The phosphorylation of organic compounds by phosphoric anhydride. Part 3. Synthesis of monosubstituted ketenes in the reaction of esters with phosphoric anhydride and cyclotrimerization of these ketenes

Cyanoketene: the microwave spectrum and structure of an unstable molecule

“…So with this method too, cyanoketene could not be re-sublimated from the solid state. These results corroborate strongly the findings of [16], and it seems very unlikely that a liquid phase of cyanoketene could be obtained as claimed in [20].…”

“…Production of the molecule under high vacuum conditions by flash thermolysis of different precursors allowed the measurement of its heat of formation and an estimate of the ionization energy by mass spectroscopic techniques [18], the determination of the IR-bands in an Ar matrix at 12 K [19], and to find the pathways of its formation also by trapping the different species in an Ar matrix at 14 K [16]. The latter paper contradicts strongly a finding of Efremov et al [20] who claim that cyanoketene can be isolated as a liquid, boiling at )34°C, and who published an NMR spectrum. In [16] however, the authors point out that the compound does not survive 80 K in condensed phase.…”

First Direct Structural Comparison of Complexes of the Same Metal Fragment to Ketenes in Both C,C- and C,O-Bonding Modes

“…Therefore, as far as we can tell, no one has used this route with monosubstituted ketenes . As a demonstration of the difficulties encountered, phenylketene has only been characterized when made in inert matrixes at temperatures below 40 K, , as a transient solution species in flash photolysis reactions, , or when generated in the gas phase, , because of its facile oligomerization reactions. − When used preparatively, phenylketene is always generated in the presence of the desired reactant. , In this study, because acid chlorides oxidatively add to Ir(I)−phosphine complexes, , direct synthesis of phenylketene complex 4 required generation of phenylketene in solution by allowing phenylacetyl chloride to react with triethylamine at 0 °C for 4 h, followed by filtration of the resulting mixture into a solution of the metal fragment. While less efficient than the fragmentation of pyridyl ester 1 (R 1 = Ph, R 2 = H) route in terms of yield, this protocol was significantly faster, allowing synthesis of phenylketene complex 4 within 1 day in 5% yield.…”

The Formation of Cyanoketene (NCCHCO) and the Isomer NCCCHO from Anionic Precursors in the Gas Phase. The Rearrangement of NCCCHO to NCCHCO

“…A number of studies of cyanoketene have been reported: − cyanoketene may be prepared by a variety of methods including flash vacuum thermolyses of cyanoacetic acid derivatives .…”

“…A number of studies of cyanoketene have been reported: [14][15][16][17][18][19][20][21][22][23][24] cyanoketene may be prepared by a variety of methods including flash vacuum thermolyses of cyanoacetic acid derivatives. 22 Cyanoketene is highly reactive, with neat cyanoketene reported to "disappear" below 80 K. 22 The photoelectron, 14 microwave, 23 and infrared 22 spectra of cyanoketene have been determined.…”