Chemistry - STEREO ISOMERISM Question with Solution | TestHub

The twist-boat is formed by twisting the boat slightly, which moves the two prow (C-1 and C-4) flagpole hydrogens apart and relieves their steric clash; this is why the twist-boat lies below the boat in energy. The half-chair is higher still (a transition-state-like form), the chair has no flagpole carbons at all, and cyclohexane has no 'envelope' conformation.