2,2,4,4-Tetramethylcyclobutanedione

2,2,4,4-Tetramethylcyclobutanedione
Names
	Preferred IUPAC name 2,2,4,4-Tetramethylcyclobutane-1,3-dione
	Other names Tetramethyl-1,3-cyclobutanedione, Tetramethylcyclobuta-1,3-dione
Identifiers
CAS Number	933-52-8;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL3183999;
ChemSpider	13028;
ECHA InfoCard	100.012.063
EC Number	213-269-6;
PubChem CID	13617;
UNII	RT4AQ22KS4;
CompTox Dashboard (EPA)	DTXSID4044745 ;
	InChI InChI=1S/C8H12O2/c1-7(2)5(9)8(3,4)6(7)10/h1-4H3 Key: RGCDVHNITQEYPO-UHFFFAOYSA-N;
	SMILES CC1(C(=O)C(C1=O)(C)C)C;
Properties
Chemical formula	C8H12O2
Molar mass	140.182 g·mol−1
Appearance	Colorless or white solid
Melting point	112–115 °C (234–239 °F; 385–388 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

2,2,4,4-Tetramethylcyclobutanedione is the organic compound with the formula (CH₃)₄C₄O₂. The compound is a diketone of cyclobutane, bearing four methyl groups. It is a white solid that is used as a precursor to diverse industrial products.

Synthesis and reactions

2,2,4,4-Tetramethylcyclobutanedione is the head-to-tail dimer of dimethylketene. It arises spontaneously when dimethylketene is produced by dehydrohalogenation of isobutyryl chloride with triethylamine.^[1]

In the presence of aluminium trichloride, 2,2,4,4-tetramethylcyclobutanedione isomerizes to the lactone dimethylketene dimer (4-isopropylidene-3,3-dimethyl-2-oxetanone).^[2] Dimethylketene dimer is a precursor to various alkyl ketene dimers, which are used in papermaking.

Hydrogenation of 2,2,4,4-tetramethylcyclobutanedione gives 2,2,4,4-tetramethylcyclobutanediol, which is of interest in polymer chemistry.

References

^ R. Huisgen, P. Otto (1968), "The mechanism of dimerization of dimethylketene", J. Am. Chem. Soc., vol. 90, no. 19, pp. 5342–5343, doi:10.1021/ja01021a090
^ R.H. Hasek; R.D. Clark; G.L. Mayberry (1968). "Dimethylketene β-Lactone Dimer". Organic Syntheses. 48: 72. doi:10.15227/orgsyn.048.0072.

[1] R. Huisgen, P. Otto (1968), "The mechanism of dimerization of dimethylketene", J. Am. Chem. Soc., vol. 90, no. 19, pp. 5342–5343, doi:10.1021/ja01021a090

[2] R.H. Hasek; R.D. Clark; G.L. Mayberry (1968). "Dimethylketene β-Lactone Dimer". Organic Syntheses. 48: 72. doi:10.15227/orgsyn.048.0072.

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