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Showing papers by "Cesar A. Sierra published in 2013"

Journal Article•DOI•
High yield and stereospecific synthesis of segmented poly (p-phenylene vinylene) by the Heck reaction

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Carlos A Díaz1, Diego M Alzate1, Ricaurte Rodríguez1, Cristian Ochoa1, Cesar A. Sierra1 •
National University of Colombia1
15 May 2013-Synthetic Metals
TL;DR: A block copolymer comprised of a 2,5 (p-phenylene vinylene) unit alternating with a hexamethylene unit was synthetized by the Heck methodology using phosphite ligands and two different sources of palladium, with high yields and good polymerization degrees as mentioned in this paper.

9 citations

Journal Article•
Aqueous citric acid as green reaction media for the synthesis of octahydroxanthenes

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A D Camilo Navarro1, Cesar A. Sierra1, Cristian Ochoa-Puentes1•
National University of Colombia1
01 May 2013-Revista Colombiana de Química
TL;DR: In this article, a simple, convenient and environmentally friendly one-pot procedure for the synthesis of 1,8-dioxo-octahydroxanthenes by the reaction of dimedone and aromatic aldehydes in aqueous citric acid is described.
Abstract: A simple, convenient and environmentally friendly one-pot procedure for the synthesis of 1,8-dioxo-octahydroxanthenes by the reaction of dimedone and aromatic aldehydes in aqueous citric acid is described. In this green synthetic protocol promoted by the reaction media, the use of any other catalysts and hazardous organic solvents are avoided, making the work up procedure greener and easier. The isolation of the products, obtained in good yields, is readily performed by filtration and crystallization from ethanol when required and the aqueous acidic media can be easily recycled and reused several times without significant loss of catalytic activity.

6 citations

Journal Article•DOI•
High-Yield Synthesis of the Novel E,E-2,5-Dimethoxy-1,4-bis[2-(4-ethylcarboxylatestyril)]benzene by the Heck Reaction

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Diego M Alzate1, Juan P. Hinestroza2, Cesar A. Sierra1•
National University of Colombia1, Cornell University2
26 Jan 2013-Synthetic Communications
TL;DR: In this paper, the Heck cross-coupling reaction using Pd(dba)2 and P(OPh)3 like catalytic system was used to obtain high trans specificity of the product produced by the Heck reaction was confirmed by Fourier Transform-infrared and NMR.

6 citations

Journal Article•DOI•
High-Yield Synthesis of the Novel E,E-2,5-Dimethoxy-1,4-bis[2-(4-ethylcarboxyl-atestyril)]benzene by the Heck Reaction.

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Diego M Alzate, Juan P. Hinestroza, Cesar A. Sierra
22 Oct 2013-ChemInform
Journal Article•
Ácido cítrico aquoso como meio de reação verde para a síntese de octaidroxantenos

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Camilo A. Navarro D.1, Cesar A. Sierra1, Cristian Ochoa-Puentes1•
National University of Colombia1
01 May 2013-Revista Colombiana de Química
Síntesis de terpiridinas 4-fenil sustituídas y su potencial uso en la determinación de mercurio synthesis of 4-phenyl-substituted-terpyridines and their potential use for the determination of mercury síntese de substituídas 4-fenil-terpyridines e sua posterior utilização na determinação de mercúrio

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Brian Castro Agudelo1, P Cristian Ochoa1, Cesar A. Sierra•
National University of Colombia1
01 Jan 2013
TL;DR: The terpyridine TpyOH is highly promising for the detection of mercury under the experimental conditions reported in this article, and its response to the presence of various metals at different concentrations was evaluated in aqueous systems.
Abstract: This paper reports the synthesis of terpyridines using the Krohnke methodology. The terpyridines obtained by this method were analyzed by UV-Vis spectroscopy and fluorescence, and its response to the presence of various metals at different concentrations was evaluated in aqueous systems. The results show that the terpyridine TpyOH is highly promising for the detection of mercury under the experimental conditions reported.