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Cyanoketene and Iminopropadienones
Daniel W. J. Moloney1, Ming Wah Wong, Robert Flammang
1Department of Chemistry, The University of Queensland, Brisbane, Queensland 4072, Australia, and Organic Chemistry Laboratory, University of Mons-Hainaut, 19 Avenue Maistriau, B-7000 Mons, Belgium.
The Journal of Organic Chemistry
|June 27, 1997
Summary
Cyanoketene was efficiently produced using flash vacuum thermolysis of Meldrum's acid and cyanoacetic acid derivatives. This highly reactive molecule was characterized, and its reaction pathways were elucidated.
Area of Science:
- Organic Chemistry
- Physical Chemistry
- Spectroscopy
Background:
- Cyanoketene is a reactive organic intermediate.
- Understanding its generation and reactivity is crucial for synthetic chemistry.
Purpose of the Study:
- To investigate the generation of cyanoketene via flash vacuum thermolysis (FVT).
- To elucidate the reaction pathways and characterize cyanoketene and its intermediates.
- To study the reactivity of cyanoketene with nucleophiles.
Main Methods:
- Flash vacuum thermolysis (FVT) of Meldrum's acid and cyanoacetic acid derivatives.
- Matrix isolation infrared (FTIR) spectroscopy.
- Tandem mass spectrometry (MS).
- Computational chemistry (density functional and ab initio calculations).
Main Results:
- High yields of cyanoketene (8) were obtained from FVT of specific Meldrum's acid derivatives (3e-j) and cyanoacetic acid derivatives (9e,f,g,j,k,m).
- Major and minor reaction pathways involving ketenimines, (alkylimino)propadienones, imidoylketenes, and oxoketenimines were identified.
- Intermediates and cyanoketene were characterized using FTIR and MS.
- Cyanoketene was found to be highly reactive, reacting at or below 80 K.
- Experimental spectroscopic data agreed well with theoretical calculations.
Conclusions:
- Flash vacuum thermolysis provides an efficient route to generate cyanoketene.
- The reaction mechanisms involving various intermediates were clarified.
- The high reactivity of cyanoketene is attributed to its electronic structure.
- Spectroscopic and computational methods confirmed the structure and properties of cyanoketene.