Neighbouring group participation of thiol through aldehyde group assisted thiolysis of active ether: ratiometric and vapor phase fast detection of hydrogen sulfide in mixed aqueous media

2015 ◽  
Vol 39 (7) ◽  
pp. 5669-5675 ◽  
Author(s):  
Avijit Kumar Das ◽  
Shyamaprosad Goswami ◽  
Ching Kheng Quah ◽  
Hoong-Kun Fun
Keyword(s):  
Hydrogen Sulfide ◽  
Vapor Phase ◽  
Aqueous Media ◽  
Aldehyde Group ◽  
Nucleophilic Attack ◽  
Ether Linkage ◽  
Fast Detection ◽  
Group Participation ◽  
Neighbouring Group Participation

Ratiometric and fast detection of H2S via NGP of thiol rather than direct nucleophilic attack to cleave active ether linkage.

Studies on the condensation of lignins in alkaline media. Part II. The formation of stilbene and arylcoumaran structures through neighbouring group participation reactions

1977 ◽  
Vol 55 (4) ◽  
pp. 593-599 ◽  
Author(s):  
Josef Gierer ◽  
Ingegerd Pettersson
Keyword(s):  
Phenolic Compounds ◽  
Alkaline Media ◽  
Aryl Ether ◽  
Model Compounds ◽  
Ether Linkage ◽  
Group Participation ◽  
Condensation Products ◽  
Neighbouring Group Participation ◽  
Alkaline Delignification ◽  
Aryl Participation

The alkaline condensation of p-hydroxyarylglycerol-β-aryl ether units in lignin with other phenolic structures and the subsequent reactions of the condensation products have been elucidated using appropriate model compounds. It is shown that the primary condensation of simple phenols (2,6-xylenol or resorcinol) into the α-position of phenolic compounds of the β-aryl ether type is followed by an aryl participation (A1-3) reaction resulting in the cleavage of the β-aryl ether bond and formation of the corresponding stilbene derivative. When resorcinol is used as reaction partner, the condensation is also followed by the cleavage of the β-aryl ether linkage through another type of neighbouring group participation reaction involving the phenolate anion ortho to the site of condensation and giving rise to the corresponding aryl-coumaran derivative.The consequences of these findings for the course of alkaline delignification processes are briefly discussed.

scholarly journals Neighbouring Group Participation in the Methanolysis of a Vicinal Diepoxide

1999 ◽  
Vol 23 (6) ◽  
pp. 356-357
Author(s):  
James R. Hanson ◽  
Peter B. Hitchcock ◽  
Ismail Kiran
Keyword(s):  
Hydroxy Group ◽  
Group Participation ◽  
Neighbouring Group Participation

The tetracyanoethylene catalysed methanolysis of 17β-acetoxy-4β,5β:6α,7α-diepoxyandrostane afforded 17β-acetoxy-4α,7α-oxido-5β-hydroxy-6β-methoxyandrostane in which the methanolysis product of the 6α,7α-epoxide has participated in the cleavage of the 4β,5β-epoxide; the reaction is modified however by an adjacent 3β-hydroxy group.

Nucleophilic Attack on Some Isothiazolium Salts

1973 ◽  
Vol 51 (18) ◽  
pp. 3081-3086 ◽  
Author(s):  
David M. Mckinnon ◽  
Mohamed E. Hassan
Keyword(s):  
Hydrogen Sulfide ◽  
Sulfur Atom ◽  
Nucleophilic Attack ◽  
Isothiazolium Salts

A variety of isothiazolium salts has been prepared and allowed to react with sodium benzoylacetate. 2-Benzoylthiophenes are obtained, suggesting that the position of initial nucleophilic attack is at the sulfur atom of the heterocyclic cation. Reaction with hydrogen sulfide gave acyclic reduction products, or 1,2-dithiole derivatives, depending on the type of substituent on nitrogen in the isothiazolium salts.

