57238-80-9

Upstream product

• 7755-92-2 piperazine-1-carbaldehyde 
• 39248-99-2 S-(4-nitrophenyl) 4-methylbenzothioate 
• 35539-23-2 S-2,4-dinitrophenyl 4-methylthiobenzoate 
• 15023-67-3 4-nitrophenyl 4-methylbenzoate 
• 36106-76-0 2,4-dinitrophenyl 4-methylbenzoate 

Relevant academic research and scientific papers

Kinetics and mechanism of the reactions of S-4-nitrophenyl 4-methylthiobenzoate with secondary alicyclic amines and pyridines

The reactions of the title substrate with a series of six secondary alicyclic amines and a series of eight pyridines are subjected to a kinetic investigation in 44 wt% ethanol-water, at 25.0°C, and an ionic strength of 0.2 mol · dm-3. Under amine excess pseudo first-order rate coefficients (kobs) are obtained. Plots of kobs against free amine concentration at constant pH are linear, with the slope (k N) independent of pH. The Bronsted-type plots (log k N against pKa of the conjugate acids of the amines) are non-linear, with the curvature center located at pKa (pX a0) 9.7 and 9.4, for the reactions of secondary alicyclic amines and pyridines, respectively. The plots are consistent with a zwitterionic tetrahedral intermediate (T±) on the reaction path and a change in rate-determining step. The greater pKa0 value for secondary alicyclic amines than pyridines is explained by the greater nucleofugality from T± of secondary alicyclic amines compared to isobasic pyridines. These pKa0 values are lower than those found for the reactions of S-4-nitrophenyl 4-Y-substituted thiolbenzoates (Y = H, Cl, NO2) with the corresponding amine series. These results indicate that electron donation from the non-leaving group in T ± favors leaving group expulsion from T± relative to amine expulsion. Copyright

Kinetics and mechanism of the reactions of S-2,4-dinitrophenyl 4-substituted thiobenzoates with secondary alicyclic amines

The title reactions, in 44 wt % ethanol-water at 25.0 °C, exhibit slightly curved Bronsted-type plots (log kN versus pK a of amines) with slopes β1 = 0.1-0.44 (at high pKa) and β2 ca. 0.7 (at low pKa). The magnitude of some of these slopes, together with the fact that the curvature center (pKa0 = 9.5-10.8) does not change with the electronic effects of the benzoyl substituent, suggests that these reactions are not stepwise, but concerted.

Effect of Acyl Substituents on the Reaction Mechanism for Aminolyses of 4-Nitrophenyl X-Substituted Benzoates

Second-order rate constants (kN) have been measured spectrophotometrically for the reaction of 4-nitrophenyl X-substituted benzoates with a series of alicyclic secondary amines in H2O containing 20 mol % dimethyl sulfoxide at 25.0°C.

Structure-reactivity correlations in the reaction of 2,4-dinitrophenyl X-substituted benzoates with alicyclic secondary amines

Apparent second-order rate constants (kapp) have been measured spectrophotometrically for the reaction of 2,4-dinitrophenyl X-substituted benzoates with a series of alicyclic secondary amines in H2O containing 20 mol% DMSO at 25°C. The microconstants involved in the reaction (k-1/k2, K1, and k1k2/k-1) have also been calculated. The magnitude of kapp, k1, and k1k2/k-1 values increases with increasing amine basicity and with increasing acid strengthening ability of the acyl substituent X. The k-1/k2 value decreases from ca. 6.5 to 0.3 with increasing the amine basicity, but remains almost constant upon changing the acyl substituent X for a given amine, indicating that the ratedetermining step is governed by the basicity of amine but not by the electronic nature of the acyl substituent X. The Bronsted-type plots for kapp show a break at pKa = 9.1, supporting the assumption that a change in the rate-determining step occurs from rate-limiting breakdown to formation of the addition intermediate as amine basicity increases. The corresponding Bronsted-type plots for k-1/k2, k1, and k1k2/k-1 are linear but their β values are different. σ+ constants show better correlation with log kapp, log kl and log k1k2/k-1 for the reaction with low basic amines (pKa a > 9.1). The magnitude of ρ1 is identical to that of ρapp and ρeq for a given amine.