Síntesis estereoselectiva, separación y actividad insecticida de compuestos piretroides

• Autores: Masuh, Héctor Mario
• Año de publicación: 1998
• Idioma: español castellano
• Tipo de recurso: tesis doctoral
• Colaborador/a o director/a de tesis: Zerba, Eduardo Nicolás
• Materia: INSECTICIDAS; PIRETROIDES; ISOMEROS; PERMETRINA; FORMULADO; CLOROSULFITOS; MODELADO MOLECULAR; INSECTICIDES; PYRETHROIDS; FORMULATION; CHLOROSULFITES; MOLECULARMODELLING
• Institución: Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales

trans-2,2 dimetil - 3 - (2,2 diclorovinil)ciclopropanocarboxílico) RN 59042-49-8 y crisantémico (ácido cis,trans-2,2 dimetil - 3 - (2-metilpropenil)ciclopropanocarboxílico) RN 10453-89-1. Cada uno de los productos obtenidos fuecaracterizado por espectrometria de masas. Se utilizaron métodos semiemplricos para sugerir posiblesvías mecanísticas del proceso. Se intenta justificar el control cinético del proceso de esterificación,evidente según resultados experimentales, mediante métodos de modelado molecular; la reacciónprocedería como un ataque nucleofilico del ácido carboxilico a especies catiónicas en solución.
Pyrethroid insectícides have stability to atmospheric influences and at the same time this familyincludes the most effective insecticides known to date. Toxicological effects of this family of insecticides are closed related with stereochemicalconsiderations. The most accepted hypothesis postulates that this effect is based in the interactionmechanism with membrane receptors, and affects sodium-potassium channels. In the search of new insecticides, with defined isomeric rate, this work was organized in threesections: In Section I new methods were described for isomer separation in analytical scale: four isomersin Permethrin and eight isomers in Cypermethrin were separated by HPLC. Column chromatography andrecrystallization achieved semipreparative and preparative scale separations of cis and trans isomersrespectively, and the cis isomer showed to be the most potent one. In section II the solid phase of cis Permethrin in crystalline form is studied. A new flowableinsecticide was formulated, and its insecticidal effect in several surfaces was evaluated. X-ray diffractionmethods complement this study.ln the last section a novel method for stereoselective synthesis of esters of permethrinic (cis,trans-2, 2 dimethyl - 3 - (2,2 dichlorovynyl) ciclopropanecarboxilic acid) - RN 59042-49- 8- andchrysantemic acid (cis, trans-2, 2 dimethyl - 3 - (2-methyl-propenyl) ciclopropanecarboxilic acid) -RN 10453-89-1- was described. Semiempirical methods were used to shed light in mechanistics aspects ofthis process. A kinetic control in the process of ester linkage formation was confirmed by molecularmodeling methods; nucleophilic attack of carboxylic acids to cationic species formed in solution seems tobe the mechanism of reaction.
Fil: Masuh, Héctor Mario. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.