2401-96-9Relevant academic research and scientific papers
Ethylenediamine and Aminoacetonitrile Catalyzed Decarboxylation of Oxalacetate
Leussing, Daniel L.,Raghavan, N. V.
, p. 5635 - 5643 (2007/10/02)
Monoprotonated ethylenediamine (ENH+) and aminoacetonitrile (AAN) are highly effective catalysts for the decarboxylation of oxalacetate (OA2-) with the latter amine showing 50percent faster rates.The mechanisms of the reactions are the same as that earlier proposed by Guthrie and Jordan from studies on the carboxylation of acetoacetate (AA-): amine and keto acid react to form ketimine which either decarboxylates or is competitively converted to enamine.We find that a prton is required to effect decarboxylation, but it also promotes enamine formation, the more so the greater basicity of the parent amine.Owing to this side reaction, the more basic amines tend to show lower catalytic activity with respect to decarboxylation. a second effect also contributes to the high activity of AAN: even though the rate constants for imine formation appear to be roughly similar with AAN and ENH+, proton catalysis has a much larger net influence on the AAN rate because changes in +> are not canceled by inverse changes in . 4-Ethyloxalacetate forms an adduct with ENH+ that has a considerably greater enamine content and a higher stability than its OA2- analogue.These differences in substrate behavior must be taken into account when esters are used as models for the parent keto acids in these reactions.Comparison of our results with those previously published for OA2- decarboxylation catalyzed by a partially quaternized poly(ethylenimine) suggests that OA2- is predominantly bound to the quaternary amine sites but decarboxylation likely proceeds via a Schiff-base mechanism.
