2-Azidoacetic acid
(N3CH2CO2H) has been
synthesized and characterized by a variety of
spectroscopic
techniques, and the thermal decomposition of this molecule studied by
matrix isolation infrared spectroscopy and
real-time ultraviolet photoelectron spectroscopy. The results are
consistent with the vapor phase thermal decomposition
following a pathway involving concerted ejection of molecular
N2 and the simultaneous formation of CO2
and
methanimine (CH2NH). No evidence was found for
the presence of intermediates such as the nitrene
NCH2CO2H
or the imine HNCHCO2H. At higher temperatures,
CH2NH further decomposes to give HCN and
H2.
The thermal decompositions of 2-azidoethanol and 2-azidoethyl acetate have been studied by matrix isolation
infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy. The products that were detected
in a flow system at different temperatures (CH2NH, H2CO, N2, CO, and HCN from N3CH2CH2OH and C2H4,
CH2NH, HCN, CO2, and N2 from N3CH2COOCH2CH3) allowed mechanisms for decomposition to be proposed.
The experimental evidence obtained is consistent with 2-azidoethyl actetate decomposing via a concerted
mechanism, similar to that found previously for azidoacetic acid, whereas the 2-azidoethanol decomposition
is consistent with a stepwise decomposition mechanism as observed previously for azidoacetone.
2-Azidoacetone (N3CH2COCH3) has been synthesized and characterized by a variety of spectroscopic
techniques, and the thermal decomposition of this molecule at temperatures in the region 300−1150 K has
been studied by matrix isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy.
The results show the effectively simultaneous production of six prominent decomposition products: CH2NH,
CH2CO, HCN, CO, N2, and CH3CHO, and several reaction pathways are proposed to account for their
formation. Results of ab initio molecular orbital calculations indicate that the primary reaction intermediate
is the imine HNCHCOCH3, with the nitrene NCH2COCH3 being a transition state. No experimental evidence
was found for the presence of the imine HNCHCOCH3, but mechanistic considerations, and the existence of
several weak unassigned IR bands point to the presence of a further decomposition product, which may be
CH2NCH3.
The thermal decomposition of 2-azidoacetamide (N3CH2CONH2) has been studied by matrix-isolation infrared
spectroscopy and real-time ultraviolet photoelectron spectroscopy. N2, CH2NH, HNCO, CO, NH3, and HCN
are observed as high-temperature decomposition products, while at lower temperatures, the novel imine
intermediate H2NCOCHNH is observed in the matrix-isolation IR experiments. The identity of this
intermediate is confirmed both by ab initio molecular orbital calculations of its IR spectrum and by the
temperature dependence and distribution of products in the photoelectron spectroscopy (PES) and IR studies.
Mechanisms are proposed for the formation and decomposition of the intermediate consistent both with the
observed results and with estimated activation energies based on pathway calculations.
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