What are the characteristic peaks of the infrared spectrum (IR) of isopropanol?

Analysis of the characteristic peaks of the infrared spectrum (IR) of isopropyl alcohol

infrared spectroscopy (IR) analysis is a common chemical analysis technique that identifies the structure of substances by measuring the absorption of different wavelengths of infrared light by molecules. As a common organic compound, isopropanol is widely used in chemical, pharmaceutical and other fields. In order to better understand and analyze isopropanol, we need to know its characteristic peaks in the infrared spectrum. This article will introduce in detail "What are the characteristic peaks of the infrared spectrum (IR) of isopropanol" and how to analyze the structure of isopropanol by these characteristic peaks.

THE RELATIONSHIP BETWEEN THE BASIC MOLECULAR STRUCTURE OF ISOPROPYL ALCOHOL AND ITS INFRARED SPECTRUM

Isopropyl alcohol (chemical formula: C≡H≡O) is a kind of alcohol compound containing hydroxyl group (-OH). Its molecule contains a hydroxyl group and an isopropyl (C-CH) group. Infrared spectroscopy analysis can help us to identify the vibration mode of each chemical bond in the molecule, so as to reveal the specific structure of the molecule. Before we understand what are the characteristic peaks of the infrared spectrum (IR) of isopropyl alcohol, we must first understand the basic molecular characteristics of isopropyl alcohol.

MAIN INFRARED ABSORPTION PEAK OF ISOPROPANOL

In the infrared spectrum of isopropanol, there are several significant absorption peaks that are its unique signature. The most prominent is the characteristic absorption peak for hydroxyl (-OH) groups. In general, the O-H stretching vibration peak of the hydroxyl group is located in the range of 3200-3550 cm¹. This peak is usually very broad, showing a broad band absorption peak, which is due to hydrogen bonding.

The C- O (alcohol group) bond in the isopropanol molecule produces a strong absorption peak in the region of about 1000-1300 cm¹. The existence of this absorption peak can help us to confirm the structure of the molecule with hydroxyl groups.

Detailed Analysis of Isopropanol Characteristic Peaks

Hydroxyl (-OH) stretching vibration peak

As mentioned above, one of the most significant characteristic peaks in the infrared spectrum of isopropanol is the O-H stretching vibration peak of the hydroxyl group. This peak generally occurs in the range of 3200-3550 cm¹, and the absorption peak width is large due to hydrogen bonding. For pure isopropyl alcohol, the O-H stretching vibration peak generally appears as a broad and strong absorption.

Methyl (-CH) and methylene (-CH) telescopic vibration peaks

In addition to the hydroxyl group, the carbon-hydrogen bond in the isopropanol molecule also produces an absorption peak. There are two methyl groups (-CHL3) and one methylene group (-CH₂) in the isopropanol molecule, and their C- H stretching vibration peaks appear in the region of 2800-3000 cm¹ respectively. The stretching vibration peaks of the methyl group are usually larger than the intensity of the less methyl group, and these peaks are located in the lower wave number region, so they can be easily identified in the infrared spectrum.

C- O telescopic vibration peak

In the region of 1000-1300 cm¹, the stretching vibration of the C- O leads to a strong absorption peak. For isopropyl alcohol, this absorption peak is very significant and usually occurs in the range of 1050-1150 cms¹. This characteristic peak is the signature absorption peak of the alcohol group in the isopropanol molecule, which can help the analyst to confirm the existence of alcohol structure in the sample.

ISOPROPANOL INFRARED SPECTROMETRY OF COMMON INTERFERENCE PEAK

In the analysis of "characteristic peaks of infrared spectrum (IR) of isopropanol", it is also necessary to pay attention to the possible interference peaks. Due to the absorption of multiple functional groups involved in the infrared spectrum analysis, overlapping absorption peaks sometimes appear, resulting in the peak position is not easy to distinguish. For example, the presence of water will produce a hydroxyl-like absorption peak in the 3200-3550 cm¹ region, so in the actual analysis, it is necessary to pay attention to whether the sample contains water.

Conclusion: How to identify isopropyl alcohol

The "infrared spectrum (IR) characteristic peaks of isopropanol" is an important tool for us to understand and identify the structure of isopropanol. By identifying the O-H stretching vibration peak, the C- H stretching vibration peak, and the C- O stretching vibration peak of the hydroxyl group, we can accurately confirm the molecular structure of isopropyl alcohol. Mastering the wave number position and intensity of these characteristic peaks is very important for the analysis of chemical, pharmaceutical and other industries.