The infra-red (IR) spectrum of an organic compound is shown below - VCE - SSCE Chemistry - Question 21 - 2020 - Paper 1

To determine the correct compound from the options given, we must analyze the features of the IR spectrum.

1. Identifying Key Peaks:

   • The spectrum shows a strong peak around 1700 cm⁻¹, which typically indicates the presence of a carbonyl (C=O) group.
   • Additionally, peaks in the region of 3200-3400 cm⁻¹ suggest -NH or -OH groups.

2. Evaluating the Options:

   • A. CH₃CH₂COOCH₃ (an ester)
     • This would produce a carbonyl peak in the ester's expected region but is less likely to present a strong amine signal.
   • B. CH₃CH₂CH₃CHO (an aldehyde)
     • An aldehyde would show a carbonyl peak, but not as strong as that observed in the spectrum, and lacks the amino signals.
   • C. NH₂CH₂CONH₂ (a diamide)
     • This could show amine related peaks, but the presence of two amide groups would dominate the carbonyl signal and show more complex behavior.
   • D. NH₂CH₂CHOCH₂CH₃ (an aldehyde with a terminal amine)
     • This structure is plausible given the combination of amine and carbonyl functionalities. It matches well with the strong carbonyl peak and amine signal observed.

3. Conclusion: Based on the analysis, the best choice aligns with option D: NH₂CH₂CHOCH₂CH₃, as it shows both a strong carbonyl and amine signal consistent with the IR spectrum observed.