CAS:64-17-5 refers to ethanol, a well - known and widely used chemical compound. As a supplier of CAS:64 - 17 - 5, I am often asked about its infrared (IR) absorption peaks. Understanding these peaks is crucial for various applications, from quality control in the production process to research in analytical chemistry.
Infrared Spectroscopy Basics
Infrared spectroscopy is a powerful analytical technique used to identify and study chemical compounds. When infrared radiation is passed through a sample, the molecules absorb certain frequencies of the radiation. These absorptions correspond to the vibrational modes of the chemical bonds within the molecules. By analyzing the absorption peaks in the infrared spectrum, we can gain insights into the structure and functional groups present in the compound.
Ethanol's Molecular Structure
Ethanol has the chemical formula (C_{2}H_{5}OH). It consists of an ethyl group ((C_{2}H_{5}-)) attached to a hydroxyl group ((-OH)). The main types of bonds in ethanol are (C - H), (C - C), and (O - H) bonds, each of which will have characteristic infrared absorption peaks.
Major Infrared Absorption Peaks of Ethanol
(O - H) Stretch
One of the most prominent peaks in the infrared spectrum of ethanol is due to the stretching vibration of the (O - H) bond. In free (O - H) groups, the absorption occurs around 3600 - 3650 (cm^{-1}) as a sharp peak. However, in ethanol, the (O - H) group can form hydrogen bonds. Hydrogen - bonded (O - H) groups have a broader absorption peak in the range of 3200 - 3550 (cm^{-1}). The exact position and shape of this peak can vary depending on factors such as the concentration of ethanol, the solvent used (if any), and the temperature. For example, in a dilute solution, the peak may be closer to the free (O - H) value, while in a concentrated solution, the hydrogen - bonding effect is more pronounced, and the peak will be broader and shifted to lower wavenumbers.
(C - H) Stretch
Ethanol contains several (C - H) bonds. The (C - H) stretching vibrations give rise to absorption peaks in the range of 2850 - 3000 (cm^{-1}). The (sp^{3}) hybridized (C - H) bonds in the ethyl group ((C_{2}H_{5}-)) typically show absorptions around 2900 - 2980 (cm^{-1}). There are two main types of (C - H) stretching vibrations in this region: symmetric and asymmetric stretches. The asymmetric (C - H) stretch usually occurs at a slightly higher wavenumber than the symmetric stretch.
(C - O) Stretch
The (C - O) bond in ethanol has a stretching vibration that results in an absorption peak around 1000 - 1200 (cm^{-1}). For ethanol, the (C - O) stretch is typically observed around 1050 - 1100 (cm^{-1}). This peak is useful for distinguishing ethanol from other compounds, especially those without a (C - O) single - bond functional group.
Bending Vibrations
In addition to the stretching vibrations, ethanol also has bending vibrations of its bonds. The (C - H) bending vibrations occur in the range of 1350 - 1470 (cm^{-1}). The scissoring and rocking motions of the (C - H) bonds in the ethyl group contribute to these absorption peaks. The (O - H) bending vibration, also known as the out - of - plane and in - plane bending, can be observed around 650 - 750 (cm^{-1}), although these peaks are usually less intense compared to the stretching peaks.
Comparison with Similar Compounds
It is interesting to compare the infrared absorption peaks of ethanol with those of similar compounds. For example, N - butanol ((C_{4}H_{9}OH)) also has an (O - H) group and (C - H) and (C - O) bonds. The (O - H) stretch in n - butanol will have a similar broad peak in the 3200 - 3550 (cm^{-1}) range due to hydrogen bonding. However, the (C - H) stretching and bending peaks may be more complex in n - butanol because of the longer carbon chain, resulting in more (C - H) bonds.
95%Ethanol is a common commercial form of ethanol. The presence of water in 95% ethanol can affect the infrared spectrum. Water also has an (O - H) stretch, and its absorption peak can overlap with the ethanol (O - H) peak, making the interpretation of the spectrum more challenging. The water (O - H) stretch is usually broader and more intense in the 3200 - 3600 (cm^{-1}) range.
Ethylene Glycol ((HOCH_{2}CH_{2}OH)) has two (O - H) groups. The infrared spectrum of ethylene glycol will show a very strong and broad (O - H) stretch in the 3200 - 3550 (cm^{-1}) range due to extensive hydrogen bonding. The (C - H) and (C - O) stretching peaks will also be present, but the relative intensities and positions may differ from ethanol due to the different molecular structure.
Applications of Infrared Spectroscopy of Ethanol
The knowledge of ethanol's infrared absorption peaks has many practical applications. In the beverage industry, infrared spectroscopy can be used to determine the ethanol content in alcoholic drinks. By analyzing the intensity of the (O - H) and (C - H) absorption peaks, the concentration of ethanol can be accurately measured.
In the pharmaceutical industry, ethanol is often used as a solvent or an ingredient in formulations. Infrared spectroscopy can be used to ensure the purity of ethanol and to detect any impurities. Impurities may have their own characteristic infrared absorption peaks, which can be identified by comparing the spectrum of the sample with that of pure ethanol.
In research laboratories, infrared spectroscopy is used to study the reaction mechanisms involving ethanol. For example, when ethanol participates in a chemical reaction, changes in the infrared absorption peaks can indicate the formation or disappearance of certain functional groups.
Our Supply of CAS:64 - 17 - 5
As a supplier of CAS:64 - 17 - 5 (ethanol), we understand the importance of providing high - quality products. Our ethanol is produced through a strict manufacturing process, and we use infrared spectroscopy as one of the quality control methods. By analyzing the infrared absorption peaks, we can ensure that the ethanol we supply meets the required purity and quality standards.
If you are in need of high - quality ethanol for your industrial, research, or other applications, we are here to help. We can provide ethanol in various grades and quantities to meet your specific requirements. Whether you are conducting a small - scale laboratory experiment or need a large - scale supply for industrial production, we have the capacity to fulfill your order.
We encourage you to contact us for procurement and further discussions. Our team of experts is ready to assist you with any questions you may have regarding our products, including their infrared absorption characteristics and how they can be used in your specific applications.
References
- Silverstein, R. M., Webster, F. X., & Kiemle, D. J. (2014). Spectrometric Identification of Organic Compounds. Wiley.
- Pavia, D. L., Lampman, G. M., Kriz, G. S., & Vyvyan, J. R. (2015). Introduction to Spectroscopy: A Guide for Students of Organic Chemistry. Cengage Learning.
- Socrates, G. (2001). Infrared and Raman Characteristic Group Frequencies: Tables and Charts. Wiley.