Research Status of Amide Herbicides and Their Safeners

The widespread use of chemical herbicides especially amide herbicides has promoted the innovation of chemical weeding in farmland, but amide herbicides have brought invisible chemical injuries to crops in addition to weeding. Herbi-cidesafeners should be applied at the same time with herbicides to ensure herbi- cides will not injure crops while controlling weeds. The research and application of safeners is of great significance to resolving or alleviating the negative effects of herbicides on crop growth. The overview, mechanism, applied research progress and existing problems of amide herbicides and their safenars are summarized.

Synthesis, Crystal Structure and Biological Activity of Novel Dichloroacetyl Oxazolidine Herbicide Safeners

A series of novel N-dichloroacetyl oxazolidine herbicide safeners was synthesized and characterized by IR, 1H NMR, 13C NMR, elemental analysis and X-ray diffraction. The preliminary biological test shows that the compounds could protect maize against injury caused by chlorsulfuron to a certain extent.

Adsorption kinetics of the herbicide safeners,benoxacor and furilazole,to activated carbon and agricultural soils

Chloroacetamide herbicides,namely acetochlor and metolachlor,are common herbicides used on corn and soybean fields.Dichloroacetamide safeners,namely benoxacor and furilazole,are commonly used in formulations containing chloroacetamide herbicides.Extensive reports on adsorption of chloroacetamide herbicides are available,yet little information exists regarding adsorption potential of co-applied safeners.Herein,the adsorption and desorption characteristics of selected herbicide safeners to granular activated carbon(GAC) and in agricultural soils are reported.Further,soil column studies were performed to understand the leaching behaviour of the herbicide Dual II Magnum.Equilibrium sorption experiments of safeners to three agricultural soils and one GAC showed that adsorption was best fitted by the Freundlich isotherm.The Freundlich adsorption constant,Kf,for benoxacor and furilazole sorption onto three agricultural soils ranged from0.1 to 0.27 and 0.1 to 0.13(mg/g) x(mg/L)(1/n),respectively.The Kf for benoxacor and furilazole to GAC was 6.4 and 3.4(mg/g) x(mg/L)(1/n),respectively,suggesting more favorable sorption of benoxacor to GAC than furilazole to GAC.The sorption to soils was reversible as almost 40%-90% of both safeners was desorbed from three soils.These results were validated in four replicated soil column studies,where S-metolachlor was shown to leach similarly to the safener benoxacor,originating from the herbicide formulation.The leaching of S-metolachlor and benoxacor was influenced by soil texture.Cumulatively,these results show that safeners will move through the environment to surface waters similarly to the active ingredients in herbicides,but may be removed during drinking water treatment via GAC.

Convenient Synthesis of Two Novel Oxazolidines and Primary Research on their Biological Activities

Two novel N-dichloroacetyl oxazolidines were synthesized with a simple, mild and convenient method in good yields. The compounds were Characterized by IR, 1^H NMR and elemental analysis. The preliminary biological test show that the compounds protected maize against injure by chlorsulfuron to some extent.

Simple,Mild and Convenient Synthesis of Two Novel N-Dichloro-acetyl Oxazolidines and their Biological Activities

Two N-dichloroacetyl oxazolidines were synthesized with a simple, mild and convenient method. All the compounds were characterized by IR, HNMR and elemental analysis. The 1 preliminary biological test showed that the compounds protected maize against injury by some herbicides to some extent.

Identification of a Herbicide Safener AD-67 Inducible cDNA in Rice

A herbicide safener AD-67 inducible cDNA was identified in an indica rice variety 9311 by mRNA differential display. The transcript was increased 6 h after sprayed with the safener solution, and 4 days later, the expression still could be detected. The fragment was recycled from the polygel and sequenced, and homologous analysis revealed the cDNA was 100% identical to some ESTs and cDNAs in rice database, and the amino acid sequence was 60-84% homologous to those of the Yippee genes in several eukaryotes. The fragment was extended to the whole long cDNA, and thus a primer pair was designed. RT-PCR analysis for the designed primer supported the induction result.

Synthesis and biological activities of N-dichloroacetyl-2-n-propyl-1-oxa-4-aza-spiro-4, 5-decane

The title compound was synthesized and characterized by IR, ^1HNMR and elemental analysis. The preliminary biological test showed that the compound protected maize against injury by imazethapyr to some extent.

