Following are infrared spectra of hexane, 1-hexene, heptanol, and 1-heptyl cyanide. Assign each compound its co and identify clearly in the IR spectrum the most important IR absorptions in each compound. 1-heptyl cyanide, hexane, 1-hexene, IR spectrum, IR spectrum, IR spectrum, heptanol, IR spectrum.
- Following are infrared spectra of hexane, 1-hexene, heptanol and 1-heptyl cyanide. Assign each compound its co and identif
The Correct Answer and Explanation is:
To correctly assign each infrared (IR) spectrum to hexane, 1-hexene, heptanol, and 1-heptyl cyanide, we focus on identifying key functional group absorptions that distinguish these compounds.
Key Functional Groups and IR Absorptions:
- Hexane (Alkane):
- C–H Stretch (sp³): ~2850–2960 cm⁻¹ (medium to strong)
- No significant peaks in the functional group region (1600–2200 cm⁻¹)
- No O–H, C=C, or C≡N peaks
- 1-Hexene (Alkene):
- C=C Stretch: ~1640–1680 cm⁻¹ (medium)
- =C–H stretch: ~3020–3100 cm⁻¹ (just above alkane C–H)
- C–H stretch (sp³): ~2850–2960 cm⁻¹
- Heptanol (Alcohol):
- O–H stretch: Broad peak ~3200–3600 cm⁻¹ (strong and wide)
- C–H stretch (sp³): ~2850–2960 cm⁻¹
- Possibly weak C–O stretch: ~1050–1150 cm⁻¹
- 1-Heptyl Cyanide (Nitrile):
- C≡N stretch: Sharp peak near 2250 cm⁻¹
- C–H stretch (sp³): ~2850–2960 cm⁻¹
- No O–H or C=C peaks
Assignment Explanation
To assign IR spectra to the compounds hexane, 1-hexene, heptanol, and 1-heptyl cyanide, we use functional group identification. Each compound has unique IR signals due to specific bond vibrations.
Hexane, a saturated hydrocarbon, shows only sp³ C–H stretching around 2850–2960 cm⁻¹ and lacks peaks in the functional group region (1600–2200 cm⁻¹). This spectrum would appear relatively simple, with no sharp or broad peaks indicative of other functional groups.
1-Hexene, an alkene, has both sp³ and sp² C–H stretching. The sp² C–H stretch appears just above 3000 cm⁻¹ (~3020–3100 cm⁻¹), which distinguishes it from alkanes. The C=C stretch also appears around 1640–1680 cm⁻¹, often weak but distinct. These features clearly identify the presence of an alkene.
Heptanol, a primary alcohol, exhibits a characteristic broad O–H stretch centered around 3300 cm⁻¹. This broad absorption results from hydrogen bonding and is usually intense. Additionally, expect sp³ C–H stretches and a possible C–O stretch in the 1050–1150 cm⁻¹ region.
1-Heptyl cyanide is identified by the presence of a sharp, strong C≡N stretch near 2250 cm⁻¹, which is the hallmark of a nitrile group. No O–H or C=C stretches appear, and the rest of the spectrum would resemble that of a saturated alkyl chain.
By identifying these diagnostic peaks, each compound can be matched with its correct IR spectrum.
If you upload the actual IR spectra images, I can label each one precisely.
