Alkanes vs. Alkenes
These classes of compounds should be easy to distinguish by IR: alkenes will have peaks for sp2 CH’s and the C=C, while alkanes will not. However, the C=C peak for an alkene can be small and hard to find unless the alkene: a) is terminal or b) has a polarizing substituent attached to it. In rare cases, you may have a tetra-substituted alkene, in which case there will of course be no sp2 C-H peaks. For alkenes, peaks in the fingerprint region can give information about the substitution pattern.
The compounds used in this exercise are hexane and 1-hexene. 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. | |