JEE ADVANCED CHEMISTRY QUESTION SEPTEMBER 2020
Answers
Which of the following options represents identical molecules )
(A) P and Q (B) Q and S
(C) Q and R (D) R and S
solution : all compounds are given in conformational forms.
conformational form : we know, single bonds in organic compounds are free to rotate, due to end to end nature of their overlap. rotation about single bond (sigma bond) results in many different possible 3d arrangements of the compounds. this different arrangements resulting from sigma bond rotation, are known as conformations in organic chemistry .
P is written in structural form as . C2H5-(CH3)C(CH3) -(CH3)C(OH)-CH3 (2,3,3-Trimethylpentan-2-ol)
Q is written in structural form as , C2H5-CH(CH2-CH3)-(CH3)C(CH3)-OH (3-Ethyl-methylpentan-2-ol)
R is written in structural form as, C2H5-CH(C2H5)-(CH3)C(OH)-CH3 (3-Ethyl-2-methylpentan-2-ol)
S is written in structural form as, C2H5-(OH)C(CH2-CH3)-CH(CH3)-CH3 (3-Ethyl-2-methypentan-3-ol)
it is clear that Q and R has identical molecules.Therefore the correct option is (C) Q and R