Dissertation > Industrial Technology > Chemical Industry > Pesticide Industry > Herbicide > Organic herbicides

Research on Synthesis Process of Clodinafop-propargyl

Author ZhuLing
Tutor WangLiangJie
School Xiangtan University
Course Chemical Engineering
Keywords clodinafop-propargyl herbicide 5-chloro-2,3-difluoropyridine (R)-2-[4-(5-chloro-3-fluoro-2-pyridyloxy)-phenoxy] propanoic acid synthesi
CLC TQ457.2
Type Master's thesis
Year 2009
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Clodinafop-propargyl is a kind of chrial,aryloxyphenoxypropionate and fluorinated hebicides which are ACCase depressors,it is highly effective to malignant gramineae weeds with a few quantities and can be easily metabolized,and little harmful to the environment.So,there is a fine development prospect of clodinafop-propargyl.There were many ways to synthesize clodinafop-propargyl.(1) After etherification, condensation reaction with chiral ester,hydrolysis and esterification with propargyl alcohol,clodinafop-propargyl could be synthesized from hydroquinone and 5-chloro-2,3-difluoropyridine,but the total yield of the product was less than 45%.(2) Clodinafop-propargyl could be synthesized from(R)-2-(4-hydroxyphenoxy) propionic acid propynyl ester and 5-chloro-2,3-difluoropyridine,the yield of which was 72%.(3) Using(R)-2-(4-hydroxyphenoxy) propionic acid,5-chloro-2,3-difluoropyridine and propargyl chloride as raw materials,clodinafop-propargyl could be get without isolation,it was called "one pot",the yield of which was 85%.The article was based on "one pot", with 5-chloro-2,3-difluoropyridine and(R)-2-(4-hydroxyphenoxy) propionic acid as raw materials,water as reaction medium,the synthesis process was improved and optimized.(R)-2-[4-(5-chloro-3-fluoro-2-pyridyloxy)-phenoxy]propanoic acid(intermediate) was synthesized from 5-chloro-2,3-difluoropyridine and(R)-2-(4-hydroxyphenoxy) propionic acid(HPPA),using water as reaction medium.The conditions of etherificaion was researched by some experimental methods using K2CO3,Na2CO3 and NaOH as acid-binding agent independently.The optimal conditions for the reaction are concerned: K2CO3 as acid-binding agent,water as solvent medium,n(K2CO3):n(HPPA)=2:1, m(water):m(HPPA)=1.075:1,reaction temperature 106℃and reacion time 3 h.Yield of the product is 85.22%under the optimal conditions,the conversion of HPPA is 97.43% and the selectivity of the process is 87.47%,content of the product is 98.23%.it is concerned that the product of this process is(R)-2-[4-(5-chloro-3-fluro-2-pyridyloxy)-phenoxy]propanoic acid by analyzing the melting point and FTIR spectrum.Clodinafop-propargyl was sythesized from(R)-2-[4-(5-chloro-3-fluoro-2-pyridyloxy) -phenoxy]propanoic acid and propargyl chloride,using DMF as solvent,the optimal conditions for the reaction are:n(propargyl chloride):n(intermediate)=1.2:1,m(DMF): m(intermediate)=1.925:1,reaction temperature 70℃and reacion time 5h.With these conditions,yield of the product is 98.54%,the conversion of the intermediate is 99.62%, with the selectivity of the process is 98.92%,content of the product is 95.63%by the chiral anlytical column of HPLC.The total yield of clodinafop-propargyl is over 84%in this process,there are many advantages of this technic such as using a few kinds of solvents,easy to isolate and purificate,mild reaction conditions,etc.So,it is indicative in industrial production.

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