Síntese e Avaliação da Atividade Fitotóxica de Éteres Derivados do Geraniol

• Autor(a) principal: Rezende, Terezinha Ruth Marques
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2143
• topic: Herbicidas; Composto orgânico; Reações de substituição; Herbicide; Organic compound; Substitution reaction; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ORGANICA

The discovery of herbicide from natural origin usually is initiated from the observation of compounds that show allelopathic activity in the environment. Geraniol ((E)-3,7-dimethylocta-2,6-dien-1-ol) is a monoterpene which has allelopathic properties of regulation of the plants growth. It is present in vegetable tissues of several species of plants, especially in flowers. Geraniol is widely used in industry as fragrance for cosmetics, cleaning supplies and food and in pharmaceutical industry as an assistant for the absorption of some medicines by the body. It is also effective as a mosquito repellent, insecticide and herbicide. Studies directed to the investigation of antimicrobial activity, antioxidant, antitumor and anti -inflammatory of geraniol has been greatly developed, mainly due to low toxicity to mammals and its biodegradation facility. Considering the importance of natural products in agriculture, the proven biological activity of geraniol and the opportunity to obtain compounds that are more effective as herbicides and less prejudicial to the environment, this study aimed to assess the phytotoxic activity of ethers derivatives from the geraniol. For the synthesis of ethers, it was used geraniol, benzyl bromides with different substituent in order to obtain compounds with lower volatility compared with geraniol, and the most significant effects in regulati ng the plants growth. Thirteen ethers were synthesized: ((3,7-dimethylocta-2,6-dienyloxy)methyl)benzene (83%); 1-((3,7-dimethylocta-2,6-dienyloxy) methyl)-2-methylbenzene (52%); 1-((3,7- dimethylocta-2,6-dienyloxy)methyl)-3-methylbenzene (78%); 1-((3,7-dimethylocta-2,6-dienyloxy)methyl)-4-methylbenzene (48%); 1-bromo-2-((3,7-dimethylocta-2,6-dienyloxy)methyl) benzene (59%); 1-bromo-4-((3,7-dimethylocta- 2,6-dienyloxy) methyl)benzene (73%); 1-chloro-2-((3,7-dimethylocta-2,6-dienyloxy)methyl)benzene (71%); 1-chloro-3-((3,7-dimethylocta-2,6-dienyloxy)methyl)benzene (28%); 1-chloro-4-((3,7-dimethylocta-2 ,6-dienyloxy)methyl)benzene (80%); 1-((3,7-dimethylocta-2,6-dienyloxy)methyl)-2-fluorobenzene (73%); 1-((3,7-dimethylocta-2,6-dienyloxy)methyl)-1,3-difluorobenzene (38%) and 1-((3,7-dimethylocta-2,6-dienyloxy)methyl)-4-nitrobenzene (40%). The yields of the reactions were influenced by the molecular mass of the substituent and its position on the benzene ring, the best yields were observed in the absence of substituent or when they were in the ortho position. The results of the test for regulating the roots growth and aerial part of seedlings of the species Cucumis sativus and Sorghum bicolor for ethers showed that the efficiency of the tested compounds is strongly influenced by the nature of the substituent and its position on the ring. Generally the presence of more electronegative groups in the para position increases the regulation activity of monocotyledonous plants growth and the presence of electron donating groups in the ortho and para positions by inductive effect increase the biological activity in dicotyledonous plants.