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Unimolecular Fragmentation of CH 3 NH 2 : Towards a Mechanistic Description of HCN Formation
Author(s) -
Roithová Jana,
Schröder Detlef,
Schwarz Helmut
Publication year - 2005
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200500029
Subject(s) - chemistry , homolysis , bond cleavage , methylamine , radical , fragmentation (computing) , hydrogen atom , density functional theory , computational chemistry , nucleophile , medicinal chemistry , photochemistry , pericyclic reaction , reaction mechanism , stereochemistry , organic chemistry , group (periodic table) , operating system , computer science , catalysis
The mechanism of the consecutive fragmentation of methylamine, CH 3 NH 2 , is studied by means of neutralization‐reionization mass spectrometry (NRMS), labeling experiments, and calculations employing density functional theory. It is shown that under the conditions of NRMS the fragmentations proceed by a radical mechanism that involves four distinct X–H bond cleavages (X = C, N). In the first step, a hydrogen atom is eliminated from the methyl group; next, homolytic cleavage of an N–H bond occurs. The so‐formed CH 2 NH intermediate then, in competition, releases a hydrogen atom either from the nitrogen or the carbon part, resulting in the formation of the radicals H 2 CN · and HCNH · , respectively. The reaction sequence is terminated by yet another homolytic bond cleavage to produce HCN. An alternative pathway proceeding by an initial 1,1‐elimination of H 2 from the methyl group of CH 3 NH 2 , followed by a 1,1‐elimination of H 2 from the amino function, is also considered, but found to be more energy‐demanding. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)