Which compound matches the IR spectrum? cyclohexane dipropyl ether trans-4-octene 1,5-hexadiene 1-methylcyclopentene 3-hexanol 1-hexen-3-ol
The Correct Answer and Explanation is:
To determine which compound matches the IR spectrum, we need to analyze the characteristic IR absorption bands of each compound and compare them with typical functional group absorptions.
- Cyclohexane: This is a saturated hydrocarbon, and its IR spectrum would show peaks around 2900 cm⁻¹ for C-H stretching and 1450 cm⁻¹ for C-H bending. There would be no significant peaks for functional groups like alcohols, alkenes, or ethers.
- Dipropyl Ether: Dipropyl ether has an ether group (-O-) and alkyl chains. In its IR spectrum, you would expect a strong absorption around 1100-1200 cm⁻¹ for the C-O stretch. There will also be C-H stretches around 2900 cm⁻¹ and C-H bending around 1450 cm⁻¹, but no significant peaks for alcohols or alkenes.
- Trans-4-Octene: Trans-4-octene contains a C=C double bond and will show a strong absorption around 1600 cm⁻¹ for the C=C stretch. In addition, there will be C-H stretching around 2900 cm⁻¹ and bending around 1450 cm⁻¹. The trans-configuration can also affect the exact position of these bands.
- 1,5-Hexadiene: This compound has two double bonds (C=C) in the chain, so its IR spectrum will show the typical C=C stretching absorption around 1600 cm⁻¹. It will also show C-H stretches around 2900 cm⁻¹ and bending around 1450 cm⁻¹. The two conjugated alkenes might lead to some slight shifts in the C=C stretching band.
- 1-Methylcyclopentene: This compound contains a C=C double bond and a methyl group. The C=C stretching absorption will appear around 1600 cm⁻¹, and C-H stretches will appear near 2900 cm⁻¹. There could also be a distinct peak for the methyl group, but no significant oxygen-related bands like those found in alcohols or ethers.
- 3-Hexanol: This is an alcohol, and its IR spectrum will show a strong, broad O-H stretch around 3300 cm⁻¹, which is a key identifier for alcohols. Additionally, there will be C-H stretching around 2900 cm⁻¹ and C-H bending around 1450 cm⁻¹, but no C=C stretch.
- 1-Hexen-3-ol: This compound contains both an alcohol (-OH) group and an alkene (C=C) bond. The IR spectrum would show a broad O-H stretch around 3300 cm⁻¹, along with a C=C stretch around 1600 cm⁻¹. It will also show C-H stretches and bending in the usual regions.
Conclusion:
Based on these general characteristics:
- 3-Hexanol and 1-Hexen-3-ol would show the distinct O-H stretch, with 1-Hexen-3-ol also showing the C=C stretch.
- Trans-4-Octene and 1,5-Hexadiene would show prominent C=C stretches.
- Dipropyl ether and Cyclohexane would show only C-H stretches with no significant functional group absorptions.
Without the actual IR spectrum data, the most likely matches based on functional group analysis are 3-Hexanol for alcohols and 1-Hexen-3-ol for alcohols with a C=C bond. If a C=C stretch is observed, 1-Hexen-3-ol would be a better match.
