Question

Which Newman projection represents the most stable conformation of (CH),CHCH(CH)2? CH3 CH3 СCH3 (B) (A) CH3 H CH3 "СHз CHз CH3 CH3 н CH3 (D) (C) H. tCH3 CH3 CH3 Н Н CH3 CH3

Answer 1

Solution :- Newman projection is a way of representing the conformation of a chemical bond from front to back , with the furont atom represented by dot, and the back Cauben as a urcle. > Newmans projection of (1913), CHCH (CH3)2 ane drawn diffecently as follows:- Here, in this case all the fcouse methyl groups are at boʻ angle and is not a stable configuration as there are ų gauchy interaction This fischer projectiên is 'reast stable 122 ph In this case, three methyl groups are at 60° angle and is "more stable than GA?" as it has 3 gauchy interaction. н In this case, two-two methyl gecoups que at 60' angle and have two-two gauchy Patenáction, which are Mense sepauated by Mydlungen atoms. Hence, this one is the 'most stable conformation"

This case is similar to the case Coy, as & all the three methyl groups are at 60° angle having | 3 gauchy interaction. It is a less stable than 1c). Mence, Option (c) represents the correct Neuman projection for CH3), CH CH (CH3)2