Deuterium exchange complexes

Substituted tetrazoles readily exchange the 5-hydrogen for deuterium in aqueous solution. A major rate-enhancing effect is observed with copper(II) or zinc ions due to complexation with the heterocycle. The rate of base-induced proton-deuterium exchange of 1-methyltetrazole is 10 times faster than 2-methyltetrazole (77AHC(2l)323). 

In the presence of strong alkali, the rhodium analog of 62, or RhCl(C8H,2)PPh3, hydrogenates aliphatic ketones at 1 atm and 20°C, and after treatment with borohydride the systems similarly reduce aromatic ketones to the alcohols (526). Deuterium exchange data for acetone reduction were interpreted in terms of hydrogen transfer within a mononuclear hydroxy complex containing substrate bound in the enol form (63). 

A further measure of acidity is provided by rates of deuterium exchange between a labeled base such as DO and a proton acid. The mechanism involves exchange within weak ion-molecule encounter complexes as shown in equation 4. 

A mixture of Pt(ll) and metallic Pt in an aqueous medium was shown to oxidize ethane to yield acetic and glycolic acids. A series of deuterium-exchange processes enabled a complex mechanism to be elucidated metallic platinum catalyzes the oxidation of intermediate alcohols to acid products, whereas the Pt(ll) salt activates the initial alkene (Scheme 7X29... 

Hydro gen-deuterium exchange in chiral ion—dipole complexes. The rates of gas phase H/D exchange reactions are most conveniently measured in a FT-ICR cell in which the ions can be trapped for extended periods of time in the presence of a fixed... 

In discussing the mechanism of the para hydrogen conversion or the hydrogen deuterium exchange reaction, Eley (117) suggested that it could occur at a single metal atom. Two orbitals are needed to bind the activated complex and these can be provided easily by the d orbitals of... 

Deuterium exchange in alkylbenzenes, catalyzed heterogeneously by platinum and homogeneously by platinum complexes, has been found by Hodges and Garnett 137) to have similar patterns and has been interpreted as an evidence of the similarity in mechanism. Shopov, Andreev, Petrov,... 

Kinetics and stereochemistry of deuterium exchange of the a-hydrogen of an amino acid moiety in metal complexes of amino acid Schiff bases with or/Jio-hydroxy-acetophenone have been studied by Belokon et al.249). 

The complexity of the adsorption process, in particular its duality as illustrated above as well as in more recent data of Wicke (12), also shows in the irregular behavior of zinc oxide as a catalyst for the hydrogen-deuterium exchange (13). Thus this reaction proceeds at measurable rates at temperature as low as 14O K., indicating that at least part of the low-temperature adsorption is of the dissociating type. The apparent activation energy at low temperatures is low, but in the temperature... 

Electrophilic substitution, aromatic, 31, 130-167, 381 1,2-ti. 1,4-addition, 195 as addition/elimination, 133 complexing with substituent, 160 deuterium exchange, 131,158 electronic effects in, 148, 158, 159 energetics of, 132, 136 field effect in, 152 hyperconjugation in, 153 inductive effect in, 22,152,153,156, 160... 

Hydrogen-Deuterium Exchange in Hydrido Transition Metal Cluster Complexes... 

---