Substituent effects in the reaction of aromatic amines and peroxydisulfate

1969 ◽  
Vol 47 (19) ◽  
pp. 3710-3713 ◽  
Author(s):  
N. Venkatasubramanian ◽  
A. Sabesan
Keyword(s):  
Nitrogen Atom ◽  
Carbon Atom ◽  
Aromatic Amines ◽  
Substituent Effects ◽  
Substituted Anilines ◽  
Electrophilic Attack ◽  
Effect Of Substituents ◽  
Hammett Constants ◽  
Kinetics Of ◽  
Electron Withdrawing Substituents

The kinetics of the reaction between aromatic amines and the peroxydisulfate ion in aqueous basic conditions have been investigated. The effect of substituents has been studied by employing about 25 ortho-, meta-, and para-substituted anilines. The reaction is accelerated by electron-releasing substituents and is retarded by electron-withdrawing substituents, pointing to an electrophilic attack by the S2O82− ion. A better correlation between rate and the Hammett constants is obtained for an electrophilic attack at the nitrogen atom of the amine rather than at the carbon atom of the amine. A good correlation also exists between the log k2 values and the pKb of the corresponding amines.

scholarly journals Rotational barrier and electron-withdrawing substituent effects: Theoretical study of -conjugation in para-substituted anilines

2020 ◽  
Vol 10 (4) ◽  
pp. 319-334
Author(s):  
Ali Hussain Yateem
Keyword(s):  
Density Functional ◽  
Amino Nitrogen ◽  
Substituent Effects ◽  
Lone Pair ◽  
Rotational Barrier ◽  
Substituted Anilines ◽  
Mechanical Approach ◽  
Resonance Stabilization ◽  
Quantum Mechanical Approach ◽  
Electron Withdrawing Substituents

The rotational barrier RB around C–NH2 bond between the minimum and maximum states of 84 electron-withdrawing groups at para-position in aniline were studied at the density functional wB97X-D/6-31G** level. The rotational barrier was found to correlate strongly with shortening of the C–NH2 bond, increase of flattening of NH2 group, decrease in negative natural charge on amino nitrogen, increase in minimum ionization potential around lone pair of amino nitrogen, increase in maximum (positive) electrostatic potential on amino hydrogens, increase in NH2 stretching frequencies, and increase in stabilization energy. The rotational barrier was also found to correlate well with empirical pKa and Hammett σp constants. The rotational barrier is shown to be a reliable quantum mechanical approach to measure p-conjugation in para-substituted anilines.  Based on RB a quantitative scale is constructed for the ability of electron-withdrawing substituents to resonate with aniline. A quinone-like structure has been proposed for stronger electron-withdrawing substituents where an extension of resonance stabilization requires the simultaneous presence of electron donor (NH2) and electron-withdrawing groups.

Substituent Effects on the Acidity of Weak Acids. 4. Anilinium Ions

2004 ◽  
Vol 69 (12) ◽  
pp. 2183-2192 ◽  
Author(s):  
Kenneth B. Wiberg
Keyword(s):  
Experimental Studies ◽  
Substituent Effects ◽  
Proton Affinities ◽  
Substituted Anilines ◽  
Group Transfer ◽  
Effect Of Substituents ◽  
Gas Phase Acidity ◽  
Calculated Effect ◽  
Protonated Aniline ◽  
Good Agreement

The gas phase acidity of anilinium ions has been calculated at a number of theoretical levels from B3LYP/6-311++G** to MP2 and CCSD/6-311++G(2dp,2pd). The highest level calculations find anilinium ion and p-protonated aniline to have essentially the same energy, in agreement with experimental studies. They also give a proton affinity for aniline that is in very good agreement with the experimental value. The B3LYP and MP2 calculations are less successful, with B3LYP favoring p-protonation and MP2 favoring N-protonation for aniline. Despite this difficulty, the calculated effect of substituents on the proton affinities of p-substituted anilines that undergo N-protonation agreed well with the experimental data. The effect of substituents on the anilinium ions and on the anilines were examined separately using a series of group transfer reaction.

