Phenylacetic Acid vs. Proton NMR of Methyl Benzoate
What's the Difference?
Phenylacetic acid and methyl benzoate are both organic compounds commonly studied in chemistry. Phenylacetic acid is a carboxylic acid with a phenyl group attached to the alpha carbon, while methyl benzoate is an ester with a methyl group attached to the benzene ring. When comparing their proton NMR spectra, several differences can be observed. Phenylacetic acid typically exhibits a broad singlet peak around 2.5-3.0 ppm, corresponding to the carboxylic acid proton. In contrast, methyl benzoate shows a sharp singlet peak around 3.7 ppm, representing the methyl group. Additionally, methyl benzoate displays a set of peaks around 7.2-7.5 ppm, corresponding to the aromatic protons of the benzene ring, which are absent in phenylacetic acid. These differences in chemical shifts and peak patterns allow for the differentiation and identification of these compounds using proton NMR spectroscopy.
Comparison
| Attribute | Phenylacetic Acid | Proton NMR of Methyl Benzoate |
|---|---|---|
| Chemical Formula | C8H8O2 | C8H8O2 |
| Molecular Weight | 136.15 g/mol | 136.15 g/mol |
| Structure |  |  |
| Physical State | Colorless liquid | Colorless liquid |
| Boiling Point | 265-267°C | 198-200°C |
| Proton NMR Peaks | Chemical shifts: 2.9-3.1 ppm (multiplet, 2H), 7.2-7.4 ppm (multiplet, 5H) | Chemical shifts: 2.2-2.4 ppm (singlet, 3H), 7.4-7.6 ppm (multiplet, 5H) |
| Functional Groups | Phenyl group, carboxylic acid group | Methyl ester group, phenyl group |
Further Detail
Introduction
Phenylacetic acid and methyl benzoate are two organic compounds that have distinct attributes and applications in various fields. Phenylacetic acid, also known as benzeneacetic acid, is a carboxylic acid with the chemical formula C8H8O2. It is a colorless liquid with a strong, sweet odor and is commonly used in the production of pharmaceuticals, fragrances, and pesticides. On the other hand, methyl benzoate, with the chemical formula C8H8O2, is an ester that is often used as a flavoring agent in the food industry and as a solvent in various applications.
Attributes of Phenylacetic Acid
Phenylacetic acid possesses several notable attributes that make it a valuable compound in different industries. Firstly, its strong, sweet odor makes it a popular choice in the production of fragrances and perfumes. It is often used as a key ingredient in floral scents due to its pleasant aroma. Additionally, phenylacetic acid is an important intermediate in the synthesis of various pharmaceuticals, including antibiotics, analgesics, and antipyretics. Its carboxylic acid group allows it to participate in chemical reactions, making it a versatile compound for drug synthesis.
Moreover, phenylacetic acid exhibits antimicrobial properties, which make it useful in the production of pesticides and preservatives. It can inhibit the growth of certain bacteria and fungi, making it an effective agent for preventing spoilage and contamination. This attribute is particularly valuable in the food industry, where phenylacetic acid can be used to extend the shelf life of perishable products.
Furthermore, phenylacetic acid is a non-toxic compound, making it safe for use in various applications. Its low toxicity profile allows it to be used in the production of cosmetics, personal care products, and even as a food additive. This attribute ensures that phenylacetic acid can be incorporated into a wide range of consumer products without posing significant health risks.
In summary, phenylacetic acid possesses a pleasant odor, is a versatile intermediate in pharmaceutical synthesis, exhibits antimicrobial properties, and has a low toxicity profile, making it a valuable compound in the fragrance, pharmaceutical, pesticide, and food industries.
Proton NMR of Methyl Benzoate
Proton nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical technique used to determine the structure and composition of organic compounds. When applied to methyl benzoate, proton NMR provides valuable information about the arrangement of hydrogen atoms within the molecule.
In the proton NMR spectrum of methyl benzoate, several distinct peaks can be observed. The peak at around 7.5-8.0 ppm corresponds to the aromatic protons in the benzene ring. This peak appears as a multiplet due to the coupling of neighboring protons. The presence of this peak confirms the presence of the benzene ring in the molecule.
Another peak can be observed at around 3.7 ppm, which corresponds to the protons attached to the ester group (-COOCH3). This peak appears as a singlet since these protons are not coupled to any neighboring protons. The chemical shift of this peak can vary slightly depending on the solvent used for the NMR measurement.
Additionally, a small peak may be observed at around 2.2 ppm, which corresponds to the protons attached to the methyl group (-CH3). This peak also appears as a singlet since these protons are not coupled to any neighboring protons. The chemical shift of this peak is relatively downfield compared to the other peaks due to the electron-withdrawing effect of the adjacent carbonyl group.
By analyzing the proton NMR spectrum of methyl benzoate, it is possible to determine the number and type of protons present in the molecule, as well as their chemical environment. This information is crucial for elucidating the structure of organic compounds and can be used to confirm the identity of methyl benzoate.
Conclusion
Phenylacetic acid and methyl benzoate are two organic compounds with distinct attributes and applications. Phenylacetic acid possesses a pleasant odor, is a versatile intermediate in pharmaceutical synthesis, exhibits antimicrobial properties, and has a low toxicity profile. On the other hand, proton NMR of methyl benzoate provides valuable information about the arrangement of hydrogen atoms within the molecule, allowing for the determination of its structure and composition.
Both compounds have their unique roles in various industries, contributing to the production of fragrances, pharmaceuticals, pesticides, and food products. Understanding the attributes and characteristics of these compounds is essential for their effective utilization and further exploration of their potential applications.
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