摘要:

AbstractIn acidic media, hydrolysis of chlorsulfuron and metsulfuron‐methyl occurs via two consecutive reactions which were followed by ultraviolet spectrophotometry. For these two reactions, the pseudo‐first‐order rate constants increase proportionally to the concentration of hydronium ion in the more acidic media and to the square of this concentration at higher pH values.A kinetic study by HPLC shows that the first reaction leads to the formation of 4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐amine and (o‐chlorophenylsulfonyl) carbamic acid for chlorsulfuron or (o‐methoxycarbonylphenylsulfonyl) carbamic acid for metsulfuronmethyl. The second reaction is the conversion of these sulfonylcarbamic acids to sulfonamides and carbon dioxide. The complete lack of saccharin and of o‐sulfamoyl benzoic acid proves that the ester function of the methoxycarbonyl group is stable.The lack of general acid‐base catalysis and a solvent deuterium isotope effect less than unity are consistent with a rate‐determining cleavage of the protonated substrate.In the basic pH range (10–14) a single reaction occurs, the nucleophilic substitution of the methoxy group on th

ISSN:0031-613X    

DOI:10.1002/ps.2780400112

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSprays of bifenthrin and paraffinic oil mixtures were applied to cotton leaves (Gossypium hirsutum L.) to investigate droplet size effects on the mortality of Heliothis virescens (F.). An air‐assisted nozzle applied mixtures at 9.4 litre ha −1 spray rate with volume median diameters (VMD) of 96 and 337 μm, as verified with a Malvern laser diffraction analyzer. An hour after spraying, susceptible 3rd‐instars walked for 2‐min through wet droplets of spray mixtures applied at bifenthrin rates of 22, 45, 67, 90. and 112 g a.i. ha −1. Mortality was assessed at 21, 26, 45, 50, 74, and 117h after exposure. Final mean mortality was affected (P =0.01) by bifenthrin rate and droplet size. Bifenthrin applied in 337 μm VMD droplets caused 75.8% mortality, whereas 96‐μm VMD droplets resulted in a mortality of 67.9%. Also, the 337 μm VMD droplets killed larvae in 13% less time than the 96μm VMD droplets, based on analysis (P =0.01) using the mean elapsed time till death as the

ISSN:0031-613X    

DOI:10.1002/ps.2780400113

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

ISSN:0031-613X    

DOI:10.1002/ps.2780400101

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY