Study On The Clean Synthesis Of Propisochlor And Butachlor

Propisochlor and butachlor are inner-absorption conducting amide herbicides,mainly used for selectively controlling pre-emergence weeds.By being absorbed into the body of the sprout,the herbicides take their effects via prohibiting and destroying the formation of the protease.They are applicable in the controlling of barnyard grass,crabgrass,foxtail and other annual grass weeds and therefore have been widely used in rice,corn and soybean cultivation.Butachlor is one of the primary amide herbicides sold out on the marketwhile and propisochlor is an excellent alternative to the herbicide that has aroused resistant by the weeds.Therefore,the synthesis research and process optimization of propisochlor and butachlor have important practical significance.In this paper,available methods for the synthesis of propisochlor and butachlor were reviewed and the most promising routes for the industrialization were chosen for further optimization.Starting from aniline,the final target product was synthesized by nucleophilic substitution reaction with paraformaldehyde,addition reaction with chloroacetyl chloride and condensation reaction with alcohol.As an example,data for the raw material cost and waste output for the production of per ton of propisochlor were collected by mass balance calculation.Meanwhile,the source of impurity in the crude oil of butachlor was analyzed.The structures and purities of the desired products and the intermediates invloled have been characterized or detected by ~1H NMR,IR,MS and GC.And the influence factors on the yields and purity of the desired products,such as molar ratio of materials,feeding mode,solvent,acid binding agent,temperature and reaction time,have been carefully examined here.Under the optimized processing conditions,the total yield of propisochlor was83.3%with the purity of 92.59%,the total yield of butachlor was 87.5%with the purity of 96.96%.Compared with the traditional process,the synthetic method here possesses a variety of advantages such as higher yield,simplermanipulation,better product purity and being environmentally benign.It shows promising industrial application since it is suitable for scaling up with cheap available materials.