Chemistry - STEREO ISOMERISM Question with Solution | TestHub
Assign priority numbers to the following groups :
(a) -CH2OH -CH3 -CH2CH2OH -H
(b) -CH=O -OH -CH3 -CH2OH
(c) -CH(CH3)2 -CH2CH2Br -Cl -CH2CH2CH2Br
(d) -CH=CH2 -CH2CH3 -C6H5 -CH3
Options:
Answer:
Solution:
List the atoms attached to the first atom of each group and look for the first point of difference (double bonds are duplicated).
(a) CH2OH : (O, H, H); CH2CH2OH : (C, H, H); CH3 : (H, H, H); H : -. So CH2OH = 1, CH2CH2OH = 2, CH3 = 3, H = 4.
(b) OH = 1 (oxygen). CH=O : (O, O, H); CH2OH : (O, H, H); CH3 : (H, H, H). So OH = 1, CH=O = 2, CH2OH = 3, CH3 = 4.
(c) Cl = 1. CH(CH3)2 : (C, C, H) = 2. CH2CH2Br and CH2CH2CH2Br both start (C, H, H); at the next atom (Br, H, H) beats (C, H, H), so CH2CH2Br = 3, CH2CH2CH2Br = 4.
(d) C6H5 : the ipso carbon counts as (C, C, C) (one aromatic bond duplicated) = 1; CH=CH2 : (C, C, H) = 2; CH2CH3 : (C, H, H) = 3; CH3 : (H, H, H) = 4.
Ans. (a) CH2OH = 1, CH2CH2OH = 2, CH3 = 3, H = 4 (b) OH = 1, CH=O = 2, CH2OH = 3, CH3 = 4 (c) Cl = 1, CH(CH3)2 = 2, CH2CH2Br = 3, CH2CH2CH2Br = 4 (d) C6H5 = 1, CH=CH2 = 2, CH2CH3 = 3, CH3 = 4
