Chemistry:Tetrahydroxy-1,4-benzoquinone
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| Preferred IUPAC name
2,3,5,6-Tetrahydroxycyclohexa-2,5-diene-1,4-dione | |
| Other names
Tetroquinone
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| Properties | |
| C6H4O6 | |
| Molar mass | 172.092 g·mol−1 |
| Appearance | Blue-black crystals |
| Density | 2.609 g/cm3 |
| Boiling point | 370.6 °C (699.1 °F; 643.8 K) at 760 mmHg |
| Slightly soluble in cold water | |
| Hazards | |
| GHS pictograms | 
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| GHS Signal word | Warning |
| H315, H319, H335 | |
| P261, P264, P271, P280, P302+352, P304+340, P305+351+338, P312, P321, P332+313, P337+313, P362, P403+233, P405, P501 | |
| Flash point | 192.1 °C (377.8 °F; 465.2 K) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
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| Infobox references | |
Tetrahydroxy-1,4-benzoquinone, also called tetrahydroxy-p-benzoquinone, tetrahydroxybenzoquinone, or tetrahydroxyquinone (THBQ, THQ), is an organic compound with formula C
6O
2(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,[2] and crystallizes as the glistening bluish-black (but non-conducting) dihydrate C
6O
2(OH)
4 · 2H2O.[2][3]
The compound can be synthesized from glyoxal[4] or from myo-inositol, a natural compound widely present in plants.[5] THBQ forms an adduct with 4,4′-bipyridine in a 2:3 ratio.[6]
Salts of THBQ
Like most phenols, THBQ is acidic and easily loses the four hydrogen ions from the hydroxyl groups, yielding anions such as C
6H
2O2−
6 and C
6O4−
6.
The calcium salt Ca
2C
6O
6 is the dark purple pigment produced from inositol by Chromohalobacter beijerinckii in the fermentation of salt beans, already noted by T. Hof in 1935.[3][7][8][9][10]
The dark purple and insoluble dipotassium salt K
2C
6H
2O
6 was prepared by Preisler and Berger in 1942, by oxidizing inositol with nitric acid and reacting the result with potassium carbonate in the presence of oxygen. Reaction of this salt with hydrochloric acid produces THBQ in good yield.[11]
The black tetrapotassium salt K
4C
6O
6 was prepared by West and Niu in 1962, by reacting THBQ with potassium methoxide in methanol. The salt is diamagnetic and the infrared spectrum suggests that the C–C and C–O distances are all equal, with the ring slightly distorted in the "chair" conformation.[12] Partial oxidation of K
4C
6O
6 affords a green, strongly paramagnetic solid, conjectured to be 3K+
· C
6O3−
6, and complete oxidation yields potassium rhodizonate 2K+
· C
6O2−
6.[12]
The greenish-black sodium salt Na
4C
6O
6 was described by Fatiadi and Sanger in 1962.[4]
The dark-violet lithium salt Li
4C
6O
6 has been proposed as an electrode material for batteries as it can be oxidized to the rhodizonate Li
2C
6O
6 and reduced to the hexahydroxybenzene salt Li
6C
6O
6.[5] In the absence of oxygen, Li
4C
6O
6 is stable to about 450 °C and then decomposes leaving a residue of lithium carbonate.[5] Indeed, the rhodizonate appears to disproportionate at about 400 °C into Li
4C
6O
6 and cyclohexanehexone C
6O
6 that promptly decomposes into carbon monoxide, carbon dioxide, and carbon.[5] Li
4C
6O
6 forms a hydrate Li
4C
6O
6 · 2H2O that loses its water at about 250 °C.[5]
References
- ↑ The Merck Index (11th ed.). p. 9177.
- ↑ 2.0 2.1 Klug, H. P. (1965). "The crystal structure of tetrahydroxy-p-benzoquinone". Acta Crystallographica 19 (6): 983. doi:10.1107/S0365110X65004760.
- ↑ 3.0 3.1 Miller, M. W. (1961). Microbial Metabolites. McGraw-Hill.
- ↑ 4.0 4.1 Fatiadi, A. J.; Sanger, W. F.. "Tetrahydroxyquinone". Organic Syntheses 42: 90.; Collective Volume, 5, pp. 1011
- ↑ 5.0 5.1 5.2 5.3 5.4 Chen, H.; Armand, M.; Courty, M.; Jiang, M.; Grey, C. P.; Dolhem, F.; Tarascon, J.-M.; Poizot, P. (2009). "Lithium salt of tetrahydroxybenzoquinone: toward the development of a sustainable Li-ion battery". Journal of the American Chemical Society 131 (25): 8984–8988. doi:10.1021/ja9024897. PMID 19476355.
- ↑ Cowan, J. A.; Howard, J. A. K.; Leech, M. A. (2001). "Interpenetrating supramolecular lattices in 4,4′-bipyridine-2,3,5,6-tetrahydroxy-1,4-benzoquinone (3/2)". Acta Crystallographica Section C 57 (10): 1196–1198. doi:10.1107/S0108270101011647. PMID 11600783.
- ↑ Hof, T. (1935). Recueil des travaux botaniques néerlandais. 32. New Zealand: F.E. Macdonald; Dutch Botanical Society. p. 92. OCLC 312975183. https://books.google.com/books?id=wlgQAQAAMAAJ.
- ↑ Kluyver, A. J.; Hof, T.; Boezaardt, A. G. J. (1939). "On the pigment of Pseudomonas beijerinckii Hof (Chromohalobacter beijerinckii)". Enzymologia 7 (257).[full citation needed]
- ↑ Elvehjem, C. A. (June 1947). "Vitamins and Hormones—Advances in Research and Applications". American Journal of Public Health and the Nation's Health 37 (6): 776. doi:10.2105/AJPH.37.6.776. ISSN 0002-9572.
- ↑ Underkofler, L. A.; Hickey, R. J. (1954). Industrial Fermentations. https://books.google.com/books?id=8ewQAAAAMAAJ.[page needed]
- ↑ Preisler, P. W.; Berger, L. (1942). "Preparation of tetrahydroxyquinone and rhodizonic acid salts from the product of the oxidation of inositol with nitric acid". Journal of the American Chemical Society 64 (1): 67–69. doi:10.1021/ja01253a016.
- ↑ 12.0 12.1 West, R.; Niu, H. Y. (1962). "Symmetrical Resonance Stabilized Anions, CnO−mn. II. K4C6O6 and Evidence for C6O−36". Journal of the American Chemical Society 84 (7): 1324–1325. doi:10.1021/ja00866a068.
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