What is "bicyclobutane"

n. 1 (context organic compound English) A bicyclic hydrocarbon consisting of two separate cyclobutane rings joined by a single bond 2 (context organic compound English) A highly strained, bicyclic hydrocarbon consisting of two fused cyclopropane rings

Bicyclobutane is an organic compound with the formula CH. Consisting of two fused cyclopropane rings, it is one of the most strained compounds isolatable on a large scale. It is a colorless easily condensed gas.

The first reported bicyclobutane was the carboxyethyl derivative, CHCOEt, which was prepared by dehydrohalogenation the corresponding bromo cyclobutanecarboxylate ester. The parent hydrocarbon was prepared by conversion of bromocyclobutanecarboxylate ester to 1-bromo-3-chlorocyclobutane, followed intramolecular Wurtz coupling using molten sodium:

Cl― ◇―Br + Na → ⏤⃟ + NaCl + NaBr

It is a nonplanar molecule, with a dihedral angle of 123°.