Cyclopropenones properties

Thus aromaticity in cyclopropenone cannot be detected by the magnetic criterion although it is suggested by other chemical and physical properties. UV, IR, and -NMR data of cyclopropenone are summarized in Table 6, but are discussed in later chapters. 

F-shifts in p-substituted fluorobenzenes are supposed to provide a measure of the a- and -electron withdrawing properties of groups para to the F atom181. Bis(p-fluorophenyl)cyclopropenone and l,2-bis(p-fluorophenyl)-4,4-dicyano triafulvene (212/213) were found to exhibit 19F resonances at 61.5 and 65.5 ppm (downfield from C6F6)182. ... 

Generally diaryl cyclopropenones are thermolyzed at lower temperatures than dialkyl cyclopropenones, e.g. diphenyl cyclopropenone 150 °C, di-n-propyl cyclopropenone 190 °C, due to the better stabilizing properties of alkyl substituents. 

Various molecular orbital calculations " provide plausible stabilization energies for cyclopropenone. Photoacoustic and bomb calorimetry have provided the heat of formation of diphenylcyclopropenone as 350 16 and 354 + 21 kJ mol respectively, which leads to a stabilization energy of 46kJmol In contrast, the physical and spectroscopic properties of the cyclopropenones have been explained without recourse to aromatic stabilization, but this is contrary to what is generally accepted. 

Problem 29.2 (a) Cyclopropenones (1) have been made, and found to have rather unusual properties. 

Diphenylcyclopropenonc formed 1 1 stable crystalline complexes 2 with carboxylic acids. The physical properties of these complexes were consistent with a hydrogen-bonded complexation between the carbonyl oxygen of the cyclopropenone and the acidic hydrogen of the carboxylic acid. - ... 

By far the most studied cyclopropenone is 2,3-diphenylcyclo-propenone and many of the properties about to be described derive from studies of this compound. 

Property Cyclopropenone (C3H2O) Cyclopropanone (C3H4O) Acetone (C3H4O)... 

POL 03] POLOUKHTINE A., PopiK V.V., Highly Efficient Photochemical Generation of a Triple Bond Synthesis, Properties, and Photodecaibonylation of Cyclopropenones , Journal of Organic Chemistry, vol. 68, pp. 7833-7840, 2003. 

Poloukhtine, A. and Popik, V.V. (2003) Highly efficient photochemical generation of a triple bond synthesis, properties, and photodecarbonylation of cyclopropenones. Journal of Organic Chemistry, 68(20), 7833-7840. 

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