2,2,4,4-Tetramethylcyclobutanedione is the organic compound with the formula (CH<sub>3</sub>)<sub>4</sub>C<sub>4</sub>O<sub>2</sub>. 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.
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.
In the presence of aluminium trichloride, 2,2,4,4-tetramethylcyclobutanedione isomerizes to the lactone dimethylketene dimer (4-isopropylidene-3,3-dimethyl-2-oxetanone). 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.