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The Photochemical and Thermal Decomposition of Azidoacetylene in the Gas Phase, Solid Matrix, and Solutions
Author(s) -
Zeng Xiaoqing,
Beckers Helmut,
Seifert Jennifer,
Banert Klaus
Publication year - 2014
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.201402153
Subject(s) - chemistry , matrix isolation , azide , flash vacuum pyrolysis , photodissociation , thermal decomposition , argon , photochemistry , decomposition , pyrolysis , organic chemistry
Decomposition of the extremely explosive and unstable parent compound of 1‐azidoalkynes, HCCN 3 (azidoacetylene), was studied in the gas phase, solid argon matrix, and solutions. In the gas phase, this azide decomposes quickly at room temperature with a half‐life time ( t 1/2 ) of 20 min at an initial pressure ( p 0 ) of 0.8 mbar. The decay ( p 0 = 1.0 mbar) is significantly increased in an atmosphere of O 2 with t 1/2 of 3 min, in which HC(O)CN was identified as the trapping product of the cyanocarbene intermediate HCCN. Trapping products of this carbene by solvent molecules (CH 2 Cl 2 and CHCl 3 ) were also found during decomposition of the azide in solution, whereas the reaction with a solution of bromine to form dibromoacetonitrile is interpreted as taking place by nucleophilic attack of the alkyne itself. The intermediary formation of triplet HCCN by flash vacuum pyrolysis and photolysis (255 nm) of the azide in the gas phase and in solid argon matrices, respectively, was confirmed by IR spectroscopy and mutual photo‐interconversion of HCCN with isomeric cyclo ‐C(H)CN (azirinylidene) and HCNC by selective irradiations at 16 K.