Safening effect of bentazon on cloransulam-methyl and halosulfuron-methyl in dry bean

Bentazon, applied as a tankmix, has been shown to have the potential for reducing the injury from some POST herbicides. Field experiments were conducted in 2008 and 2009 at Exeter, ON and in 2009 at Ridgetown, ON to determine if the addition of bentazon reduces the injury from cloransulam-methyl or halosulfuron-methyl applied POST in black, cranberry, kidney and white beans. Bentazon added to cloransulam-methyl reduced the level of injury 0 to 6% at 17.5 g·ai·ha–1 and 0 to 9% at 35 g·ai·ha–1 in dry bean. Bentazon added to halosulfuron-methyl reduced the level of injury as much as 4% at 35 g·ai·ha–1 and 6% at the 70 g·ai·ha–1. Bentazon added to cloransulam-methyl increased plant height as much as 3 cm. The addition of bentazon to halosulfuron-methyl had no effect on the height of various market classes of dry bean. Bentazon added to cloran-sulam-methyl generally has no effect on seed moisture content in black and white bean but decreased seed moisture content of cranberry and kidney bean as much as 4%. The addition of bentazon to halosulfuron-methyl caused no effect on seed moisture content of dry bean. Cloransulam-methyl caused a 7% to 18% reduction in dry bean yield compared to halosulfuron-methyl and 12% to 21% reduction in yield compared to bentazon. Bentazon added to cloransulam-methyl increased dry bean yield by 0.16 and 0.31 t·ha–1 at Exeter (2009) and Ridgetown (2009) respectively. The addition of bentazon to halosulfuron-methyl had no effect on dry bean yield.

Synthesis and Crystal Structure of 4-(Dichloroacetyl)-1-oxa-4-azaspiro[4.5]decane

The title compound 4-(dichloroacetyl)-1-oxa-4-azaspiro[4. 5] decane (CAS number 71526-07-3, C10H15Cl2NO2, Mr= 252.13) was obtained by the reaction of dichloroacetic acid with 1-oxa-4-azaspiro[4. 5] decane. The crystal is of monoclinic, space group P21ln with the unit cell constants: a = 5.9619(4),b= 10.0066(8), c = 20.0986(4) A,β = 90.194(3)°, V= 1199(4) A3,Z = 4, Dc= 1.397 g/cm3, F(000) = 528, μ(MoKα) = 0.522 mm-1, R = 0.0611 and wR = 0.1656 for 1276 observed reflections (I > 2σ(I)). X-ray analysis reveals that the cyclohexyl adopts a chair conformation and the compound is a chiral one.

Microwave-assistant Syntheses, Crystal Structures and Safener Activities of Two Substituted Phenyl Isoxazole Derivatives

Two novel substituted phenyl isoxazole benzoxazine formamide derivatives were designed and synthesized with substituted o-aminophenol,1,2-dibromoethane and different phenyl substituted isoxazole formyl chloride as the raw materials via microwave assistant synthesis.The target compounds were characterized by IR,^(1)H NMR,^(13)C NMR and HRMS.Both single-crystal structures were further determined by X-ray diffraction.3-(2’-Chloro-6’-fluoro-phenyl)-4-(2’,3’-dihydro-1’,4’-benzoxazine)-5-methyl-isoxazole formamide (4a) crystallizes in orthorhombic system,P2_(1) space group with a=8.9414(18),b=10.834(2),c=17.706(4)A,V=1715.1(6)A^(3),D_(c)=1.444 Mg/m^(3),Z=4,F(000)=768,μ(Mo Kα)=0.255 mm^(-1),R=0.0406 and wR=0.1171.3-Phenyl-4-(6-methyl-2’,3’-dihydro-1’,4’-benzoxazine)-5-methyl-isoxazole formamide (4b) is of triclinic system,space group PI with a=7.7659(16),b=8.3626(17),c=13.484(3)A,α=76.04(3)°,β=100.63(3)°,γ=82.01(3)°,V=841.6(3)A^(3),D_(c)=1.319 Mg/m^(3),Z=2,F(000)=352,μ(Mo Kα)=0.090 mm^(-1),R=0.0672 and wR=0.2671.Both crystals are packed through C–H···O hydrogen bonding interaction.There is C–H···F hydrogen bond between 4a molecules,and C–H···N between 4b molecules.Bioassay results showed that compounds 4a and 4b exhibited detoxification on maize and restored maize growth index.