Agroquímica

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http://repositorio.ufes.br/handle/10/17376
Programa de Pós-Graduação em Agroquímica

Centro: CCENS
Telefone: (28) 3552 8731
URL do programa: http://www.agroquimica.alegre.ufes.br/pos-graduacao/PPGAQ

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Navegando Agroquímica por Assunto "2-fenoxiacetato de fenilas"

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    Síntese e atividade fitotóxica de ésteres obtidos a partir de fenóis e do ácido fenoxiacético
    (Universidade Federal do Espírito Santo, 2020-09-02) Gonçalves, Patrícia Martins; Pinheiro, Patricia Fontes; https://orcid.org/0000000340195773; http://lattes.cnpq.br/7891884643619330; https://orcid.org/0000-0003-1897-3436; http://lattes.cnpq.br/7827129110600073; Osório, Vanessa Moreira; https://orcid.org/0000-0001-5156-4568; http://lattes.cnpq.br/3282723304057244; Parreira, Luciana Alves ; https://orcid.org/0000-0001-7041-9999; http://lattes.cnpq.br/0824035845605716
    Due to the increase of the world population and consequently the increase of food consumption, the demand in agricultural production has been growing in recent years. Thus, the use of agrochemicals in plantations has become important for favoring productivity. Weeds bring several damages to the plantations, leading to a great need for the use of herbicides in crops. Therefore, we have some main problems in plantations that use agrochemicals continuously: the resistance that weeds have developed over the years and the impact that these herbicides have generated on the environment and on human health, leading to the need of preparing substances with potential herbicidal activity against weeds, and which generate less toxicity to ecosystems. Considering these factors, the objective of this work was to synthesize esters from phenols of phenoxyacetic acid starting from some compounds that already have potential herbicide, aiming to obtain compounds that may be less harmful to the environment and the health of man and animals. For this, first phenoxyacetic acid (1) was synthesized starting from phenol and 2-chloroacetic acid, the product obtained was purified by chemically active liquid-liquid extraction. Acid 1 was used in the synthesis of 8 molecules belonging to the phenyl 2-phenoxyacetate class by means of Steglich esterification, using DCC (N, N'-dicyclohexylcarboiimide) and DMAP (N, Ndimethylpyridin-4-amine), in the presence of natural phenols (carvacrol, thymol, eugenol, guaiacol and vanillin) and p-cresol, phenol and β-naphthol, giving rise to their respective esters [5-isopropyl-2- methylphenyl 2-phenoxyacetate (2), 2 2-isopropyl-5-methylphenyl-phenoxyacetate (3), 4-allyl-2- methoxyphenyl 2-phenoxyacetate (4), 2-methoxyphenyl 2-phenoxyacetate (5), 5-formyl-2- 2- phenoxyacetate methoxyphenyl (6), p-tolyl 2-phenoxyacetate (7), phenyl 2-phenoxyacetate (8) and naphthalen-2-yl 2-phenoxyacetate (9)]. All synthesized compounds were characterized by mass spectrometry, hydrogen and carbon magnetic resonance (1H and 13C NMR) and some were subjected to biological tests in order to evaluate the herbicidal potential of these substances. To carry out the phytotoxic tests, solutions of the acid (1), of the synthesized esters (2,3, 6 and 8), of the positive control were prepared: the herbicide 2,4-D (2,4-dichlorophenoxyacetic acid) at 3 mmol. L-1, using dichloromethane as the solvent. A 1% aqueous solution of the commercial glyphosate herbicide (v.v-1) was also prepared to be used as another positive control, distilled water and dichloromethane (solvent) were used as negative controls. These compounds were tested in vitro to evaluate the germination and root development of sorghum (Sorghum bicolor) and lettuce (Lactuca sativa) seeds, model plants used in phytotoxic tests. The tested esters 3 and 6 inhibited the root growth of lettuce seeds and were comparable to the herbicides 2,4-D and glyphosate. The results were very promising, the phenyl class 2-phenoxyacetate esters may have great phytotoxic potential and may be useful in obtaining new herbicides