In the following structures, which two forms are staggered conformations of ethane ?

Question

In the following structures, which two forms are staggered conformations of ethane ? (A) 1 and 4 (B) 2 and 3 (C) 1 and 2 (D) 1 and 3

Tardigrade Admin · Accepted Answer

A chemical conformation of an ethane-like molecule

ab c X - Y

def in which the substituents

a, b,

and

c

are at the greatest distance from

d, e

, and

f

is called a staggered conformation.
Explanation
Atoms/substituents connected to neighboring carbons are as widely apart as feasible in staggered conformation.

H

atoms on consecutive carbons have a dihedral angle

6 0^{\circ} (18 0^{\circ}

or

30 0^{\circ})

in ethane, resulting in a staggered conformation.
The dihedral angle in (1) and (2) is

6 0^{\circ}

degrees.
The ethane in (3) is in eclipse conformation, with a dihedral angle of

0^{\circ}

.
It is in skew conformation in (4) (dihedral angle is greater than

6 0^{\circ}

).
Thus, the configuration (1) and (2) is in staggered conformation.

Q. In the following structures, which two forms are staggered conformations of ethane ?

1 and 4

2 and 3

1 and 2

1 and 3