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José G. Santos - One of the best experts on this subject based on the ideXlab platform.
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Cucurbit[7]uril as a Supramolecular Catalyst in Base-Catalyzed Reactions. Experimental and Theoretical Studies on Carbonate and Thiocarbonate Hydrolysis Reactions
The Journal of organic chemistry, 2020Co-Authors: Angélica Fierro, Luis García-río, Sandra Arancibia-opazo, Jackson J. Alcázar, José G. Santos, Margarita E. AliagaAbstract:Cucurbit[7]uril (CB7) catalyzes the hydrolysis reaction of bis(4-nitrophenyl)carbonate (1) but inhibits that of bis(4-nitrophenyl)Thiocarbonate (2). Two relevant CB7 effects are proposed, a base-catalyst mediated by the CB7 portal and an inhibitory role attributed to the lower interaction of the thiocarbonyl group with the solvent in the host cavity, respectively.
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experimental and theoretical studies on the nucleofugality patterns in the aminolysis and phenolysis of s aryl o aryl Thiocarbonates
Journal of Organic Chemistry, 2009Co-Authors: Enrique A Castro, Margarita E. Aliaga, Paola R Campodonico, Marjorie Cepeda, Renato Contreras, José G. SantosAbstract:The reactions of S-phenyl, S-(4-chlorophenyl), and S-(2,3,4,5,6-pentafluorophenyl) 4-nitrophenyl Thiocarbonates (9, 11, and 16, respectively) with a series of secondary alicyclic (SA) amines and those of S-(4-methylphenyl) 4-nitrophenyl Thiocarbonate (8) and compounds 9 and 11 with a series of phenols are subjected to a kinetic investigation in 44 wt % ethanol−water, at 25.0 °C and an ionic strength of 0.2 M. The reactions were followed spectrophotometrically. Under nucleophile excess, pseudo-first-order rate coefficients (kobsd) were found. For all these reactions, plots of kobsd vs. free amine or phenoxide anion concentration at constant pH are linear, the slope (kN) being independent of pH. The Bronsted-type plots (log kN vs. pKa of the conjugate acids of the nucleophiles) for the aminolysis of 9, 11, and 16 are linear with slopes β = 0.85, 0.90, and 0.67, respectively. The two former slopes are consistent with a stepwise mechanism, through a zwitterionic tetrahedral intermediate, which breaking to pro...
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kinetics and mechanism of the benzenethiolysis of o ethyl s 2 4 dinitrophenyl and o ethyl s 2 4 6 trinitrophenyl diThiocarbonates and o methyl o 2 4 dinitrophenyl Thiocarbonate
Journal of Organic Chemistry, 2003Co-Authors: Enrique A Castro, Paulina Pavez, José G. SantosAbstract:Reactions of O-ethyl 2,4-dinitrophenyl diThiocarbonate (EDNPDTC), O-ethyl 2,4,6-trinitrophenyl diThiocarbonate (ETNPDTC), and O-methyl O-(2,4-dinitrophenyl) Thiocarbonate (MDNPTOC) with a series of benzenethiolate anions in aqueous solution, at 25.0 °C and an ionic strength of 0.2 M (KCl), are subjected to a kinetic investigation. Under excess benzenethiolate, these reactions obey pseudo-first-order kinetics and are first order in benzenethiolate. Nonetheless, similar reactant concentrations were used in the reactions of 4-nitrobenzenethiolate anion with the ethyl trinitrophenyl ester (ETNPDTC), which showed overall second-order kinetics. The nucleophilic rate constants (kN) are pH independent, except those for the reactions of ETNPDTC with the X-benzenethiolates with X = H, 4-Cl, and 3-Cl, which increase as pH decreases. The Bronsted-type plots (log kN vs pKa of benzenethiols) are linear with slopes β = 0.66 for the reactions of both ethyl dinitrophenyl ester (EDNPDTC) and ethyl trinitrophenyl ester (ETN...
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concerted mechanism of the reactions of secondary alicyclic amines with o ethyl s 2 4 6 trinitrophenyl Thiocarbonate
Journal of Organic Chemistry, 1994Co-Authors: Enrique A Castro, Mirtha Salas, José G. SantosAbstract:The title reactions are subjected to a kinetic study in water, 25.0 o C, ionic strength 0.2 M (KCl). Under amine excess, pseudo-first-order coefficients (k obsd ) are obtained. Plots of k obsd vs free amine concentration at constant pH are linear, with the slope (k N ) independent of pH. The Bronsted-type plot (log k N vs pK a of the amine) found is linear, with slope β=0.48, indicating a concerted mechanism
Enrique A Castro - One of the best experts on this subject based on the ideXlab platform.
