Question

IR spectroscopy interpretation: what is this compund? (done in lab)

(SOLID 100 Tue Nov 12 15:40:55 2019 (GMT-05:00) 1464.64 823.88 2282.52 11297405.74 % Transmittance 255745 2668.83 1026.34 926.15 1516.09 1578.05 3027.76 2981.88 843.87 1180.1769.44 1449 928.44 772.03 1682.44 1604.56 1298.594329.9906.12 3500 3000 2500 1000 2000 Wavenumbers (cm-1) Tue Nov 12 15:41:47 2019 (GMT-05:00) FIND PEAKS Spectrum Tue Nov 12 15:40:55 2019 (GMT-05:00) Region: 3635.26 765.02 Absolute threshold: 99.454 Sensitivity: Peak list: Position: 772.03 Intensity: 75 447 Position 823 88 Intensity: 91.497 Position: 843.87 Intensity: 76.741 Position: 926.15 Intensity: 84.436 Position 1026.34 Intensity 85.308 Position: 1106.74 Intensity: 89.366 Position: 1129.75 Intensity: 89.510 Position: 1169.44 Intensity: 78.889

Answer 1

1.Region above 3200 cm^-1: No peak is observed

Interpretation: absence of amine(N-H), alcohol(-OH), carboxylic acid(-OH) stretching's hence these groups are absent.

2. In region 3000 cm^-1- 2000 cm^-1:

3027.76 cm^-1( C-H stretching of alkenes)

2981.88 cm^-1(C-H stretching of alkane)

2688.83 cm^-1 and 2557.45 cm^-1(doublets of C-H stretching of aldehyde).

Interpretation: presence of aldehyde group and alkene group.

3. In region 1700 cm^-1 to 1600 cm^-1:

1682.44 cm^-1( conjugated carbonyl(CO) stretching frequency)

Interpretation: alkene and aldehyde may be present in conjugation.

4. In region 1500-1400 cm^-1: so many peaks shows presence of aromatic ring

Interpretation: presence of benzene ring.

5. Below 850 cm^-1: two peaks

Interpretation : mono-substitued benzene

Conclusion: a conjugated aldehyde with phenyl group substitution near alkenyl carbon. It may be (or similar to) cinnamaldehyde .