The reaction of N-t-Butyl-2,4,6-trinitrobenzamide with sodium hydroxide. A unimolecular nucleophilic aromatic substitution

1965 ◽  
Vol 18 (5) ◽  
pp. 699 ◽  
Author(s):  
PJ Hutchison ◽  
RJL Martin
Keyword(s):  
Nucleophilic Substitution ◽  
Equilibrium Constant ◽  
Kinetic Data ◽  
Zero Order ◽  
Ion Concentration ◽  
Nucleophilic Aromatic Substitution ◽  
Anionic Complex ◽  
Aromatic Substitution ◽  
Ion Concentrations ◽  
Hydroxyl Ion

N-t-Butyl-2,4,6-trinitrobenzamide undergoes a nucleophilic substitution with hydroxyl ions to form nitrite ions. The amide is stable during this reaction and will only undergo hydrolysis under the more drastic conditions of higher hydroxyl ion concentrations at higher temperatures. The observed rate of the nucleophilic substitution is inversely proportional to the hydroxyl ion concentration. In the presence of alkali, the amide is in equilibrium with a red anionic complex and the equilibrium constant has been calculated from the kinetic data. When allowance has been made for this equilibrium, it is found that the formation of nitrite ions from the amide is zero order with respect to the hydroxyl ion concentration.

Nucleophilic substitution of meso-nitrooctaethylporphyrins

1985 ◽  
Vol 63 (2) ◽  
pp. 406-411 ◽  
Author(s):  
Liang-Chu Gong ◽  
David Dolphin
Keyword(s):  
Nucleophilic Substitution ◽  
Nucleophilic Addition ◽  
Nucleophilic Aromatic Substitution ◽  
Redox Potentials ◽  
Aromatic Substitution ◽  
Halogen Atoms

Nitrooctaethylporphyrins readily undergo nucleophilic aromatic substitution in the presence of HCl or HBr. In the presence of methoxide, nucleophilic addition to give a porphodimethane occurs, followed by autoxidation to the methoxyporphyrin. Unlike the nitrated complexes, the chlorosubstituted porphyrins exhibit redox potentials similar to those of unsubstituted analogs. Meso-halogenated porphyrins do, however, show steric distortion due to the bulk of the halogen atoms.

How Does Nucleophilic Aromatic Substitution in Nitroarenes Really Proceed: General Mechanism

Synthesis ◽  
2017 ◽  
Vol 49 (15) ◽  
pp. 3247-3254 ◽  
Author(s):  
Mieczysław Mąkosza
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Nucleophilic Substitution ◽  
Experimental Studies ◽  
Secondary Reaction ◽  
Nucleophilic Aromatic Substitution ◽  
General Mechanism ◽  
Primary Process ◽  
Nucleophilic Substitution Of Hydrogen ◽  
Aromatic Substitution

On the basis of previously published experimental studies and ab initio calculations, a general corrected mechanism of nucleophilic aromatic substitution was formulated. It was shown that conventional nucleophilic substitution of halogens is a slow secondary reaction whereas nucleophilic substitution of hydrogen is the fast primary process. The general mechanism embraces both of these alternative and complementary reactions.

THE MECHANISMS OF PERMANGANATE OXIDATION VI. THE OXIDATION OF CYANIDE ION

1960 ◽  
Vol 38 (11) ◽  
pp. 2237-2255 ◽  
Author(s):  
Ross Stewart ◽  
R. Van der Linden
Keyword(s):  
Salt Effect ◽  
Ion Concentration ◽  
Cyanide Ion ◽  
Barium Ions ◽  
Ion Concentrations ◽  
Permanganate Oxidation ◽  
Parallel Processes ◽  
Hydroxyl Ion ◽  
Kinetic Expression ◽  
Tracer Experiments

Kinetic and oxygen-18 tracer experiments have been used in an attempt to elucidate the mechanism(s) of permanganate oxidation of cyanide. From pH 12 to 14.6 the oxidation is represented by the equation,[Formula: see text]From pH 12 to 6 the reaction was found to be complex and unstoichiometric yielding cyanate, carbon dioxide, cyanide ion, and finally cyanogen at pH 9 to 6.The rate of reduction of permanganate, as followed iodometrically and spectrophotometrically, is found to be markedly dependent on the pH of the medium and reactant concentration. The rate is negligible in acid solution but rapid in basic media.At pH greater than 12 two parallel processes are indicated which have been designated as reaction A and reaction B. Reaction A appears at low reactant concentrations 0.0004 M cyanide and higher hydroxyl ion concentrations pH 13 and is represented by the kinetic expression[Formula: see text]where k2 is independent of hydroxyl ion concentration and is insensitive to the presence of manganate and barium ions. A positive salt effect is observed and labeling experiments using permanganate enriched in oxygen18 showed that the oxygen introduced into the product cyanate comes mainly from the oxidant (70%–80% oxygen-18 transferred).The existence of a second process reaction B was indicated by the changing kinetics at higher reactant concentrations and lower basicities, by the non-linear Arrhenius plots, and by the observation that only 15–25% oxygen-18 transfer from permanganate to substrate had occurred at pH 13. The rate of this latter process is approximately represented by the kinetic expression[Formula: see text]These reactions are discussed in terms of mechanism

