A Novel Synthesis And Purification Of Glufosinate

Glufosinate is a non-selective organophosphorus herbicide with low toxicity and high efficiency,which is more and more widely used in forestry,agriculture and other industries.The amount of glufosinate used is increasing year by year,and it has huge market potential.At present,there are many shortcomings in the route of synthesis and purification glufosinate in China,such as emission of large three wastes,low purity of products,high cost,complicated process route and the need for sodium cyanide as raw material,which is not conducive to the development of industrial cleaner production technology.In this paper,the existing routes of synthesis and purification of glufosinate were discussed.In the meanwhile,a new route of synthesis and purification of glufosinate was designed through comparison and study,and the process parameters were optimized to obtain the optimal experimental conditions.Firstly,n-butyl methyl hypophosphite was synthesized taking yellow phosphorus as raw material.It reacted with 1,1-diacetoxy-2-propene to obtain 3,3-diacetoxy-propyl methylphosphinic acid n-butyl ester,which was hydrolyzed in a hydrochloric acid solution to synthesis 3-methyl-n-butoxy-phosphorylpropionaldehyde.Then,(3-acetyla mino-4-oxo-4-((toluenesulfonylmethyl)amino)butyl)(methyl)phosphinate was prepared taking 3-methyl-n-butoxyphos phorylpropionaldehyde and p-toluene sulfonylmethyl isocyanide as raw material.Finally,it was hydrolyzed and ammoniated to obtain glufosinate ammonium salt.The yield of reaction was 45.3%.In the route of synthesizing n-butyl methyl hypophosphite by yellow phosphorus method,the best phase transfer catalyst was catalyst A by the screening of the phase transfer catalyst.The yield was 74.6%.In the route of synthesizing(3-acetylamino-4-oxo-4-((toluene sulfonylmethyl)amino)butyl)(methyl)phosphinate by Ugi reaction,the optimum molar ratio was 3-methyl-n-butoxy phosphorylpropionaldehyde(0.016 mol):ammonia:p-toluenesul fonylmethyl isocyanide:acetic acid=1:9:1:18.The optimum reaction time,reaction temperature and the volume of the solvent A were 20 h,30?and 65 mL,respectively.Under the condition,the yield was 51.2%.In the process of purifying glufosinate,because of its high solubility in water,the separation is extremely difficult from a large amount of inorganic salts and colored organic impurities.Hence,a co-separation method combining electrodialysis membrane and a macroporous adsorption resin was developed to obtain glufosinate with higher purity in the paper.For the electrodialysis process,a glufosinate reaction solution was placed in a dilute chamber and desalinated.The concentration of inorganic salts in the resultant glufosinate aqueous solution was only 0.99 g/L under the optimal conditions of an operating voltage and volume ratio of 9 V and 1:1,respectively.For the macroporous resin adsorption/desorption process,the sample solution treated by electrodialysis was pumped into the resin-filled column,which was eluted to obtain the eluent when the adsorption reached equilibrium.Consequently,nearly all the coloured organic impurities were removed under the optimal conditions,in which the resin type,pH value,flow rate,glufosinate concentration,temperature,ratio of ethanol and volume of eluent were LX-300C,3,0.5 mL/(cm~2·min),20 mg/mL,25?,50%and 400 mL,respectively.After the electrodialysis and adsorption/desorption process,the purity of the glufosinate was increased to 95.2%,and its yield was as high as 98.1%.The advantages of this process include its ease of operation,environmental friendliness and low cost,which provide strong potential for its use in industrial applications.In summary,a new route for the preparation of glufosinate was designed,and the process conditions were optimized.The synthetic route avoided the use of inorganic salt ammonium chloride and highly toxic substance sodium cyanide,and overcome the shortcomings in Strecker route,such as more wastes and longer steps.It had the advantages of mild reaction conditions,simple operation and higher atomic economy.At the same time,a method of purifying glufosinate by combining electrodialysis membrane with macroporous resin was designed,and the process parameters were optimized.The purification process had the advantages of simple operation,less waste,low cost and high yield,which conformed to the principles of green chemistry and economy.