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experimental and theoretical studies on the nucleofugality patterns in the aminolysis and phenolysis of s aryl o aryl Thiocarbonates
Journal of Organic Chemistry, 2009Co-Authors: Enrique A Castro, Margarita E. Aliaga, Paola R Campodonico, Marjorie Cepeda, Renato Contreras, José G. SantosAbstract:The reactions of S-phenyl, S-(4-chlorophenyl), and S-(2,3,4,5,6-pentafluorophenyl) 4-nitrophenyl Thiocarbonates (9, 11, and 16, respectively) with a series of secondary alicyclic (SA) amines and those of S-(4-methylphenyl) 4-nitrophenyl Thiocarbonate (8) and compounds 9 and 11 with a series of phenols are subjected to a kinetic investigation in 44 wt % ethanol−water, at 25.0 °C and an ionic strength of 0.2 M. The reactions were followed spectrophotometrically. Under nucleophile excess, pseudo-first-order rate coefficients (kobsd) were found. For all these reactions, plots of kobsd vs. free amine or phenoxide anion concentration at constant pH are linear, the slope (kN) being independent of pH. The Bronsted-type plots (log kN vs. pKa of the conjugate acids of the nucleophiles) for the aminolysis of 9, 11, and 16 are linear with slopes β = 0.85, 0.90, and 0.67, respectively. The two former slopes are consistent with a stepwise mechanism, through a zwitterionic tetrahedral intermediate, which breaking to pro...
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kinetics and mechanism of the aminolysis of thioesters and Thiocarbonates in solution
Pure and Applied Chemistry, 2009Co-Authors: Enrique A CastroAbstract:The aminolysis reactions of thioesters and Thiocarbonates, in either aqueous solu- tion or in 44 wt % aqueous ethanol at 25 °C, are subjected to a kinetic investigation. The Bronsted-type plots (lg k N vs. amine pK a , where k N is the nucleophilic rate constant) obtained for these reactions can be grouped in three categories: linear plots with slopes 0.8-1, biphasic plots (two linear portions and a curve in between), and linear plots with slopes 0.4-0.6. The two former plots are attributed to stepwise reactions through a zwitterionic tetrahedral inter- mediate. The latter plots are associated with a concerted mechanism. The fact that some re- actions are stepwise and others concerted depends on the stability of the zwitterionic tetra- hedral intermediate. This work shows how the experimental data allows one to assess the mechanism of these reactions. Also discussed are the factors that affect the stability of this intermediate, which in turn determines the pathway followed by the reaction. The factors an- alyzed in this work are (i) the leaving group of the substrate, (ii) the nature of the amine, (iii) the non-leaving group of the substrate, (iv) the electrophilic group of the substrate (CS vs. CO), and (v) the solvent.
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kinetics and mechanism of the benzenethiolysis of o ethyl s 2 4 dinitrophenyl and o ethyl s 2 4 6 trinitrophenyl diThiocarbonates and o methyl o 2 4 dinitrophenyl Thiocarbonate
Journal of Organic Chemistry, 2003Co-Authors: Enrique A Castro, Paulina Pavez, José G. SantosAbstract:Reactions of O-ethyl 2,4-dinitrophenyl diThiocarbonate (EDNPDTC), O-ethyl 2,4,6-trinitrophenyl diThiocarbonate (ETNPDTC), and O-methyl O-(2,4-dinitrophenyl) Thiocarbonate (MDNPTOC) with a series of benzenethiolate anions in aqueous solution, at 25.0 °C and an ionic strength of 0.2 M (KCl), are subjected to a kinetic investigation. Under excess benzenethiolate, these reactions obey pseudo-first-order kinetics and are first order in benzenethiolate. Nonetheless, similar reactant concentrations were used in the reactions of 4-nitrobenzenethiolate anion with the ethyl trinitrophenyl ester (ETNPDTC), which showed overall second-order kinetics. The nucleophilic rate constants (kN) are pH independent, except those for the reactions of ETNPDTC with the X-benzenethiolates with X = H, 4-Cl, and 3-Cl, which increase as pH decreases. The Bronsted-type plots (log kN vs pKa of benzenethiols) are linear with slopes β = 0.66 for the reactions of both ethyl dinitrophenyl ester (EDNPDTC) and ethyl trinitrophenyl ester (ETN...
