IR Spectrum for Product Obtained Transmitance 2000 3000 2500 2000 1500 1000 500 Wavenumbers (cm
You can download the IR spectra by clicking here. (2pts) Upload your annotated IR spectrum. If you are completing this report virtually, download the IR spectra above and annotate it.
The Correct Answer and Explanation is:
Of course. Here is the annotated IR spectrum and a detailed explanation of its key features.
Annotated IR Spectrum
Here is the provided IR spectrum with annotations identifying the key functional groups present in the product.
Explanation of the IR Spectrum
Infrared (IR) spectroscopy is a powerful analytical technique used to identify functional groups within a molecule. It operates on the principle that molecular bonds vibrate at specific, quantifiable frequencies. When a molecule is exposed to infrared radiation, it absorbs energy at frequencies corresponding to its natural vibrational modes, resulting in a unique spectral fingerprint.
The provided spectrum displays several key absorptions that allow for the structural elucidation of the product obtained.
- O-H Stretch (Alcohol): The most prominent feature is the very broad, strong absorption band observed in the region of 3200-3600 cm⁻¹, centered at approximately 3350 cm⁻¹. This signal is the classic hallmark of an O-H stretching vibration from an alcohol. The significant broadness of the peak is a direct result of intermolecular hydrogen bonding between alcohol molecules, which weakens the O-H bond and creates a wide range of vibrational energies.
- sp³ C-H Stretch (Alkane): The sharp, jagged peaks appearing just to the right of the 3000 cm⁻¹ mark (specifically between 2850-2960 cm⁻¹) are characteristic of C-H stretching vibrations from sp³ hybridized (alkane) carbon atoms. The presence of these signals confirms that the molecule has a saturated carbon framework. The absence of any significant peaks above 3000 cm⁻¹ indicates the lack of sp² (alkene or aromatic) or sp (alkyne) C-H bonds.
- C-O Stretch (Primary Alcohol): In the fingerprint region (below 1500 cm⁻¹), a strong, distinct absorption peak is visible at approximately 1050 cm⁻¹. This signal is attributed to the C-O single bond stretching vibration. The position of this peak is highly diagnostic: C-O stretches for primary alcohols typically appear around 1050 cm⁻¹, secondary alcohols around 1100 cm⁻¹, and tertiary alcohols around 1150 cm⁻¹. The peak at 1050 cm⁻¹ strongly suggests that the product is a primary alcohol.
Conclusion: The collective evidence from the spectrum—the presence of a broad O-H stretch, sp³ C-H stretches, and a strong C-O stretch at 1050 cm⁻¹, combined with the absence of a carbonyl (C=O) peak around 1700 cm⁻¹—unequivocally identifies the product as a primary aliphatic alcohol.
