45797-13-5Relevant articles and documents
Identification of dimethyl sulfide in dimethyl sulfoxide and implications for metal-thiolate disulfide exchange reactions
Garusinghe, Gamage S. P.,Bessey, S. Max,Boyd, Chelsea,Aghamoosa, Mostapha,Frederick, Brian G.,Bruce, Mitchell R. M.,Bruce, Alice E.
, p. 40603 - 40606 (2015)
The concentration of dimethyl sulfide (DMS) in seven different samples of research grade dimethyl sulfoxide (DMSO), including one deuterated sample, was measured by GC-MS. The average concentration of DMS is 0.48 ± 0.14 mM (range: 0.44-0.55 mM) and ca. 0.
Reactions of O-aryl S-aryl dithiocarbonates with secondary alicyclic amines in aqueous ethanol. Kinetics and mechanism
Castro, Enrique A.,Gazitua, Marcela,Santos, Jose G.
supporting information; scheme or table, p. 466 - 473 (2012/01/19)
The reactions of O-(4-methylphenyl) S-(4-nitrophenyl), O-(4-chlorophenyl) (4-nitrophenyl), O-(4-chlorophenyl) S-phenyl, and O-(4-methylphenyl) S-phenyl dithiocarbonates (1, 2, 3, and 4, respectively) with a series of secondary alicyclic (SA) amines 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 are followed spectrophotometrically. Under amine excess, pseudo-first-order rate coefficients (kobs) are found. For some of the reactions, plots of kobs vs. free amine concentration at constant pH are linear but others are nonlinear upwards. This kinetic behavior is in accordance with a stepwise mechanism with two tetrahedral intermediates, one zwitterionic (T ±) and the other anionic (T-). In some cases, there is a kinetically significant proton transfer from T± to an amine to yield T-. Values of the rate micro constants k1 (amine attack to form T±), k-1 (its back step), k2 (nucleofuge expulsion from T±), and k 3 (proton transfer from T± to the amine) are determined for some reactions. The Bronsted plots for k1 are linear with slopes β1 = 0.2-0.4 in accordance with the slope values found when T± formation is the rate-determining step. The sensitivity of log k1 and log k-1 to the pK a of the amine, leaving and non-leaving groups are determined by a multiparametric equation. For the reactions of 1-4 with 1-formylpiperazine and those of 3 and 4 with morpholine the k2 and k3 steps are rate determining. Copyright
Kinetics and mechanism of the reactions of O-aryl S-(4-nitrophenyl) dithiocarbonates with anilines in aqueous ethanol
Castro, Enrique A.,Gazitua, Marcela,Santos, Jose G.
scheme or table, p. 176 - 180 (2010/08/20)
The reactions of O-(4-methylphenyl) S-(4-nitrophenyl) dithiocarbonate and O-(4-chlorophenyl) S-(4-nitrophenyl) dithiocarbonate with a series of anilines are subjected to a kinetic investigation in 44wt% ethanol-water, at 25.0 °C and an ionic strength of 0.2 M. The reactions are followed spectrophotometrically at 420nm (appearance of 4-nitrobenzenethiolate anion). Under excess amine, pseudo-first-order rate coefficients (kobs) are found. For the reactions of both substrates with anilines, plots of k obs versus free amine concentration at constant pH are nonlinear upwards, according to a second-order polynomial equation. This kinetic behavior is in agreement with a stepwise mechanism consisting of two tetrahedral intermediates, one zwitterionic (T±) and the other anionic (T-), with a kinetically significant proton transfer from T ± to an aniline to yield T-. The rate equation was derived from the proposed mechanism. By nonlinear least-squares fitting of the rate equation to the experimental data, values of the rate micro-coefficients involved in both steps were determined. Copyright
Reactions of O-aryl S-aryl dithiocarbonates with pyridines in aqueous ethanol: Kinetics and mechanism
Castro, Enrique A.,Gazitua, Marcela,Santos, Jose G.
scheme or table, p. 1003 - 1008 (2010/07/04)
The reactions of O-(4-methylphenyl) S-(4-nitrophenyl) dithiocarbonate (1), O-(4-chlorophenyl) S-(4-nitrophenyl) dithiocarbonate (2), and O-(4-chlorophenyl) S-phenyl) dithiocarbonate (3) with a series of pyridines were subjected to a kinetic investigation
Reactions of phosphate and phosphorothiolate diesters with nucleophiles: Comparison of transition state structures
Ye, Jing-Dong,Barth, Christofer D.,Anjaneyulu, Potluri S. R.,Tuschl, Thomas,Piccirilli, Joseph A.
