2-Nitroaniline, also known as ortho-nitroaniline, is a crucial organic compound with a wide range of applications in the chemical and pharmaceutical industries. As a leading supplier of 2-Nitroaniline, I am often asked about its spectral characteristics. In this blog post, I will delve into the various spectral features of 2-Nitroaniline, including its infrared (IR), nuclear magnetic resonance (NMR), and ultraviolet-visible (UV-Vis) spectra.
Infrared (IR) Spectroscopy
Infrared spectroscopy is a powerful tool for identifying functional groups in organic compounds. When 2-Nitroaniline is analyzed using IR spectroscopy, several characteristic peaks can be observed.
The most prominent peaks in the IR spectrum of 2-Nitroaniline are related to the functional groups present in the molecule. The amino group (-NH₂) shows characteristic N - H stretching vibrations. These vibrations typically appear as two peaks in the range of 3300 - 3500 cm⁻¹. The asymmetric and symmetric stretching of the N - H bonds in the amino group contribute to these peaks. For 2-Nitroaniline, the N - H stretching peaks are usually found around 3420 cm⁻¹ and 3350 cm⁻¹.
The nitro group (-NO₂) also has distinct IR absorption peaks. The asymmetric stretching vibration of the nitro group appears as a strong peak around 1520 - 1550 cm⁻¹, while the symmetric stretching vibration is observed as a medium - strong peak around 1340 - 1370 cm⁻¹. In the case of 2-Nitroaniline, the asymmetric stretching of the nitro group is typically seen at about 1530 cm⁻¹, and the symmetric stretching is around 1360 cm⁻¹.
The aromatic C - H stretching vibrations in the benzene ring of 2-Nitroaniline are observed in the range of 3000 - 3100 cm⁻¹. These peaks are relatively weak and are characteristic of the sp² hybridized carbon - hydrogen bonds in the aromatic system. The C = C stretching vibrations in the benzene ring occur in the range of 1450 - 1600 cm⁻¹. For 2-Nitroaniline, multiple peaks in this region are due to the different modes of vibration of the benzene ring, with peaks around 1600 cm⁻¹ and 1500 cm⁻¹ being prominent.
Nuclear Magnetic Resonance (NMR) Spectroscopy
Nuclear magnetic resonance spectroscopy provides valuable information about the structure and connectivity of atoms in a molecule. Both proton (¹H NMR) and carbon - 13 (¹³C NMR) NMR spectra are important for analyzing 2-Nitroaniline.
¹H NMR Spectroscopy
In the ¹H NMR spectrum of 2-Nitroaniline, the protons on the benzene ring give distinct signals. The amino group protons (-NH₂) are usually observed as a broad singlet in the range of 4 - 6 ppm. The broadness of the signal is due to the exchange of the amino protons with traces of water or other protic solvents in the sample.
The protons on the benzene ring of 2-Nitroaniline are affected by the electron - withdrawing nitro group and the electron - donating amino group. The protons in the ortho and para positions to the amino group are deshielded compared to a simple benzene ring. The signals for the benzene ring protons typically appear in the range of 6.5 - 8 ppm. The protons ortho to the nitro group are more deshielded and are observed at higher chemical shifts. For example, the proton ortho to the nitro group and meta to the amino group may appear around 8 ppm, while the other ring protons are in the 6.5 - 7.5 ppm range. The coupling constants between the benzene ring protons can also be used to determine the relative positions of the substituents on the ring.
¹³C NMR Spectroscopy
The ¹³C NMR spectrum of 2-Nitroaniline shows signals for the carbon atoms in the benzene ring and the carbon attached to the amino group. The carbon atoms in the benzene ring are affected by the nitro and amino groups. The carbon atom attached to the nitro group is highly deshielded and appears at a relatively high chemical shift, typically around 140 - 150 ppm. The carbon atom attached to the amino group is less deshielded and is observed around 110 - 120 ppm. The other carbon atoms in the benzene ring give signals in the range of 120 - 130 ppm, with the exact chemical shifts depending on their relative positions to the substituents.
Ultraviolet - Visible (UV - Vis) Spectroscopy
Ultraviolet - visible spectroscopy is used to study the electronic transitions in a molecule. 2-Nitroaniline has a characteristic absorption in the UV - Vis region due to the presence of the conjugated π - electron system in the benzene ring, along with the electron - withdrawing nitro group and the electron - donating amino group.
The absorption in the UV - Vis spectrum of 2-Nitroaniline is mainly due to π - π* transitions. The nitro group is a strong chromophore, and the interaction between the nitro group and the benzene ring, as well as the amino group, leads to an absorption maximum (λmax) in the range of 300 - 400 nm. For 2-Nitroaniline, the λmax is typically around 380 nm. The absorption in this region is relatively strong, and the intensity of the absorption can be used for quantitative analysis of 2-Nitroaniline in solution.
Significance of Spectral Characteristics
The spectral characteristics of 2-Nitroaniline are of great significance in several aspects. In the field of chemical synthesis, these spectra are used to confirm the identity and purity of the synthesized 2-Nitroaniline. By comparing the experimental spectra with the expected spectra based on the structure, chemists can ensure that the correct product has been obtained and that there are no significant impurities.
In the pharmaceutical industry, 2-Nitroaniline is used as an intermediate in the synthesis of various drugs. The spectral characteristics help in quality control during the manufacturing process. For example, any deviation in the IR, NMR, or UV - Vis spectra from the standard values may indicate a problem in the synthesis or the presence of contaminants, which could affect the efficacy and safety of the final drug product.
Other Related Compounds and Their Spectral Relevance
It is also worth mentioning some related compounds and their spectral characteristics in comparison to 2-Nitroaniline. For example, 2-Acetylthiophene has different functional groups such as the acetyl group and the thiophene ring. In its IR spectrum, the carbonyl group of the acetyl group shows a strong absorption around 1700 cm⁻¹, which is quite different from the characteristic peaks of 2-Nitroaniline.
1-fluoronaphthalene has a fluorine atom attached to the naphthalene ring. The presence of fluorine in 1 - fluoronaphthalene affects its ¹H and ¹³C NMR spectra. The fluorine atom causes deshielding of the adjacent carbon and hydrogen atoms, leading to characteristic chemical shifts in the NMR spectra that are distinct from those of 2-Nitroaniline.
Chlorphenesin contains a chloromethyl group and a phenyl group. Its IR spectrum shows characteristic peaks for the C - Cl stretching vibration around 600 - 800 cm⁻¹, which is not present in the spectrum of 2-Nitroaniline. These differences in spectral characteristics are important for distinguishing between these compounds in a mixture or during the synthesis process.
Conclusion
In conclusion, the spectral characteristics of 2-Nitroaniline, including its IR, NMR, and UV - Vis spectra, are essential for understanding its structure, confirming its identity, and ensuring its quality. As a supplier of 2-Nitroaniline, we are committed to providing high - quality products that meet the strictest spectral and purity standards. Whether you are a researcher in a laboratory, a chemist in a synthesis facility, or a pharmaceutical manufacturer, our 2-Nitroaniline can be a reliable choice for your applications.
If you are interested in purchasing 2-Nitroaniline or have any questions regarding its spectral characteristics or other properties, please feel free to contact us for further discussions and to initiate a procurement process. We look forward to working with you to meet your chemical needs.
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.
- Skoog, D. A., Holler, F. J., & Crouch, S. R. (2014). Principles of Instrumental Analysis. Cengage Learning.