Elsevier

Tetrahedron

Volume 42, Issue 22, 1986, Pages 6253-6262
Tetrahedron

Generation and ion-molecule reactions of ethyl diazoacetate anion radical (EtO2CCHN2XXX)

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Abstract

Thermal electron attachment to EtO2CCHN2 produced the parent anion radical EtO2CCHN2-(m/z 114). The ion-molecule reactions of m/z 114 with 30 neutral substrates were examined. Using the bracketing method, PA(EtO2CCHN2XXX) = 355±4 kcal mol-1 was determined. The reaction of m/z 4 with CH3SH produced H2CSXXX, the product of β-elimination of H+2 from the thiol. From a series of bracketing studies and determination of the equilibrium constant for the electron transfer (ET) process CH3C(O)C(O)CH3-+EtO2CCHN2 = CH3C(O)C(O)CH3+EtO2CCHN2XXX EA(EtO2CCHN2) = 19.7 kcal mol-1 was derived. Both associative and dissociative ET were observed in the reactions of m/z 114 with certain perhalomethanes (depending on their EA) as well as halogen-atom abstraction from BrCCl3. While no reaction was observed between m/z 114 with CH3CHO or (CH3)2CO, m/z 114 reacted with certain other ketones and esters (CF3CO2R) mainly to yield enolate anions of the β-keto esters, EtO2CCHC(O-)R. These enolate anions are believed to be formed by nucleophilic addition of Cα of m/z 114 to the carbonyl group of the neutral substrate followed by loss of N2 and radical β-fragmentation.

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