1,3-Cyclobutanedione
Chemical compound
From Wikipedia, the free encyclopedia
1,3-Cyclobutanedione is an organic compound with the formula (CH2)2(CO)2. It is an isomer of 1,2-cyclobutanedione. The compound would be of little interest except that its tautomer is a subunit in some commercial dyes.
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| Names | |
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| Preferred IUPAC name
Cyclobutane-1,3-dione | |
| Identifiers | |
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3D model (JSmol) |
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| ChemSpider | |
PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |
| C4H4O2 | |
| Molar mass | 84.074 g·molâ1 |
| Appearance | colorless or white solid |
| Density | 1.12 g/cm3 |
| Melting point | 119â120 °C (246â248 °F; 392â393 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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In solution, 1,3-cyclobutanedione exists in equilibrium with a less stable tautomer, called squaraine, 3-hydroxycyclobut-2-enone.[1] Squaraine dyes are, formally at least, derivatives of squaraine. In such dyes, the ene-one tautomer predominates.
The mixture of tautomers can be prepared by hydrolysis of 1-ethoxycyclobutene-3-one, which is prepared from the cycloaddition of ethoxyacetylene to ketene. [2]
Substituted derivatives
A variety of substituted 1,3-Cyclobutanediones form upon spontaneous dimerization of disubstituted ketenes.[3] 2,2,4,4-Tetramethylcyclobutanedione is thus formed by dehydrochlorination of isobutyryl chloride:[4]
- (CH3)2CHCOCl + Et3N â (CH3)2C=C=O + Et3NHCl
- 2 (CH3)2C=C=O â (CH3)2C)2(C=O)2
Ketene itself dimerizes mainly to give the lactone called diketene as well as a small amount of 1,3-cyclobutanedione.
Related compounds
- Moniliformin, a naturally occurring derivative of 3-hydroxycyclobut-2-enone