Study On Preparation And Application Of Novel Herbicide

Large doses of chemical herbicides were used to solve the increasingly serious problem of weed resistance.However,the superfluous herbicides not only aggravated the weed resistance,but also caused a serious threat to the environment.For some weeds with serious resistance,few herbicides could control them effectively.Therefore,it is urgent and necessary to develop high efficient and environmentally friendly herbicides with new structures and action sites.New herbicidal compounds and formulations were developed using the strategies of me-too method,cluster effect and ionic liquids.The herbicidal activities and environmental effect of these compounds were also investigated.This research mainly contains four parts as follows:1.Study on the synthesis and herbicidal activities of amitrole derivativesBased on the mechanism of action of amitrole(? and ? carotenoids synthetic inhibitors),a series of herbicidal compounds were prepared using amitrole as a lead compound,and the structures were identified by 1H NMR and elemental analysis.Herbicidal trial showed that the fresh weight reductions of ?-17,?-19 and ?-21 against common single cotyledon and dicotyledonous weeds were more than 70%and much higher than amitrole.When the substituent group was alkyl acyl,the herbicidal activities of the compounds increased first and then decreased with increasing of the length of carbon chain.When the substituent group was substituted benzoyl,the compounds with para orientation had good herbicidal activities,and the herbicidal activities were in the order as follows:nitro substituted>methyl substituted>chloro substituted>fluoro substituted.2.Study on the synthesis and application of auxinic herbicide derivativesA series of auxinic herbicide derivatives were prepared using 2,4-D,MCPA and dicamba as lead compounds by me-too method.The structures of synthetic compounds were confirmed by 1H NMR,13C NMR and elemental analysis.Results of volatility test indicated that the majority of synthetic compounds showed lower volatilities than that of corresponding lead compound except ?a-(7-8)and?b-(7-8).In the herbicidal activity test,?a-(7-9),?b-9 and ?c-9 had faster and higher herbicidal activities than corresponding lead compounds.IIb-7 also showed an excellent herbicidal activity against barnyard grass and may have multiple mechanisms.Comprehensive consideration of volatility and herbicidal activity,IIa-9,IIb-9 and IIc-9 could be potential herbicides for further development.3.Study on the synthesis and application of auxinic herbicide dimersA series of auxinic herbicide dimers were synthesized by cluster effect strategy using 2,4-D,dicamba and MCPA as monomers.The results indicated all of the synthetic dimers had much lower volatilities than that of their corresponding monomers.The linker R had a great effect on herbicidal activity when monomer was kept same.When the chemical bond between alkyl linker and monomer was double-O-,the dimers showed faster and higher herbicidal activity than their corresponding monomers.The dimers with-NH-showed much higher herbicidal activities than their corresponding monomers at 270g AI ha-1 at 3 DAT and their mode of action was suspected to be both contact poisoning and systemic action at the same time.The dimers ?b-(7-9)showed the excellent herbicidal activities against barnyard grass at 450g AI ha-1 and might have multiple modes of action.The dimers ?a-2,?a-4,?b-2 and IIIc-2 could be developed as the postemergence herbicides to control broadleaf weeds.The metabolism study showed that the dimers might not act as the "prodrug" and had different acting site with their corresponding monomers.4.Study on the synthesis and application of fomesafen ionic liquids and picloram ionic liquids New herbicide ionic liquids(HILs)based fomesafen and picloram were prepared to improve the herbicidal activity and reduce the risk to the aquatic organisms.The octanol-water partition coefficient(Kow),surface activity,leaching,soil adsorption and herbicidal activity of HILs were tested and made a comparative analysis with fomesafen and picloram.The results show that the water solubility,Kow,surface tension,leaching and adsorbed ability of HILs can be regulated and optimized by selecting different counter cations.Compared with fomesafen sodium,ionic liquids FHIL-1 showed a higher and faster herbicidal activity due to its good lipophilicity and low surface tension.PHILs with longer carbon chain had higher herbicidal activities.Compared with picloram potassium,ionic liquids PHIL-3 showed a higher herbicidal activity.HILs with lower water solubility and greater adsorption capacity in soil have less risk to environment and aquatic organisms than fomesafen and picloram.