Tetraphenylcyclopentadienone is an organic compound with the formula (C6H5)4C4CO. It is a dark purple to black crystalline solid that is soluble in organic solvents. It is an easily made building block for many organic and organometallic compounds.
Structure
The C5O core of the molecule is planar and conjugated, but the bonds have a definite alternating single- and double-bond nature. The C2–C3 and C4–C5 distances are 1.35 Å, while the C1–C2, C3–C4, C5–C1 are closer to single bonds with distances near 1.50 Å.[1] The phenyl groups of tetraphenylcyclopentadienone adopt a "propeller" shape in its 3D conformation. The four phenyl rings are rotated out of the plane of the central ring because of steric repulsion with each other.[3]
Unlike the parent compound cyclopentadienone, which rapidly dimerizes,[4] the tetraphenyl derivative is stable.
Synthesis
Tetraphenylcyclopentadienone can be synthesized by a double aldol condensation involving benzil and dibenzyl ketone in the presence of a basic catalyst.[2][5]
^ a bJ. C. Barnes; W. M. Horspool; F. I. Mackie (1991). "2,3,4,5-Tetraphenylcyclopenta-2,4-dien-1-one and 5,6,7,8-tetrachloro-3a,9a-dihydro-2,3,3a,9a-tetraphenylcyclopenta[2,3-b][1,4]benzodioxin-1-one–toluene (2/1): Compounds of photochemical interest". Acta Crystallogr. C. 47 (1): 164–168. Bibcode:1991AcCrC..47..164B. doi:10.1107/S0108270190005145.
^ a bJohn R. Johnson, J. R.; Grummitt, O. (1943). "Tetraphenylcyclopentadienone". Organic Syntheses. 23: 92{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 3, p. 805.
^Sheley, C. F.; Shechter, H. (1970). "Cyclopentadienones from 1,2,4-cyclopentanetriones, 2-cyclopentene-1,4-diones, and 3-cyclopentene-1,2-diones". The Journal of Organic Chemistry. 35 (7): 2367–2374. doi:10.1021/jo00832a058.
^Ogliaruso, Michael A.; Romanelli, Michael G.; Becker, Ernest I. (1965). "Chemistry of Cyclopentadienones". Chemical Reviews. 65 (3): 261–367. doi:10.1021/cr60235a001.
^ a bFieser, L. F. (1966). "Hexaphenylbenzene". Organic Syntheses. 46: 44; Collected Volumes, vol. 5, p. 604.
^Feng, Xinliang; Pisula, Wojciech; Müllen, Klaus (31 January 2009). "Large polycyclic aromatic hydrocarbons: Synthesis and discotic organization". Pure and Applied Chemistry. 81 (12): 2203–2224. doi:10.1351/PAC-CON-09-07-07. S2CID 98098882.
^Hawkins, P. J.; Janz, J. G. (1949). "315. The reaction of cyanogen and related nitriles with 1 : 3-dienes. Part I. Thermodynamic considerations, and a study of the uncatalysed reaction of cyanogen and related nitriles with 1 : 3-butadiene". Journal of the Chemical Society: 1479–148. doi:10.1039/JR9490001479.