, p. 2491 - 2497 (2008/02/14)
A series of methyl aryl phosphorothiolate esters (SP) were synthesized and their reactions with pyridine derivatives were compared to those for methyl aryl phosphate esters (OP). Results show that SP esters react with pyridine nucleophiles via a concerted SN2(P) mechanism. Bronsted analysis suggests that reactions of both SP and OP esters proceed via transition states with dissociative character. The overall similarity of the transition state structures supports the use of phosphorothiolates as substrate analogues to probe mechanisms of enzyme-catalyzed phosphoryl transfer reactions. This journal is The Royal Society of Chemistry.
Kinetics and mechanism of the pyridinolysis of S-4-nitrophenyl 4-substituted thiobenzoates in aqueous ethanol
Castro, Enrique A.,Vivanco, Melissa,Aguayo, Raul,Santos, Jose G.
, p. 5399 - 5404 (2007/10/03)
The pyridinolysis of S-4-nitrophenyl 4-X-substituted thiobenzoates (X = H, Cl, and NO2; 1, 2, and 3, respectively) is studied kinetically in 44 wt % ethanol-water, at 25.0 °C and an ionic strength of 0.2 M (KCl). The reactions are measured spectrophotometrically (420-425 nm) by following the appearance of 4-nitrobenzenethiolate anion. Pseudo-first-order rate coefficients (kobsd) are obtained throughout, under excess of amine over the substrate. Plots of kobsd vs [free amine] at constant pH are linear with the slope (kN) independent of pH. The Bronsted-type plot (log kN vs pKa of the conjugate acids of the pyridines) for the reactions of thiolbenzoate 1 is curved with a slope at high pK a, β1 = 0.20, and slope at low pKa, β2 = 0.94. The pKa value for the center of the Bronsted curvature is pKa0 = 9.7. The pyridinolysis of thiolbenzoates 2 and 3 show linear Bronsted-type plots of slopes 0.94 and 1.0, respectively. These results and other evidence indicate that these reactions occur with the formation of a zwitterionic tetrahedral intermediate (T±). For the pyridinolysis of thiolbenzoate 1, breakdown of T± to products (k2 step) is rate-limiting for weakly basic pyridines and T± formation (k1 step) is rate-determining for very basic pyridines. The k2 step is rate-limiting for the reactions of thiolbenzoates 2 and 3. The smallest pK a0 value for the reaction of 1 is due to a the weakest electron withdrawal of H (relative to Cl and NO2) in the acyl group, which results in the smallest k-1/k2 ratio. The pK a0 values for the title reactions are smaller than those for the reactions of secondary alicyclic amines with thiolbenzoates 1-3. This is attributed to a lower leaving ability from the T± of pyridines than isobasic alicyclic amines. The lower pKa0 value found for the pyridinolysis of 2,4-dinitrophenyl benzoate (pK a0 = 9.5), compared with that for the pyridinolysis of 1, is explained by the greater nucleofugality from T± of 2,4-dinitrophenoxide than 4-nitrobenzenethiolate, which renders the k -1/k2 ratio smaller for the reactions of the benzoate relative to thiolbenzoate 1. The title reactions are also compared with the aminolysis of similar thiolbenzoates in other solvents to assess the solvent effect.
Enhanced reactivity in the ammonolysis of phenyl thiolacetates in aqueous medium
Rajarathnam,Babu,Nadar, P. Ananthakrishna
, p. 18 - 26 (2007/10/03)
The ammonolysis of several substituted phenyl thiolacetates is kinetically studied in aqueous medium, 18°C, ionic strength 0.1 M (KCl). By following the leaving groups spectrophotometrically (λmax = 260-410 nm), under excess free ammonia, pseud
Kinetics and mechanism of the reactions of quinuclidines with ethyl S- aryl thiolcarbonates
Castro, Enrique A.,Munoz, Patricio,Santos, Jose G.
