NUCLEAR MAGNETIC RESONANCE STUDIES OF RATE AND MECHANISM OF STEREOSPECIFIC ACID-AND BASE-CATALYZED DEUTERATIONS OF ALPHA-HYDROGEN ATOMS IN ETHYLENEDIAMINE-N,N'-DIACETATOCOBALT(3) CHELATES

Certain α-hydrogen atoms in aminoc arboxylate chelates of cobalt (III) undergo stereospecific deuteration in both acidic and alkaline D2O. The reactions are ster eospecific in that particular α-hydrogen atoms are deuterated more rapidly than their geminal α-hydrogen atoms. Base-ca talyzed deuterations, often complete in minutes at room temperature, are more rapid than acid-catalyzed deuterations, a nd are approximately ten times more stereospecific. Enol and enolate species are pro¬posed as intermediates in the deuteration reactions. The same reaction stereochemistry applies to all of the CoIII-EDTA analogs studied thus far (EDTA is ethylenediamine-N,N,N′,N′-tetraacetate). This work makes possible a better under-standing of nmr spectral assignments in these chelates and suggests better methods for the synthesis of deuterated chelating agents. © 1968, American Chemical Society. All rights reserved.