August 26, 2025 | UR Gate
Phenylalanine (C9H11NO2) Structure, Properties and Nomenclature
Discover Phenylalanine (C9H11NO2), an essential aromatic amino acid. Learn its structure, key properties, IUPAC name, synonyms, and its vital roles in protein synthesis, neurotransmitter production, and as a precursor to tyrosine.
What is Phenylalanine (C9H11NO2)?
Phenylalanine is an essential alpha-amino acid, meaning the human body cannot synthesize it and must obtain it from dietary sources. It is characterized by its aromatic side chain, a benzyl group attached to the alpha-carbon. This structure makes it hydrophobic. Phenylalanine is a precursor to tyrosine, another amino acid, which is then used to synthesize important neurotransmitters like dopamine, norepinephrine, and epinephrine, as well as thyroid hormones and melanin. It is found in protein-rich foods such as meat, fish, eggs, dairy products, legumes, nuts, and seeds. Individuals with phenylketonuria (PKU) must restrict their intake of phenylalanine due to a metabolic disorder.
Properties of Phenylalanine (C9H11NO2)
| Property | Value |
|---|---|
| Molecular Formula | C₉H₁₁NO₂ |
| Molecular Weight | 165.19 g/mol |
| Density | 1.17 g/cm³ |
| Boiling Point | Decomposes upon heating (around 285 °C) |
| Melting Point | 285 °C (decomposes) |
| Hybridization | Alpha-carbon atom is sp³ hybridized. Carbons in the phenyl ring are sp² hybridized. |
| Appearance | White crystalline solid |
| Solubility | Slightly soluble in water; insoluble in ethanol. |
Nomenclature of Phenylalanine
- Common name: Phenylalanine
- IUPAC name: 2-amino-3-phenylpropanoic acid
Synonyms
- L-Phenylalanine (for the naturally occurring enantiomer)
- (S)-2-Amino-3-phenylpropanoic acid
- α-Amino-β-phenylpropionic acid
- Phe
- D-Phenylalanine (for the non-natural enantiomer)
- (R)-2-Amino-3-phenylpropanoic acid
