57966-62-8Relevant articles and documents
Unraveling structure-reactivity relationships in SNV reactions: Kinetics of the reactions of methoxybenzylidenemalononitrile, 2-(methylthiobenzylidene)- 1,3-indandione, 2-(benzylthiobenzylidene)-1,3-indandione, and methyl β-methylthio-α-nitroci
Bernasconi,Ketner,Ragains,Chen,Rappoport
, p. 2155 - 2164 (2007/10/03)
The kinetics of the title reactions were determined in 50% DMSO-50% water (v/v) at 20 °C; n-BuS-, HOCH2CH2S-, and MeO2CCH2S- were used as thiolate ions. The reactions with the th
Lifetimes of iminium ions in aqueous solution
Eldin, Sherif,Jencks, William P.
, p. 4851 - 4857 (2007/10/02)
Iminium cations have been generated in aqueous solution from the solvolysis of anilinothioethers ArN-(CH3)CH2SR at 25 °C. Common ion inhibition of the solvolysis of anilinothioethers was observed when the thiolate anion leaving group
Kinetics of Reversible Thiolate Ion Addition to Substituted β-Nitrostyrenes in Water. Radicaloid Transition State or Principle of Nonperfect Synchronization?
Bernasconi, Claude F.,Schuck, David F.
, p. 2365 - 2373 (2007/10/02)
The kinetics of reversible nucleophilic thiolate ion (RS- with R = n-Bu, HOCH2CH2, MeO2CCH2CH2 and MeO2CCH2) addition to Z-substituted β-nitrostyrenes (Z = 4-Me2N, 4-MeO, 4-MeS, 4-Me, H, 3-Cl, 4-Cl, 3-CN, 4-CN, and 3-NO2), to form ArCH(RS)CH=NO2-, have been measured in water at 20 deg C.Rate constants in the forward (k1) and reverse direction (k-1) and equilibrium constants (K1) correlate reasonably well with Hammett ?-constants for the non-?-donor substituents but show deviations for the ?-donors 4-Me2N, 4-MeO, and 4-MeS.These deviations are negativefor K1 but positive for k1 and k-1; the positive deviations for the ?-donor substituents are also observed when plotting log k1 vs log K1 (Broensted plots).The negative deviations of K1 are a consequence of resonance stabilization of the olefin.The positive deviations are attributed to a transition-state stabilization stemming from a preorganization created by the ?-donor which leads to a better delocalization of the negative charge into the nitro group.An alternative interpretation of the rate acceleration in terms of a radicaloid transition state (Gross, Z.; Hoz, S.J.Am.Chem.Soc. 1988, 110, 7489) cannot be ruled out but is shown to be less attractive and unnecessary.Broensted parameters such as βnuc, βeq, βnnuc, and βnlg, and intrinsic rate constants (k0 = k1 = k-1 when K1 = 1) were determined from the dependence on the RS- basicity for β-nitrostyrene and 3-cyano-β-nitrostyrene. βeq is low (0.5), indicating that the carbon basicity of RS- is less sensitive to electronic effects in R than its proton basicity. βnuc (βnnuc) is very low, suggesting a transition state withvery little C-S bond formation.The low βnnuc (0.22) contrasts with a large αnnuc = d log k1/d log K1 = 0.74 (variation of Z), indicating a large transition-state imbalance (αnnuc - βnnuc), as previously observed in the reaction of RS- with α-nitrostilbenes.The intrinsic rate constant (log k0 = 3.5) is also similar to that for the reaction of RS- with α-nitrostilbenes and significantly higher than for the reaction of amines with β-nitrostyrenes.Most of these features can, at least in part, be attributed to the soft acid-soft base interactions of RS- with the nitroolefins.Rate constants for carbon protonation of several of the ArCH(RS)CH=NO2- adducts by acetic acid (kHAp were also determined.They display the unusual, but for nitronate ions typical, acceleration when Ar and/or R is made more electron withdrawing.
