2015 |
Alarcon-Esposito, J; Tapia, R A; Contreras, R; Campodonico, P R Changes in the Snar Reaction Mechanism Brought About by Preferential Solvation Artículo de revista Rsc Advances, 5 (120), pp. 99322-99328, 2015, ISSN: 2046-2069. Resumen | Enlaces | BibTeX | Etiquetas: aminolysis, benzenesulfonates, binary ionic liquids, mixtures, molecules, nucleophilic-substitution pathways reactions, regioselectivity, secondary-amines, solvent @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} } 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. |
2013 |
Castro, E A; Canete, A; Campodonico, P R; Cepeda, M; Pavez, P; Contreras, R; Santos, J G Kinetic and Theoretical Study on Nucleofugality in the Phenolysis of 3-Nitrophenyl and 4-Nitrophenyl 4-Cyanophenyl Thionocarbonates Artículo de revista Chemical Physics Letters, 572 , pp. 130-135, 2013, ISSN: 0009-2614. Resumen | Enlaces | BibTeX | Etiquetas: aminolysis, carbonates, electronic elimination, ester geminal groups, interactions, leaving mechanism, quality, reactivity, scale @article{castro2013kinetic, title = {Kinetic and Theoretical Study on Nucleofugality in the Phenolysis of 3-Nitrophenyl and 4-Nitrophenyl 4-Cyanophenyl Thionocarbonates}, author = { E.A. Castro and A. Canete and P.R. Campodonico and M. Cepeda and P. Pavez and R. Contreras and J.G. Santos}, url = {/brokenurl#<Go to ISI>://WOS:000319332600025}, doi = {10.1016/j.cplett.2013.04.002}, issn = {0009-2614}, year = {2013}, date = {2013-01-01}, journal = {Chemical Physics Letters}, volume = {572}, pages = {130-135}, publisher = {2013 Elsevier B.V.}, abstract = {The phenolysis of 3-nitrophenyl 4-cyanophenyl thionocarbonate (1) and 4-nitrophenyl 4-cyanophenyl thionocarbonate (2) are subjected to a kinetic investigation in order to evaluate the nucleofugality of the corresponding leaving groups. For the reaction of 2 only 4-nitrophenoxide is obtained as leaving group. For the reaction of 1 the nucleofugality ratio 3-nitrophenoxide/4-cyanophenoxide is 1/3 from the corresponding T intermediate. Theoretical calculations confirm the experimental results. From these results it can be concluded that the non-leaving group affects the nucleofugality ratio.}, keywords = {aminolysis, carbonates, electronic elimination, ester geminal groups, interactions, leaving mechanism, quality, reactivity, scale}, pubstate = {published}, tppubtype = {article} } The phenolysis of 3-nitrophenyl 4-cyanophenyl thionocarbonate (1) and 4-nitrophenyl 4-cyanophenyl thionocarbonate (2) are subjected to a kinetic investigation in order to evaluate the nucleofugality of the corresponding leaving groups. For the reaction of 2 only 4-nitrophenoxide is obtained as leaving group. For the reaction of 1 the nucleofugality ratio 3-nitrophenoxide/4-cyanophenoxide is 1/3 from the corresponding T intermediate. Theoretical calculations confirm the experimental results. From these results it can be concluded that the non-leaving group affects the nucleofugality ratio. |
2012 |
Ormazabal-Toledo, R; Castro, E A; Santos, J G; Millan, D; Canete, A; Contreras, R; Campodonico, P R Predicting the Reaction Mechanism of Nucleophilic Substitutions at Carbonyl and Thiocarbonyl Centres of Esters and Thioesters Artículo de revista Journal of Physical Organic Chemistry, 25 (12), pp. 1359-1364, 2012, ISSN: 0894-3230. Resumen | Enlaces | BibTeX | Etiquetas: aminolysis, carbonyl carboxylic center, contrasting density derivatives, dithiocarbonates, electron electrophilic esters, fukui function, group group, kinetic kinetics, leaving measurements, mechanisms, o-ethyl phenyl, reaction reactivity, reorganization, secondary @article{RN103, title = {Predicting the Reaction Mechanism of Nucleophilic Substitutions at Carbonyl and Thiocarbonyl Centres of Esters and Thioesters}, author = { R. Ormazabal-Toledo and E.A. Castro and J.G. Santos and D. Millan and A. Canete and R. Contreras and P.R. Campodonico}, url = {/brokenurl#<Go to ISI>://WOS:000313125800038}, doi = {10.1002/poc.3048}, issn = {0894-3230}, year = {2012}, date = {2012-01-01}, journal = {Journal of Physical Organic Chemistry}, volume = {25}, number = {12}, pages = {1359-1364}, publisher = {2012 John Wiley & Sons, Ltd.