Propose a synthesis of bicyclohexylidene, starting from cyclohexanone as the only source of carbon.

Organic reactions involve changing one functional group to another by using oxidizing agents or reducing agents depending on the compound we want.For example, a ketone is converted to alcohol using${\text{LiAlH}}_{\text{4}}$ (a reducing agent).

Starting from cyclohexanone, the ketone group is reduced to secondary alcohol by using a reducing agent ${\text{LiAlH}}_{\text{4}}$, ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$. The cyclohexanol formed is now treated with ${\text{PBr}}_{\text{3}}$; it converts alcohol to alkyl bromide, and we get bromocyclohexanol.

On further treating bromocyclohexanol with Mg, ether, we get ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}\text{MgBr}$(Grignard reagent). When this Grignard reagent is treated with Cyclohexanone and acid in the water, we get a compound which, further on reaction with ${\text{H}}_2{\text{SO}}_4$, gives the Bicyclohexylidene (desired product).

Synthesis of bicyclohexylidene from cyclohexanone