Nicotinamide coenzyme regeneration. The rates of some 1,4-dihydropyridine, pyridinium salt, and flavin mononucleotide hydrogen-transfer reactions

1976 ◽  
Vol 54 (19) ◽  
pp. 2974-2980 ◽  
Author(s):  
J. Bryan Jones ◽  
Keith E. Taylor
Keyword(s):  
Hydrogen Transfer ◽  
Isotope Effects ◽  
Pyridinium Salt ◽  
Transfer Reactions ◽  
Flavin Mononucleotide ◽  
Pyridinium Salts ◽  
Significant Extent ◽  
Redox Couples ◽  
Donor Acceptor ◽  
Deuterium Isotope Effects

The rates of H-transfer between various 1,4-dihydropyridines and pyridinium salts (including NADH and NAD+), and from 1,4-dihydropyridines to FMN, have been measured. The reactions are found to be sufficiently slow for H-transfer to be rate-determining to a significant extent when such Systems are applied for nicotinamide coenzyme recycling purposes. The rates of H-transfer parallel the magnitudes of the donor–acceptor redox potential differences (ΔE0′); ΔE0′ values may therefore be used as qualitative guides in formulating and selecting redox couples of NAD/H recycling value. On the basis of deuterium isotope effects, it is concluded that formation of a complex prior to H-transfer is not rate determining for 1,4-dihydropyridine–NAD+ reactions. This behavior is in contrast to that of other model alcohol dehydrogenase Systems.

Mechanism of initiation in the thermal polymerization of styrene. Kinetic deuterium isotope effects in the initiation step of the thermal polymerization of some deuterated styrenes

1969 ◽  
Vol 47 (21) ◽  
pp. 4049-4058 ◽  
Author(s):  
Karl R. Kopecky ◽  
Syamalarao Evani
Keyword(s):  
Hydrogen Transfer ◽  
Deuterium Oxide ◽  
Isotope Effects ◽  
Thermal Polymerization ◽  
Convenient Synthesis ◽  
Initiation Step ◽  
Deuterium Isotope Effects

A convenient synthesis of 2,6-dideuteriostyrene starts with N,N-dimethyl-(1-phenylethyl)-amine which is deuterated in the 2 and 6 positions by a series of exchanges using n-butyllithium followed by deuterium oxide. The deuterium isotope effects at 70° on the rates of the thermal polymerization, [Formula: see text], of 2,6-dideuterio-, α-deuterio-, and β,β-dideuteriostyrene are 1.29, 1.00, and 0.78, respectively. The deuterium isotope effects at 70° on the 2,2′-azobis-(2-methylpropionitrile) initiated rates of polymerization,[Formula: see text], are 0.96, 0.86, and 0.81, respectively. From these values the deuterium isotope effects on the rates of initiation of the thermal polymerization, k1H/k1D, are calculated to be 1.80, 1.31, and 0.92, respectively. At 147° the presence of 1.5% potassium t-butoxide decreases the rate of the thermal polymerization of neat styrene by a factor of 17, and results in the formation of 1-phenyltetralin as the greatly predominant dimer. The results support the suggestion that the thermal polymerization of styrene is initiated by hydrogen transfer from 1-phenyl-1,2,3,9-tetrahydronaphthalene, formed by a concerted dimerization of two molecules of styrene, to a third molecule of styrene.

Secondary deuterium isotope effects for certain acyl transfer reactions of phenyl formates

1979 ◽  
Vol 101 (1) ◽  
pp. 169-173 ◽  
Author(s):  
Luciano Do Amaral ◽  
Marilene P. Bastos ◽  
Herbert G. Bull ◽  
Juan J. Oritz ◽  
E Cordes
Keyword(s):  
Isotope Effects ◽  
Acyl Transfer ◽  
Transfer Reactions ◽  
Deuterium Isotope Effects ◽  
Acyl Transfer Reactions

Trajectories of proton transfer reactions. Experimental determination of the magnitude of primary deuterium isotope effects for proton-transfers occuring at acute angles

1988 ◽  
Vol 110 (8) ◽  
pp. 2667-2668 ◽  
Author(s):  
Dennis. Liotta ◽  
Manohar. Saindane ◽  
Liladhar. Waykole ◽  
Julie. Stephens ◽  
Judy. Grossman
Keyword(s):  
Proton Transfer ◽  
Experimental Determination ◽  
Isotope Effects ◽  
Transfer Reactions ◽  
Proton Transfers ◽  
Proton Transfer Reactions ◽  
Deuterium Isotope Effects
Sign in / Sign up

Export Citation Format

Share Document