1,2-Cyclobutanedione is an organic compound with the formula (CH2)2(CO)2.

It is one of two isomers of cyclobutanedione, the other being 1,3-cyclobutanedione.

It is prone to polymerization.

It is prepared by desilylation of 1,2-bis(trimethylsiloxy)cyclobutene.

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