Acids vs. Esters vs. Anhydrides
Even though they will all have a carbonyl peak, only the acid will have a big, broad, ugly O-H peak. This should also be readily distinguishable from an alcohol O-H peak. Anhydrides are characterized by the presence of two carbonyl peaks. The relative intensity of these peaks depends on whether the anhydride is cyclic or acyclic.
The compounds used in this exercise are acetic anhydride, ethyl acetate, and propanoic acid. 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 | 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. | |
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. | |
Compound C
| 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. | |