scholarly journals Photochemical rearrangements of substituted thiochromanone sulfoxides

1976 ◽  
Vol 54 (3) ◽  
pp. 455-470 ◽  
Author(s):  
I. W. J. Still ◽  
P. C. Arora ◽  
M. S. Chauhan ◽  
M.-H. Kwan ◽  
M. T. Thomas
Keyword(s):  
Reaction Mechanisms ◽  
Hydrogen Abstraction ◽  
Structural Variations ◽  
Photochemical Behavior ◽  
Photochemical Rearrangements ◽  
Derivatives Of

The photochemical behavior of a number of substituted derivatives of thiochroman-4-one 1-oxide has been examined. In contrast to the analogous sulfones these sulfoxides undergo a variety of photochemical rearrangements. At least three distinct pathways have been recognized; β-hydrogen abstraction or rearrangement to cyclic sulfenates, which then undergo further reaction by homolysis of the S—O bond, appearing to be particularly favorable processes. In a small number of examples, photochemical deoxygenation is observed as a competing reaction. Mechanisms which attempt to account for the influence of structural variations on the particular pathway followed have been proposed.

Radiotracer Studies of Carbon Black Surface Interactions with Organic Systems. I. Experimental Approach and Initial Results from Chemisorption and Vinyl Polymerization Studies

1968 ◽  
Vol 41 (2) ◽  
pp. 382-399 ◽  
Author(s):  
Marvin L. Deviney ◽  
Lawrence E. Whittington
Keyword(s):  
Carbon Black ◽  
Functional Groups ◽  
Reaction Mechanisms ◽  
Hydrogen Abstraction ◽  
Surface Interactions ◽  
Carbon Surface ◽  
Organic Systems ◽  
Carbon Black Surface ◽  
Basic Reaction ◽  
Black Surface

Abstract Radiotracer techniques have been applied to the study of interactions of carbon black surface functional groups with two chosen organic systems. The basic reaction mechanisms demonstrated in this study may have implications in elastomer reinforcement. Direct radiochemical evidence supports the conclusions of Hallum and Drushel (based on less direct polarographic data) that surface quinonic groups exhibit hydrogen abstraction activity toward tertiary hydrogens in paraffinic hydrocarbons. Studies on the system carbon black and styrene using tritium radiotracer have provided direct evidence that phenolic hydrogens participate in the polymerization acceleration and graft polymer formation reaction and are transferred to the growing polystyrene chains as postulated by Donnet. Several methods have been developed for specifically labelling certain oxygenated functional groups on the carbon surface with tritium and for tritium labelling carbon black in aromatic hydrogen positions. The techniques developed in this work and the basic reaction mechanisms derived will permit this investigation to be extended into a radiochemical study of carbon black surface interactions with elastomer related systems of interest to the rubber industry.

Synthesis of Azidoaniline Derivatives of Oligonucleotides and Investigation of Their Photochemical Behavior

1996 ◽  
Vol 7 (3) ◽  
pp. 343-348 ◽  
Author(s):  
Tatyana S. Godovikova ◽  
Vera D. Knorre ◽  
Galiya A. Maksakova ◽  
Vladimir N. Sil'nikov
Keyword(s):  
Photochemical Behavior ◽  
Derivatives Of

Rubber Chemicals from Cyclic Amines. II Dithioamines and Sulfenamides as Accelerators and Curing Agents

1968 ◽  
Vol 41 (3) ◽  
pp. 721-735 ◽  
Author(s):  
Eiichi Morita ◽  
John J. D'Amico ◽  
Evan J. Young
Keyword(s):  
Thermal Analyses ◽  
Empirical Relation ◽  
Basic Structure ◽  
Cure Rate ◽  
Structural Variations ◽  
Cyclic Amine ◽  
Cure Characteristics ◽  
Cyclic Amines ◽  
Curing Agents ◽  
Derivatives Of

Abstract Dithioamines and sulfenamides derived from various cyclic amines were evaluated as accelerators and vulcanizing agents. Structural variations of these compounds are correlated with their scorch delaying properties, accelerating activity and vulcanization efficiency, employing the Mooney Viscometer and the Monsanto Oscillating Disk Rheometer. The relative cure characteristics differed with changes in the basic structure of the compounds, and with the size and type of the cyclic amine moiety. However, the piperidine derivatives consistently showed longer scorch delay and slower mean cure rate than the corresponding derivatives of pyrrolidine, hexamethylenimine or heptamethylenimine. In the case of the thiazolyl sulfenamides, the type of substitution in the thiazolyl group also influenced scorch delay. An empirical relation was observed between the effect of concentration of the thiazolyl sulfenamides on scorch delay and the results of differential thermal analyses of sulfenamide and sulfur blends.

THE REACTION OF 2,2-DIPHENYL-1-PICRYLHYDRAZYL WITH SECONDARY AMINES

1958 ◽  
Vol 36 (12) ◽  
pp. 1729-1734 ◽  
Author(s):  
J. E. Hazell ◽  
K. E. Russell
Keyword(s):  
Secondary Amine ◽  
Rate Constants ◽  
Reaction Mechanisms ◽  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Major Product ◽  
The Other ◽  
Secondary Amines ◽  
First Order ◽  
Kinetics Of

The reaction of DPPH (2,2-diphenyl-1-picrylhydrazyl) with N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine, diphenylamine, and methylaniline has been studied and has been shown to be primarily a hydrogen abstraction process. Two moles DPPH react with 1–1.15 moles secondary amine to give 1.7–1.8 moles 2,2-diphenyl-1-picrylhydrazine and further products.The reaction between DPPH and N-phenyl-1-naphthylamine is first order with respect to each reactant. The reaction of DPPH with the other amines is retarded by the major product 2,2-diphenyl-1-picrylhydrazine and the kinetics of the over-all reaction are complex. However second-order rate constants and activation energies have been obtained using initial rates of reaction. Possible reaction mechanisms are discussed.

