Elson Santiago de Alvarenga

Pyrethroids are among the most potent pesticides known, with great potential for structural variation with retention or enhancement of potency. The simple methyl ester is easier to prepare (at least one step shorter) than the more complex pyrethroids modified on the alcohol moiety. The objective was to synthesise methyl esters of pyrethroid acids containing an aromatic ring on the acid moiety and evaluate their biological activity against Ascia monuste orseis Latr., Tuta absoluta Meyrick, Periplaneta americana (L.), Musca domestica L. and Sitophilus zeamais (Motsch.). The synthetic sequence required seven steps: protection of the hydroxyl groups of D-mannitol, diol oxidative cleavage with sodium metaperiodate, alkene formation by Wittig reaction with methoxycarbonylmethylidene(triphenyl)phosphorane, cyclopropanation, acetal hydrolysis with perchloric acid and oxidative cleavage with sodium metaperiodate gave methyl (1S, 3S)-3-formyl-2,2-dimethylcyclopropane-1-carboxylate. The final step comprised reaction of the aldehyde with five different aromatic phosphorus ylides to give the pyrethroids. An efficient and versatile synthesis of ten new pyrethroid methyl esters has been accomplished from the readily available D-mannitol in seven steps. All compounds showed insecticidal activity, and methyl (1S, 3S)-3-[(Z)-2-(4-chlorophenyl)vinyl]-2,2-dimethylcyclopropane-1-carboxylate was the most active, killing 90% of A. monuste orseis and 100% of T. absoluta and P. americana.

ABSTRACT Introdução Tensoativos ou surfactantes são uma interessante classe de substâncias anfifílicas, ou seja, que apresentam uma natureza lipofílica-hidrofílica. Graças a essa dualidade são capazes de formar agregados, denominados micelas, quando atingem uma concentração característica, a concentração micelar crítica (cmc). A cmc depende da estrutura do surfactante e das condições do meio. A formação de micelas é acompanhada por mudanças distintas em várias propriedades físicas tais como, viscosidade, condutividade elétrica, tensão superficial. 1 Nas últimas décadas, com a finalidade de se melhorar ou inibir algumas propriedades dos surfactantes, têm crescido o estudo de interações entre os surfactantes e, polímeros hidrossolúveis, sais inorgânicos, sais orgânicos e até entre misturas de surfactantes. 1 O cloridrato de D-glicosamina é um sal orgânico obtido pela hidrólise com ácido clorídrico concentrado da quitina isolada de carapaça de caranguejo. Neste trabalho estudamos o efeito do cloridrato de D -glicosamina (CG) na concentração micelar crítica do dodecilsulfato de sódio (SDS) por condutividade. Resultados e Discussão Inicialmente determinou-se a condutividade molar do sal orgânico, encontrando-se uma condutividade molar, em uma concentração 0,001 mol dm -3 . O valor encontrado, 114,5 Ω -1 cm 2 mol -1 , é inferior ao valor da condutividade molar do NaCl (123,7 Ω -1 cm 2 mol -1), porém bem maior que a do CH 3 COOH, que (48,7 Ω -1 cm 2 mol -1), à mesma concentração. As titulações condutivimétricas foram realizadas variando-se a concentração de SDS (0,0 a 25,0 mM) em presença diferentes concentrações de CG. Com os resultados construiu-se gráficos da condutividade em função da concentração de sds, obtendo-se uma curva com perfil semelhante ao apresentado por uma curva de SDS em presença de NaCl. através de regressão linear obteve-se os valores de CMC. Os valores obtidos foram comparados com os valores obtidos com comcentrações equivalentes de NaCl e CsCl, Tabela 1. Os valores de cmc obtidos para o SDS em presença do Cloridrato de D -Glicosamina são maiores que os valores obtidos em presença de mesma concentrações de NaCl e CsCl, como pode ser observado na Tabela 1.

