For a substituted biphenyl compound to be chiral and exhibit optical activity, it must satisfy speci — Haloalkanes and Haloarenes Chemistry Question

💡 Solution & Explanation

Biphenyls exhibit atropisomerism—chirality arising from hindered rotation about a single bond. A) True. Without severe steric hindrance at the ortho positions, the single bond rotates freely, allowing the molecule to periodically pass through a planar, achiral conformation. B) True. Even if the rings are locked perpendicular to each other, if either ring has a local plane of symmetry (e.g., both ortho positions on one ring have identical groups), the entire molecule will have a plane of symmetry and be achiral. C) False. The presence of any improper axis of rotation, including a center of inversion ($S_2$), guarantees that the molecule is achiral and optically inactive. D) True. Groups must be large enough to collide sterically if the molecule attempts to become planar. Standard bulky groups include nitro, bromo, and carboxyl groups.