Chemistry - STEREO ISOMERISM Question with Solution | TestHub
Are these compounds chiral ? Draw diagrams to justify your answer.
(1) 
(2) 
(3) 
(4) 
(5) 
Options:
Answer:
Solution:
Ans. Compounds (2), (4) and (5) are chiral; (1) and (3) are not.
Sol. Only one thing matters - does the molecule have a plane of symmetry (or any other improper symmetry element)? Do not just look for chiral centres; look for a plane of symmetry.
(1) trans-1,4-Dimethylcyclohexane: a plane through C1 and C4 reflects the two halves onto each other : NOT chiral. (2) trans-1,2-Dimethylcyclohexane: no plane, centre or alternating axis : CHIRAL. (3) cis-1,2-Dimethylcyclohexane: a plane bisecting the C1-C2 bond exchanges the two halves (meso) : NOT chiral. (4) Butan-2-ol: four different groups on C2, no symmetry : CHIRAL. (5) 3-Methylhexane: C3 bears H, CH3, C2H5 and C3H7 : CHIRAL.
