The SN Mechanism in aromatic compounds. 25. Substituent effects of multiple-bond nitrogen.

1958 ◽  
Vol 11 (3) ◽  
pp. 302 ◽  
Author(s):  
J Miller ◽  
AJ Parker
Keyword(s):  
Double Bond ◽  
Nitrogen Atom ◽  
Nucleophilic Substitution ◽  
Benzene Ring ◽  
Aromatic Compounds ◽  
Halogen Atom ◽  
Multiple Bond ◽  
Substituent Effects ◽  
Aromatic Nucleophilic Substitution ◽  
Substituent Constants

The substituent effects in aromatic nucleophilic substitution of groups attached to the benzene ring by a multiple-bond nitrogen atom are considered. Attachment is para to a replaceable halogen atom, and generally as a 4-substituent to l-chloro-2-nitrobenzene. Comparisons with some other groups are shown. Reasons are given for the greater T effect of a triple than of a double bond. Hammett substituent constants (σ*) are computed. Those for the nitroso and diazonium groups .are the largest so far obtained for electrically neutral and cationic groups respectively. The activating power of four of the nitrogen groups in electrophilic as well as nucleophilic substitution is discussed briefly.

Infrared spectra of aqueous sodium benzoates and salicylates in the carboxyl-stretching region: chelation in aqueous sodium salicylates

1969 ◽  
Vol 47 (24) ◽  
pp. 4577-4588 ◽  
Author(s):  
G. E. Dunn ◽  
R. S. McDonald
Keyword(s):  
Salicylic Acid ◽  
Carbon Tetrachloride ◽  
Infrared Spectra ◽  
Aromatic Compounds ◽  
Deuterium Oxide ◽  
Substituent Effects ◽  
Good Evidence ◽  
Frequency Region ◽  
Aqueous Sodium ◽  
Substituent Constants

Infrared spectra in the frequency region 1300–1760 cm−1 are reported for 41 substituted sodium benzoates and 10 substituted sodium salicylates in deuterium oxide solution, and for 9 substituted salicylic acids in chloroform and carbon tetrachloride solutions. Carboxylate stretching frequencies of benzoates and salicylates correlate poorly with substituent constants, but the asymmetric frequencies of benzoates and salicylates correlate well with each other, and the asymmetric frequencies of benzoates correlate well with the asymmetric frequencies of the corresponding nitrobenzenes. It is suggested that, among substituted aromatic compounds, group vibrations which couple with the ring vibrations may correlate well with similar vibrations of other groups, but not with coupled vibrations of different symmetry, uncoupled vibrations, or substituent constants. Chelation in chloroform solutions of salicylic acid dimers can be detected by its influence on substituent effects, but infrared spectra provide no good evidence for chelation in aqueous sodium salicylates.

scholarly journals Microbial Transformation of Some Natural and Synthetic Aromatic Compounds by Fungi: Aspergillus and Neurospora Strains

2017 ◽  
Vol 12 (8) ◽  
pp. 1934578X1701200 ◽  
Author(s):  
Nurunajah Ab Ghani ◽  
Nor Hadiani Ismail ◽  
Yoshiaki Noma ◽  
Yoshinori Asakawa
Keyword(s):  
Double Bond ◽  
Aspergillus Niger ◽  
Neurospora Crassa ◽  
Benzene Ring ◽  
Aromatic Compounds ◽  
Microbial Transformation ◽  
The Other ◽  
Aspergillus Species ◽  
Naturally Occurring ◽  
Direct Hydroxylation

Microbial transformation of chalcone (1), 4-hydroxychalcone (2) and 4′-hydroxychalcone (3), 1,1-diphenylmethane (4), 1,3-diphenylacetone (5), 1,3-diphenylpropane (6), bibenzyl (7), ( E)-stilbene (8a)- and ( Z)-stilbenes (8b), and phenylcyclohexane (9), (1 R,2 S)-1-phenyl-2-hydroxycyclohexane (9a) and (1 S,2 R)-1-phenyl-2-hydroxycyclohexane (9b), and a naturally occurring bis-bibenzyl, marchantin A (10) were performed by using Aspergillus niger TBUYN-2 and the other Aspergillus strains, and Neurospora crassa which were capable to hydrogenation and epoxidation of a conjugated double bond, and direct hydroxylation and hydroperoxidation on benzene ring, and hydroxylation and carbonization on cyclohexane ring. Aspergillus species converted chalcone (1) to dihydrochalcone (1a) almost quantitatively.

Electrophilic and nucleophilic substitution in the Benzene ring and the Hammett Equation

1956 ◽  
Vol 9 (1) ◽  
pp. 61 ◽  
Author(s):  
J Miller
Keyword(s):  
Large Deviations ◽  
Nucleophilic Substitution ◽  
Benzene Ring ◽  
Electrophilic Substitution ◽  
Substituent Effects ◽  
Hammett Equation ◽  
Wide Range ◽  
Good Agreement

The Hammett equation as applied to aromatic nuclear electrophilic and nucleophilic substitution is tested for a wide range of substituents. For nucleophilic substitution quite good agreement is obtained for electron-attracting substituents using σ* values, but large deviations occur with substituents releasing electrons by the conjugative mechanism. In electrophilic substitution, in so far as results are available, a fair measure of agreement obtains for electron-attracting substituents, but very large and to some extent irregular deviations occur for the conjugative electron- releasing substituents. The deviations occur whether σ or σ* values are used, and new sets of σN** and σE** values are defined and the values recorded. A comparison is made of substituent effects in nuclear electrophilic and nucleophilic substitution.

