HU176401B - Process for producing 0,0-dimethyl-0-2,2-dichloro-vinyl-phosphate - Google Patents

Description

The present invention relates to a process for the preparation of O, O-dimethyl-O-2,2-dichloro-vinyl phosphate, a compound known as Dichlorphos, a phosphorous organic insecticide. This substance is widely used in various formulations for the control of plant pests in veterinary and health care.

There are two basic processes for producing Dichlophos. The first process is described, for example, in U.S. Patent Nos. 2,899,456 and 2,956,073, according to which trimethyl phosphite is reacted with Moral. The reaction is carried out in a high yield of about 90% and the product obtained is easily purified from volatile impurities, so that the Dichlorphos concentrate produced by this process is of high quality. The disadvantage of this process is that the trimethyl phosphate and chloral used must be of high purity, which results in a significant increase in the cost of producing Dichlorphos.

Alternatively, as disclosed in, for example, German Patent Nos. 1,003,720 and French Patent Nos. 1,550,237, l-hydroxy-2,2,2-trichloroethyl, on-dimethylphosphonate, Trichlorphon is used to transform Dichlorphos into trivial insecticidal agents, such as alkali metal hydroxides and carbonates and ammonium hydroxide and carbonate. This process is complicated both by the removal of hydrogen chloride molecules from the Trichlorphon molecules and by the intracellular rearrangement to the Dichlorphos structure. THE

The faster the basic medium that binds hydrogen chloride and the higher the temperature, the greater the rate at which Trichlorphon is converted to Dichlorphos. When Trichlorphon is converted to Dichlorphos in the presence of a base, there are side reactions whereby Dichlorphos and Trichlorphon are degraded, primarily by hydrolysis and desalkylation. Particularly prone to hydrolysis in basic aqueous solutions is Dichlorphos, which has a half-life of 12 minutes at 28 ° C and pH 11. The formation of Dichlorphos from Trichlorphon is dependent on the course of the side reactions and how the side reactions are hindered, for example, by lowering the temperature, reducing the reaction time, selecting a suitable concentration of the appropriate base, a water immiscible organic solvent. and, there are various possible ways of doing this. The yield of Dichlorphos produced by this process is generally less than 60% and the product contains more impurities than the product produced by the phosphite chloral process. Despite its low yields, the process is widespread in practice, as the cost of the process is significantly lower compared to the phosphite-chloral process and Trichlorphon can be easily converted to Dichlorphos.

It is an object of the present invention to provide a process for the preparation of Dichlorphos from Trichlorphon which has a higher yield than previously known.

Surprisingly, it has been found that when Trichlorphon is added in the range of 0.1 to 10% by weight quaternary ammonium salt and / or tertiary amine, the degree of conversion of Trichlorphon to alkaline materials will be greatly limited and the reaction medium will be severely limited Hydrolytic decomposition of Dichlorphos.

When using a catalytic amount of a quaternary ammonium salt and a tertiary amine, the ratio of the components in the mixture can range from 1: 10 to 10: 1.

The quaternary ammonium salts of the present invention may be used in catalytic amounts, in particular quaternary ammonium salts having at least one alkyl group of more than 6 carbon atoms in the molecule and / or at least six -OC ₂ H ₄ units. containing a polyoxyethylene group.

Tertiary amines are preferably trialkanolamines.

In the process of the present invention, Dichlorphos is prepared by treating Trichlorphon with alkaline metal hydroxides or carbonates, such as sodium and potassium hydroxides and carbonates, and calcium or ammonium hydroxides in the presence of basic hydrogen chloride binding agents. or carbonate is converted. Said hydroxides and carbonates can be used in the form of aqueous solutions over a wide concentration range. Most suitable is an aqueous solution of 5-25% by weight. To ensure that the process runs in the right direction, the basic substances are used in an excess relative to the amount of Trichlorphon. The amount of base used to convert Trichlorphon to Dichlorpos depends on the nature and concentration of the base, as well as the temperature and reaction time. The molar ratio of base to Trichlorphon generally corresponds to the following ratio: 1.2: 1.6-1.

