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Search Results: 1 - 10 of 599747 matches for " Elson A. de Alvarenga "
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Metals Complexes Formed with Oleanolic Acid  [PDF]
Nilton C. Ribeiro, Antonio J. Demuner, Marcelo H. dos Santos, Célia R. A. Maltha, Elson A. de Alvarenga, Slavko Komarnytsky
International Journal of Organic Chemistry (IJOC) , 2018, DOI: 10.4236/ijoc.2018.81011
Abstract: The oleanolic acid possesses diverse pharmacological properties, it is considered as a good starting material for creating new compounds. The oleanolic acid isolated of Plumeria obtusa leaves was used as raw material to obtained calcium, magnesium, zinc, nickel and copper complexes. The structures of complexes were confirmed by HRMS, 1H NMR, and 13C NMR. Five new compounds were synthesized to promote increased biological activity of oleanolic acid and PCR assays for the different type of cancer.
Synthesis of Benzyl 4-Hydroxy-5-iodo-2,3-dimethoxy-6-methylbenzoate: The Aromatic Unit of Calicheamicin gamma1
Alvarenga, Elson Santiago de;Mann, John;
Journal of the Brazilian Chemical Society , 1999, DOI: 10.1590/S0103-50531999000200006
Abstract: orsellinic acid (6) was benzylated, and the benzyl 4-benzyloxy-2-hydroxy-6-methylbenzoate (7) was then elaborated into the title compound (2), which is the aromatic constituent of calicheamicin g1i.
Synthesis of Benzyl 4-Hydroxy-5-iodo-2,3-dimethoxy-6-methylbenzoate: The Aromatic Unit of Calicheamicin g1
Alvarenga Elson Santiago de,Mann John
Journal of the Brazilian Chemical Society , 1999,
Abstract: Orsellinic acid (6) was benzylated, and the benzyl 4-benzyloxy-2-hydroxy-6-methylbenzoate (7) was then elaborated into the title compound (2), which is the aromatic constituent of calicheamicin gamma1I.
A HIGH YIELD SYNTHESIS OF 1,2:5,6-DI-O-ISOPROPYLIDENE-D-MANNITOL
ALVARENGA,ELSON SANTIAGO DE; TEIXEIRA CARNEIRO,V?NIA MARIA; OLIVEIRA SILVéRIO,FLAVIANO; ARGOLO SALIBA,WILLIAM;
Journal of the Chilean Chemical Society , 2006, DOI: 10.4067/S0717-97072006000300013
Abstract: a high yield synthesis of 1,2:5,6-di-o-isopropylidene-d-mannitol: a great improvement in the synthesis of 1,2:5,6-di-o-isopropylidene-d-mannitol (2) using d-mannitol (1) as starting material, is described. the acetalation of (1) was performed in acetone in the presence of zinc chloride as catalyst to give (2) in 87% yield. some studies on the acetal stability were carried out to explain the high yields. high field nmr spectra were obtained and assignment of all signals was accomplished with the aid of double irradiation, difference noe and hetcor spectra
Montagem de camara com lampada de ultravioleta de baixo custo
Alvarenga, Elson Santiago de;Saliba, William Argolo;Milagres, Benjamin Gon?alves;
Química Nova , 2005, DOI: 10.1590/S0100-40422005000500034
Abstract: thin layer chromatography is a quick, inexpensive and effective way of screening mixtures of non-volatile organic compounds and it is highly recommended for analytical studies. inspection of plates under ultraviolet light for the detection of colourless compounds should be performed before any further chemical methods are applied. construction of a low-cost uv-viewing cabinet with lamp employing parts easily found on the local market is described.
Effect of Magnesia Phosphorica 12C on SDS by 13C Nuclear Magnetic Resonance.
Elson Santiago de Alvarenga,Rosmeri Terezinha Batirola da Silva,Vicente Wagner Dias Casali
International Journal of High Dilution Research , 2009,
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.
Montagem de camara com lampada de ultravioleta de baixo custo
Alvarenga Elson Santiago de,Saliba William Argolo,Milagres Benjamin Gon?alves
Química Nova , 2005,
Abstract: Thin layer chromatography is a quick, inexpensive and effective way of screening mixtures of non-volatile organic compounds and it is highly recommended for analytical studies. Inspection of plates under ultraviolet light for the detection of colourless compounds should be performed before any further chemical methods are applied. Construction of a low-cost UV-viewing cabinet with lamp employing parts easily found on the local market is described.
A HIGH YIELD SYNTHESIS OF 1,2:5,6-DI-O-ISOPROPYLIDENE-D-MANNITOL
ELSON SANTIAGO DE ALVARENGA,V?NIA MARIA TEIXEIRA CARNEIRO,FLAVIANO OLIVEIRA SILVéRIO,WILLIAM ARGOLO SALIBA
Journal of the Chilean Chemical Society , 2006,
Abstract: A HIGH YIELD SYNTHESIS OF 1,2:5,6-DI-O-ISOPROPYLIDENE-D-MANNITOL: A great improvement in the synthesis of 1,2:5,6-di-O-isopropylidene-D-mannitol (2) using D-mannitol (1) as starting material, is described. The acetalation of (1) was performed in acetone in the presence of zinc chloride as catalyst to give (2) in 87% yield. Some studies on the acetal stability were carried out to explain the high yields. High field NMR spectra were obtained and assignment of all signals was accomplished with the aid of double irradiation, difference NOE and HETCOR spectra
Synthesis and phytotoxicity of 4,5 functionalized tetrahydrofuran-2-ones
Resende, Gabriela C.;Alvarenga, Elson S.;Galindo, Juan C. G.;Macias, Francisco A.;
Journal of the Brazilian Chemical Society , 2012, DOI: 10.1590/S0103-50532012001200016
Abstract: in this work we report a versatile synthesis of fourteen γ-lactones all structurally related, nine of which are novel compounds, accomplished from the readily available furfural. the phytotoxic activity of the synthesized compounds was evaluated in vitro by the influence on the growth of wheat coleoptiles. the percentages of inhibition were mostly small and not statistically different from control after the third dilution (100 μmol l-1). in general, α,β-unsaturated lactones presented better activities than the saturated ones. the most active compounds presented 51, 68 and 76% of inhibition in 1000 μmol l-1. the results indicate that regardless of saturation, the presence of the γ-lactone moiety is important for the bioactivity, but their presence has no implications with potency.
Preparation and evaluation of chitosan beads immobilized with Iron(III) for the removal of As(III) and As(V) from water
Marques Neto, José de O.;Bellato, Carlos R.;Milagres, Jaderson L.;Pessoa, Kenia D.;Alvarenga, Elson S. de;
Journal of the Brazilian Chemical Society , 2013, DOI: 10.1590/S0103-50532013000100017
Abstract: the crosslinked chitosan-fe(iii) (ch-fecl) adsorbent was developed using fe(iii) immobilized on chitosan beads. after drying, the beads presented a diameter of approximately 1 mm and are stable in air. the adsorption behavior of as(iii) and as(v) on the ch-fecl was evaluated at ph 7 by studies conducted in batch and in columns. maximum adsorption capacities estimated by the langmuir adsorption model were 21.24 and 27.59 mg g-1 for as(iii) and as(v), respectively. adsorption kinetics is described by the pseudo second order kinetic equation. the results of column adsorption indicated that arsenic was not found in the effluent solution from roughly 60 and 759 bed volumes for as(iii) and as(v), respectively. results were satisfactory when employing the adsorbent for removal of as(iii) and as(v) from groundwater, tap water and river water samples.
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