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concerted mechanism of the reactions of secondary alicyclic amines with o ethyl s 2 4 6 trinitrophenyl Thiocarbonate
Journal of Organic Chemistry, 1994Co-Authors: Enrique A Castro, Mirtha Salas, José G. SantosAbstract:The title reactions are subjected to a kinetic study in water, 25.0 o C, ionic strength 0.2 M (KCl). Under amine excess, pseudo-first-order coefficients (k obsd ) are obtained. Plots of k obsd vs free amine concentration at constant pH are linear, with the slope (k N ) independent of pH. The Bronsted-type plot (log k N vs pK a of the amine) found is linear, with slope β=0.48, indicating a concerted mechanism
Michael D Pluth - One of the best experts on this subject based on the ideXlab platform.
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kinetic insights into hydrogen sulfide delivery from caged carbonyl sulfide isomeric donor platforms
Journal of the American Chemical Society, 2017Co-Authors: Yu Zhao, Hillary A Henthorn, Michael D PluthAbstract:Hydrogen sulfide (H2S) is a biologically important small gaseous molecule that exhibits promising protective effects against a variety of physiological and pathological processes. To investigate the expanding roles of H2S in biology, researchers often use H2S donors to mimic enzymatic H2S synthesis or to provide increased H2S levels under specific circumstances. Aligned with the need for new broad and easily modifiable platforms for H2S donation, we report here the preparation and H2S release kinetics from a series of isomeric caged-carbonyl sulfide (COS) compounds, including thiocarbamates, Thiocarbonates, and diThiocarbonates, all of which release COS that is quickly converted to H2S by the ubiquitous enzyme carbonic anhydrase. Each donor is designed to release COS/H2S after the activation of a trigger by activation by hydrogen peroxide (H2O2). In addition to providing a broad palette of new, H2O2-responsive donor motifs, we also demonstrate the H2O2 dose-dependent COS/H2S release from each donor core, ...
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kinetic insights into hydrogen sulfide delivery from caged carbonyl sulfide isomeric donor platforms
Journal of the American Chemical Society, 2017Co-Authors: Yu Zhao, Hillary A Henthorn, Michael D PluthAbstract:Hydrogen sulfide (H2S) is a biologically important small gaseous molecule that exhibits promising protective effects against a variety of physiological and pathological processes. To investigate the expanding roles of H2S in biology, researchers often use H2S donors to mimic enzymatic H2S synthesis or to provide increased H2S levels under specific circumstances. Aligned with the need for new broad and easily modifiable platforms for H2S donation, we report here the preparation and H2S release kinetics from a series of isomeric caged-carbonyl sulfide (COS) compounds, including thiocarbamates, Thiocarbonates, and diThiocarbonates, all of which release COS that is quickly converted to H2S by the ubiquitous enzyme carbonic anhydrase. Each donor is designed to release COS/H2S after the activation of a trigger by activation by hydrogen peroxide (H2O2). In addition to providing a broad palette of new, H2O2-responsive donor motifs, we also demonstrate the H2O2 dose-dependent COS/H2S release from each donor core, establish that release profiles can be modified by structural modifications, and compare COS/H2S release rates and efficiencies from isomeric core structures. Supporting our experimental investigations, we also provide computational insights into the potential energy surfaces for COS/H2S release from each platform. In addition, we also report initial investigations into dithiocarbamate cores, which release H2S directly upon H2O2-mediated activation. As a whole, the insights on COS/H2S release gained from these investigations provide a foundation for the expansion of the emerging area of responsive COS/H2S donor systems.
