Publicaciones 2011-2020

@article{RN420,
title = {Activation of Electrophile/Nucleophile Pair by a Nucleophilic and Electrophilic Solvation in a Snar Reaction},
author = { B. Sanchez and C. Calderon and R.A. Tapia and R. Contreras and P.R. Campodonico},
url = {/brokenurl#<Go to ISI>://WOS:000447985400001},
doi = {10.3389/fchem.2018.00509},
issn = {2296-2646},
year = {2018},
date = {2018-01-01},
journal = {Frontiers in Chemistry},
volume = {6},
abstract = {Nucleophilic aromatic substitution reactions of 4-chloroquinazoline toward aniline and hydrazine were used as a model system to experimentally show that a substrate bearing heteroatoms on the aromatic ring as substituent is able to establish intramolecular hydrogen bond which may be activated by the reaction media and/or the nature of the nucleophile.},
keywords = {anion aromatic-substitution catalysis, effect, effects, electronic ionic liquids, mixtures, organic-reactions, potentials preferential reactions, secondary-amines, solvation, solvent solvent, temperature theory},
pubstate = {published},
tppubtype = {article}
}

@article{RN273,
title = {Changes in the Snar Reaction Mechanism Brought About by Preferential Solvation},
author = { J. Alarcon-Esposito and R.A. Tapia and R. Contreras and P.R. Campodonico},
url = {/brokenurl#<Go to ISI>://WOS:000365328000069},
doi = {10.1039/c5ra20779g},
issn = {2046-2069},
year = {2015},
date = {2015-01-01},
journal = {Rsc Advances},
volume = {5},
number = {120},
pages = {99322-99328},
abstract = {We herein report an experimental and theoretical study on preferential solvation effects for the reactions of 1-fluoro and 1-chloro-2,4-dinitrobenzene towards morpholine in acetonitrile, water and mixtures of them of varying compositions. A detailed kinetic study opens the possibility of analyzing preferential solvation and reaction rates. The kinetic study was complemented with an exploration of the potential energy surface in order to analyze the nature of the molecular interactions. For the fluorine derivative, this analysis reveals that the solvation of the TS in the mode TS1F-water/MeCN clearly outweighs the solvation of TS1F-MeCN/water, thereby suggesting that there is preferential solvation in favor of the aqueous phase.},
keywords = {aminolysis, benzenesulfonates, binary ionic liquids, mixtures, molecules, nucleophilic-substitution pathways reactions, regioselectivity, secondary-amines, solvent},
pubstate = {published},
tppubtype = {article}
}

@article{RN167,
title = {Specific Nucleophile-Electrophile Interactions in Nucleophilic Aromatic Substitutions},
author = { R. Ormazabal-Toledo and R. Contreras and R.A. Tapia and P.R. Campodonico},
url = {/brokenurl#<Go to ISI>://WOS:000316011300012},
doi = {10.1039/c3ob27450k},
issn = {1477-0520},
year = {2013},
date = {2013-01-01},
journal = {Organic & Biomolecular Chemistry},
volume = {11},
number = {14},
pages = {2302-2309},
abstract = {We herein report results obtained from an integrated experimental and theoretical study on aromatic nucleophilic substitution (SNAr) reactions of a series of amines towards 1-fluoro-2,4-dinitrobenzene in water. Specific nucleophile-electrophile interactions in the title reactions have been kinetically evaluated. The whole series undergoes SNAr reactions where the formation of the Meisenheimer complex is rate determining. Theoretical studies concerning specific interactions are discussed in detail. It is found that H-bonding effects along the intrinsic reaction coordinate profile promote the activation of both the electrophile and the nucleophile. Using these results, it is possible to establish a hierarchy of reactivity that is in agreement with the experimental data. Second order energy perturbation energy analysis highlights the strong interaction between the ortho-nitro group and the acidic hydrogen atom of the amine. The present study strongly suggests that any theoretical analysis must be performed at the activated transition state structure, because the static model developed around the reactant states hides most of the relevant specific interactions that characterize the aromatic substitution process.},
keywords = {base binary catalysis, group, groups, leaving mechanism, mixtures, nitro ortho-para ratio, reactions, secondary-amines, snar solvent},
pubstate = {published},
tppubtype = {article}
}

@article{RN163,
title = {Hydrogen Bond Contribution to Preferential Solvation in Snar Reactions},
author = { R. Ormazabal-Toledo and J.G. Santos and P. Rios and E.A. Castro and P.R. Campodonico and R. Contreras},
url = {/brokenurl#<Go to ISI>://WOS:000319649800012},
doi = {10.1021/jp4005295},
issn = {1520-6106},
year = {2013},
date = {2013-01-01},
journal = {Journal of Physical Chemistry B},
volume = {117},
number = {19},
pages = {5908-5915},
abstract = {Preferential solvation in aromatic nucleophilic substitution reactions is discussed using a kinetic study complemented with quantum chemical calculations. The model system is the reaction of a series of secondary alicyclic amines toward phenyl 2,4,6-trinitrophenyl ether in aqueous ethanol mixtures of different compositions. From solvent effect studies, it is found that only piperidine is sensitive to solvation effects, a result that may be traced to the polarity of the solvent composition in the ethanol/water mixture, which points to a specific electrophilic solvation in the aqueous phase.},
keywords = {amines aromatic behavior, binary chemical ether, kinetics, mixtures, molecules, nucleophilic-substitution, piperidine, probes, solvent},
pubstate = {published},
tppubtype = {article}
}

@article{RN21,
title = {Ferrospectral Sorbed on Deae Sephadex a-25 for the Solid Phase Spectrophotometric Determination of Iron and Cobalt by Batch and Continuous Flow Modes},
author = { M.I. Toral and G. Sanchez and P. Fernandez and P. Pizarro and V. Moncada and J. Rivas and P. Richter},
url = {/brokenurl#<Go to ISI>://WOS:000293676300013},
doi = {10.4067/S0717-97072011000200013},
issn = {0717-9324},
year = {2011},
date = {2011-01-01},
journal = {Journal of the Chilean Chemical Society},
volume = {56},
number = {2},
pages = {682-687},
abstract = {In this work, Ferrospectral;3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazine (FST) sorbed on DEAE Sephadex A-25 is used as solid phase for spectrophotometric determination of iron and cobalt by batch and continuos flow modes. In batch simultaneous determination, the second derivative at 536.0 and 601.4 nm were used for iron and cobalt determination, respectively. In this modality, the detection limits (3 sigma criterion), for iron and cobalt were 1.3, 9.1, mu g L(-1) and the determination ranges were: 4.3 to 220 and 30.3 to 800 mu g L(-1). The method by FIA mode was carried out by stopped flow and then the analytical signal was evaluated by second derivative at 560.9 and 482.3 nm for iron and cobalt determination; respectively. In FIA modality, the detection limits for iron and cobalt were 6.4, 31 mu g L(-1), and the determination ranges 21 to 200 and 106 to 1000 mu g L(-1) iron and cobalt, respectively. In both modalities the repeatability for iron and cobalt were <4% and the recovery was near to 100%. These methods were applied successfully in drinking water and soil samples.},
keywords = {continuous determination, determinations, electrode, elements extraction, fe food heavy-metal ions, mixtures, phase samples, sephadex solid spectrometric spectrometry, stripping voltammetry, water},
pubstate = {published},
tppubtype = {article}
}