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4-Nitro-L-Phenylalanine stands out as an aromatic amino acid, structurally derived from L-phenylalanine by introducing a nitro group at the fourth position on the benzene ring. The compound carries the molecular formula C9H10N2O4, and its typical molecular weight falls around 210.19 g/mol. Looking at this amino acid in physical form, it appears as a pale yellow to yellowish solid, often encountered as powder or crystalline flakes sometimes even as small pearls. Its distinctive color signals the presence of the nitro group on the aromatic ring, something that noticeably sets it apart from the native amino acid.
4-Nitro-L-Phenylalanine has found a place in research and synthesis settings as a valuable building block. Researchers tend to favor this compound when exploring the effect of electronic modifications on peptides or proteins. The presence of the nitro group gives it potential use in pharmaceutical synthesis, where it provides more than a simple phenyl backbone—a difference that can alter biological activity and binding profiles. There is also demand for this amino acid in material science, as changes on the aromatic ring yield new possibilities for self-assembly and responsive materials, especially with the electron-withdrawing nature of the nitro group.
At its core, 4-Nitro-L-Phenylalanine resembles other L-amino acids: an alpha amino group, a carboxylic acid, and a variable side chain. Here, the side chain carries a nitrophenyl group, specifically with the nitro group at the para position (4th position) relative to the main chain attachment. Structural diagrams show the aromatic ring with a –NO2 substituent directly opposite to the –CH2 group. This molecular tweak impacts both its electronic properties and how it fits in an active site or protein chain, a detail that might seem technical but becomes important in laboratory work.
Most people who handle 4-Nitro-L-Phenylalanine notice it arrives as a fine, free-flowing powder, though larger crystalline forms also exist. Flakes and small pearls occasionally turn up, especially from recrystallized batches. The powder shows little to no odor, and its yellow color is usually stable under room lighting—direct sunlight tends to speed up decomposition, a factor that points to the need for cool, dry storage. The density typically hovers between 1.4 and 1.5 g/cm3, depending on polymorphic form and granule size. Solubility lands in the moderate range for polar solvents like water; complete dissolution often needs gentle heating or pH adjustment. In less polar media, the compound resists solvation, a fact that keeps it from leaching away unintentionally during benchwork.
Adding a nitro group does more than shift color. 4-Nitro-L-Phenylalanine turns from a dietary amino acid to a specialty chemical, now classified as hazardous by several jurisdictions. Handling it in the lab, I always reach for gloves and eye protection: skin or eye exposure can result in irritation, and inhalation should be avoided. Dust management—using a hood or mask during weighing—remains important, especially with fine powders that can become airborne. The compound is not classified as a known carcinogen, but the presence of the nitro group marks it as potentially harmful if mishandled over long periods. Most suppliers place 4-Nitro-L-Phenylalanine under HS Code 29224995, signaling its status as a modified amino acid. Compliance with proper hazardous chemical handling guidelines ensures a safe environment for users and bystanders alike.
Labs and suppliers quote purity levels, typically upwards of 98%, since even low-level contaminants can impact fine-scale reactions or biological tests. Water content, checked by Karl Fischer titration or thermogravimetric analysis, usually falls under 0.5%. The melting point lies in the range of 160-165°C, with decomposition often preceding full melting due to the nitro group's sensitivity. Solution preparation benefits from mild heating; concentrations of 10-50 mM are common for biological studies. In terms of storage, amber glass bottles restrict light exposure. Bulk shipments in polyethylene-lined fiber drums can hold several kilos, but most users see it in small, tightly sealed ampoules.
4-Nitro-L-Phenylalanine doesn’t belong in regular waste streams. My own lab experience shows proper waste handling—segregation into labeled, secondary containment—avoids unintentional environmental release. It resists biodegradation compared to simple amino acids, and the nitro group raises concerns if release occurs near aquatic environments or plant systems. Local regulations require professional disposal. Accidental releases or poorly managed waste create risk for water or soil contamination, and chronic exposure in workplace settings calls for ventilation and monitoring. Inhalation remains the most common risk, with powder handling especially needing dust controls. Safety data sheets usually recommend prompt response to spills with dampened cloths, minimizing dust clouds.
In my own project work, I’ve used 4-Nitro-L-Phenylalanine as a precursor for peptidomimetics and for studying electron-demand effects on aromatic residues in enzymatic assays. Sometimes it starts as a fine crystal, sometimes as a powder—the form impacts how fast it dissolves, but not the performance in reactions. As a raw material, it offers a nitro group primed for further reduction or transformation. Chemists can convert it into amines or other functionalized phenylalanines. In solution, the pH often drifts slightly acidic. It shows reasonable thermal stability at working concentrations, especially in buffered media.
Managing 4-Nitro-L-Phenylalanine safely means keeping dust to a minimum, wearing gloves, goggles, and using well-ventilated spaces. Routine monitoring of storage conditions extends shelf life and reduces risks linked to decomposition products. Bulk users benefit from clear segregation into hazardous waste streams, and comprehensive training for new personnel lowers accident rates. Emergency procedures—spill controls, eyewash availability—prove wise investments. Clear, visible labeling at every point, from raw material storage through final disposal, helps keep the workspace safer. Investing in these procedures not only keeps people safe, it cuts down on waste and costs over the long term.
4-Nitro-L-Phenylalanine, C9H10N2O4, comes as yellow powder, flakes, or crystal, density around 1.4-1.5 g/cm3. Used in chemical synthesis, pharmaceutical work, and biochemical research, the compound’s nitro group brings hazards requiring gloves, masks, and secure storage. Purity typically exceeds 98%, with water content below 0.5%. Handling needs controlled conditions—cool, dry, ventilated areas, and avoidance of direct sunlight. Not fit for human consumption, not suitable for regular disposal. Hazards include breathing dust, skin or eye exposure, and aquatic risks, all of which respond to careful procedure, good housekeeping, and regulated disposal.
