Cyclobutene is a cycloalkene. It is of interest as a fundamental value, not for practical applications. It is a colorless easily condensed gas. A modern synthesis involves the 2-step dehydration of cyclobutanol. The compound was first prepared by thermolysis of the ammonium salt OH. Cyclobutene is a cycloalkene. It is of interest as a fundamental value, not for practical applications. It is a colorless easily condensed gas. A modern synthesis involves the 2-step dehydration of cyclobutanol. The compound was first prepared by thermolysis of the ammonium salt OH.