26227-87-2

Upstream product

• 556-50-3 glycylglycine 
• 70-34-8 2,4-Dinitrofluorobenzene 
• 154853-46-0 2,4-dinitrophenyl 4-methoxybenzenesulfonate 
• 32101-47-6 1-(4-cyanophenoxy)-2,4-dinitrobenzene 
• 1094-62-8 1-(4-acetophenoxy)-2,4-dinitrobenzene 
• 2363-38-4 1-(m-chlorophenoxy)-2,4-dinitrobenzene 
• 2548-96-1 1-(4-chlorophenoxy)-2,4-dinitrobenzene 
• 2486-07-9 2,4-dinitrophenyl phenyl ether 
• 2363-36-2 (2,4-dinitro-phenyl)-(4-nitro-phenyl)-ether 
• 88831-00-9 Dnp-Gly-Gly-Trp-Arg-OH 
• 88830-91-5 Dnp-Gly-Gly-Phe-Arg-OH 
• 88830-96-0 Dnp-Gly-Gly-Met-Arg-OH 

Relevant academic research and scientific papers

The α-effect in SNar reaction of y-substituted-phenoxy-2, 4-dinitrobenzenes with amines: Reaction mechanism and origin of the α-effect

Second-order rate constants (kN) have been measured spectrophotometrically for SNAr reactions of Ysubstituted-phenoxy-2, 4-dinitrobenzenes (1a-1g) with hydrazine and glycylglycine in 80 mol % H 2O/20 mol % DMSO at 25.0 ± 0.1 °C. Hydrazine is 14.6-23.4 times more reactive than glycylglycine. The magnitude of the α-effect increases linearly as the substituent Y becomes a stronger electron-withdrawing group (EWG). The Bronsted-type plots for the reactions with hydrazine and glycylglycine are linear with βlg = -0.21 and -0.14, respectively, which is typical for reactions reported previously to proceed through a stepwise mechanism with expulsion of the leaving group occurring after rate-determining step (RDS). The Hammett plots correlated with so constants result in much better linear correlations than s- constants, indicating that expulsion of the leaving group is not advanced in the transition state (TS). The reaction of 1a-1g with hydrazine has been proposed to proceed through a five-membered cyclic intermediate (TIII), which is structurally not possible for the reaction with glycylglycine. Stabilization of the intermediate TIII through intramolecular H-bonding interaction has been suggested as an origin of the α-effect exhibited by hydrazine.

Effect of substituent on regioselectivity and reaction mechanism in aminolysis of 2,4-dinitrophenyl X-substituted benzenesulfonates

(Chemical Equation Presented) We report on a kinetic study for the nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted benzensulfonates (X = 4-MeO, 1a, and X = 4-NO2, 1c) with a series of primary amines in 80 mol % H2O/20 mol % DMSO at 25.0 °C. The reactions proceed through S-O and C-O bond fission pathways competitively. The fraction of the S-O bond fission increases as the attaching amine becomes more basic and the substituent X changes from 4-MeO to 4-NO2, indicating that the regioselectivity is governed by the electronic nature of the substituent X as well as the basicity of amines. The S-O bond fission has been suggested to proceed through an addition intermediate with a change in the rate-determining step (RDS) at pK°a = 8.9 ± 0.1. The electronic nature of the substituent X influences kNS-O and k1 values, but not the k2/k-1 ratios and the pK°a value significantly. Stabilization of the ground state (GS) through resonance interaction between the electron-donating substituent and the electrophilic center has been suggested to be responsible for the decreased reactivity of 1a compared to 1c. The second-order rate constants for the C-O bond fission exhibit no correlation with the electronic nature of the substituent X. The distance effect and the nature of the reaction mechanism have been suggested to be responsible for the absence of the correlation.

Kinetic study and analytical application of the hexadecyltrimethylammonium bromide-catalyzed reaction of 1-fluoro-2,4-dinitrobenzene with amines

Arylation of amines by reaction with 1-fluoro-2,4-dinitrobenzene is catalyzed by micelles of cetrimonium bromide. This catalysis has been exploited to reduce the analysis time in the spectrophotometric determination of amines as their dinitrophenyl derivatives. The kinetics of the catalysis were studied for the five amines: alanine, phenylalanine, aniline, 4-methylaniline, and 4-methoxyaniline. The dependence of rate constant on surfactant concentration can be quantitatively accounted for by Berezin's model, in which uptake of the amine and the 1-fluoro-2,4-dinitrobenzene by the micelle is described as a partitioning phenomenon for both species. An alternative model is developed in which one reactant partitions into the micellar phase and the other binds to the micelle with 1:1 stoichiometry; the two models are formally equivalent. Intrinsic catalytic rate constants and binding constants were evaluated. About one-third to one-half of the maximum observed micellar acceleration is attributed to a true micellar catalysis, the remainder being ascribed to an increase in local reactant concentrations in the micelle.

ISOLATION AND CHARACTERIZATION OF AN ACID PROTEINASE FROM Aspergillus oryzae

The heat stability, substrate specificity, and the pH optima of activation and inhibition of an acid proteinase isolated from the industrial preparation amilorizin Pkh have been studied.The enzyme has been found active in the hydrolysis of chromophoric pe