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P-Hydroxybenzaldehyde, commonly known in the chemical industry by its molecular formula C7H6O2, stands out among aromatic aldehydes. This compound presents itself as a white to light yellow crystalline solid at room temperature. Folks working in labs often refer to it as 4-hydroxybenzaldehyde, a name that highlights its para-substituted hydroxy group attached to the benzene ring. Although just one of many benzaldehyde derivatives, p-Hydroxybenzaldehyde has carved out a solid spot in the pharma, fragrance, and specialty chemical markets. Its CAS number is 123-08-0, and the material ships worldwide under the HS Code 2912.49. It owes its popularity to both broad utility and straightforward structure, which consists of a benzene ring bearing an aldehyde group at one end and a hydroxy group at the para position.
This chemical exists as a solid under normal conditions but can sometimes arrive in flakes or as a fine powder. Transparency, color, and texture may shift slightly by source or method of purification, but the density generally comes in at around 1.226 g/cm3, and its melting point clocks in between 112°C and 115°C. P-Hydroxybenzaldehyde resists dissolving in cold water—though you can coax it into solution in hot water, and it mixes easily with ethanol, ether, and other organic solvents. Its odor carries the typical almond-like scent shared with other benzaldehydes, which points to its use in fragrances. From an analytical viewpoint, its molecular mass is 122.12 g/mol. Rapid advances in separation science have made it easier to find the compound at higher purity, usually above 98%, to match pharmaceutical or fine chemical applications.
As a molecule, p-Hydroxybenzaldehyde traces its roots to the benzene ring, anchoring a formyl (–CHO) group at one end and a hydroxy (–OH) group directly opposite. Chemists recognize its systematic name—4-hydroxybenzaldehyde—because it’s the hydroxy position relative to the formyl group that determines its reactivity and functionality. The formula C7H6O2 leaves no room for ambiguity: it houses seven carbon atoms, six hydrogens, and two oxygens. As a result of this arrangement, the molecule houses both an electron-donating group (hydroxy) and an electron-withdrawing group (formyl), adding complexity to its chemical behavior. Whether you look at reactivity, boiling point, or expected spectral data, its structure shapes everything.
From supplier catalogs to laboratory stockrooms, you’ll spot p-Hydroxybenzaldehyde showing up in different physical forms—solid, powder, crystals, and sometimes as flakes or pearls. Manufacturers generally package the compound in tightly sealed containers to protect from moisture and oxidation, which can hurt both yield and purity. Some commercial batches specify mean particle size, bulk density, or solubility profile, depending on the final field of use. Industrial users pay close attention to specs such as melting point, appearance, water content (by Karl Fischer titration), and assay by HPLC or GC—since unwanted residues or side-products can affect downstream performance in synthetic or analytical procedures.
Experience in specialty chemicals makes clear why p-Hydroxybenzaldehyde draws steady demand. Fragrance and flavor houses use it to make vanillin and other prized aromatic compounds. Pharma labs value its role as an intermediate during the synthesis of active pharmaceutical ingredients, dyes, and pesticides, pointing to just how widely it turns up. The hydroxy and formyl groups support further chemical modification, allowing downstream products with tailored activity. In polymer science, p-Hydroxybenzaldehyde sometimes steps in as a building block for specialty resins or as a cross-linking agent, drawing on its sturdy aromatic structure. Though simple, the molecule keeps surprising chemists with its broad adaptability—serving as raw material for new drugs and advanced materials.
Anyone who has spent time around organic reagents recognizes that p-Hydroxybenzaldehyde calls for responsible handling. Contact with skin or eyes produces irritation, and inhalation can cause coughing or shortness of breath because of its mild volatility. Long-term exposure needs to stay low, since benzaldehyde derivatives sometimes carry toxicological concerns. Safety data sheets list it as harmful if swallowed and suggest gloves, goggles, and a fume hood during handling. Storage requires a cool, dry place away from strong oxidizers or acids. For waste, strict adherence to local hazardous chemical disposal protocols stays mandatory; pouring leftover solutions into general drains always risks environmental harm. Workplace training and good labeling reduce accident chances, further safeguarding folks on the job.
Wider access to p-Hydroxybenzaldehyde stands as both an opportunity and a responsibility. Rapid growth in pharmaceuticals and specialty materials means more tons move through global trade, multiplying both economic value and potential hazards. ASTM and ISO standards have improved transparency on specifications, but counterfeit or contaminants continue to threaten supply chains. Researchers and manufacturers must work their way through confusing labeling, changing regulatory codes, and unexpected swings in raw material purity. Governments keep ramping up chemical tracking through revised HS Codes and mandatory reporting of hazardous materials, which might slow exports but cuts down on misuse or smuggling. From my own experience in contract research, I’ve found that clear contracts, transparency in supply sources, and in-house quality testing go further than handshake deals or generic spec sheets.
