Oxidative cyclizations. I. The mechanism of the oxidation of ortho-substituted anilines with phenyliodoso acetate

1967 ◽  
Vol 20 (8) ◽  
pp. 1625 ◽  
Author(s):  
LK Dyall ◽  
JE Kemp
Keyword(s):  
Free Radical ◽  
Cyclic Oxidation ◽  
Reaction Path ◽  
Heterocyclic Ring ◽  
Azo Compounds ◽  
Substituted Anilines ◽  
Aryl Azides ◽  
Oxidative Cyclizations ◽  
Amine Oxidation ◽  
Ortho Substituent

A comparison has been made of the types of ortho substituents which can be incorporated into a new heterocyclic ring by pyrolysis of aryl azides or during oxidation of anilines with phenyliodoso acetate. The results enable a new mechanism to be proposed for the amine oxidation. In its key step, the ortho substituent displaces iodobenzene from an intermediate iodoso ester to form the cyclic oxidation product. A competing reaction path involves homolysis of this iodoso ester to yield the free-radical precursors of azo compounds.

Oxidative cyclizations. VII. Cyclization of 2-substituted anilines with alkaline hypohalite

1984 ◽  
Vol 37 (10) ◽  
pp. 2013 ◽  
Author(s):  
LK Dyall
Keyword(s):  
Oxidative Cyclization ◽  
Azo Compounds ◽  
Substituted Anilines ◽  
Oxidative Cyclizations ◽  
Visible Spectra ◽  
Transient Intermediates ◽  
Ortho Substituent

The Green-Rowe oxidation of 2-nitroanilines with alkaline hypochlorite, to yield benzofuroxans, is demonstrated by studies of the visible spectra of transient intermediates to proceed through N-chlorination and a singlet nitrene. Two variations on the route to the nitrene are possible. The cyclization step is represented as an internal capture of the nitrene by the ortho substituent, and on this basis the Green-Rowe oxidative cyclization is now extended to anilines whose ortho substituent is benzoyl or phenylazo. It is not however successful for ortho phenyl. Azo compounds were observed as byproducts in some of these reactions, and are shown to arise via N,N-dichloroanilines.

scholarly journals New Method for Determination of Free-Radical Production Efficiency of Organic Peroxides and Azo Compounds

1997 ◽  
Vol 29 (9) ◽  
pp. 733-736 ◽  
Author(s):  
Yasumasa Watanabe ◽  
Hideyo Ishigaki ◽  
Hiroshi Okada ◽  
Shuji Suyama
Keyword(s):  
Free Radical ◽  
Production Efficiency ◽  
New Method ◽  
Azo Compounds ◽  
Organic Peroxides ◽  
Free Radical Production ◽  
Radical Production

Oxidative Cyclizations. V. The Oxidation of ortho-Substituted Benzenamines with Lead(IV) Tetraacetate

1979 ◽  
Vol 32 (3) ◽  
pp. 643 ◽  
Author(s):  
LK Dyall
Keyword(s):  
Experimental Evidence ◽  
Base Pair ◽  
Reactive Intermediates ◽  
Oxidative Cyclization ◽  
Azo Compounds ◽  
Acid Base ◽  
Oxidative Cyclizations ◽  
Conjugate Acid

Lead(IV) tetraacetate has been used to oxidize 1-aminoanthraquinone, 1-arylazonaphthalen-2-amines and benzenamines whose ortho-substitutents were arylazo, nitro, or benzopl. Only the amines with ortho-arylazo substituents underwent oxidative cyclization, to yield triazoles; the others yielded azo compounds and polymers. Experimental evidence shows that neither nitrenes nor arenamino ('anilenium') cations can be the reactive intermediates in some of these reactions. All the results can be rationalized in terms of the conjugate acid-base pair of intermediates, arenamine cation ArNH2+' and arenamino ArNH.

Aromatic amides. V. Intramolecular hydrogen bonding in ortho-substituted anilides

1970 ◽  
Vol 23 (8) ◽  
pp. 1667 ◽  
Author(s):  
JM Appleton ◽  
BD Andrews ◽  
ID Rae ◽  
BE Reichert
Keyword(s):  
Hydrogen Bonding ◽  
Molecular Geometry ◽  
Intramolecular Hydrogen Bonding ◽  
Amide Group ◽  
Amide Proton ◽  
Substituted Anilines ◽  
Real Value ◽  
Intramolecular Hydrogen ◽  
Acyl Derivatives ◽  
Ortho Substituent

The proton magnetic resonance spectra of deuterochloroform solutions of a number of ortho-substituted anilines and their S-acyl derivatives have been measured. Variations in the acylation shifts of the ring protons are explained in terms of intramolecular hydrogen bonding between the amide proton and the ortho-substituent. Calculations of the contribution made to the acylation shifts by the anisotropy of the amide group were found to be too sensitive to the molecular geometry to be of any real value. Acylation shifts for a series of 4'-substituted 2'-nitroacetanilides correlate well with the σp values of the 4'-substituents.

Oxidative cyclizations. III. Kinetic studies of the oxidation of 2,4-dinitroaniline and 2-benzoylaniline with (diacetoxyiodo)benzene

1973 ◽  
Vol 26 (9) ◽  
pp. 1969 ◽  
Author(s):  
LK Dyall ◽  
JE Kemp
Keyword(s):  
Acetic Acid ◽  
Equilibrium Constants ◽  
Kinetic Studies ◽  
Reaction Rates ◽  
Oxidative Cyclization ◽  
Toluene Solution ◽  
Common Mechanism ◽  
Substituted Anilines ◽  
Oxidative Cyclizations ◽  
Cyclic Product

For the oxidative cyclization of 2,4-dinitroaniline and 2- benzoylaniline with (diacetoxyiodo)benzene in toluene solution, the kinetic orders are unity in amine and oxidant, zero in iodobenzene and cyclic product, and -1 in monomeric acetic acid. These characteristic orders are also those observed for 2-nitroaniline and, together with evidence for a specific solvation effect by acetic acid on the reaction rates of all three amines, indicate that a common mechanism of oxidative cyclization applies to a range of ortho-substituted anilines. For 2-benzoylaniline, there is infrared evidence of an N-H bond in an iodoso intermediate. ��� Equilibrium constants for the monomer ↔ dimer equilibrium of acetic acid in toluene solution have been determined at four temperatures between 25� and 46�.

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