ABSTRACT Several new compounds with potential herbicidal activity were synthesized from 2α,4α‐dimethyl‐6,7‐exo‐isopropylidenedioxy‐8‐oxabicyclo[3.2.1]octan‐3‐one (4). Seven aromatic alcohols were prepared by reaction of (4) with aryllithium reagents, where the aryl groups were 4‐ethoxyphenyl (5, 70% yield), 4‐ethylphenyl (6, 82% yield), 4‐butylphenyl (7, 78% yield), 4‐tert‐butylphenyl (8, 81% yield), 2,4‐dimethoxyphenyl (9, 75% yield), 2‐ethylphenyl (10, 12% yield) and para‐(4‐bromophenoxy)phenyl (11, 24% yield). Reaction of the acetonide (4) with Grignard reagents formed also four aliphatic alcohols where the alkyl groups are ethyl (13, 78%), butyl (14, 85%), hexyl (15, 81%) and octyl (25, 92%). The alcohols (5), (6), (7), (8), (13), (14), (15) and (25) were reacted with thionyl chloride in pyridine, forming their respective alkenes (17, 76%), (18, 74%), (19, 83%), (20, 73%), (22, 78%), (26, 62%), (23, 77%) and (24, 66%). The effect of these compounds, at the concentration of 5.5 µg g−1, on the development of radicle and aerial parts of Sorghum bicolor (L) Moench, Euphorbia heterophylla L, Brachiaria decumbens and Desmodium tortuosum DC was evaluated. Copyright © 2003 Society of Chemical Industry

ABSTRACT Sodium dodecylsulphate (SDS) dissolved in water forms aggregates whose thermodynamic properties are well defined. The interest in polymer-surfactant systems derives from increasing possibilities to apply them in pharmaceutics, cosmetics and environmental protection. Nutrient content of soils after many years of use is a concern in many areas; on the other hand, the metabolism of plants approaches equilibrium when the conditions necessary for their growth are present. Magnesium and phosphorus are important nutrients for plants and high dilutions of Magnesium phosphoricum (Mag-p) may carry information related to them. Aims: To study the influence of Mag-p on SDS aggregates. Methods: the effect of Mag-p dilution 12c on the structure of SDS aggregates was assayed through 13C nuclear magnetic resonance. Results: The spectrum of SDS and Mag-p 12c in D2O presented an extra signal in 221.41 ppm when compared to the SDS / D2O spectrum. The C=O group of ketones and aldehydes absorb around 200 ppm. The carbon carbonyl shows large spin-lattice relaxation times (T1) and weak NOE (Nuclear Overhauser Effect) enhancement, thus signal from this type of atom are very weak when compared to signals from carbon atoms with hydrogen. The signal present in 221.41 ppm was comparable in size to the other signals in the spectrum indicating that it was not a machine-generated artifact. The experiments carried out in this work suggest that this signal was induced by a combination of SDS and the high diluted solution.

Large quantities of poultry litter are being produced in Brazil, which contain appreciable amounts of phosphorus (P) that could be of environmental concern. To assess the immediate environmental threat, five poultry litters composed of diverse bedding material were incubated for 43 days under greenhouse conditions. The litters consisted of: coffee bean husk (CH); wood chips (WC); rice husk (RH); ground corn cobs (CC) and ground napier grass (NG) (Pennisetum purpureum Schum.), in which the change in forms of soluble P was evaluated using 31P NMR spectroscopy. On average, 80.2 and 19.8 % of the total P in the extract, respectively, accounted for the inorganic and organic forms before incubation and 48 % of the organic P was mineralized to inorganic P in 43 days of incubation. Wide variation in the organic P mineralization rate (from 82 % -WC to 4 % - NG) was observed among litters. Inorganic orthophosphate (99.9 %) and pyrophosphate (0.1 %) were the only inorganic P forms, whereas the...

... Elson Santiago de Alvarenga Corresponding Author Contact Information , a , E-mail The Corresponding Author , Cristiane Pereira de Oliveira a and Carlos ... temperature is raised, thus titration was carried out under temperature control (25 °C, in a thermostatic bath) (Ewing, 1969 ...

Sorgoleone (1) is one of the major constituents of sorghum root exudates. Sorgoleone is an allelochemical that reduces the growth of broad-leaf plants. The 3,5-dimethoxybenzylic alcohol (3) was used as starting material for the synthesis of 2-methoxy-6-(non-1-yl)benzo-1,4-quinone (9) in 69% yield. Acetylation of (9) with acetic anhydride gave the triacetate (10) in 82% yield. The triacetate (10) was then converted in two steps in 2-hydroxy-5-methoxy-3-(non-1-yl)benzo-1,4-quinone (11) and 2-acetoxy-5-methoxy-3-(non-1-yl)benzo-1,4-quinone (12) in 8% and 37% yield, respectively. Quinone (11) was obtained also by reaction of (12) with DBU in 63% yield. Alkylation of (3) and oxidation with chromic anhydride formed the new quinones (16) (17) and (18) in 23%, 16% and 12% overall yield, respectively. The effect of these quinones and sorgoleone (1) at concentrations of 5.5 μg g–1 on the development of radicle and aerial parts of Cucumis sativus, Brachiaria decumbens, Hyptis lophanta, and Eup...