Elimination of H2 from CH3CH=N+HCH3: a synchronous, concerted 1,4-H2 elimination.
Most H2 eliminations from cations in the gas phase are formally 1,1- or 1,2- processes. Larger ring size H2 eliminations are rare and little studied. Thus, whether the 6-center, 1,4- elimination CH3CH=N+HCH3-->CH2=CHN+H=CH2+H2 is concerted and synchronous, as indicated by isotope effects and predicted by conservation of orbital symmetry, is a significant question. This reaction is characterized here by application of QCI and B3LYP theories. CH bond-breaking and H-H bond-making in this reaction are found by theory to be highly synchronized, consistent with previously established isotope effects and in contrast to "forbidden" 1,2-eliminations from organic cations in the gas phase. This reaction is made feasible by its conservation of orbital symmetry, the energy supplied by formation of the H-H bond, and a favorable geometry of the ion for eliminating H2.
Hudson
Charles E
CE
Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555-1043, USA.
Bowen
Richard D
RD
McAdoo
David J
DJ
D004735:Energy Transfer; D006859:Hydrogen / Q000737:chemistry*; D008958:Models, Molecular; D009861:Onium Compounds / Q000737:chemistry*; D013816:Thermodynamics
D009861:Onium Compounds; D006859:Hydrogen