Tetrachlorodibenzo-p-Dioxin Isomer Differentiation by Capillary Gas Chromatography Fourier Transform-Infrared Spectroscopy

1987 ◽  
Vol 41 (5) ◽  
pp. 809-820 ◽  
Author(s):  
James Grainger ◽  
Leslie T. Gelbaum
Keyword(s):  
Gas Chromatography ◽  
Fourier Transform ◽  
Vapor Phase ◽  
Valence Bond ◽  
Fourier Transform Infrared ◽  
Molecular Geometry ◽  
Ether Linkage ◽  
Relative Electron ◽  
Ft Ir ◽  
Infrared Frequencies

Reference infrared vapor-phase spectra of the 22 tetrachlorodibenzo-dioxin (TCDD) isomers were recorded at low microgram concentrations. These reference spectra of synthetic mixture components separated chromatographically or by spectral subtraction exhibit distinct infrared spectra for each isomer. The infrared frequencies are delineated in correlation tables and are interpreted in terms of substitution patterns which determine the strength of the ether linkage. Absorbance values in the 1330–1280 cm−1 (C-O-C asymmetric stretch) region correlate with specific substitution patterns and molecular geometry. Relative electron-withdrawing capacities for chlorinated aromatic rings in TCDD isomers were estimated on the basis of relative capacities determined for model compounds. Qualitative correlations were established between electron-withdrawing capacities and the effects of resonance and field interactions on the ether linkage absorption frequencies of individual TCDD isomers. Gas chromatography Fourier transform infrared (GC/FT-IR) isomer assignments are generally consistent with those obtained by proton Fourier transform nuclear magnetic resonance (1H FT/NMR) and flame ionization gas chromatography (GC/FID). A chromatographically independent method of assigning TCDD isomer structures on the basis of ether linkage asymmetric stretching frequencies was established by utilization of valence-bond approximations. GC/FT-IR assignments for several TCDD isomers differ from isomer assignments in previously published results. A user-generated, vapor-phase reference library, containing individual TCDD spectra and spectra of isomer pairs that are incompletely resolved on chromatographic columns, correctly identified each isomer in variety of mixtures by means of a software algorithm.

Pyrolysis of aryl azides. II. Naphthyl azides

1972 ◽  
Vol 25 (3) ◽  
pp. 599 ◽  
Author(s):  
G Boshev ◽  
LK Dyall ◽  
PR Sadler
Keyword(s):  
Nitro Group ◽  
Steric Effect ◽  
Kinetic Studies ◽  
Oxidative Cyclization ◽  
Nitrobenzene Solution ◽  
Aryl Azides ◽  
Phenyl Azide ◽  
Group Participation ◽  
Neighbouring Group Participation ◽  
Group Effects

Kinetic studies of the pyrolyses of 1- and 2-naphthyl azides reveal neighbouring group participation by nitro and phenylazo substituents. The acceleration observed in 1-nitro-2-naphthyl azide, 1-phenylazo-2-naphthyl azide, and 2-nitro-1-naphthyl azide is 1730-, 211-, and 23.6-fold, respectively, in nitrobenzene solution at 120�. These effects are all smaller than that of the 2-nitro group in phenyl azide (3370-fold), which is ascribed to the steric effect of the peri hydrogen at C8 in naphthyl azides. The sizes of these neighbouring group effects correlate with the success of oxidative cyclization of ortho-substituted naphthylamines with (diacetoxyiodo)benzene.

scholarly journals Neighbouring group participation in the unblocking of phosphotriesters of nucleic acids

1979 ◽  
Vol 6 (6) ◽  
pp. 2237-2259 ◽  
Author(s):  
J.F.M. de Rooij ◽  
G.Wille Hazeleger ◽  
P.M.J. Burgers ◽  
J.H. van Boom
Keyword(s):  
Nucleic Acids ◽  
Group Participation ◽  
Neighbouring Group Participation
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