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URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11800
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Item Síntese de novas fitotoxinas derivadas do 8- oxabiciclo[ 3. 2. 1] oct- 6- en- 3- ona(Química Nova, 2005-05) Barbosa, Luiz C. A.; Maltha, Célia R. A.; Demuner, Antônio J.; Ganen, Flávia R.; Silva, Antônio A. daThe [4+3] cycloaddition was utilized in order to prepare 8-oxabicyclo[3.2.1]oct-6-en-3-one (1) derivatives. The correspondent acetonide 6 was converted into several alcohols (11-16). Addition of aryllithium reagents to 6 resulted in 3-(2-fluorophenyl)-6,7-exo-isopropylidenedioxy -8-oxabicyclo[3.2.1]octan-3a-ol (11, 72%) and 3-(2,4-dimethoxyphenyl)-6,7-exo-isopropylidenedioxy-8-oxabicyclo[3.2.1]octan -3a-ol (16, 20%). The 3-butyl-6,7-exo-isopropylidenedioxy-8-oxabicyclo[3.2.1]octan-3 a-ol (15, 56%) was obtained through a Grignard reaction. Reduction of 6 resulted in 6,7-exo-isopropylidenedioxy-8-oxabicyclo[3.2.1]octan-3 b-ol (7, 62%) and 6,7-exo-isopropylidenedioxy-8-oxabicyclo[3.2.1]octan-3 a-ol (8, 20%). The alcohols were treated with thionyl chloride in pyridine, and the corresponding alkenes were obtained with 31-80% yield. The effect of these compounds on the development of radicle and aerial parts of Sorghum bicolor was evaluated.Item Impact of percentage and particle size of sugarcane biochar on the sorption behavior of clomazone in Red Latosol(Anais da Academia Brasileira de Ciências, 2018-10) Silva, Marcos R. F. da; Queiroz, Maria Eliana L. R. de; Neves, Antônio A.; Silva, Antônio A. da; Oliveira, André F. de; Oliveira, Renan L. de; Azevedo, Mariane M.Biochar is a carbonaceous material that has excellent potential as a fertilizer and soil conditioner. However, there is a lack of information concerning the effects of the amount and particle size of this pyrogenic material on the soil sorption capacity. In this work, evaluation was made of changes in clomazone (CMZ) sorption in a Red Latosol following soil conditioning using different percentages (0.25, 0.5, and 1% w/w) of sugarcane biochar in three particle sizes (<106, 106-508, and 508-610 μm). The conditioned soils presented apparent sorption coefficients (Kd) up to 1300 times higher than that of pure soil, besides changes in the behavior of CMZ sorption. The biochar particle size and percentage influenced sorption of the herbicide as well as its retention in the amended soil during desorption processes. Both sorption and desorption Freundlich constants were linearly correlated with the external surface area of the biochar present in the soil.Item Mobility and persistence of the herbicide fomesafen in soils cultivated with bean plants using SLE/LTP and HPLC/DAD(Environmental Science and Pollution Research, 2014-09-23) Costa, Anna I. G.; Queiroz, Maria Eliana L. R.; Neves, Antônio A.; Assis, Roberta C. de; Soares, Carlos E. S. dos; Silva, Antônio A. da; D’Antonino, Leonardo; Oliveira, André F. de; Bellato, Carlos R.A method has been optimized and validated for the determination of fomesafen in soils using solid–liquid extraction with low-temperature partitioning (SLE/LTP) and analysis by liquid chromatography with a high-efficiency diode array detector (HPLC/DAD). The method was used to evaluate the persistence and mobility of this herbicide in different soils cultivated with bean plants. Recovery values were ≥98.9 %, with variations in the repeatability coefficients of ≤15 %, and a detection limit of 7.3 μg kg−1. Half-life values of fomesafen were between 60 and 71 days in soil cultivated using a no-till system and 99 and 114 days in soil cultivated using a conventional tillage system. The mobility of fomesafen was moderate and mainly influenced by the organic matter content, pH, and soil type. In Red-Yellow Argisol, which has a higher content of organic matter, the leaching of fomesafen was less pronounced. In Red-Yellow Latosol, which has smaller amounts of organic matter and high pH, the leaching of fomesafen was more pronounced.