Isotope effects in acid-catalyzed aromatic hydrogen exchange

1991 ◽  
Vol 4 (4) ◽  
pp. 233-241 ◽  
Author(s):  
Robin A. Cox
Keyword(s):  
Hydrogen Exchange ◽  
Isotope Effects ◽  
Acid Catalyzed ◽  
Aromatic Hydrogen

Secondary isotope effects and aromatic hydrogen exchange

1959 ◽  
Vol 1 (13) ◽  
pp. 20-23 ◽  
Author(s):  
A.J. Kresge ◽  
D.P.N. Satchell
Keyword(s):  
Hydrogen Exchange ◽  
Isotope Effects ◽  
Aromatic Hydrogen

Hydrogen exchange and isomerization in ortho substituted benzamides. On the question of free rotation in an N-protonated amide

1979 ◽  
Vol 57 (22) ◽  
pp. 2896-2901 ◽  
Author(s):  
Robert A. McClelland ◽  
William F. Reynolds
Keyword(s):  
Exchange Reaction ◽  
Rate Constants ◽  
Hydrogen Exchange ◽  
Isomerization Reaction ◽  
Free Rotation ◽  
Bond Rotation ◽  
Diffusion Limited ◽  
Deprotonation Reaction ◽  
Substituted Benzamides ◽  
Acid Catalyzed

Rate constants have been obtained for the acid-catalyzed N–H exchange of N-methyl, 2,N-dimethyl, and 2,4,6,N-tetramethylbenzamide and the acid-catalyzed isomerization of the three corresponding N,N-dimethylbenzamides. The ratio [Formula: see text] increases significantly with increased number of ortho methyl substituents. This is explained in terms of a suggestion of Perrin, that C—N bond rotation is not completely free in the N-protonated amide, since it must compete with a diffusion limited deprotonation reaction. The isomerization reaction, which requires such a rotation, is therefore slowed by ortho methyl substituents which hinder rotation, relative to the exchange reaction, which does not require rotation.

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