How many optically active stereoisomers exist for 1,2-dibromocyclopropane? — Haloalkanes and Haloarenes Chemistry Question

💡 Solution & Explanation

1,2-dibromocyclopropane has two stereocenters (C1 and C2). It can exist in cis and trans geometries. 1) In cis-1,2-dibromocyclopropane, the two bromine atoms are on the same side of the ring. This configuration possesses a plane of symmetry bisecting the C1-C2 bond and passing through C3. Due to this internal symmetry, the cis isomer is a meso compound and is optically inactive. 2) In trans-1,2-dibromocyclopropane, the bromine atoms are on opposite sides. This geometry lacks any plane or center of symmetry. Therefore, the trans isomer is chiral and exists as a pair of non-superimposable mirror images (two enantiomers). Consequently, there are exactly 2 optically active stereoisomers.