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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

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
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
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. N-2 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.
azides, ir spectroscopy, matrix isolation, photoelectron spectrosopy gas-phase reactions, 3-membered rings, spectra, argon, nitrogen, acid
0947-6539
1665-1676
Dyke, J.M.
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Levita, G.
ef218c00-047c-4ec3-a056-b78237ca2e94
Morris, A.
378f6b9c-92e7-4783-b7be-cafca74b5372
Ogden, J.S.
d022e70d-b424-4100-9517-64a46486dd8c
Dias, A.A.
221a2ab3-3cc5-4635-b9df-bfce6f767364
Algarra, M.
771edccf-5ceb-4186-b7d5-d82468a3177f
Santos, J.P.
2903abeb-2c58-4e5a-8e79-ada8f8bb7251
Costa, M.L.
1dca80c6-c314-453c-b853-382fbeac2770
Rodrigues, P.
0d6b7020-ef36-41c7-aa1a-3d3f259882b4
Andrade, M.M.
d94bb091-12d9-4860-9422-b345fd6b4e16
Barros, M.T.
eee3509f-d7a0-4011-bb00-e4f561fda538
Dyke, J.M.
46393b45-6694-46f3-af20-d7369d26199f
Levita, G.
ef218c00-047c-4ec3-a056-b78237ca2e94
Morris, A.
378f6b9c-92e7-4783-b7be-cafca74b5372
Ogden, J.S.
d022e70d-b424-4100-9517-64a46486dd8c
Dias, A.A.
221a2ab3-3cc5-4635-b9df-bfce6f767364
Algarra, M.
771edccf-5ceb-4186-b7d5-d82468a3177f
Santos, J.P.
2903abeb-2c58-4e5a-8e79-ada8f8bb7251
Costa, M.L.
1dca80c6-c314-453c-b853-382fbeac2770
Rodrigues, P.
0d6b7020-ef36-41c7-aa1a-3d3f259882b4
Andrade, M.M.
d94bb091-12d9-4860-9422-b345fd6b4e16
Barros, M.T.
eee3509f-d7a0-4011-bb00-e4f561fda538

Dyke, J.M., Levita, G., Morris, A., Ogden, J.S., Dias, A.A., Algarra, M., Santos, J.P., Costa, M.L., Rodrigues, P., Andrade, M.M. and Barros, M.T. (2005) 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. Chemistry - A European Journal, 11 (5), 1665-1676. (doi:10.1002/chem.200400767).

Record type: Article

Abstract

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. N-2 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.

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Published date: 18 February 2005
Keywords: azides, ir spectroscopy, matrix isolation, photoelectron spectrosopy gas-phase reactions, 3-membered rings, spectra, argon, nitrogen, acid

Identifiers

Local EPrints ID: 20786
URI: http://eprints.soton.ac.uk/id/eprint/20786
ISSN: 0947-6539
PURE UUID: b1130136-c9dc-46ca-9eba-096ca75fae2e
ORCID for J.M. Dyke: ORCID iD orcid.org/0000-0002-9808-303X

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Date deposited: 03 Mar 2006
Last modified: 19 Nov 2019 02:03

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Contributors

Author: J.M. Dyke ORCID iD
Author: G. Levita
Author: A. Morris
Author: J.S. Ogden
Author: A.A. Dias
Author: M. Algarra
Author: J.P. Santos
Author: M.L. Costa
Author: P. Rodrigues
Author: M.M. Andrade
Author: M.T. Barros

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