Chemistry - STEREO ISOMERISM Question with Solution | TestHub
In the Newman projection for 1,2-dichloropropane, X and Y can respectively be :
(A) Cl and H (B) Cl and CH₃
(C) CH₃ and Cl (D) H and CH₂Cl
Options:(select one or more)
Answer:
Solution:
Ans : (B, D).
Put the values of X and Y in each structure and read off the carbon skeleton :
(A) :
The front carbon carries Cl, H, H and the back carbon carries Cl, H, H : the molecule is ClCH₂-CH₂Cl (1,2-dichloroethane) - only two carbons, so it is not 1,2-dichloropropane.
(B) :
The molecule is ClCH₂-CHCl-CH₃ = 1,2-dichloropropane - correct.
(C) :
The molecule is CH₃-CHCl₂ (1,1-dichloroethane) - both chlorines on the same carbon, so it is not 1,2-dichloropropane.
(D) :
The molecule is CH₃-CHCl-CH₂Cl = 1,2-dichloropropane, viewed from the CH₃ end - correct.
Hence X and Y can be Cl and CH₃, or H and CH₂Cl : (B) and (D).
