Synthesis And Herbicidal Activity Of Toxins â…¢ From Phoma Herbarbum Derivatives

In order to improve the herbicidal activity of toxins III (2-methyl-3,5-dinitrobenzoic acid methyl ester) from Phoma herbarbum, its structure was optimized by derivation. This paper designed and synthesis of thirty four substituted benzoic esters and sixteen benzamides, the herbicidal activity against some weeds such as Digitaria sanguinalis and Amaranthus retroflexus were tested by bioassay method. Five compounds showed high herbicidal activity, including three substituted benzoic esters, whose inhibition rate against A. retroflexus root were good, one substituted benzoic acid ester, whose fresh weight efficacy against D. sanguinalis and A. sretroflexus were 100%, and one benzamide had good herbicidal activity against D. sanguinalis, A. sretroflexus and E. crusgalli. Those results provide a theoretical basis for the further research of the synthesis and herbicidal activity of benzoic esters and benzamides.Thirty four novel benzoic esters were synthesized by nitration, esterification from o-toluic acid as starting material. Their structure were confirmed by IR,1H NMR and GC-MS. The herbicidal activity was tested by bioassay method. Firstly, using the weed seed germination rate method tested the herbicidal activity against some weeds of the thirty four substituted benzoic esters, and chosen the compounds whose germination rate higher than 70% in preliminary bioassay test to rescreen. The herbicidal activity screening showed that the inhibition rate of the target compounds on the roots of weed was higher than that of the shoots. The inhibition rate of J-L-15, J-L-16 and J-L-26 against A. retroflexus root were 92.8%,92.0% and 87.4% at 100μg/mL, respectively. They had significant herbicidal activity. The fresh weight efficacy of J-L-1 against D. sanguinalis and A. sretroflexus was 100% at 1000 g a. i./hm2, which had high herbicidal activity. The ED50 value for Digitaria sanguinalis was 94.89 g a. i./hm2.Sixteen novel benzamides were synthesized by nitration, acylation from o-toluic acid as starting material. Their structure were confirmed by IR,1H NMR and GC-MS. The herbicidal activity was tested by bioassay method. Firstly, using the weed seed germination rate method tested the herbicidal activity against some weeds of the sixteen substituted benzamides, and chosen the compounds whose germination rate higher than 70% in preliminary bioassay test to rescreen.The herbicidal activity screening showed that the inhibition rate of J-L-59 against E. crusgalli root was 93.7% at 100μg/mL. The fresh weight efficacy of J-1-59 against A. theophrasti and A. retroflexus were 100% at 1000 g a. i./hm2. The ED50 value for A. retroflexus was 94.06 g a. i./hm2, which had high herbicidal activity.This paper studied the synthesis and herbicidal activity of benzoic acid esters and benzamides, selected high herbicidal activity compounds J-L-1、J-L-15、J-L-16、J-L-26 and J-L-59, and set a foundation for further study.