Base-catalyzed hydrogen-deuterium exchange in some 5- and 6-substituted benzothiazoles. Activity of the sulphur and nitrogen heteroatoms in the transmission of the substituent effects

1976 ◽  
Vol 13 (5) ◽  
pp. 1021-1024 ◽  
Author(s):  
Orazio Attanasi ◽  
Giuseppe Bartoli ◽  
Paolo E. Todesco
Keyword(s):  
Substituent Effects ◽  
Deuterium Exchange ◽  
Hydrogen Deuterium Exchange ◽  
Hydrogen Deuterium

2,4-Diazapentadienes. II. A Carbanion Cyclization

1972 ◽  
Vol 50 (5) ◽  
pp. 678-689 ◽  
Author(s):  
D. H. Hunter ◽  
S. K. Sim
Keyword(s):  
Isotope Effect ◽  
Solvent Effects ◽  
Isotope Effects ◽  
Substituent Effects ◽  
Deuterium Exchange ◽  
Hydrogen Deuterium Exchange ◽  
Deuterium Isotope Effect ◽  
Potassium Methoxide ◽  
Proton Shift ◽  
Hydrogen Deuterium

The mechanism of the cyclization and 1,3-proton shift of 1,3,5-triaryl-2,4-diaza-1,3-pentadienes (1) catalyzed by phenyllithium and by potassium methoxide–methanol has been studied. On the basis of substituent effects, hydrogen–deuterium exchange, isotope effects, and solvent effects, it was deduced that both the cyclization and prototropy involve a common W-shaped carbanion which rapidly cyclizes. A kinetic deuterium isotope effect of 2 was calculated for protonation of this intermediate carbanion in methanol.

The hydrazinolysis of heterocyclic compounds. V. Reactions of 1-Amino-4,6-dimethylpyrimidin-2(1H)-one hydrazone in water

1978 ◽  
Vol 31 (9) ◽  
pp. 2023 ◽  
Author(s):  
RG Dickinson ◽  
NW Jacobsen ◽  
IH Pitman
Keyword(s):  
Aqueous Solutions ◽  
Heterocyclic Compounds ◽  
Substituent Effects ◽  
Deuterium Exchange ◽  
Neutral Molecule ◽  
Hydrogen Deuterium Exchange ◽  
Ultraviolet Spectra ◽  
Hydrogen Deuterium

The cation of 1-amino-4,6-dimethylpyrimidin-2(1H)-one hydrazone (1) is stable in aqueous solutions. By contrast the neutral molecule species decomposes to yield 3,5-dimethylpyrazole (3) and 1-amino-4,6- dimethylpyrimidin-2(1H)-one (6) as major products, and 1,2,4-triazole-3,4,5-triamine (7) and other unidentified compounds as minor products. Covalent hydration and substituent effects in the cation species of (1) are discussed in seeking an explanation for anomalous ultraviolet spectra. Hydrogen deuterium exchange in methyl substituents is reported.

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