6320-01-0Relevant articles and documents
Oxidative cleavage of S-Arylmercaptoacetic acids by pyridinium chlorochromate: Kinetic and correlation analysis
Kabilan,Girija,Rajagopal
, p. 683 - 688 (2007/10/03)
Kinetics of oxidation of 24 S-Arylmercaptoacetic acids (SAMA) by pyridinium chlorochromate (PCC) have been studied in acid medium. The product of oxidation is the corresponding thiophenol. The rate data of meta- and para-substituted acids have been correlated well with σI, σ°R values and the meta-compounds correlate well with F,R values. The reaction constants are negative and of smaller magnitudes. Further, the ortho-substituted acids show a good correlation with triparametric equation involving Taft's σI and σ°R and charton's steric parameter v. There is no considerable steric contribution to the total orthosubstituent effect. Based on these observations, the mechanism involving the formation of protonated arylsulfinylacetic acid intermediate, followed by an intramolecular rearrangement leading to the product thiophenol has been proposed.
Oxidative Cleavage of S-Arylmercaptoacetic Acids by Sodium Perborate: Kinetic and Correlation Study
Kabilan, S.,Pandiarajan, K.,Krishnasamy, K.,Sankar, P.
, p. 443 - 452 (2007/10/02)
Kinetics of oxidation of twenty six S-arylmercaptoacetic acids (SAMA) (I) by sodium perborate (PB) have been studied in acid medium.The product of oxidation is the corresponding thiophenol.The rate data of meta- and para-substituted acids have been correlated with DSP equations.While the para-compounds correlate well with ?I and ?0R values, the meta-compounds correlate well with ?I and ?-R values.The reaction constants are negative and of smaller magnitudes.Further, the ortho-substituted acids show a good correlation with a triparametric equation involving Taft's ?I and ?0R and Charton's steric parameter ν.There is a considerable steric contribution to the total ortho-substituent effect.Based on these observations, mechanism involving the formation of protonated arylsulfinylacetic acid intermediate, followed by an intramolecular rearrangement leading to the product thiophenol has been proposed.
Electrophilic Aromatic Substitution. Part 33. Partial Rate Factors for Protiodetritiation of Benzothiophen; the Resonance-dependent Reactivity of the Ring Positions
Amin, Hassan B.,Awad, Amin A.,Archer, William J.,Taylor, Roger
, p. 1489 - 1492 (2007/10/02)
Rate coefficients for detriation of benzothiophen, specifically labelled with tritium at each position, have been measured in anhydrous trifluoroacetic acid, and, for benzothiophen, in a range of trifluoroacetic acid-acetic acid mixtures, all at 70 deg C.The dependence of rate upon acidity is consistent with the effect of hydrogen bonding between sulphur and trifluoroacetic acid, as found previously for other sulphur-containing heterocycles.Partial rate factors, corrected for the effect of hydrogen bonding are (positions in parentheses): 8.84 * 105 (2); 1.18 * 106 (3); 360 (4); 13200 (5); 16200 (6); and 26.2 (7); the corresponding ?+ values are -0.68, -0.695, -0.29, -0.47, -0.48, and -0.16.The positional reactivity order is the same as found in pyrolysis of 1-arylethyl acetates, and solvolysis of 1-arylethyl chlorides, but the ?+ values are more negative due to the greater demand for resonance stabilization of the transition states in hydrogen exchange.Comparison of the 2- : 3-isomer ratios in various substitutions leads to the unexpected conclusion that substitution at the 2-position is subject to steric effects, probably due to the proximity of the sulphur d-orbitals.
