Groups are considered different if there is anystructural variation(if the groups could not be superimposed if detached they are different In cyclic molecules, we compare by following in each direction in a ring Symmetry plane H CH3 H CH Me exane 2- Methylcyclohexanone (chiral) Thomson· Brooks cole
• Groups are considered “different” if there is anystructural variation (if the groups could not be superimposed if detached, they are different) • In cyclic molecules, we compare by following in each direction in a ring
CHo HoC CHo CHo HoC CH CHo Carvone(spearmint oil) Nootkatone(grapefruit oil) C2004 Thomson-Brooks/Cole 香芹酮 诺卡酮(葡萄柚油)
香芹酮 诺卡酮(葡萄柚油)
6.2 The reason for Handedness: Chirality Molecules that are not superimposable with their mirror images are chiral(have handedness) a molecule with a plane of symmetr is the same as its mirror image and is said to be achiral
6.2 The Reason for Handedness: Chirality • Molecules that are not superimposable with their mirror images are chiral (have handedness) • A molecule with a plane of symmetry is the same as its mirror image and is said to be achiral
Plane of symmetry The plane has the same thing on both sides for the flask There is no mirror plane for a hand
Plane of Symmetry • The plane has the same thing on both sides for the flask • There is no mirror plane for a hand
6.3 Optical activity The source passes through a polarizer and then is detected at a second polarizer The angle between the entrance and exit planes is the optical rotation Unpolarized Polarized Light source Polarizer Sample tube containing analyzer Observer organic molecules Thomson· Brooks cole
• The source passes through a polarizer and then is detected at a second polarizer • The angle between the entrance and exit planes is the optical rotation. 6.3 Optical Activity