Question

`CH_(3)-CHCI-CH_(2)=CH_(3)` has a chiral centre. Which one of the following represents its `R` configuration?
A. `CI-overset(C_(2)H_(5))overset(|)underset(H)underset(|)C-CH_(3)`
B. `H-overset(CH_(3))overset(|)underset(C_(2)H_(5))underset(|)C-CI`
C. `H_(3)C-overset(C_(2)H_(5))overset(|)underset(H)underset(|)C-CI`
D. `H-overset(C_(2)H_(5))overset(|)underset(CI)underset(|)C-CH_(3)`

Answer 1

Correct Answer - A
The priority order is `CI gtC_(2)H_(5) gtCH_(3) gt H`.

The `R` (for Laton word 'rectus', meaning right) configuraiton is assigned to chiral carbon if the order of decreasing priority of the three higher ranking substituents is clockwise. The `S` (for Latin word 'sinister'n meaning left) configuration is assinged if the order of decreasing priority is anticlockwise.