Cyclopropane

Cyclopropane is a cycloalkane with the chemical formula C3H6. It consists of a three-membered carbon ring, with bond angles close to 60 degrees. The small ring size induces significant ring strain, making cyclopropane more reactive than larger cycloalkanes and influencing its chemistry in characteristic ways.

At room temperature, cyclopropane is a colorless, highly flammable gas. It boils at about −33 °C and has a faint odor. It is sparingly soluble in water and more soluble in organic solvents. Because it is a gas at ambient conditions, handling requires proper pressurized containment and ventilation. In addition to flammability, high concentrations can displace air and pose asphyxiation hazards.

Preparation and reactions: Cyclopropane can be produced by several routes, including the dehalogenation of 1,2-dihalo cyclopropanes and by cyclopropanation of alkenes using methylene transfer reagents (for example, the Simmons–Smith reaction). The high ring strain drives various reactions, including ring-opening under acidic, radical, or thermal conditions, which yields linear or branched products. Cyclopropane rings can also serve as masked allyl equivalents in synthesis, and they can be oxidized or functionalized to give diverse cyclopropyl derivatives.

Uses and history: Cyclopropane is primarily a synthetic building block in organic and medicinal chemistry, used to construct cyclopropyl-containing compounds found in pharmaceuticals and agrochemicals. Historically, it was explored as a general anesthetic but has largely been replaced by other agents due to safety, regulatory, and control considerations. Today, its role is mainly in research and industrial synthesis rather than routine medical use.