Fang Oxygen Chiral Phenoxy Acid Herbicides Oh Grass Ester Synthesis Process

Propaquizafop,a high efficient aryloxyphenoxypropionate chiral herbicide,has good herbicidal activity against annual and perennial grass weed,such as Wild oat, Squitch,Sotghum halepense,Cynodon dactylon and so on.And it is widely applied in wheat,potato,soja,sole,cotton,flax,sugar beet and pea.It has many advantages, such as high efficiency,easy degradation,low pollution and so on.Propaquizafop is a good alternation of some commercial organic phosphorus herbicides,such as Glyphosate and Zytron which cause serious environmental pollution.In abroad,the synthesis of Propaquizafop is started from the raw material of(L)-2-chloropropionic acid or(L)-lactic acid.However the source of(L)-2- chloropropionic acid is limited and its price is twice as that of L-lactic acid.Base on this situation we chose natural fermentation production(L)-lactic acid as the starting material,to synthesise propaquizafop through esterification,sulfonylation and etherification.This paper focused on the last two steps,sulfonylation and etherification reation.When the molar ratio of 2-[(isopropylideneamino)-oxy]-ethy-(S)-lactate to p-toluenesulfonyl chloride to base A was 1:1:1.1,and solvent B, 2-[(isopropylideneamino)oxy]-ethy-(S)-2-(toxyloxy)-propionate was prepared with the yield of 92～96%,e.e.≥98%;In solvent C,base D and with cat.E as catalyst, propaquizafop was prepared from 2-[(isopropylideneamino)oxy]ethy-(S)-(toxyoxy)-propionate and 4-[(6-chloroquinoxalinyl)oxy]phenol,with the crude product yeild of 80%,purity＞85%and e.e.＞82%.The active ingredient of the product through recrystallization is over 93%.The reactions were monitored with GC or HPLC.