On the Mechanism of Base-catalyzed Hydrogen Isotope Exchange in Cyclic Ketones

1975 ◽  
Vol 53 (7) ◽  
pp. 1099-1101 ◽  
Author(s):  
Sujit Banerjee ◽  
Nick H. Werstiuk
Keyword(s):  
Hydrogen Isotope ◽  
Isotope Exchange ◽  
Rate Ratio ◽  
Isotope Effects ◽  
Cyclic Ketones ◽  
Hydrogen Isotope Exchange ◽  
Dual Mechanism ◽  
Kinetics Of ◽  
Exchange Selectivity

The kinetics of H → D exchange in norcamphor (1) and of D → H exchange in norcamphor-3,3-d2 (6) have been determined. The rate ratio kexo/kendo drops from 661 in H → D exchange to 72 for D → H exchange. These data imply the presence of a dual mechanism for endo exchange and emphasize the importance of isotope effects in dictating exchange selectivity.

Two-film effects on the kinetics of hydrogen isotope exchange between CHCl3 and D2O in two liquid phase system

1993 ◽  
Vol 25 (5) ◽  
pp. 363-374
Author(s):  
Matae Iwasaki ◽  
Tetsuo Sakka ◽  
Shigeyuki Ohashi ◽  
Yoshikazu Miyake ◽  
Hiroshi Matsushita
Keyword(s):  
Liquid Phase ◽  
Hydrogen Isotope ◽  
Isotope Exchange ◽  
Phase System ◽  
Hydrogen Isotope Exchange ◽  
Kinetics Of

On the mechanisms of acid-catalyzed enolization and hydrogen isotope exchange of cyclic ketones

1977 ◽  
Vol 55 (1) ◽  
pp. 173-176 ◽  
Author(s):  
Nick Henry Werstiuk ◽  
Sujit Banerjee
Keyword(s):  
General Theory ◽  
Hydrogen Isotope ◽  
Isotope Exchange ◽  
Rate Data ◽  
Cyclic Ketones ◽  
Proton Pair ◽  
Hydrogen Isotope Exchange ◽  
Bicyclic Ketones ◽  
Acid Catalyzed ◽  
Reactivity Order

The acid-catalyzed hydrogen isotope exchange of norcamphor 1 in DOAc–DCl–D2O is shown to follow the general theory (4) for exchange of a diastereotopic proton pair α to a carbonyl group. That is, the less reactive proton undergoes exchange via two channels. Through an analysis of a combination of the rate data for acid-catalyzed bromination and the pKBH+ values for a series of cyclic and bicyclic ketones, we establish that the reactivity order in the former is controlled by ketone basicity and not, as has been suggested previously, by angle strain developed in a very enol-like transition state.

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