}, abstract = {In nucleophilic substitution reactions at carbonyl centres, there are two possible channels. The first one occurs when the attack of nucleophilic agents takes place simultaneously with the departure of the nucleofuge. This process is named as concerted. The second possibility is the formation of a reaction intermediate, typically a tetrahedral intermediate from which the nucleofuge departs after passing through a second transition state. This second mechanism is defined as stepwise. Whether a concerted or stepwise mechanism is to be expected for a given reaction depends on several factors. Among these determinants are the nucleophilicity of the attacking group, the leaving group ability of the nucleofuge, and the solvent, which affects both the stability of the intermediate or the transition states involved. The role of the electrophilic centre can however become an important factor that can determine the reaction mechanism. In this work we show that the group nucleophilic Fukui function model may be used to rationalize and to predict the reaction mechanism of the title compounds towards alicyclic amines. In general, when the electrophilic carbon centre is attached to the soft sulfur atom, the reaction mechanism is predicted to follow a stepwise route. When the electrophilic carbon atom is attached to a harder oxygen centre, the reaction mechanism is determined by chemical substitution at the nucleofuge moiety. Experimental verification for a set of four substrates is presented.}, keywords = {aminolysis, carbonyl carboxylic center, contrasting density derivatives, dithiocarbonates, electron electrophilic esters, fukui function, group group, kinetic kinetics, leaving measurements, mechanisms, o-ethyl phenyl, reaction reactivity, reorganization, secondary}, pubstate = {published}, tppubtype = {article} } In nucleophilic substitution reactions at carbonyl centres, there are two possible channels. The first one occurs when the attack of nucleophilic agents takes place simultaneously with the departure of the nucleofuge. This process is named as concerted. The second possibility is the formation of a reaction intermediate, typically a tetrahedral intermediate from which the nucleofuge departs after passing through a second transition state. This second mechanism is defined as stepwise. Whether a concerted or stepwise mechanism is to be expected for a given reaction depends on several factors. Among these determinants are the nucleophilicity of the attacking group, the leaving group ability of the nucleofuge, and the solvent, which affects both the stability of the intermediate or the transition states involved. The role of the electrophilic centre can however become an important factor that can determine the reaction mechanism. In this work we show that the group nucleophilic Fukui function model may be used to rationalize and to predict the reaction mechanism of the title compounds towards alicyclic amines. In general, when the electrophilic carbon centre is attached to the soft sulfur atom, the reaction mechanism is predicted to follow a stepwise route. When the electrophilic carbon atom is attached to a harder oxygen centre, the reaction mechanism is determined by chemical substitution at the nucleofuge moiety. Experimental verification for a set of four substrates is presented. |
2015 |
Changes in the Snar Reaction Mechanism Brought About by Preferential Solvation Artículo de revista Rsc Advances, 5 (120), pp. 99322-99328, 2015, ISSN: 2046-2069. |
2013 |
Kinetic and Theoretical Study on Nucleofugality in the Phenolysis of 3-Nitrophenyl and 4-Nitrophenyl 4-Cyanophenyl Thionocarbonates Artículo de revista Chemical Physics Letters, 572 , pp. 130-135, 2013, ISSN: 0009-2614. |
2012 |
Predicting the Reaction Mechanism of Nucleophilic Substitutions at Carbonyl and Thiocarbonyl Centres of Esters and Thioesters Artículo de revista Journal of Physical Organic Chemistry, 25 (12), pp. 1359-1364, 2012, ISSN: 0894-3230. |