Base-Catalyzed Acyl Exchange Reactions ofN,O-Diacyl-o-aminophenols. Substituent and Temperature Effects on the Equilibrium Constants

1996 ◽  
Vol 69 (3) ◽  
pp. 775-778 ◽  
Author(s):  
Tadamitsu Sakurai ◽  
Tohru Nagaoka ◽  
Jun Kamiya ◽  
Hiroyasu Inoue
Keyword(s):  
Temperature Effects ◽  
Equilibrium Constants ◽  
Exchange Reactions ◽  
Acyl Exchange

A nuclear magnetic resonance study of the kinetics and equilibria for the oxidation of penicillamine and N-acetylpenicillamine by glutathione disulfide

1984 ◽  
Vol 62 (9) ◽  
pp. 1672-1680 ◽  
Author(s):  
Dallas L. Rabenstein ◽  
Yvon Theriault
Keyword(s):  
Equilibrium Constants ◽  
Reducing Power ◽  
Thiol Group ◽  
Nuclear Magnetic Resonance Study ◽  
Second Step ◽  
Glutathione Disulfide ◽  
Exchange Reactions ◽  
H Nmr ◽  
Mixed Disulfide ◽  
Ph Range

The kinetics and equilibria of the oxidation of penicillamine by glutathione disulfide to form, in the first step, penicillamine–glutathione mixed disulfide and glutathione and, in the second step, penicillamine disulfide and glutathione have been studied over the pH range 4–9 by 1H nmr. The reactive species are found to be penicillamine with its amino group protonated and its thiol group deprotonated and glutathione disulfide and penicillamine–glutathione mixed disulfide with their two amino groups protonated. The rate and equilibrium constants for the first step are much larger than those for the second step, indicating a small tendency for penicillamine to form its symmetrical disulfide by thiol/disulfide exchange reactions. This and the smaller reducing power of penicillamine as compared to glutathione are attributed to steric hindrance from the methyl groups adjacent to the sulfur. The kinetics and equilibria of the oxidation of N-acetylpenicillamine by glutathione disulfide were studied at neutral pH. Conditional equilibrium and rate constants for the oxidation of penicillamine by glutathione disulfide at pH 7.4 are presented and discussed in terms of the metabolism of penicillamine.

ChemInform Abstract: Base-Catalyzed Acyl Exchange Reactions of N,O-Diacyl-o-aminophenols

ChemInform ◽  
2010 ◽  
Vol 28 (40) ◽  
pp. no-no
Author(s):  
T. SAKURAI ◽  
K. KUBO ◽  
H. INOUE
Keyword(s):  
Exchange Reactions ◽  
Acyl Exchange

THERMODYNAMIC PROPERTIES AND GEOCHEMISTRY OF ISOTOPIC COMPOUNDS OF SELENIUM

1962 ◽  
Vol 40 (2) ◽  
pp. 367-375 ◽  
Author(s):  
H. R. Krouse ◽  
H. G. Thode
Keyword(s):  
Partition Function ◽  
Kinetic Isotope Effect ◽  
Chemical Reduction ◽  
Equilibrium Constants ◽  
Elemental Selenium ◽  
Exchange Reactions ◽  
Kinetic Isotope ◽  
Naturally Occurring ◽  
Selenium Isotope ◽  
Selenium Isotopes

Using "normal vibration equations" and statistical mechanics, the isotopic vibrational frequencies and the partition function ratios for various Se76- and Se82-containing compounds have been calculated. The equilibrium constants for selenium isotope exchange reactions derived from these partition function ratios indicate that noticeable fractionation of selenium isotopes can be expected in the laboratory and in naturally occurring processes.The Se82/Se76 ratios for 16 natural samples have been compared mass spectrometrically. Variations of up to 1.5% found in this ratio are discussed.A kinetic isotope effect of 1.5% found in a chemical reduction of selenite ion to elemental selenium is also discussed.

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