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Kinetic Insights into Hydrogen Sulfide Delivery from Caged-Carbonyl Sulfide Isomeric Donor Platforms
2017Co-Authors: Yu Zhao, Hillary A Henthorn, Michael D PluthAbstract:Hydrogen sulfide (H2S) is a biologically important small gaseous molecule that exhibits promising protective effects against a variety of physiological and pathological processes. To investigate the expanding roles of H2S in biology, researchers often use H2S donors to mimic enzymatic H2S synthesis or to provide increased H2S levels under specific circumstances. Aligned with the need for new broad and easily modifiable platforms for H2S donation, we report here the preparation and H2S release kinetics from a series of isomeric caged-carbonyl sulfide (COS) compounds, including thiocarbamates, Thiocarbonates, and diThiocarbonates, all of which release COS that is quickly converted to H2S by the ubiquitous enzyme carbonic anhydrase. Each donor is designed to release COS/H2S after the activation of a trigger by activation by hydrogen peroxide (H2O2). In addition to providing a broad palette of new, H2O2-responsive donor motifs, we also demonstrate the H2O2 dose-dependent COS/H2S release from each donor core, establish that release profiles can be modified by structural modifications, and compare COS/H2S release rates and efficiencies from isomeric core structures. Supporting our experimental investigations, we also provide computational insights into the potential energy surfaces for COS/H2S release from each platform. In addition, we also report initial investigations into dithiocarbamate cores, which release H2S directly upon H2O2-mediated activation. As a whole, the insights on COS/H2S release gained from these investigations provide a foundation for the expansion of the emerging area of responsive COS/H2S donor systems
Yu Zhao - One of the best experts on this subject based on the ideXlab platform.
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kinetic insights into hydrogen sulfide delivery from caged carbonyl sulfide isomeric donor platforms
Journal of the American Chemical Society, 2017Co-Authors: Yu Zhao, Hillary A Henthorn, Michael D PluthAbstract:Hydrogen sulfide (H2S) is a biologically important small gaseous molecule that exhibits promising protective effects against a variety of physiological and pathological processes. To investigate the expanding roles of H2S in biology, researchers often use H2S donors to mimic enzymatic H2S synthesis or to provide increased H2S levels under specific circumstances. Aligned with the need for new broad and easily modifiable platforms for H2S donation, we report here the preparation and H2S release kinetics from a series of isomeric caged-carbonyl sulfide (COS) compounds, including thiocarbamates, Thiocarbonates, and diThiocarbonates, all of which release COS that is quickly converted to H2S by the ubiquitous enzyme carbonic anhydrase. Each donor is designed to release COS/H2S after the activation of a trigger by activation by hydrogen peroxide (H2O2). In addition to providing a broad palette of new, H2O2-responsive donor motifs, we also demonstrate the H2O2 dose-dependent COS/H2S release from each donor core, ...
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kinetic insights into hydrogen sulfide delivery from caged carbonyl sulfide isomeric donor platforms
Journal of the American Chemical Society, 2017Co-Authors: Yu Zhao, Hillary A Henthorn, Michael D PluthAbstract:Hydrogen sulfide (H2S) is a biologically important small gaseous molecule that exhibits promising protective effects against a variety of physiological and pathological processes. To investigate the expanding roles of H2S in biology, researchers often use H2S donors to mimic enzymatic H2S synthesis or to provide increased H2S levels under specific circumstances. Aligned with the need for new broad and easily modifiable platforms for H2S donation, we report here the preparation and H2S release kinetics from a series of isomeric caged-carbonyl sulfide (COS) compounds, including thiocarbamates, Thiocarbonates, and diThiocarbonates, all of which release COS that is quickly converted to H2S by the ubiquitous enzyme carbonic anhydrase. Each donor is designed to release COS/H2S after the activation of a trigger by activation by hydrogen peroxide (H2O2). In addition to providing a broad palette of new, H2O2-responsive donor motifs, we also demonstrate the H2O2 dose-dependent COS/H2S release from each donor core, establish that release profiles can be modified by structural modifications, and compare COS/H2S release rates and efficiencies from isomeric core structures. Supporting our experimental investigations, we also provide computational insights into the potential energy surfaces for COS/H2S release from each platform. In addition, we also report initial investigations into dithiocarbamate cores, which release H2S directly upon H2O2-mediated activation. As a whole, the insights on COS/H2S release gained from these investigations provide a foundation for the expansion of the emerging area of responsive COS/H2S donor systems.
