Study On The Synthesis Technology Of Picoxystrobin

Picoxystrobin is a high-efficiency,low-toxic,broad-spectrum methoxy acrylate fungicide.Its synthesis has attracted great interest from chemists at home and abroad.At present,several manufacturers in China have produced it.It was selected firstly to introduce methoxymethylidene to the side chain of methy o-methylphenylacetate,then the target product was obtained by the methylacetate reacting with 6-trifluoromethyl-2-hydroxy-pyridine via Williamson etherification.The research procedure can be described as follows:using the methyl o-methylphenylacetateas as the starting material,Picoxystrobin was obtained by sesterification,formylation,methylation,bromination and etherification in five steps.The reaction of each steps was systematically studied and optimized.The structure of the target product and some important intermediates were characterized by IR,1HNMR,13CNMR,MS,and the contents were determined by GC and HPLC.The optimal conditions for each step of the reaction are:In the esterification reaction,the esterification of methyl o-methyl phenylacetate,n(o-methylphenylacetic acid):n(methanol)=1,24.75,the amount of concentrated sulfuric acid of catalyst is 0.75%of methanol volume,the reaction time is 65? for 18 h,Methyl orthomethyl phenylacetate was obtained with 98%yield and 99%contents.In formylation reaction,methyl 3-hydroxy-2-o-toluenyl acrylate was synthesized by condensation of a-carbon upper ester.The optimum conditions were as follows:solvent selective toluene,alkali selective sodium hydride,formate selective methyl formate,reaction temperature 30?,reaction time 12h,reaction temperature 30?,reaction time 12h.N(methyl orthomethyl phenylacetate,):n(methyl formate,):n(sodium hydride)=1,3,3,the yield is 95%,and the content is 93.7%.The synthesis of 3-methoxy-2-o-tolyl methyl acrylate by methylatio-n reaction is as follows:n(tetrabutyl bromide):n(3-hydroxy-2-o-tolyl methyl acrylate):n((CH3O)2SO2):n(NaOH)=0.01:1:1.4:1.6,water as solvent,reaction time of 10 h,reaction temperature of 30?,The yield was 85%and the content was 96.8%.Bromination is the synthesis of(E)-3-methoxy-2-(2-bromomethyl phenyl)-2-methyl acrylate by bromination of benzyl groups.The optimum reaction conditions were as follows:n(3-methoxy-2-o-toluenyl acrylate):n(NBS)=1:1.1,carbon tetrachloride as solvent and AIBN was used as initiator at 70? for 6 h.The yield was 85.0%and the content was 97.3%.In the etherification reaction,(E)-3-methoxy-2-(2-bromomethylphe-nyl)-2-methyl acrylate and 6-trifluoromethyl-2-hydroxy-methyl acrylate are used as the raw materials to generate(E)-3-methoxy-2-{2ethyl)-2-me-thyl]phenyl} methyl acrylate,and the reaction conditions are as follows:with potassium carbonate as base,acetone as solvent,n((E)-3-methoxy-2-(2-bromomethylphenyl)-2-methyl acrylate):n(6-triflu-oromethyl-2-hydroxy-methyl):n(K2C03)=1:1:1,temperature of 56?,and reaction time of 9 h,The yield was 74.6%and the purity was 98.1%.The synthetic route of picoxystrobin obtained in this study has the characteristics of cheap and easy to obtain raw materials,simple process operation and friendly environment.Under the optimum process conditions of each step,the total yield was 50.1%(based on methyl o-methyl phenylacetate,),and the content was 98.1%,which met the requirements of the industry for the product.