30924-74-4Relevant articles and documents
Kinetic study on reactions of O-Y-substituted phenyl thionobenzoates with quinuclidine: Factors governing reactivity and reaction mechanism
Yang, Eun-Ji,Kim, Min-Young,Um, Ik-Hwan
, p. 1120 - 1125 (2015/08/11)
Second-order rate constants (kquin) for the reactions of O-Y-substituted phenyl thionobenzoates (3a-3i) with quinuclidine have been measured spectrophotometrically. Comparison of kquin with the rate constants reported previously for the corresponding reactions with benzylamine (kBzNH2) has revealed that quinuclidine is less reactive than benzylamine toward 3a-3i although the former is 2.1 pKa units more basic than the latter. Steric hindrance exerted by quinuclidine has been suggested to be responsible for the decreased reactivity of the tertiary amine. The Bronsted-type plot for the reactions of 3a-3i with quinuclidine is linear with βlg = -0.37. The Hammett plot correlated with σ(Formula presented.) constants exhibits many scattered points (R2 = 0.982). In contrast, the Yukawa-Tsuno plot results in an excellent linear correlation (R2 = 0.9992) with ρY = 0.96 and r = 0.51, indicating that a negative charge develops partially on the O atom of the leaving group. Thus, the reactions of 3a-3i with quinuclidine have been concluded to proceed through a concerted mechanism in which expulsion of the leaving group is advanced only a little in the rate-determining transition state.
Curved Hammett Plot in Alkaline Hydrolysis of O-Aryl Thionobenzoates: Change in Rate-Determining Step versus Ground-State Stabilization
Um, Ik-Hwan,Lee, Ji-Youn,Kim, Han-Tae,Bae, Sun-Kun
, p. 2436 - 2441 (2007/10/03)
Second-order rate constants have been measured for alkaline hydrolysis of O-aryl thionobenzoates (X-C6H4-CS-OC6H 4-Y) in 80 mol % H2O-20 mol % DMSO at 25.0 ± 0.1 °C. The Hammett plot for the reaction of O-4-nitrophenyl X-substituted thionobenzoates (X-C6H4-CS-OC6H 4-NO2, 1a-e) exhibits a downward curvature. However, a possible traditional explanation in terms of a change in the rate-determining step (RDS) has been considered but rejected. The proposed explanation involves stabilization of the ground-state (GS) through-resonance interaction between the electron-donating substituent X and the thionocarbonyl functionality on the basis of the linear Yukawa-Tsuno plot obtained for the same reaction. The Bronsted-type plot for the reaction of O-aryl thionobenzoates (C 6H5-CS-OC6H4-Y, 2a-i) is linear but exhibits many scattered points with a small βlg, (-0.35). The Hammett plot for the same reaction shows rather poor correlation with σ- constants but much better correlation with σ° constants. The alkaline hydrolysis of O-aryl thionobenzoates (1a-e and 2a-i) has been proposed to proceed through an addition intermediate in which bond formation is the RDS.
Elektroreduktion organischer Verbindungen, 26. Einelektronenreduktion der O-Phenylester aromatischer Thiocarbonsaeuren-eine polarographische und cyclovoltammetrische Untersuchung
Prangova, Lilia,Osternack, Kai,Voss, Juergen
, p. 1551 - 1567 (2007/10/02)
Die Halbstufenpotentiale der Elektroreduktion ortho-, meta- und para-substiturierter Thiobenzoesaeure-O-phenylester 1-4 in wasserfreiem Acetonitril werden gemessen.Sie werden mit Hammetts Substituentenkonstanten und mit den UV-VIS-Absorptionsbanden korrel