Properties of electrochemically generated primary anion radicals of 2,5-dimethyl-1-nitrophenylpyrroles

1981 ◽  
Vol 46 (10) ◽  
pp. 2494-2502 ◽  
Author(s):  
Pavel Kubáček
Keyword(s):  
Nitrogen Atom ◽  
Carbon Atom ◽  
Anion Radical ◽  
Platinum Electrode ◽  
Spin Population ◽  
Kinetics Of Decomposition ◽  
Primary Anion ◽  
Stable Anion ◽  
Kinetics Of ◽  
Anion Radicals

The first step of electrochemical reduction of 2,5-dimethyl-1-nitrophenylpyrroles on a platinum electrode in anhydrous acetonitrile consists in an one-electron process producing relatively stable anion radicals. The prediction based on HMO calculations concerning an almost complete localization of the LFMO in the nitrophenyl part of the studied molecules is fully confirmed by means of EPR spectroscopy. Magnitude of the found proton splitting constants is very close to the values found for anion radical of nitrobenzene. The splitting by nucleus of nitrogen atom of pyrrole cycle can be explained exclusively by the mechanism of π-σ spin polarization of σ C-N bond and by the spin population at the carbon atom. The EPR method has also been used for following the kinetics of decomposition of anion radicals of the molecules studied.

Analysis of Aromatic Amines in Industrial Wastewater by Capillary Gas Chromatography-Mass Spectrometry

2000 ◽  
Vol 35 (2) ◽  
pp. 245-262 ◽  
Author(s):  
Francis I. Onuska ◽  
Ken A. Terry ◽  
R. James Maguire
Keyword(s):  
Gas Chromatography ◽  
Aromatic Amines ◽  
Methylene Chloride ◽  
Solid Phase ◽  
Stationary Phases ◽  
Gas Chromatography Mass Spectrometry ◽  
Substituted Anilines ◽  
Environmental Media ◽  
Solid Phase Extraction Cartridge ◽  
Wide Range

Abstract The analysis of aromatic amines, particularly benzidines, at trace levels in environmental media has been difficult because of the lack of suitable deactivated capillary column stationary phases for gas chromatography. This report describes the use of an improved type of column as well as a method for the analysis of anilines and benzidines in water, wastewater and sewage samples. Extraction procedures are applicable to a wide range of compounds that are effectively partitioned from an aqueous matrix into methylene chloride, or onto a solid-phase extraction cartridge. The extracted analytes are also amenable to separation on a capillary gas chromatographic column and transferable to the mass spectrometer. These contaminants are converted to their N-trifluoroacetyl derivatives. Aniline and some substituted anilines, and 3,3’-dichlorobenzidine and benzidine were determined in 24-h composite industrial water, wastewater, primary sludge and final effluent samples at concentrations from 0.03 up to 2760 µg/L.

Nucleophile/Electrophile Combinations in Aromatic Substitution: From Wheland to Wheland–Meisenheimer Intermediates Using Strongly Activated Arenes

Synthesis ◽  
2017 ◽  
Vol 49 (15) ◽  
pp. 3347-3356 ◽  
Author(s):  
Gabriele Micheletti ◽  
Carla Boga
Keyword(s):  
Nitrogen Atom ◽  
Carbon Atom ◽  
Short Review ◽  
Alkyl Halides ◽  
Aryl Halides ◽  
Aromatic Substitution ◽  
Aromatic Carbon ◽  
Isolation And Characterization ◽  
Acyl Halides

This short review provides an overview on the interaction between 1,3,5-triaminobenzene derivatives and different kinds of electrophiles. Due to the ambident reactivity of these nucleophiles (i.e., at the nitrogen atom of the substituents and at the aromatic carbon atom) different compounds can be obtained. Particular attention is devoted to the detection, isolation, and characterization of covalent intermediates of aromatic substitution, starting from Wheland intermediates until the first detection and characterization of Wheland–Meisenheimer intermediates.1 Introduction2 Reactions between 1,3,5-Triaminobenzene Derivatives and Charged Electrophiles2.1 The Proton as an Electrophile2.2 Arenediazonium Salts as Electrophiles3 Reactions between 1,3,5-Triaminobenzene Derivatives and Neutral­ Electrophiles3.1 Alkyl Halides as Electrophiles3.2 Acyl Halides and Sulfonyl Chlorides as Electrophiles3.3 Aryl Halides and Heteroaryl Halides as Electrophiles3.4 Polynitroheteroaromatics as Electrophiles4 Conclusion

Dative behavior of N-heterocyclic carbenes (NHCs) with selenium in Se-NHC compounds

