Cyclohexanehexone, also known as hexaketocyclohexane and triquinoyl, is an organic compound with formula C6O6, the sixfold ketone of cyclohexane. It is an oxide of carbon (an oxocarbon), a hexamer of carbon monoxide.

As of December 2016, this compound had yet to be synthesized in bulk.[1][2]

triquinoyl molecule
IUPAC name
Other names
hexaketocyclohexane, triquinoyl
3D model (JSmol)
ECHA InfoCard 100.007.649
Molar mass 168.06 g mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Related compounds

Cyclohexanehexone can be viewed as the neutral counterpart of the rhodizonate anion C
. The singly charged anion C
has been detected in mass spectrometry experiments by R. Wyrwas and C. Jarrold, formed by oligomerization of carbon monoxide through the formation of molybdenum carbonyls.[3]

According to X-ray diffraction analysis, the reagent traded under the name "cyclohexanehexone octahydrate" or equivalent names is actually dodecahydroxycyclohexane dihydrate, a solid that decomposes at 95 °C.[4][5]

In 1966, H. E. Worne of Natick Chemical Industries patented compounds with formulas C10O8 and C14O10, which can be described as the fusion of two or three molecules of C6O6, claimed to be produced by the action of ultraviolet radiation on a hot water solution of the parent compound.[6]

Triquinoyl therapy

In the late 1940s, W. Hale claimed that triquinoyl, being a trimer of W. Koch's glyoxylide, should be just as effective as the latter against "diabetes, arthritis, poliomyelitis, and even cancer".[7] Even though there is no research supporting this claim (and Koch's glyoxylide preparations were found to be just distilled water),[8] triquinoyl is still listed as an ingredient of some alternative medicine remedies.[9][10]


  1. ^ Gunther Seitz; Peter Imming (1992). "Oxocarbons and pseudooxocarbons". Chemical Reviews. 92 (6): 1227–1260. doi:10.1021/cr00014a004.
  2. ^ Schröder, Detlef; Schwarz, Helmut; Dua, Suresh; Blanksby, Stephen J.; Bowie, John H. (1999). "Mass spectrometric studies of the oxocarbons CnOn (n = 3–6)". International Journal of Mass Spectrometry. 188 (1–2): 17–25. doi:10.1016/S1387-3806(98)14208-2. ISSN 1387-3806.
  3. ^ Wyrwas, Richard B.; Jarrold, Caroline Chick (2006). "Production of C6O6-from Oligomerization of CO on Molybdenum Anions". Journal of the American Chemical Society. 128 (42): 13688–9. doi:10.1021/ja0643927. PMID 17044687.
  4. ^ Thomas M. Klapötke; Kurt Polborn; Jan J. Weigand (2005). "Dodecahydroxycyclohexane dihydrate". Acta Crystallographica E. 61 (5): o1393. doi:10.1107/S1600536805010007.
  5. ^ Person, Willis B.; Williams, Dale G. (1957). "Infrared Spectra and the Structure of Leuconic Acid and Triquinoyl". The Journal of Physical Chemistry. 61 (7): 1017–1018. doi:10.1021/j150553a047. ISSN 0022-3654.
  6. ^ Howard E Worne, U.S. Patent 3,227,641 "Polycarbonyls", issued Jan 4, 1966
  7. ^ William J. Hale (1949), "Farmer Victorious"
  8. ^ William W. Goodrich (1986), interview for FDA History (Part 2)
  9. ^ U. S. Food and Drug Administration (1989), Import Alert #66-46 – Unapproved Version of Rodaquin
  10. ^ Renewal & Wellness, LLC (2009) Archived 2009-04-03 at the Wayback Machine, an alternative medicine claimed to contain triquinoyl. Last accessed on March 25, 2009

See also


The molecular formula C6O6 (molar mass : 168.06 g/mol) may refer to:


Ethylenetetracarboxylic dianhydride


Carbon (from Latin: carbo "coal") is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Three isotopes occur naturally, 12C and 13C being stable, while 14C is a radionuclide, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity.Carbon is the 15th most abundant element in the Earth's crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. Carbon's abundance, its unique diversity of organic compounds, and its unusual ability to form polymers at the temperatures commonly encountered on Earth enables this element to serve as a common element of all known life. It is the second most abundant element in the human body by mass (about 18.5%) after oxygen.The atoms of carbon can bond together in different ways, termed allotropes of carbon. The best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form. For example, graphite is opaque and black while diamond is highly transparent. Graphite is soft enough to form a streak on paper (hence its name, from the Greek verb "γράφειν" which means "to write"), while diamond is the hardest naturally occurring material known. Graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials. All carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form at standard temperature and pressure. They are chemically resistant and require high temperature to react even with oxygen.

