Kinetic isotope effects in proton-transfer reactions

German ED, Kuznetsov AM, Dogonadze RR (1980) Theory of the kinetic isotope effect in proton transfer reactions in a polar medium. J Chem Soc, Faraday Trans 2 76 1128-1146... 

Large hydrogen isotope effects were found experimentally very soon after the discovery of deuterium in 1932, and there is now an extensive literature on the subject, recently supplemented by work with tritium. Much of this relates to the kinetics of reactions involving proton transfer, but there is also a large amount of information on acid-base equilibria. A recent review estimated that about 300 papers on isotope effects are now published each year, and a considerable proportion of these relate to the isotopes of hydrogen. The present chapter will be devoted to the effect of isotope substitution on acid-base equilibrium constants, while Chapter 12 will deal with kinetic isotope effects in proton transfer reactions. 

Kinetic Isotope Effects in Proton-Transfer Reactions... 

Kinetic Isotope Effects in Proton-Transfer Reactions (Equation 132) we must write... 

There is little direct information about the magnitude of secondary kinetic isotope effects in proton-transfer reactions. Model calculations predict that in the absence of changes in force constants the effect of deuterium substitution on atoms adjacent to the reaction site should not exceed 1-2%. Moderately large effects have been observed when several atoms are substituted. Thus the transfer of a proton from the ketones... 

Kinetic Isotope Effects in Proton-Transfer Reactions 263 Table 25. isotope effects in the ionization of carbon acids in water at 25°C and /cb = velocity constants for transfer of protons and deuterons respectively, dm mol" s Ap = p sH P BH ApK = statistically corrected value of ApK ... 

---