The competition between rearrangement of the excited allyl radical via a 1,3 sigmatropic shift versus sequential 1,2 shifts has been observed and characterized using isotopic substitution, laser excitation, and molecular beam techniques. Both rearrangements produce a 1-propenyl radical that subsequently dissociates to methyl plus acetylene. The 1,3 shift and 1,2 shift mechanisms are equally probable for CH2CHCH2, whereas the 1,3 shift is favored by a factor of 1.6 in CH2CDCH2. The translational energy distributions for the methyl and acetylene products of these two mechanisms are substantially different. Both of these allyl dissociation channels are minor pathways compared to hydrogen atom loss.
Competing sigmatropic shift rearrangements in excited allyl radicals / Stranges, Domenico; P., O'Keeffe; G., Scotti; DI SANTO, Roberto; P. L., Houston. - In: THE JOURNAL OF CHEMICAL PHYSICS. - ISSN 0021-9606. - STAMPA. - 128:(2008), pp. 151101-1-151101-4. [10.1063/1.2907714]
Competing sigmatropic shift rearrangements in excited allyl radicals
STRANGES, Domenico;DI SANTO, Roberto;
2008
Abstract
The competition between rearrangement of the excited allyl radical via a 1,3 sigmatropic shift versus sequential 1,2 shifts has been observed and characterized using isotopic substitution, laser excitation, and molecular beam techniques. Both rearrangements produce a 1-propenyl radical that subsequently dissociates to methyl plus acetylene. The 1,3 shift and 1,2 shift mechanisms are equally probable for CH2CHCH2, whereas the 1,3 shift is favored by a factor of 1.6 in CH2CDCH2. The translational energy distributions for the methyl and acetylene products of these two mechanisms are substantially different. Both of these allyl dissociation channels are minor pathways compared to hydrogen atom loss.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