The most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes. The largest sources of inorganic carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil, and methane clathrates. Carbon forms a vast number of compounds, more than any other element, with almost ten million compounds described to date, and yet that number is but a fraction of the number of theoretically possible compounds under standard conditions. For this reason, carbon has often been referred to as the "king of the elements".

Carbon monoxide

Carbon monoxide (CO) is a colorless, odorless, and tasteless gas that is slightly less dense than air. It is toxic to animals that use hemoglobin as an oxygen carrier (both invertebrate and vertebrate) when encountered in concentrations above about 35 ppm, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal biological functions. In the atmosphere, it is spatially variable and short lived, having a role in the formation of ground-level ozone.

Carbon monoxide consists of one carbon atom and one oxygen atom, connected by a triple bond that consists of two covalent bonds as well as one dative covalent bond. It is the simplest oxocarbon and is isoelectronic with other triply-bonded diatomic molecules having ten valence electrons, including the cyanide anion, the nitrosonium cation and molecular nitrogen. In coordination complexes the carbon monoxide ligand is called carbonyl.


Cyclobutanetetrone, also called tetraoxocyclobutane, is an organic compound with formula C4O4 or (CO)4, the fourfold ketone of cyclobutane. It would be an oxide of carbon, indeed a tetramer of carbon monoxide.

The compound seems to be thermodynamically unstable. As of 2000, it had yet to be synthesized in significant amounts but may have transient existence as detected by mass spectrometry.


Cyclopentanepentone, also known as leuconic acid, is a hypothetical organic compound with formula C5O5, the fivefold ketone of cyclopentane. It would be an oxide of carbon (an oxocarbon), indeed a pentamer of carbon monoxide.

As of 2000, the compound had yet to be synthesized in bulk, but there have been reports of trace synthesis.


Dodecahydroxycyclohexane is an organic compound with molecular formula C6O12H12 or C6(OH)12. It is a sixfold geminal diol with a cyclohexane backbone and can be regarded as a sixfold hydrate of cyclohexanehexone (C6O6).

Ethylene dione

Ethylene dione or ethylenedione, also called dicarbon dioxide, ethenedione, or ethene-1,2-dione, is a chemical compound with the formula C2O2 or OCCO. It is the carbon-carbon covalent dimer of carbon monoxide and belongs to the oxocarbon series. Because it is a dimer, it shares an empirical formula with CO. It can be thought of as ketene of glyoxylic acid (OHCCOOH).

The existence of OCCO was first suggested in 1913. However, despite its deceptively "simple" structure, for over a century the compound had eluded all attempts to synthesize and observe it. Such elusive nature had earned OCCO the reputation of a hypothetical compound and a mysterious, "exceedingly coy molecule".It was not until 2015 that a group of chemists from the University of Arizona in Tucson (United States) reported the first spectroscopic characterization of OCCO, confirming its existence as a transient molecule. The Arizona group created OCCO using laser light to eject electrons from the corresponding stable singly-charged anions. Recently, spectra of oxyallyl diradical, C₃H₄O, were also found to have features nearly identical to those reported for OCCO and the spectra for ethylenedione reported by the Arizona group is reassigned to the oxyallyldiradical. In conclusion, the long-lived states of ethylenedione, sought experimentally for over a century, remain unobserved. Recently, the in situ preparation and characterization of the OCCO through low-energy free-electron induced single molecular engineering has also been theoretically proposed by scientists from Bhabha Atomic Research Centre (India). Despite the existence of the closed-shell Kekulé structure, O=C=C=O, the lowest bound state of ethyledione is a triplet. Therefore, bound OCCO is formally a diradical, with an electronic structure motif similar to the oxygen molecule. However, when the molecule is distorted away from its equilibrium geometry, the potential surfaces of the triplet and singlet states intersect, allowing for intersystem crossing to the singlet state, which is unbound and dissociates to two ground-state CO molecules. The timescale of the intersystem crossing was predicted to be 0.5 ns, making triplet OCCO a transient, yet spectroscopically long-lived molecule.