In the process of the invention, Dichlorphos can be prepared from Trichlorphon over a wide temperature range, i.e., from -20 ° C to 100 ° C. The temperature depends primarily on the quality and concentration of the base used. The most favorable result is obtained when the Trichlorphon is transformed at 0-50 ° C in the presence of alkali metal carbonates.

The present invention utilizes organic, water-immiscible solvents which do not react with alkali metal hydroxides and alkali metal carbonates at temperatures between -20 ° C and 100 ° C. Examples are: benzene, toluene, chlorobenzene, methylene chloride, trichloroethylene, carbon tetraldoride. Particularly suitable solvents are those in which Trichlorphon and Dichlorphos are relatively soluble.

The possibility of driving the process at a relatively high temperature with the rapid progress of the reaction and thus facilitating the release of reaction heat, and the possibility of hydrolytic decomposition of Dichlorphos in a barely sensitive basic medium in the presence of quaternary ammonium salts and / or tertiary amines makes it possible to apply the process of the invention periodically or continuously. The process is well suited to large-scale production, and has improved productivity compared to known Dichlorphos production processes, less dependent on possible changes in various characteristics.

The process of the invention is illustrated by the following embodiments.

Example 1

Into a glass flask equipped with a 200 mL stirrer, a thermometer and a dropping funnel, was added Trichlorphon (27.1 g, 95% l-hydroxy-0.0-dimethylphosphonate), 100 mL methylene chloride and 0.8 g triethanolamine. The contents of the flask were stirred at 20 ° C and 56.1 g of 20% aqueous potassium hydroxide solution was added dropwise with cooling over 10 minutes, and the contents were stirred for an additional 30 minutes. The resulting two-phase separator was separated and the organic phase was concentrated in a rotary evaporator at 50 ° C and 20 mm Hg. 30.3 g

96% Dichlorphos containing O, O-dimethyl-2,2-dichloro-vinyl phosphate is obtained. Yield: 88%. The product was identified by magnetic proton and phosphor resonance and quantitated by infrared spectrophotometry.

In analogy to the above, but without the addition of the tertiary amine, 13.4 g (86%) of Dichlorphos were obtained, yield 52%.

Example 2

Into the flask of Example 1 was introduced 27.1 g of 95% Trichlorphon, 100 ml of chloroform and 0.8 g of methyl di (polyoxyethylene) stearylammonium chloride (11-OC ₂ H ₄ polyoxyethylene group). ). The contents of the flask were stirred at 60 ° C and 79.5 g of 20% aqueous sodium carbonate solution were added dropwise over 10 minutes and the contents of the flask were stirred for another 30 minutes at the same temperature. After cooling, the two phases are separated and the organic phase is concentrated in a rotary evaporator at 50 ° C and 20 mm Hg. 20.6 g of 94% Dichlorphos are obtained. Yield: 87%.

When carried out in an analogous manner, but without addition of the quaternary ammonium salt, 15.9 g of 86% Dichlorphos are obtained. Yield: 62%.

Example 3

Into the flask of Example 1 was charged 27.1 g of 95% Trichlorphon, 100 g of methylene chloride, 0.5 g of triethanolamine and 0.5 g of methyl di (polyoxyethylene) stearylammonium chloride (11-OC 2 H 4 unit polyoxyethylene). -group). The flask contents were agitated at 20 ^e C and cooling 36 g of 20% aqueous sodium carbonate was added dropwise over 10 minutes and the contents were stirred at the same temperature for another 30 minutes. The resulting two-phase separator is separated and the organic phase is evaporated in a rotary evaporator at 50 ° C and 20 mm Hg. 20.5 g of Dichlorphos containing 96% O, O-dimethyl-O-2,2, -dichloro vinyl phosphate were obtained. Yield: 89%.

Claims (1)

A method of 0,0-dimethyl-0-2.2-dichlorovinyl phosphate preparation of 1-hydroxy-2,2,2-trichloroethyl-O, O-dimethyl phosphorothioate upon ^five basic plexus organic materials, water-immiscible solvent, wherein to 0, l% 10súly quaternary ammonium salt and / or tertiary amine is carried out in the presence ^{of 10} of appearance after the process I-2,2,2-trikióretil hydroquinone-O, O-dimethyl phosphonate quantities.