Question

Question: Identify the structures of isomers E and F (molecular formula C₄H₈0₂ ). Relative areas are given above each signal.

a.

b.

Short answer

Answer

a.

b.

Step-by-step solution

Isomers  

The isomers (with the same molecular formula) have different chemical shifts due to the different orientations of the groups. The different orientations give varied chemical environments.

Explanation for a

IR absorption at 1743cm^-1 : CO

1 degree of unsaturation

NMR data: H_a : quartet at 4.1 ppm

H_b: singlet at 2.0 ppm

H_c: triplet at 1.4 ppm

$Totalintegrationofunits=\frac{23+29+30}{8}$

=10

structure

Explanation for b

IR absorption at 1730cm^-1 : CO

1 degree of unsaturation

H_a: singlet at 4.1 ppm

H_b: singlet at 3.4 ppm

H_c: singlet at 2.1 ppm

$Totalintegrationofunits=\frac{18+30+31}{2}$

=10

Structure