, p. 8298 - 8301 (2007/10/03)
The reactions of quinuclidines with ethyl S-(4-nitrophenyl) thiolcarbonate (NPTC), ethyl S-(2,4-dinitrophenyl) thiolcarbonate (DNPTC), and ethyl S-(2,4,6-trinitrophenyl) thiolcarbonate (TNPTC) are subjected to a kinetic study in aqueous solution, 25.0°C, ionic strength 0.2 (KCl). The reactions are studied by following spectrophotometrically (400 nm) the release of the corresponding substituted benzenethiolate anion. Under quinuclidine excess, pseudo-first-order rate coefficients (k(obsd)) are found. Plots of k(obsd) vs [N] (N is the free substituted quinuclidine) are linear and pH independent, with slope k(N). The Bronsted-type plots (log k(N) vs pK(a) of quinuclidinium ions) are linear, with slope β = 0.85 for NPTC, in agreement with a stepwise mechanism where the breakdown of a tetrahedral addition intermediate (T±) is rate determining, and β = 0.54 and 0.47 for DNPTC and TNPTC, respectively, consistent with a concerted mechanism. By comparison of the reactions under investigation among them and with similar aminolyses, the following conclusions can be drawn: (i) Substitution of the 4-nitrobenzenethio group in T± by 2,4-dinitrobenzenethio or 2,4,6- trinitrobenzenethio destabilizes the tetrahedral intermediate. (ii) Quinuclidines destabilize the tetrahedral intermediate relative to secondary alicyclic amines, anilines, and pyridines. The leaving abilities of isobasic amines from T± follow the sequence pyridines anilines secondary alicyclic amines quinuclidines. (iii) Quinuclidines are more reactive toward the carbonyl group of phenyl 4-nitrophenyl carbonate than that of NPTC.
Concerted mechanisms of the reactions of ethyl S-aryl thiocarbonates with substituted phenoxide ions
Castro,Paves,Santos
, p. 2310 - 2313 (2007/10/03)
The reactions of 4-nitrophenyl, 2,4-dinitrophenyl, and 2,4,6- trinitrophenyl O-ethyl thiolcarbonates with substituted phenoxide ions are subjected to a kinetic study in water, 25.0 °C, ionic strength 0.2 M (KCl). By following the reactions spectrophotometrically, pseudo-first-order rate coefficients (k(obsd)) are found under excess of the nucleophile. Plots of k(obsd) vs phenoxide anion concentration at constant pH are linear, with the slope (k(N)) independent of pH. The Bronsted-type plots (log k(N) vs pK(a) of the phenols) are linear with slopes β = 0.92, 0.77, and 0.61 for the reactions of the 4-nitrophenyl, 2,4-dinitrophenyl, and 2,4,6-trinitrophenyl derivatives, respectively. For these reactions, a concerted mechanism is proposed since the slope values are similar to those found in the concerted phenolysis of aryl acetates; the slope magnitudes are not consistent with a stepwise mechanism where the formation of a tetrahedral intermediate is rate limiting. Our results are in line with the finding that the reactions of the 2,4-dinitrophenyl and 2,4,6-trinitrophenyl derivatives with secondary alicyclic amines in water are concerted. In contrast, the reactions of the same substrates with pyridines are stepwise, which means that substitution of a pyridine moiety in a tetrahedral intermediate with a benzenethio group by a phenoxy group destabilizes the intermediate.
Photochemistry of nitrobenzenethiol. Selective generation of the thio radical and thione triplet state as a function of solvent polarity
Alam,Ito
, p. 1285 - 1290 (2007/10/03)
Transient absorption spectra of p-nitrobenzenethiol (NBSH) have been measured by the nanosecond laser flash photolysis method. In nonpolar and less polar solvents, nitrobenzenethio radical (NBS(·)) was predominantly formed by the homolytic fission of the
