Details

Autor(en) / Beteiligte

• Dyke, John M.
• Levita, Giacomo
• Morris, Alan
• Ogden, J. Steven
• Dias, Antonio A.
• Algarra, Manolo
• Santos, Jose P.
• Costa, Maria L.
• Rodrigues, Paula
• Andrade, Marta M.
• Barros, M. Teresa

Titel

Contrasting Behavior in Azide Pyrolyses: An Investigation of the Thermal Decompositions of Methyl Azidoformate, Ethyl Azidoformate and 2-Azido-N, N-dimethylacetamide by Ultraviolet Photoelectron Spectroscopy and Matrix Isolation Infrared Spectroscopy

Ist Teil von

• Chemistry : a European journal, 2005-02, Vol.11 (5), p.1665-1676

Ort / Verlag

Weinheim: WILEY-VCH Verlag

Erscheinungsjahr

2005

Quelle

Wiley HSS Collection

Beschreibungen/Notizen

• The thermal decompositions of methyl azidoformate (N3COOMe), ethyl azidoformate (N3COOEt) and 2‐azido‐N,N‐dimethylacetamide (N3CH2CONMe2) have been studied by matrix isolation infrared spectroscopy and real‐time ultraviolet photoelectron spectroscopy. N2 appears as an initial pyrolysis product in all systems, and the principal interest lies in the fate of the accompanying organic fragment. For methyl azidoformate, four accompanying products were observed: HNCO, H2CO, CH2NH and CO2, and these are believed to arise as a result of two competing decomposition routes of a four‐membered cyclic intermediate. Ethyl azidoformate pyrolysis yields four corresponding products: HNCO, MeCHO, MeCHNH and CO2, together with the five‐membered‐ring compound 2‐oxazolidone. In contrast, the initial pyrolysis of 2‐azido‐N,N‐dimethyl acetamide, yields the novel imine intermediate Me2NCOCHNH, which subsequently decomposes into dimethyl formamide (HCONMe2), CO, Me2NH and HCN. This intermediate was detected by matrix isolation IR spectroscopy, and its identity confirmed both by a molecular orbital calculation of its IR spectrum, and by the temperature dependence and distribution of products in the PES and IR studies. Mechanisms are proposed for the formation and decomposition of all the products observed in these three systems, based on the experimental evidence and the results of supporting molecular orbital calculations. N2 appears as an initial pyrolysis product in the thermal decompositions of methyl azidoformate (N3COOMe), ethyl azidoformate (N3COOEt) and 2‐azido‐N,N‐dimethylacetamide (N3CH2CONMe2). However, the fate of the accompanying organic fragment differs in the three cases studied. For N3COOMe, the products were HNCO, H2CO, CH2NH and CO2; for N3COOEt, the products were HNCO, MeCHO, MeCHNH and CO2, together with the five‐membered‐ring compound 2‐oxazolidone; in contrast, N3CH2CONMe2 yields the novel imine intermediate Me2NCOCHNH, which subsequently decomposes into HCONMe2, CO, Me2NH and HCN.