Hydrogen-deuterium exchange, rate

The hydrogen-deuterium exchange rates for 1,2-dimethylpyrazolium cation (protons 3 and 5 exchange faster than proton 4 Section 4.04.2.1.7(iii)) have been examined theoretically within the framework of the CNDO/2 approximation (73T3469). The final conclusion is that the relative reactivities of isomeric positions in the pyrazolium series are determined essentially by inductive and hybridization effects. 

The kinetic acidity of phosphonium salts was first studied by NMR measurements of the hydrogen-deuterium exchange rate for a series of phosphonium salts565 ... 

The hydrogen-deuterium exchange rates of indolizine and some methyl derivatives have been measured at 50 °C in D20/dioxane. It has been shown that the exchange rates reflect the regioselectivity of protonation. Kinetic data have been discussed using HMO and PPP calculations (71T4171). Some pKa values of indolizines and azaindolizines are given in Table 9. 

Hydrogen-deuterium exchange rates of H2 and in some 3-substituted pyrazine 1 -oxides in Na0D-D20 have been correlated with a constants, and the log of the H2 exchange rates have been shown to be rectilinearly related to the pK values of these compounds (745). A considerable exchange-rate enhancement was caused by replacement of the =C4-H function in a pyridine A-oxide by a =N4 with formation of a pyrazine A-oxide (745). 

Hydrogen-deuterium exchange rates ofH2 in 3-cyanopyrazine 1-oxide (pA 1.12 ... 

Let kunfold he the rate constant for unfolding, kfdd the rate constant for folding, and be the hydrogen/deuterium exchange rate for an amide... 

Freitas, M.A., Hendrickson, C.L., Emmett, M.R., Marshall, A.G. (1999) Gas-phase Bovine Ubiquitin Cation Conformations Resolved by Gas-phase Hydrogen/ Deuterium Exchange Rate and Extent. Int. J. Mass Spectrom. 185/186/187 565-575. 

The hydrogen-deuterium exchange rate between EtOH and [Cb(C N)6D] ion has been obtained in EtOH-HsO mixtures and the activation energy changes from 7.9 to 22.1 kcal as the percental of EtOH varies. ... 

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