"Substituted cyclohexanes are the most common cycloalkanes and occur widely in nature. A large number of compounds, including steroids and many pharma ceutical agents, have cyclohexane rings. The flavoring agent menthol, for instance, has three substituents on a six-membered ring. … Cyclohexane adopts a strain-free, three-dimensional shape that is called a chair conformation because of its similarity to a lounge chair, with a back, seat, and footrest … The easiest way to visualize chair cyclohexane is to build a molecular model. … In addition to the chair conformation of cyclohexane, an alternative called the twist-boat conformation is also nearly free of angle strain."