Study On The Synthesis And Herbicidal Activity Of Novel Derivatives Of Di-N-oxide Quinoxaline Formaldehyde

Nowadays, the use of chemical herbicides has been used world wide. It reduces theharm caused by weeds on crops, traffic and shipping, and brings tremendous economicalbenefit.But, the herbicides in use at present have some defects, for example, the security isunder suspicion, the selectivity is not satisifactory, the antiherbicide of weed is also aproblem which can not neglect. So the development of novel herbicides has become themost popular subject in pesticide field.Derivatives of di-N-oxide quinoxaline formaldehyde have been widely used in theresearch of medicine,animal remedy and food additives due to their antibacterial activityand innocuity to human and livestock. Recently, we found derivatives of di-N-oxidequinoxaline formaldehyde had obvious herbicidal activity. They could be potential andnovel herbicides. Base on our early research, this paper accomplished the works asfollows:1. Benzofurazane was synthesized using o-nitroaniline, followed by reacting withacetone to produce the methyl di-N-oxide quinoxaline through Beirut reaction. Theproduct was oxidized by selenium dioxide to form the di-N-oxide quinoxalineformaldehyde (intermediate A). The reaction equation as follows:2. Ten kinds of single hydrazone (intermediate B) were obtained by reaction ofaliphatic and aromatic aldehyde ketone with hydrazine hydrate respectively.The reaction equation as follows: 3. Amino acids were transferred into amido acyl chloride by thionyl chloride. Then,amido acyl chloride were alcoholysed to form amino acid ester muriate, which werefollowed by hydrazinolysis to obtain ten sorts of amido acylhydrazine muriate.The reaction equation as follows:4. Using intermediate B and C reacted with intermediate A, which synthesized twentykinds of novel compounds of 1,4-dioxoquinoxaline formaldehyde dihydrazones (finalproduct D) and amido acylhydrazone (final product E) respectively as the finalproducts.The reaction equation as follows:5. The investigation of correlative reaction conditions was carried out in order toimprove the rate of production. The structures of some final products were characterizedby IR MS and ~1H-NMR.6. Monocotyledon Oryza sativa and dicotyledon Amaranthus ascendens Loisel wereselected as biomarker to testify the herbicidal activity of final products by measuring thegrowth restraining-ratio under different mass concentration of final products.The result shows that, the herbicidal activity varies from different species andconcentration of novel compounds. When mass concentration of novel compounds was100mg/L, the herbicidal activity on Oryza sativa and Amaranthus ascendens Loisl was not obvious. As the increase of mass concentration, the herbicidal activity also improved.When mass concentration got 800mg/L, virulence index increased significantly: that of1,4-dioxoquinoxaline formaldehyde 4-(dimethylamino) benzaldehyde dihydrazone and1,4-dioxoquinoxaline formaldehyde furfural dihydrazone reached 65.83 and 73.33respectively (the virulence index of all weed died is 100). As a whole, the herbicidalactivity of novel compounds to monocotyledon Oryza sativa was more active than todicotyledon Amaranthus ascendens Loisel.This paper accumulated the scientific research data for synthesis and herbicidal activityof a late-model kind of derivatives of quinoxaline di-N-oxide formaldehyde.