The Sn Mechanism in aromatic compounds. XXIII. Substituent groups attached by saturated sulphur

1958 ◽  
Vol 11 (3) ◽  
pp. 290 ◽  
Author(s):  
NJ Daly ◽  
G Kruger ◽  
J Miller
Keyword(s):  
Nucleophilic Substitution ◽  
Strong Evidence ◽  
Aromatic Compounds ◽  
Aromatic Nucleophilic Substitution

The activating power of p-SMe and p-SMe2+ in aromatic nucleophilic substitution has been compared with available data for ?NH2, -NMe3+, and OMe. The ?Sme2+; group is very powerfully activating and there is strong evidence for a -T effect of ?Sme2+ but not of -SMe, involving expansion of the valency shell beyond an octet. The -SMe group, like -Cl, -Br, and -I, is however also activating, whereas ?NH2, -OMe, and -F are more or less deactivating.

Reductive Dehalogenation of Environmental Contaminants: A Critical Review

1989 ◽  
Vol 24 (2) ◽  
pp. 299-322 ◽  
Author(s):  
R. M. Baxter
Keyword(s):  
Hydrogen Atom ◽  
Aromatic Compounds ◽  
Reductive Dechlorination ◽  
Halogen Atom ◽  
Environmental Contaminants ◽  
Methanogenic Bacteria ◽  
Photochemical Reactions ◽  
Reductive Dehalogenation ◽  
Iron Porphyrins ◽  
Aliphatic Compounds

Abstract It is generally recognized that reductive processes are more important than oxidative ones in transforming, degrading and mineralizing many environmental contaminants. One process of particular importance is reductive dehalogenation, i.e., the replacement of a halogen atom (most commonly a chlorine atom) by a hydrogen atom. A number of different mechanisms are involved in these reactions. Photochemical reactions probably play a role in some instances. Aliphatic compounds such as chloroethanes, partly aliphatic compounds such as DDT, and alicyclic compounds such as hexachlorocyclohexane are readily dechlorinated in the laboratory by reaction with reduced iron porphyrins such as hematin. Many of these are also dechlorinated by cultures of certain microorganisms, probably by the same mechanism. Such compounds, with a few exceptions, have been found to undergo reductive dechlorination in the environment. Aromatic compounds such as halobenzenes, halophenols and halobenzoic acids appear not to react with reduced iron porphyrins. Some of these however undergo reductive dechlorination both in the environment and in the laboratory. The reaction is generally associated with methanogenic bacteria. There is evidence for the existence of a number of different dechlorinating enzymes specific for different isomers. Recently it has been found that many components of polychlorinated biphenyls (PCBs), long considered to be virtually totally resistant to environmental degradation, may be reductively dechlorinated both in the laboratory and in nature. These findings suggest that many environmental contaminants may prove to be less persistent than was previously feared.

Substituent effects in 1,3-indanediones

1982 ◽  
Vol 47 (5) ◽  
pp. 1486-1493 ◽  
Author(s):  
Alexander Perjéssy
Keyword(s):  
Substituent Effects ◽  
Empirical Equations ◽  
Substituent Constants ◽  
Complex Structural

The carbonyl stretching frequencies correlate well with substituent constants in a series of 166 1,3-indanediones using improved and extended Seth-Paul-Van Duyse equation. Transmissive factors and group electronegativities have been used to find empirical equations for calculation of substituent constants of more complex structural fragments.

Gradient-Enhanced Inverse-Detected NMR Techniquesfor Determination of 1H-15N Coupling Constants in 2,2-Dimethylpenta-3,4-dienal Derivatives

1997 ◽  
Vol 62 (11) ◽  
pp. 1747-1753 ◽  
Author(s):  
Radek Marek
Keyword(s):  
Double Bond ◽  
Chemical Shifts ◽  
Multiple Bond ◽  
Coupling Constants ◽  
Single Quantum ◽  
Nmr Techniques ◽  
Phase Sensitive ◽  
Heteronuclear Coupling

Determination of 15N chemical shifts and heteronuclear coupling constants of substituted 2,2-dimethylpenta-3,4-dienal hydrazones is presented. The chemical shifts were determined by gradient-enhanced inverse-detected NMR techniques and 1H-15N coupling constants were extracted from phase-sensitive gradient-enhanced single-quantum multiple bond correlation experiments. Stereospecific behaviour of the coupling constants 2J(1H,15N) and 1J(1H,13C) has been used to determine the configuration on a C=N double bond. The above-mentioned compounds exist predominantly as E isomers in deuteriochloroform.

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