claims (4)

Method for reducing the content of 3-methyl-4-nitrophenol in the technique of 0,0-dimethyl-O- (3-methyl-4-nitrophenyl) thiophosphate by extraction, characterized in that the extraction is carried out with an aqueous solution of sodium carbonate and sodium hydroxide wherein the molar ratio of sodium hydroxide to sodium carbonate is 0.1: 1 to 100: 1 and the molar ratio of 3-methyl-4-nitrophenol to carbonate and sodium hydroxide is 1: 0.5 to 1: 5. 2. The method of claim 1, wherein the extraction is carried out with an aqueous sodium carbonate solution and successively adding the aqueous sodium hydroxide solution to the extraction mixture during the extraccle. 3. Method according to claim 1, characterized in that the extraction is carried out in at least two extraction steps, in which a countercurrent flow is applied and the aqueous solution from the second extraction step is used for the subsequent extraction of 3-methyl-4-nitrophenol in the first extraction step. . 4. Method according to claim 3, characterized in that the aqueous solution of the second extraction step is enriched in the subsequent use by the addition of an aqueous sodium hydroxide solution, the molar ratio of 3-methyl-4-nitrophenol from the aqueous solution of the second extraction step to the added sodium hydroxide solution. is 0.2: 1 to 2: 1.