Kinetics and mechanism of the osmium-tetroxide-catalysed oxidation of mandelate ion by hexacyanoferrate(III) ion

1968 ◽  
Vol 21 (12) ◽  
pp. 2913 ◽  
Author(s):  
NP Singh ◽  
VN Singh ◽  
MP Singh
Keyword(s):  
Benzoic Acid ◽  
Oxidation Product ◽  
Osmium Tetroxide ◽  
Reaction Rate ◽  
Zero Order ◽  
Ion Concentration ◽  
First Order ◽  
First Order Kinetics ◽  
Catalysed Oxidation ◽  
Hydroxyl Ion

The osmium-tetroxide-catalysed oxidation of mandelate ion by hexacyanoferrate(111) ion has been studied kinetically. The reaction rate has been found to be independent of hexacyanoferrate(111) ion while the order with respect to both osmium tetroxide and mandelate ion comes out to be unity. The reaction rate follows first-order kinetics at low hydroxyl ion concentration and becomes zero order at higher concentrations. The course of the reaction has been considered to proceed through the formation of an activated mandelate-OsO4, complex which decomposes in alkaline medium giving reduced osmium(V1) followed by a fast oxidation by hexacyanoferrate(111) ion. The probable course of the reactions is also described with the help of its oxidation product, benzoic acid.

Mechanism of Hg(II) Oxidation of D-Galactose in Alkaline Medium

1978 ◽  
Vol 33 (6) ◽  
pp. 657-659 ◽  
Author(s):  
M. P. Singh ◽  
A. K. Singh ◽  
Mandhir Kumar
Keyword(s):  
Alkaline Medium ◽  
Reaction Rate ◽  
Reducing Sugar ◽  
Zero Order ◽  
Ion Concentration ◽  
Kinetics Of Oxidation ◽  
Ion Concentrations ◽  
First Order ◽  
Kinetics Of ◽  
Direct Proportionality

Abstract The present paper deals with the kinetics of oxidation of D-galactose by Nessler's reagent in alkaline medium. The reaction is zero order with respect to Hg(II) and first order with respect to reducing sugar. The direct proportionality of the reaction rate at low hydroxide ion concentrations shows retarding trend at higher concentrations. The reaction rate is inversely proportional to iodide ion concentration. A mechanism has been proposed taking HgI3- as the reacting species

Ironcyclopentadienyl mediated 2-alkyl-2-arylphenylsulphonylacetonitrile synthesis

1995 ◽  
Vol 73 (2) ◽  
pp. 289-295 ◽  
Author(s):  
Alaa S. Abd-El-Aziz ◽  
Christine R. de Denus ◽  
Harold M. Hutton
Keyword(s):  
Nucleophilic Substitution ◽  
Room Temperature ◽  
Nucleophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Efficient Route ◽  
Cyclopentadienyliron Complexes ◽  
Formation Of Complexes

A unique route to the synthesis of 2-alkyl-2-arylphenylsulphonylacetonitriles via the nucleophilic aromatic substitution (SNAr) of chloroarene cyclopentadienyliron complexes with 2-alkyl phenylsulphonylacetonitriles has been investigated. Reactions of chloroarene complexes (1a–d) with 2-alkyl phenylsulphonylacetonitrile (2a,b) in the presence of K2CO3 in DMF at room temperature led to the formation of complexes 3a–d and 4a,c,d in good yields. The use of alkylated phenylsulphonylacetonitriles as nucleophiles in the reactions with the p-dichlorobenzene complex (1e) allowed the formation of the disubstituted complexes (5,6). Photolytic demetallation provided an efficient route to the liberation of the arylated phenylsulphonylacetonitriles 7a–d, 8a,c,d, 9, and 10. Keywords: chloroarene, phenylsulphonylacetonitrile, nucleophilic substitution.

scholarly journals Utilizing the σ-complex stability for quantifying reactivity in nucleophilic substitution of aromatic fluorides

