Question

I have the following IR spectrum but I can't decide whether it has a Nitro group, ketone/aldehyde group and or aromatic group. I just need to identify all the functional groups. Thank You!

TRANSMETTANCEI%! D + 4000 2000 2000 1500 100 HAVENUMBERI - 3067 62 | 2671 601496 67 3027 47 2614 60 1450 27 2977 53 2598 58 1423 35 2837 63 2650 6D1341 62 2720 60 1686 4 1335 46 2096 80 1631 9 1912 26 2683 60 1678 601303 47 1280 16 1224 31 1207 55 987 66 982 24 945 50 926 6B 917 60 769 31 712 25 698 60 684 57 592 55 644 68

Answer 1

• 3000-3100 cm-1 : sp2 C-H stretching ( alkene/Aromatic)
• Aldehydes frequently have a weak but
  very distinctive absorption at 2720 cm-1 caused by the stretching of the C!H of the
  CHO group.
• Strong peak 1686 cm-1 : due to C=O stretching ( most probably Aldehydic -C=O , in conjugation with -C=C-). : The presence of an adjacent carbon-carbon double bond or benzene ring in
  conjugation with the carbonyl group results in a shift of the C=O absorption
  to a lower frequency. Conjugation occurs when the pi electrons of adjacent
  pi bonds interact with each other due to overlap of the unhybridized 2p orbitals
  and is a consequence of the special properties of extended pi systems.
• 1631 cm-1 : C=C stretching . (Aromatic hydrocarbons show absorptions in the regions 1640-1585 cm-1 and 1500-1400 cm-1 due to carbon-carbon stretching vibrations in the aromatic ring. )