Method for preparing acephate

Abstract

Production of acephate by ketene is carried out by taking ketene and 0,0-dimethyl-thiophosphoryl triamide as raw materials, acetylating reacting ketene with 0,0-dimethyl-thiophosphoryl triamide under condition of acidation catalyst and organic solvent to obtain acetylated 0,0-dimethyl-thiophosphoryl triamide, reacting for acetylated 0,0-dimethyl-thiophosphoryl triamide under isomerization catalyst condition to prepare acephate solution, crystallizing, solid-liquid separating and drying to obtain acephate coarse powders. It has better recovery rate and purity, has less consumption and no environmental pollution.

Description

1. Technical field: [0001] The invention relates to a method for preparing an insecticide, in particular to a new method for preparing acephate from ketene. 2. Background technology: [0002] Acephate is an acetylated derivative of the insecticide methamidophos. It is a good high-efficiency, low-toxicity, and low-residue broad-spectrum insecticide. It is effective against major pests of rice, cotton, vegetables, and fruit trees. It has good control effect and is one of the ideal varieties to replace highly toxic and high residue pesticides. Especially in the current social and economic development, some highly toxic pesticides such as methamidophos, parathion (1605), methyl parathion (methyl 1605), monocrotophos, ammonium phosphate and other five highly toxic pesticides Since January 1, 2007, the use in agriculture has been completely prohibited, and the structural adjustment of the agricultural industry is inevitable. [0003] At present, the production method of acephate...

AI Technical Summary

Problems solved by technology

In above-mentioned these methods, all there is common problem: produce a large amount of acetic acid in the production process; Need to consume a large amount of ammoniacal liquor (or liquid ammonia) and because by-product ammonium acetate is too much in the neutralization process, ammonium acetate and acephate are both Substances that are easily soluble in water have certain similarities in their properties, and it is difficult to completely separate them. Most production methods use ammonia water legally, and then use dozens of times the organic solvent to extract

[0009] 1. Almost all of the acephate obtained by the reaction meets with water (JP-B48-34583) is to extract the acephate crude oil with chloroform and then treat it with brine; Methamidophos crude oil), and acephate is easily decomposed in aqueous solution (especially in alkaline solution), so the loss of acephate may be larger in the separation process, resulting in a low total yield of separation

[0010] 2. Methamidophos is easily soluble in water, difficult to extract and has high solvent consumption; and when recovering the solvent, acephate is decomposed due to distillation, which reduces the yield and purity of the product

[0011] 3. A large amount of industrial wastewater is generated during the production process. The water cannot be recycled during the separation process and can only be discharged as wastewater in the end. This may cause the discharge loss of organic solvents and acephate, further increasing the separation cost

[0012] 4. Although neutralization with liquid ammonia can partially solve the above problems, such as CN1362415, the by-product ammonium acetate is too much, and it is difficult to separate. A part of acephate is entrained in the ammonium acetate, and solid-liquid separation and desorption are also required in the production process. High-purity acephate raw powder was obtained through complex processes such as dissolution and crystallization separation, and coarse crystal purification, resulting in a decrease in yield

Since the emulsifiable concentrate prepared with mother liquor contains more impurities, the stability is generally poor

Images