ABC26OR0039 · General Organic Chemistry
Subject: Organic Chemistry · Chapter: General Organic Chemistry · Topic: Conformational Analysis · Exam: CSIR-NET JUNE 2015 · Marks: 2 · Difficulty: Medium
The correct statements about conformations X and Y of 2-butanone are 
(X) (Y) (A) X is more stable than Y (B) Y is more stable than X (C) Methyl groups in X are anti (D) Methyl groups in Y are gauche
(X) (Y) (A) X is more stable than Y (B) Y is more stable than X (C) Methyl groups in X are anti (D) Methyl groups in Y are gauche(a)A and D
(b)A and C
(c)B and C
(d)A, C and D
Answer
Answer (as printed): D
Explanation
• The relationship between groups or atoms whose dihedral angle is 180o is said to be anti- periplanar. • The relationship between groups or atoms whose dihedral angle is more than 0o but less than 120o are said to be gauche. A conformation which has one or more gauche interactions is called gauche conformation.
Explanation as extracted from the printed page; notation may be imperfect.