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Munazzah Yaqoob ◽  
Mahvish Abbasi ◽  
Hira Anwar ◽  
Javed Iqbal ◽  
Mohammad Asad ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Carbon Atom ◽  
Lone Pair ◽  
Heterocyclic Ring ◽  
Heterocyclic Carbenes ◽  
The Other ◽  
Donor Ligands ◽  
Important Research ◽  
Dative Bond ◽  
Back Bonding

Abstract N-heterocyclic carbenes (NHCs) are an eminent class of carbenes having a heterocyclic ring in which a divalent carbon atom is attached directly to a nitrogen atom. In the NHCs, the donation of lone pair is another important research in the dative bonding and not only in NHCs the dative bond plays a functionalized role in the other classes of complex formation like ylidones L → E ← L and carbones L → C ← L. M–NHC bond is L-M sigma-dative bond and NHCs are considered as strong sigma-donor ligands. The clear picture of the M–NHC bond can be better understood by M–NHC pi-interaction. M-L pi interaction is comprised of two steps. One is L → M sigma-donation and M → L π* back bonding. This dative donor nature of NHC and also its behavior in organoselenium is studied through DFT in which it’s optimized structure, bond lengths, molecular vibrations are calculated.

Hydroboration of acyclic allenes with disiamylborane

1969 ◽  
Vol 47 (6) ◽  
pp. 1083-1086 ◽  
Author(s):  
D. S. Sethi ◽  
G. C. Joshi ◽  
D. Devaprabhakara
Keyword(s):  
Carbon Atom ◽  
Transition State ◽  
Steric Effects ◽  
Electrophilic Attack ◽  
Terminal Carbon Atom ◽  
Central Carbon Atom ◽  
Central Carbon

The present investigation demonstrates the hydroboration of 1,2-nonadiene, phenylpropadiene, 3-phenyl-1,2-butadiene, 4,5-nonadiene, and tetramethylallene with disiamylborane. All the allenes except tetramethylallene underwent 100% conversion. Examination of the products indicated preferential electrophilic attack of boron on the least substituted terminal carbon atom in the case of 1,2-nonadiene, phenylpropadiene, 3-phenyl-1,2-butadiene, and on the central carbon atom in 4,5-nonadiene. In tetramethylallene boron, attack was exclusively on the central carbon atom. These results have been explained in terms of steric effects on a four-centered transition state.

scholarly journals Structure–property Effects in the Generation of Transient Aqueous Benzoic Acid Anhydrides by Carbodiimide Fuels

2019 ◽  
Author(s):  
Lasith Kariyawasam ◽  
Julie Kron ◽  
Run Jiang ◽  
André Sommer ◽  
Scott Hartley
Keyword(s):  
Atp Hydrolysis ◽  
Substituent Effects ◽  
Coupled Processes ◽  
Dissipative Systems ◽  
Nonequilibrium Systems ◽  
Structure Property ◽  
Ethylcarbodiimide Hydrochloride ◽  
Kinetics Of Formation ◽  
Acid Anhydrides ◽  
Kinetics Of

<div>The design of dissipative systems, which operate out-of-equilibrium by consuming chemical fuels, is challenging. As yet, there are few examples of privileged fuel chemistry that can be broadly applied in abiotic systems in the same way that ATP hydrolysis is exploited throughout biochemistry. The key issue is that designing nonequilibrium systems is inherently about balancing the relative rates of coupled processes. The use of carbodiimides as fuels to generate transient aqueous carboxylic anhydrides has recently been used in examples of new nonequilibrium materials and supramolecular assemblies. Here, we explore the kinetics of formation and decomposition of a series of benzoic anhydrides generated from the corresponding acids and EDC under prototypical conditions (EDC = <i>N</i>-(3-dimethylaminopropyl)-<i>N</i>′-ethylcarbodiimide hydrochloride). The reactions can be described by a simple mechanism that merges known behavior for the two processes independently. Structure–property effects in these systems are dominated by differences in anhydride decomposition rate. The kinetic parameters allow trends in concentration-dependent properties to be simulated, such as reaction lifetimes, peak anhydride concentrations, and efficiencies (i.e., total anhydride produced per equivalent of carbodiimide). For key properties there are diminishing returns with the addition of increasing amounts of fuel. This is particularly significant for the lifetimes, where substituent effects exert a much greater influence than fuel quantity under typical conditions. These results should provide useful guidelines for the design of functional systems making use of this chemistry.</div><div><br></div>

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