Aldehydes vs. Ketones
Both will have carbonyl peaks (the peak for an aldehyde is usually at higher frequency than that for a ketone), but an aldehyde will also have two peaks for the sp2 C-H. These will be at lower frequency than the sp3 C-H peaks, and should be fairly easy to spot. A possible complication is air-oxidation of the aldehyde to the corresponding carboxylic acid - be on the lookout for an acid O-H peak as an indication of impurity.
The compounds used in this exercise are acetophenone and benzaldehyde. See if you can figure out which one is which.
Compound A
| Expand any region: | ||||||
| 4000 - 3200 cm-1 | 3200 - 2700 cm-1 | 2700 - 2000 cm-1 | 2000 - 1660 cm-1 | 1656 - 1400 cm-1 | 1400 - 900 cm-1 | 900 - 600 cm-1 |
| Get the molecular formula of this compound. | Get the name of this compound. | Get the structure of this compound. | Go to the IR data tables. | Get an unknown. | Go back to the IR exercise homepage. | |
Compound B
| Expand any region: | ||||||
| 4000 - 3200 cm-1 | 3200 - 2700 cm-1 | 2700 - 2000 cm-1 | 2000 - 1660 cm-1 | 1660 - 1400 cm-1 | 1400 - 900 cm-1 | 900 - 600 cm-1 |
| Get the molecular formula of this compound. | Get the name of this compound. | Get the structure of this compound. | Go to the IR data tables. | Get an unknown. | Go back to the IR exercise homepage. | |