Synthesis, Characterization, and Photochemical Behavior of {Ru(arene)}2+Derivatives of α-[PW11O39]7-:  An Organometallic Way to Ruthenium-Substituted Heteropolytungstates†

2005 ◽  
Vol 44 (8) ◽  
pp. 2826-2835 ◽  
Author(s):  
V. Artero ◽  
D. Laurencin ◽  
R. Villanneau ◽  
R. Thouvenot ◽  
P. Herson ◽  
...  
Keyword(s):  
Photochemical Behavior ◽  
Derivatives Of

scholarly journals Synthesis of 5-arylacetylene 1,2,4-oxadiazoles and their transformations under superelectrophilic activation conditions

2021 ◽  
Author(s):  
Andrey I Puzanov ◽  
Dmitry S Ryabukhin ◽  
Anna S Zalivatskaya ◽  
Dmitriy N Zakusilo ◽  
Darya S Mikson ◽  
...  
Keyword(s):  
Double Bond ◽  
Dft Calculations ◽  
Reaction Mechanisms ◽  
Room Temperature ◽  
Triflic Acid ◽  
Activation Conditions ◽  
First Time ◽  
Vinyl Triflates ◽  
Derivatives Of ◽  
Acetylene Derivatives

Acetylene derivatives of 1,2,4-oxadiazoles, 5-(2-arylethynyl)-3-aryl-1,2,4-oxadiazoles, have been obtained, for the first time, from 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles by their bromination at the carbon-carbon double bond followed by di-dehydrobromination with NaNH2 in liquid NH3.  Reaction of the acetylene 1,2,4-oxadiazoles with arenes in neat triflic acid TfOH (CF3SO3H) at room temperature for 1 h result in the formation of E-/Z-5-(2,2-diarylethenyl)-3-aryl-1,2,4-oxadiazoles as products of regioselective hydroarylation of the acetylene bond. Addition of TfOH to acetylene bond of these oxadiazoles gives rise quantitatively to E-/Z-vinyl triflates. Reaction cationic intermediates have been studied by DFT calculations. The reaction mechanisms have been discussed.

scholarly journals Radical Formation in Sugar-Derived Acetals under Solvent-Free Conditions

Molecules ◽  
2021 ◽  
Vol 26 (19) ◽  
pp. 5897
Author(s):  
Aleksandra A. Wróblewska ◽  
H. Y. Vincent Ching ◽  
Jurrie Noordijk ◽  
Stefaan M. A. De Wildeman ◽  
Katrien V. Bernaerts
Keyword(s):  
Hydrogen Abstraction ◽  
Solvent Free ◽  
Paramagnetic Resonance ◽  
Cyclic Acetals ◽  
Radical Degradation ◽  
Solvent Free Conditions ◽  
Amide Exchange ◽  
Methylene Unit ◽  
Electron Paramagnetic ◽  
Derivatives Of

The degradation of acetal derivatives of the diethylester of galactarate (GalX) was investigated by electron paramagnetic resonance (EPR) spectroscopy in the context of solvent-free, high-temperature reactions like polycondensations. It was demonstrated that less substituted cyclic acetals are prone to undergo radical degradation at higher temperatures as a result of hydrogen abstraction. The EPR observations were supported by the synthesis of GalX based polyamides via ester-amide exchange-type polycondensations in solvent-free conditions at high temperatures in the presence and in the absence of radical inhibitors. The radical degradation can be offset by the addition of a radical inhibitor. The radical is probably formed on the methylene unit between the oxygen atoms and subsequently undergoes a rearrangement.

Intramolecular Homolytic Displacement. XXIII. Selectivity in the Induced Decomposition of Ethyl t-Butylperoxymethylpropenoate by Radicals Formed From Methyl Propanoate and Derivatives

1995 ◽  
Vol 48 (2) ◽  
pp. 233 ◽  
Author(s):  
M Degueilcastaing ◽  
C Navarro ◽  
F Ramon ◽  
B Maillard
Keyword(s):  
Thermal Decomposition ◽  
Double Bond ◽  
Iodine Atom ◽  
Hydrogen Abstraction ◽  
Alkyl Iodide ◽  
Alkyl Radicals ◽  
Tributyltin Hydride ◽  
Induced Decomposition ◽  
Derivatives Of ◽  
Methyl Propanoate

Thermal decomposition of t-butyl peracetate in a solution of ethyl t- butylperoxymethylpropenoate in methyl propanoate led to the products of substitution of the three different hydrogens in the molecule of the methyl ester by the 2,3-epoxy-2-ethoxycarbonylpropyl group. An SHi reaction on the peroxide function, following the addition to the double bond, is responsible for the formation of these epoxides . Such a result is due to the low regioselectivity of the hydrogen abstraction from methyl propanoate by t- butoxyl radicals, and no improvement could be obtained by changing the relative ratios of the reactants, in converse to previous results described for similar reactions. Thus, selective creation of alkyl radicals was developed through the generation of tributylstannyl radicals as mediator radicals, by reaction of t- butoxyl radicals on tributyltin hydride or hexabutylditin ; the mediator radicals abstract an iodine atom from the alkyl iodide. Application of this methodology to the three iodo derivatives of methyl propanoate permitted us to obtain selectively each of the three epoxides.

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