“…Because of its chemical structure, 1-(4,6-dimethoxypyrimidin-2-yl)-3-(3-dimethylcarbamoyl-2-pyridylsulfonyl)urea, which exhibits a pyridyl-sulfonylurea bridge in place of the usual phenyl-sulfonylurea, nicosulfuron 1 ( Figure ) belongs to the substituted pyridinesulfonylurea group that also includes herbicides such as rimsulfuron, flupyrsulfuron-methyl, and flazasulfuron. The pyridylsulfonylurea structure of these herbicides provides interesting structure−activity relationships ( , ). 1 Alcoholysis and hydrolysis of nicosulfuron 1 .…”
Alcoholysis (methanol or ethanol) and hydrolysis (pH ranging from 4 to 11) of the herbicide nicosulfuron at 30 degrees C principally involves the breakdown of the urea part of the molecule. A high yield of the corresponding carbamate was obtained along with aminopyrimidine during alcoholysis. Hydrolysis led to both aminopyrimidine and pyridylsulfonamide. The latter compound may be easily cyclized (pH > or = 7). First-order kinetics describe the rates of alcoholysis and hydrolysis well. The rate constants (0.44 days(-1) for methanolysis) decreased from 0.50 to 0.002 days(-1) as pH increased from 4 to 8, then remained stable under alkaline conditions. In acidic or neutral solution, the hydrolysis path appeared prevalent (> or =70%), whereas in an alkaline medium it decreased when pH increased. The chemical degradation of nicosulfuron on various dry minerals (calcium bentonite, kaolinite, silica gel, H(+) bentonite, montmorillonite K10, and alumina) was investigated at 30 degrees C. The best conditions for the degradation are obtained on acidic minerals after herbicide deposition using the liquid method. Under these conditions an acceptable correlation with pseudo-first-order kinetics was observed, and the major degradation path is similar to that proposed for chemical hydrolysis. Conversely, alumina seemed to favor other unknown degradation processes. The hydrolysis paths of nicosulfuron and rimsulfuron appeared to be different.
“…Because of its chemical structure, 1-(4,6-dimethoxypyrimidin-2-yl)-3-(3-dimethylcarbamoyl-2-pyridylsulfonyl)urea, which exhibits a pyridyl-sulfonylurea bridge in place of the usual phenyl-sulfonylurea, nicosulfuron 1 ( Figure ) belongs to the substituted pyridinesulfonylurea group that also includes herbicides such as rimsulfuron, flupyrsulfuron-methyl, and flazasulfuron. The pyridylsulfonylurea structure of these herbicides provides interesting structure−activity relationships ( , ). 1 Alcoholysis and hydrolysis of nicosulfuron 1 .…”
Alcoholysis (methanol or ethanol) and hydrolysis (pH ranging from 4 to 11) of the herbicide nicosulfuron at 30 degrees C principally involves the breakdown of the urea part of the molecule. A high yield of the corresponding carbamate was obtained along with aminopyrimidine during alcoholysis. Hydrolysis led to both aminopyrimidine and pyridylsulfonamide. The latter compound may be easily cyclized (pH > or = 7). First-order kinetics describe the rates of alcoholysis and hydrolysis well. The rate constants (0.44 days(-1) for methanolysis) decreased from 0.50 to 0.002 days(-1) as pH increased from 4 to 8, then remained stable under alkaline conditions. In acidic or neutral solution, the hydrolysis path appeared prevalent (> or =70%), whereas in an alkaline medium it decreased when pH increased. The chemical degradation of nicosulfuron on various dry minerals (calcium bentonite, kaolinite, silica gel, H(+) bentonite, montmorillonite K10, and alumina) was investigated at 30 degrees C. The best conditions for the degradation are obtained on acidic minerals after herbicide deposition using the liquid method. Under these conditions an acceptable correlation with pseudo-first-order kinetics was observed, and the major degradation path is similar to that proposed for chemical hydrolysis. Conversely, alumina seemed to favor other unknown degradation processes. The hydrolysis paths of nicosulfuron and rimsulfuron appeared to be different.
“…Nicosulfuron, foramsulfuron, rimsulfuron, and halosulfuron-methyl are all used in maize. Nicosulfuron is a selective postemergence herbicide, developed by Ishihara Sangyo Kaisha, Ltd. to control annual grass weeds, broad-leaved weeds, and perennials . Rimsulfuron, which was introduced by DuPont Co. and first marketed in Europe in 1991, displays good safety on maize, especially spring maize with no effect on succeeding crops.…”
Section: Application Of the Intermediate
Derivatization
Approach In A...mentioning
“…Sulfonylurea compounds recently emerged as inhibitors of the bacterial acetohydroxyacid synthase (AHAS) 5. Quantitative structure–activity relationships (QSAR) have been used with homologous series of such compounds having herbicidal/herbicide‐safener potencies6, 7 in order to find correlative parameters between experimental and predicted activities, as well as to understand the drug–receptor interaction. These QSAR methods are based on 3D descriptors,8–10 derived from optimized structures to account for the topological characteristics of molecules, such as steric and electrostatic fields.…”
Both MIA-QSAR models showed high predictive ability, comparable with that of a reference methodology based on 3D descriptors. The method is suggested as a suitable tool for predicting novel herbicides.
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