Question

Use the following NMR and mass spectral data to identify the structures of an unknown compound. 1H NMR: δ = 0.92 (t, J = 6 Hz, 3 H), 1.32 (broad s, 12 H), 2.28 (broad s, 2 H), and 2.69 (t, J = 7 Hz, 2 H) ppm. Mass spectrum m/z (relative intensity) = 129 (0.6) and 30 (100).

Answer 1

1H NMR spectrum shows integration of 19 protons. A triplet at 0.92 with integration shows the presence of –CH3 close to –CH2 group. A triplet at 2.69 with integration of 2 shows the presence of CH2 close to CH2. The broad singlet at 1.32 ppm with integration of 12 H suggests (CH₂)₆. Broad singlet with integration of 2 suggests the presence of NH₂ group.

Intense peak at m/z = 30 must be due to the [CH₂NH₂]⁺ ion. Molecular ion peak at 129 confirms the structure

Octylamine CH₃(CH₂)₆CH₂NH₂