Question

Calculate the index of hydrogen deficiency (IHD), label each sepectra as the TYPE of spectra it is, label the significant peaks in each spectra, determine the structure and draw a box around it.

C₅H₁₃N

Answer 1

Given MF: C5H13N
1) Hydrogen deficiency and Unsaturation sites:
i) MF: C5H13N.
Corresponding hydrocarbon formula C5H12 (Removal of 1N accompanied with removal of 1H).
With 5C corresponding saturated hydrocrbon formula will be C5H12 (General formula CnH2n+2).
This indicate that there is no Hydrogen deficiency.
And hence NO Unsaturation Sites.
2) Spectra-1: It's Infra Red (IR) spectra.
Analysis:
i) Doublet of absorption at 3290 and 3388 cm-1 indicate 2 -N-H stretches and corresponds to -NH2 group.
ii) 3 Medium strong absorptions between 2850 - 2950 cm-1 indicative of sp3 C-H stretches hence saturated hydrocarbon groups or chain possible.
iii) No other important functional group present.
3) Spectra-2: It's Proton Magnetic resonance spectra. (PMR):
Analysis:
i) (0.88,t, 6H) indicate 2-CH3 groups with adjascent CH2 group.
ii) (1.25,septate/multiplate,2H) indicative of -CH2 group with adjascent -CH2/-CH and -CH3 group.
iii) (1.45,septate/multiplet,2H) indicative of -CH2 group indicative of -CH2/-CH and -CH3 group.
iv) (1.7,broad singlet, 2H) indicates -NH2 group.
v) (2.52, quintet,1H) indicate -CH group bearing -NH2 group.
On the basis of IR and PMR spectral findings the structure proposed is,

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(3290 and 3388 cm) H H-N (1.7,Broad singlet) H2N 2.52,quintet) H2N H H3C CH3 CH3 (0.88,t) H3C CH3 (2850-2950 cm-) Pentan-3-amine Diastereotopic protons IR absorptions