1094-62-8

Upstream product

• 2486-07-9 2,4-dinitrophenyl phenyl ether 
• 75-36-5 acetyl chloride 
• 70-34-8 2,4-Dinitrofluorobenzene 
• 99-93-4 4-Hydroxyacetophenone 

Downstream Products

• 26227-87-2 Dnp-Gly-Gly-OH 
• 119-26-6 (2,4-dinitro-phenyl)-hydrazine 
• 51-28-5 2,4-Dinitrophenol 
• 839-93-0 1-(2,4-dinitrophenyl)piperidine 
• 610-54-8 2,4-dinitro-1-ethoxybenzene 

Relevant academic research and scientific papers

Alkali-Metal Ion Catalysis and Inhibition in SNAr Displacement: Relative Stabilization of Ground State and Transition State Determines Catalysis and Inhibition in SNAr Reactivity

We report here the first observation of alkali-metal ion catalysis and inhibition in SNAr reactions. The plot of kobsd versus [alkali-metal ethoxide] exhibits downward curvature for the reactions of 1-(4-nitrophenoxy)-2,4-dinitrobenzene with EtOLi, EtONa, and EtOK, but upward curvature for the corresponding reaction with EtOK in the presence of 18-crown-6-ether (18C6). Dissection of kobsd into the second-order rate constants for the reactions with the dissociated EtO- and the ion-paired EtOM (i.e., k EtO - and kEtOM, respectively) has revealed that the reactivity increases in the order EtOLi-+, Na+, and K+ ions but is catalyzed by 18C6 K+ ion. The reactions of 1-(Y-substituted-phenoxy)-2,4-dinitrobenzenes have been proposed to proceed through a stepwise mechanism, in which expulsion of the leaving group occurs after the rate-determining step based on the kinetic result that σo constants exhibit a much better Hammett correlation than σ- constants. Alkali-metal ion catalysis or inhibition has been discussed in terms of differential stabilization of ground-state and transition-state complexes through a qualitative energy profile. A π-complexed transition-state structure is proposed to account for the kinetic results.

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.

Kinetic study on SNAr reaction of 1-Y-substituted-phenoxy-2,4- dinitrobenzenes with hydroxide ION: Effect of substituent y on reactivity and reaction mechanism

A kinetic study is reported for the SNAr reaction of 1-Y-substituted- phenoxy-2,4-dinitrobenzenes (1a-1h) with OH- in 80 mol % H2O/20 mol % DMSO at 25.0 ± 0.1 °C. The second-order rate constant (kOH-) increases as the substituent Y in the leaving group changes from an electron-donating group (EDG) to an electronwithdrawing group (EWG). The Bronsted-type plot for the reactions of 1a-1h is linear with βlg = -0.16, indicating that the reactivity of substrates 1a-1h is little affected by the leaving-group basicity. A linear Bronsted-type plot with βlg = -0.3 ± 0.1 is typical for reactions reported previously to proceed through a stepwise mechanism in which formation of a Meisenheimer complex is the rate-determining step (RDS). The Hammett plot correlated with σY o constants results in a much better correlation than that correlated with σY - constants, implyng that no negative charge is developing on the O atom of the leaving group (or expulsion of the leaving group is not advanced at all in the TS). This excludes a possibility that the SNAr reaction of 1a-1h with OH- proceeds through a concerted mechanism or via a stepwise pathway with expulsion of the leaving group being the RDS. Thus, the current reactions have been concluded to proceed through a stepwise mechanism in which expulsion of the leaving group occurs rapidly after the RDS.

Kinetic study on SNAr reaction of 1-(Y-Substituted-phenoxy)-2,4- dinitrobenzenes with cyclic secondary amines in acetonitrile: Evidence for cyclic transition-state structure

A kinetic study is reported for SNAr reactions of 1-(Y-substituted-phenoxy)-2,4-dinitrobenzenes (1a-1h) with amines in MeCN. The plots of pseudo-first-order rate constant versus amine concentration curve upward, indicating that the reactions are catalyzed by a second amine molecule. The Br?nsted-type plots for the reaction of 1-(4-nitrophenyl)-2,4- dinitrobenzene (1a) with secondary amines are linear with βnuc = 1.10 and 0.85 for the uncatalyzed and catalyzed reactions, respectively, while the Yukawa-Tsuno plots for the reactions of 1a-1h with piperidine result in excellent linear correlations with ρY = 1.85 and r = 0.27 for the uncatalyzed reaction and ρY = 0.73 and r = 0.23 for the catalyzed reaction. The catalytic effect decreases with increasing amine basicity or electron-withdrawing ability of the substituent Y in the leaving group. Activation parameters calculated from the rate constants measured at five different temperatures for the catalyzed reaction of 1a with piperidine are ΔH? = 0.38 kcal/mol and ΔS? = -55.4 cal/(mol K). The catalyzed reaction from a Meisenheimer complex (MC ±) is proposed to proceed through a concerted mechanism with a cyclic transition-state rather than via a stepwise pathway with an anionic intermediate, MC-. Deuterium kinetic isotope effects provide further insight into the nature of the concerted transition state.