Ester Intermediates Of The Chiral Herbicide Oh Grass Synthesis Process

Propaquizafop,a highly efficient aryloxyphenoxypropionate chiral herbicide, has good herbicidal avtivity against to annual or perennial grass weed and is widely applied in soja,cole,cotton,sugar beet,pea and so on.It has many advantages,such as high efficiency,easy degradation,low pollution,et.al.This paper made a study on the synthesis of three key intermediates of propaquizafop:2-[(isopropylidieneamino) oxy]ethanol,2-[(isopropylidieneamino)oxy]ethyl-L-lactate and 4-[(6-chloro-2-quin-oxalinyl) oxy]phenol.The reaction factors for every step,such as catalyst or acid binding agent,solvent,molar ratio,temperature,reaction time were entirely investigated.(1) The optimal parameters of 2-[(isopropylidieneamino)oxy]ethanol were obtained as follows:it was synthesized from acetone oxime and ethylene oxide using WZ-1 as catalyst,molar ratio of acetone oxime to ethylene oxide was 1:1.8, catalyst amount was 5.0%(based on acetone oxime),solvent was solvent(A),reaction temperature was 35.0～40.0℃,reaction time was 6.5 h and the yield was 45.2%.(2) The optimal parameters of 2-[(isopropylidieneamino)oxy]ethyl-L-lactate were obtained as follows:it was synthesized from L-lactic acid and 2-[(isopropylidieneamino)oxy]ethanol using WZ-2 as catalyst,molar ratio of L-lactic acid to 2-[(isopropylidieneamino)oxy]ethanol was 1:3,catalyst amount was 5.0%(based on L-lactic acid),water-carrying reagent was solvent(B),reflux time was 3.5 h and the yield was 78.5%.(3) The optimal parameters of 4-[(6-chloro-2-quinoxalinyl)oxy]phenol were obtained as follows:it was synthesized from 2,6-dichloroquinoxaline and hydroquinone using WZ-3 as base, n(2,6-dichloroquinoxaline):n(hydroquinone):n(WZ-3)=1:1.2:3,solvent was solvent(C),reaction temperature was 105.0～110.0℃,reaction time was 2.5 h and the yield was 78.2%.Their structures were characterized by elemental analysis,IR, NMR.reaction was monitored and the products were quantitatively analysed using gas chromatography.