The mass spectra of organic compounds. 8th Communication. 1-Buten-3-yn-2-ol. A new kinetically unstable C4H4O isomer
✍ Scribed by František Tureček; ZdenêK Havlas; Francis Maquin; Tino Gäumann
- Book ID
- 102858183
- Publisher
- John Wiley and Sons
- Year
- 1986
- Tongue
- German
- Weight
- 517 KB
- Volume
- 69
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
The unstable neutral enol, 1-buten-3-yn-2-01, and its deuterium-labelled analogues were generated in the gas phase by high-vacuum flash pyrolysis of the corresponding 2-ex0 -ethynylnorborn-5-en-2-01~, or alternatively from 1-ethynylcyclobutdnol. The ionization energy of the enol was measured as 8.92 f 0.03 eV. The cation radical (HC=C(OH)=CH2)+' was prepared by electron-impact ionization of the neutral enol, or by dissociative ionization of 1-hexyn-3-01 and 1-ethynylcyclobutanol, and its heat of formation was determined as 944 kJ 'mo1-l. The heat of formation of the neutral enol was assessed as 83 f 7 kJ .mol-l in good agreement with MNDO calculations. Cation radicals HC=C-C(OH)=CH2+' undergo four main unimolecular fragmentations due to losses of the OH H-atom, a CH, group incorporating the C(1) methylene and the OH H-atom, CO, and H20. The structure of the neutral enol and the mechanisms of the ionic decompositions are discussed.