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Kinetic Insights into Hydrogen Sulfide Delivery from Caged-Carbonyl Sulfide Isomeric Donor Platforms
2017Co-Authors: Yu Zhao, Hillary A Henthorn, Michael D PluthAbstract:Hydrogen sulfide (H2S) is a biologically important small gaseous molecule that exhibits promising protective effects against a variety of physiological and pathological processes. To investigate the expanding roles of H2S in biology, researchers often use H2S donors to mimic enzymatic H2S synthesis or to provide increased H2S levels under specific circumstances. Aligned with the need for new broad and easily modifiable platforms for H2S donation, we report here the preparation and H2S release kinetics from a series of isomeric caged-carbonyl sulfide (COS) compounds, including thiocarbamates, Thiocarbonates, and diThiocarbonates, all of which release COS that is quickly converted to H2S by the ubiquitous enzyme carbonic anhydrase. Each donor is designed to release COS/H2S after the activation of a trigger by activation by hydrogen peroxide (H2O2). In addition to providing a broad palette of new, H2O2-responsive donor motifs, we also demonstrate the H2O2 dose-dependent COS/H2S release from each donor core, establish that release profiles can be modified by structural modifications, and compare COS/H2S release rates and efficiencies from isomeric core structures. Supporting our experimental investigations, we also provide computational insights into the potential energy surfaces for COS/H2S release from each platform. In addition, we also report initial investigations into dithiocarbamate cores, which release H2S directly upon H2O2-mediated activation. As a whole, the insights on COS/H2S release gained from these investigations provide a foundation for the expansion of the emerging area of responsive COS/H2S donor systems
Vedova, Carlos O. Della - One of the best experts on this subject based on the ideXlab platform.
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Vibrational properties, crystal X-ray diffraction structure and quantum chemical calculations on a divalent sulfur substituted phthalimide: 1H-Isoindole-1,3(2H)-dione, 2-[(methoxycarbonyl)thio]
ELSEVIER SCIENCE BV, 2010Co-Authors: Torrico-vallejos Sonia, Erben, Mauricio F., Piro, Oscar E., Castellano, Eduardo Ernesto, Vedova, Carlos O. DellaAbstract:Structural and conformational properties of 1H-Isoindole-1,3(2H)-dione, 2-[(methoxycarbonyl)thio] (S-phthalimido O-methyl Thiocarbonate) are analyzed using a combined approach including X-ray diffraction, vibrational spectra and theoretical calculation methods. The vibrational properties have been studied by infrared and Raman spectroscopies along with quantum chemical calculations (B3LYP and B3PW91 functional in connection with the 6-311++G** and aug-cc-pVDZ basis sets). The crystal structure was determined by X-ray diffraction methods. The substance crystallizes in the monoclinic P2(1)/c space group with a = 6.795(1), b = 5.109(1), c = 30.011(3) angstrom, beta = 90.310(3)degrees and Z = 4 molecules per unit cell. The conformation adopted by the N-S-C=O group is syn (C=O double bond in synperiplanar orientation with respect to the N-S single bond). The experimental molecular structure is well reproduced by the MP2/aug-cc-pVDZ method. (C) 2010 Elsevier B.V. All rights reserved
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Vibrational properties, crystal X-ray diffraction structure and quantum chemical calculations on a divalent sulfur substituted phthalimide: 1H-Isoindole-1,3(2H)-dione, 2-[(methoxycarbonyl)thio]
ELSEVIER SCIENCE BV, 2010Co-Authors: Torrico-vallejos Sonia, Erben, Mauricio F., Piro, Oscar E., Castellano, Eduardo Ernesto, Vedova, Carlos O. DellaAbstract:Structural and conformational properties of 1H-Isoindole-1,3(2H)-dione, 2-[(methoxycarbonyl)thio] (S-phthalimido O-methyl Thiocarbonate) are analyzed using a combined approach including X-ray diffraction, vibrational spectra and theoretical calculation methods. The vibrational properties have been studied by infrared and Raman spectroscopies along with quantum chemical calculations (B3LYP and B3PW91 functional in connection with the 6-311++G** and aug-cc-pVDZ basis sets). The crystal structure was determined by X-ray diffraction methods. The substance crystallizes in the monoclinic P2(1)/c space group with a = 6.795(1), b = 5.109(1), c = 30.011(3) angstrom, beta = 90.310(3)degrees and Z = 4 molecules per unit cell. The conformation adopted by the N-S-C=O group is syn (C=O double bond in synperiplanar orientation with respect to the N-S single bond). The experimental molecular structure is well reproduced by the MP2/aug-cc-pVDZ method. (C) 2010 Elsevier B.V. All rights reserved.Facultad de Ciencias Exactas, Universidad Nacional de La PlataFacultad de Ciencias Exactas, Universidad Nacional de La PlataDeutscher Akademischer Austauschdienst (DAAD)DAA
