Study on the Synthesis of Clethodim
|Keywords||herbicide clethodim synthesis optimize|
Clethodim, (1-(3-chloroallyloxyimino)propyl5-(2-(ethylthio)propyl)-3-hy-droxycyclohex-2-enone, is one of cyclohexdione herbicides with goodherbicidal activity. Clethodim has been widely and rapidly applied .It combinesthe adventages of high effect, good selectivity, broadspectrum weed control andlow mammalian toxicity. Many international companies has invested lots ofmoney into the development of clethodim.In the research process of this paper, I firstly refered to many papers to findout the research background. The synthesis route of clethodim intermediates waselaborately chosen, the condition of reaction was optimized, and the yield ofproduct was improved.The syntheses of 6-(ethylthio)hept-3-en-2-one and o-(3-chloro-2-propenyl)hydroxylamine are the key processes. There are many facts influencing thereaction such as the proportion of reactants, solvent, the time of reaction, thetemperature, the amount of catalyst, and so on. We optimized the reactionconditions through lots of experiments. In addition, preferable yields of someintermediates were obtained by modified reaction conditions.The intermediate O-(3-Chloro-2-propenyl)hydroxylamine was preparedusing acetic ester and hydroxylamine hydrochloride by three steps viaacetylamination, etherification, and hydrolysis.The intermediate 5-(2-( ethylthio)propyl)-3-hydroxy-2-propionylcyclohex-2-enone and the other intermediate O-(3-Chloro-2-propenyl)-hydroxylamine wasused to produce target compound clethodim.Some of the intermediates obtained during the process of the synthesis andthe target compound were confirmed by means of spectra analysis, such as1HNMR, 13CNMR, IR, HPLC/MS, GC/ MS.