78957-08-1Relevant articles and documents
Ionized ethylidene ketene and its homologue methylene ketene
Terlouw, Johan K.,Holmes, John L.,Lossing, F. P.
, p. 1722 - 1724 (2007/10/02)
The gas phase pyrolyses of crotonic and acrylic-trifluoroacetic anhydrides were shown to yield ethylidene ketene and methylene ketene , respectively.The former was identified via the collisional activation mass spectrum of its molecular ion.The ionization energies of the two ketenes, 8.68 and 9.12 +/- 0.05 eV respectively, measured using energy selected electrons, lead to 215 and 233 kcal mol-1 for their ionic heats of formation.
Gasphasen-Reaktionen, 22. Thermische Erzeugung von C4H4O: Vinylketen und Ethylidenketen
Mohmand, Shamsher,Hirabayashi, Takakuni,Bock, Hans
, p. 2609 - 2621 (2007/10/02)
Thermal HX elimination from unsatured carboxylic acid derivatives CH3-RC=CH-COX represents another method to generate the short-lived isomers C4H3RO with R = H, CH3 in the gas phase.The temperature-dependent changes of amounts of products in the heated flow system are analyzed by photoelectron spectra: based on MNDO calculations and in accordance with literature data, the vinylketene structure CH2=CR-HC=C=O is assigned to the thermolysis product.The isomeric alkylideneketenes H3C-RC=C=C=O with R = H, CH3 are produced in the 760 K short-path pyrolysis of alkylidenemalonates and rearrange on prolonged residence time in the heating zone into the thermodynamically more stable vinylketene derivatives.
