66291-19-8Relevant articles and documents
Kinetic Isotope Effect and Tunnelling in the Reaction between 4-Nitrophenylnitromethane in Acetonitrile and Toluene
Blanch, Jan H.,Rogne, Otto,Rossemyr, Leif I.
, p. 1905 - 1910 (1980)
Rates and activation parameters for the proton and deuteron transfer reaction of 4-nitrophenylnitromethane with pentamethylguanidine in acetonitrile have been determined.The isotope effect and differences in activation parameters are larger than the semic
Kinetic study of the reactions of various types of C-acids with amine bases in acetonitrile. An unusual effect of common BH+ cation on the rate constants
Galezowski, Wlodzimierz,Grzeskowiak, Iwona,Jarczewski, Arnold
, p. 1042 - 1049 (2007/10/03)
The rates of proton transfer reactions between C-acids of different types such as 1-(4-nitrophenyl)-1-nitroalkanes, 4-nitrophenylcyanomethanes, and 2,4,6-trinitrotoluene, and organic bases such as 1,1,3,3-tetrametylguanidine, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), and tri-n-butylamine have been measured in acetonitrile at pseudo-first-order conditions. A general equation for the rates of proton transfer reactions between C-acids and bases with product existing in two forms, ions and ion pairs, has been derived and its applicability tested. The equation works well except for reactions of 1-(4-nitrophenyl)-1-nitroalkanes with guanidines for which the second-order rate constant is diminished with concentration of guanidinium cation, while tetrabutylammonium salts accelerate the reactions. Possible reasons for this are discussed.
Hydrolysis of substituted α-nitrostilbenes: Dissection of rate coefficients for individual steps in the four-step mechanism. Estimates of intrinsic rate constants and transition-state imbalances
Bernasconi, Claude F.,Fassberg, Julianne
, p. 514 - 522 (2007/10/02)
A kinetic study of the hydrolysis of substituted α-nitrostilbenes (NS-Z with Z = 4-Me, H, 4-Br, 3-NO2, and 4-NO2) in 50% Me2SO-50% water (v/v) at 20 °C is reported. The mechanism consists of four steps: nucleophilic addition to NS-Z of water (k1H2O) and OH- (k1OH) to form PhCH(OH)C(Ar)NO2- (TOH-); carbon protonation of TOH- by water (k2H2O), H3O+ (k2H), and buffer acids (k2BH) to form PhCH(OH)CH(Ar)NO2 (TOH0); rapid oxygen deprotonation of TOH0 (KaOH) to form PhCH(O-)CH(Ar)NO2 (TO-); collapse of TO- (k4) into benzaldehyde and arylnitromethane anion. The aci-form of TOH0, PhCH(OH)CH(Ar)NO2H (TOH,aci0), can also be generated as a transient by reaction of TOH- with strong acid. A combination of kinetic experiments involving the reaction of the olefin with water and OH-, the reaction of TOH- with acid, and the reaction of independently synthesized TOH0 with base allowed the dissection of the rate coefficients of most of the individual steps. From the substituent dependence of these rate coefficients, it is concluded that water and OH- addition to NS-Z (k1H2O and k1OH) as well as the collapse of TO- to benzaldehyde and ArCH=NO2- (k4) is characterized by substantial transition-state imbalances, reminiscent of the imbalance observed in the deprotonation of ArCH2NO2. It is also shown that the intrinsic rate constants for the k1OH and k4 steps are low compared to those for the corresponding steps in the hydrolysis of other olefins of the type PhCH=CXY (XY = (H, NO2), (CO)2C6H4, (COO)2C(CHj)2, and (CN)2). This again parallels the behavior in the deprotonation of ArCH2NO2.