2013 ◽  
Vol 9 ◽  
pp. 791-799 ◽  
Author(s):  
Magnus Liljenberg ◽  
Tore Brinck ◽  
Tobias Rein ◽  
Mats Svensson
Keyword(s):  
Nucleophilic Substitution ◽  
Density Functional ◽  
Reaction Rates ◽  
Nucleophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Functional Theory ◽  
Aromatic Substrates ◽  
Complex Approach ◽  
Mechanistic Analysis ◽  
Rate Limiting

A computational approach using density functional theory to compute the energies of the possible σ-complex reaction intermediates, the “σ-complex approach”, has been shown to be very useful in predicting regioselectivity, in electrophilic as well as nucleophilic aromatic substitution. In this article we give a short overview of the background for these investigations and the general requirements for predictive reactivity models for the pharmaceutical industry. We also present new results regarding the reaction rates and regioselectivities in nucleophilic substitution of fluorinated aromatics. They were rationalized by investigating linear correlations between experimental rate constants (k) from the literature with a theoretical quantity, which we call the sigma stability (SS). The SS is the energy change associated with formation of the intermediate σ-complex by attachment of the nucleophile to the aromatic ring. The correlations, which include both neutral (NH3) and anionic (MeO−) nucleophiles are quite satisfactory (r = 0.93 to r = 0.99), and SS is thus useful for quantifying both global (substrate) and local (positional) reactivity in SNAr reactions of fluorinated aromatic substrates. A mechanistic analysis shows that the geometric structure of the σ-complex resembles the rate-limiting transition state and that this provides a rationale for the observed correlations between the SS and the reaction rate.

Methylsulfone as a leaving group for synthesis of hyperbranched poly(arylene pyrimidine ether)s by nucleophilic aromatic substitution

RSC Advances ◽  
2015 ◽  
Vol 5 (17) ◽  
pp. 12821-12823 ◽  
Author(s):  
Yue Guan ◽  
Chunbo Wang ◽  
Daming Wang ◽  
Guodong Dang ◽  
Chunhai Chen ◽  
...  
Keyword(s):  
Nucleophilic Substitution ◽  
Nucleophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Hyperbranched Poly ◽  
Leaving Group

Using a novel leaving group, methylsulfone activated by pyrimidine, 4,6-dichloro-2-(methylsulfonyl)pyrimidine was used to synthesize two new hyperbranched poly(arylene pyrimidine ether)s with diphenol via a nucleophilic substitution polymerization.

scholarly journals Experiments on the removal of chromium (VI) from its aqueous solution in batch reactors

2018 ◽  
Vol 1 (1) ◽  
pp. 12-18
Author(s):  
P Mullai Mullai ◽  
◽  
S. Kothai Nayaki ◽  
R. Nirmala Nirmala ◽  
◽  
...  
Keyword(s):  
Activated Carbon ◽  
Kinetic Data ◽  
Metal Ion ◽  
Batch Reactor ◽  
Ion Concentration ◽  
Batch Reactors ◽  
Adsorption Models ◽  
Ion Concentrations ◽  
First Order ◽  
Chromium Vi

The adsorption of chromium (VI) onto activated carbon experimented in a batch reactor under two different conditions, namely, initial metal ion concentration and adsorbent dosages. For the five different initial metal ion concentrations such as 500, 600, 800, 900, 1000 mg/L, the steady-state values of chromium removal efficiency were 64, 92, 83, 71 and 66 %, respectively, using 5 grams of activated carbon under shaking at the end of 8th hour. The equilibrium of the process was found to fit into the two well-known adsorption models, Freundlich and Langmuir. It was also observed that the experimental kinetic data followed the first order rate expression.

scholarly journals Oxidation of Mandelic Acid by Os(VIII)

1978 ◽  
Vol 33 (3) ◽  
pp. 291-292 ◽  
Author(s):  
B. L. Chandwani ◽  
G. D. Menghani
Keyword(s):  
Mandelic Acid ◽  
Activation Parameters ◽  
Zero Order ◽  
Ion Concentration ◽  
Order Dependence ◽  
Hydroxyl Ion ◽  
Different Temperatures

Abstract Mandelic Acid, Osmium(VIII) In the reaction between mandelic acid and Os(VTII), the rate of Os(VIII) disappearance was found to be proportional to the concentration of mandelate ion and Os(VIII). At low and high hydroxyl ion concentration the rate shows second and zero order dependence respectively. The reaction was studied at different temperatures and various activation parameters ⊿E, PZ, ⊿S* etc. were evaluated.

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