Question

Question: Identify the structures of isomers H and I (molecular form C₈H₁₁N)

a.

b.

Short answer

Answer

a.

b.

Step-by-step solution

Amines  

Amines contain nitrogen; therefore, they are called nitrogen-containing compounds. They also contain lone pairs of electrons. Therefore, amines are called Lewis bases.

IR of amines

The IR range of amines is 3300 to 3400cm^-1 . The nitrogen protons give a broad signal.

Explanation

The degree of unsaturation is 4.

IR absorption at 3365cm^-1 : N–H, 3284cm^-1 : N–H, 3026cm^-1 ,$C_{s{p}^3}-H$ 2932cm^-1 ,$C_{s{p}^3}-H$ 1603 cm^-1 : due to benzene 1497cm^-1 : due to benzene: CO

NMR data:

Multiplet at 7.2–7.4 ppm, 5 H on a benzene ring.

H_a: triplet at 2.9 ppm, 2 H, split by 2 H's

H_b: triplet at 2.8 ppm, 2 H, split by 2 H's

H_c: singlet at 1.1 ppm, 2 H, no splitting (on )

Structure

The degree of unsaturation is 4.

IR absorptions at 3367cm^-1 : N–H 3286cm^-1 : N–H 3027cm^-1 : $C_{s{p}^3}-H$2962cm^-1 : $C_{s{p}^3}-H$1604 cm^-1 : due to benzene 1492cm^-1 : due to benzene

NMR data: multiplet at 7.2–7.4 ppm, 5 H on a benzene ring

H_a: quartet at 4.1 ppm, 1 H, split by 3H's : H_bsinglet at 1.45 ppm, 2 H, no splitting H_c : doublet at 1.4 ppm, 3 H, split by 1 H

Structure