On the other hand, the monoanion of ethylenedione, OCCO−, as well as the divalent anion C2O2−2, called acetylenediolate, are both stable.

Ethylenetetracarboxylic dianhydride

Ethylenetetracarboxylic dianhydride is a chemical compound with formula C6O6, that can be seen as the twofold anhydride of ethylenetetracarboxylic acid C6H4O8. Its molecular backbone consists of two five-atom maleic anhydride rings, each containing one oxygen atom and four carbon atoms, sharing a pair of carbons. It is one of the oxides of carbon. It is a pale yellow oily liquid, soluble in dichloromethane and trichloromethane.The compound and its reactions were studied in 1967 by Sauer, Schröder and others. Synthesis of the compound by pyrolysis of ethylenetetracarboxylic acid was reported in 1981 by Patterson and others.The compound was also obtained in 2009 by Taherpour, by microwave pyrolysis of solid Meldrum's acid. Two molecules of the acid are believed to dimerize via an alkene linkage. The meldrum's-acid rings open via hydrolysis to form ethylenetetracarboxylic acid, and then the carboxylic acid units recyclize with different partners to form the dianhydride.


An oxocarbon or oxide of carbon is a chemical compound consisting only of carbon and oxygen.The simplest and most common oxocarbons are carbon monoxide (CO) and carbon dioxide (CO2) with IUPAC names carbon(II) oxide and carbon(IV) oxide respectively. Many other stable (practically if not thermodynamically) or metastable oxides of carbon are known, but they are rarely encountered, such as carbon suboxide (C3O2 or O=C=C=C=O) and mellitic anhydride (C12O9).

While textbooks will often list only the first three, and rarely the fourth, a large number of other oxides are known today, most of them synthesized since the 1960s. Some of these new oxides are stable at room temperature. Some are metastable or stable only at very low temperatures, but decompose to simpler oxocarbons when warmed. Many are inherently unstable and can be observed only momentarily as intermediates in chemical reactions or are so reactive that they can exist only in the gas phase or under matrix isolation conditions.

The inventory of oxocarbons appears to be steadily growing. The existence of graphene oxide and of other stable polymeric carbon oxides with unbounded molecular structures suggests that many more remain to be discovered.

Rhodizonic acid

Rhodizonic acid is a chemical compound with formula C6H2O6 or (CO)4(COH)2. It can be seen as a two-fold enol and four-fold ketone of cyclohexene, more precisely 5,6-dihydroxycyclohex-5-ene-1,2,3,4-tetrone.

Rhodizonic acid is usually obtained in the form of a "dihydrate" C6H2O6·2H2O. The latter is actually 2,3,5,5,6,6-hexahydroxycyclohex-2-ene-1,4-dione, where two of the original ketone groups are replaced by two pairs of geminal diols. The orange to deep-red and highly hygroscopic anhydrous acid can be obtained by low-pressure sublimation of the dihydrate.Like many other enols, rhodizonic acid can lose the hydrogen cations H+ from the hydroxyls (pK1 = 4.378 ± 0.009, pK2 = 4.652 ± 0.014 at 25 °C), yielding the hydrogenrhodizonate anion C6HO6− and the rhodizonate anion C6O62−. The latter is aromatic and symmetric, as the double bond and the negative charges are delocalized and evenly distributed over the six CO units. Rhodizonates tend to have various shades of red, from yellowish to purplish.

Rhodizonic acid has been used in chemical assays for barium, lead, and other metals. In particular, the sodium rhodizonate test can be used to detect gunshot residue (which contains lead) in a subject's hands, and to distinguish arrow wounds from gunshot wounds for hunting regulation enforcement.


Tetrahydroxy-1,4-benzoquinone, also called tetrahydroxy-p-benzoquinone, tetrahydroxybenzoquinone, or tetrahydroxyquinone (THBQ, THQ), is an organic compound with formula C6O2(OH)4. Its molecular structure consists of a cyclohexadiene ring with four hydroxyl groups and two ketone groups in opposite (para) positions.

The compound gives a light red solution in water, and crystallizes as the glistening bluish-black (but non-conducting) dihydrate C6O2(OH)4·2H2O.The compound can be synthesized from glyoxal or from myo-inositol (phytic acid), a natural compound widely present in plants. THBQ forms an adduct with 4,4'-bipyridine in the 2:3 ratio.

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