p-Hydroxybenzaldehyde (4-Hydroxybenzaldehyde) – CAS 123-08-0

Product Overview

p-Hydroxybenzaldehyde (4-Hydroxybenzaldehyde) is an aromatic aldehyde bearing a hydroxyl group at the para position relative to the aldehyde.

CAS Number: 123-08-0

• Molecular Formula: C₇H₆O₂

• Molecular Weight: 122.12 g/mol

• Purity: ≥99.0% (HPLC)

• Physical Appearance: White to off-white (or pale yellow) crystalline powder

• Melting Point: 115–118 °C

• Boiling Point: 310–311 °C (decomposes)

• Storage: Keep in a cool, dry, well-ventilated place; protect from light and moisture.

Key Physical & Chemical Properties

p-Hydroxybenzaldehyde is stable under normal handling conditions but may discolor upon prolonged exposure to air or light. It is non-hygroscopic and can be stored safely in sealed containers.

Major Applications

1. Pharmaceutical Intermediate

• API synthesis: Building block for sulfonamides, trimethoprim (antibacterial), and artesunate derivatives.

• Mannich base reactions: Used to prepare functionalized phenols with biological activity.

• Enzyme inhibitors: Forms the structural core of certain tyrosinase and aldehyde dehydrogenase inhibitors.

2. Flavor & Fragrance Industry

• Precursor for vanillin (4-hydroxy-3-methoxybenzaldehyde) through methylation and oxidation.

• Contributes to sweet, nutty, and almond-like notes in flavor compositions.

• Used in the production of cherry, vanilla, and berry flavor profiles.

3. Polymer & Liquid Crystal Materials

• Monomer for thermotropic liquid crystalline polyesters.

• Crosslinking agent in epoxy and phenolic resins.

• Component in high-performance engineering plastics.

4. Agrochemicals

• Intermediate for herbicides and plant growth regulators.

• Starting material for the synthesis of phenoxyalkanoic acid derivatives.

5. Organic Synthesis Reagent

• Substrate for Schiff base formation and Michael additions.

• Building block for coumarins, flavones, and chalcones.

Advantages of Using p-Hydroxybenzaldehyde

• High purity available (≥99% by HPLC), minimizing side reactions.

• Versatile functionality – both aldehyde and phenol groups allow diverse derivatization.

• Stable crystalline solid – easy to weigh, handle, and store.

• Widely available at competitive quality levels.

• Low toxicity profile compared to many aromatic aldehydes, though standard precautions apply.

Typical Packaging & Supply

• 25 kg fiber drums with inner PE liner

• 1 kg, 5 kg, 10 kg aluminum foil bags for R&D or sample orders

• Custom packaging available upon request

Each batch is accompanied by a Certificate of Analysis (COA) including appearance, melting point, purity by HPLC, and moisture content.

Frequently Asked Questions (FAQs)

Q1: What is the appearance of p-Hydroxybenzaldehyde?
It is typically a white to off-white crystalline powder. Lower purity or aged material may appear pale yellow to light beige. The pure form consists of needle-like crystals.

Q2: Is p-Hydroxybenzaldehyde soluble in water?
It is slightly soluble in water (approx. 8.45 g/L at 25 °C). Solubility increases significantly in organic solvents such as ethanol, methanol, acetone, and diethyl ether.

Q3: How should I store p-Hydroxybenzaldehyde?
Store in a tightly sealed container away from light, heat, and moisture. Keep at room temperature (15–30 °C) in a dry well-ventilated area. Avoid contact with strong oxidizing agents and strong bases. Under proper storage, shelf life exceeds 24 months.

Q4: What is the difference between p-hydroxybenzaldehyde and vanillin?
Vanillin (4-hydroxy-3-methoxybenzaldehyde) has an additional methoxy group at the meta position. p-Hydroxybenzaldehyde is the direct precursor for vanillin via methylation. It has a more aldehyde‑dominated odor profile compared to the sweeter vanilla note of vanillin.

Q5: Is p-hydroxybenzaldehyde hazardous?
It is classified as a skin and eye irritant (H315, H319). Inhalation of dust may cause respiratory irritation. Standard PPE (lab coat, gloves, safety goggles) and ventilation should be used. It is not classified as carcinogenic, mutagenic, or toxic to reproduction.

Q6: Can you supply high purity (>99.5%) grade?
Yes. Aozunchem offers both industrial grade (≥99%) and high‑purity grade (≥99.5% by HPLC) for pharmaceutical and electronic applications. Please specify your requirement when requesting a quote.

Q7: What reactions can p-hydroxybenzaldehyde undergo?
It participates in:

• Aldol condensation

• Schiff base formation (with amines)

• Etherification (methylation → vanillin)

• Esterification (through the phenolic OH)

• Reduction to p-hydroxybenzyl alcohol

• Oxidation to p-hydroxybenzoic acid

Q8: Is this compound listed on major regulatory inventories?
Yes. p-Hydroxybenzaldehyde (CAS 123-08-0) is registered under TSCA (USA), EINECS (EU), ECL (Korea), IECSC (China), and other regional chemical inventories. It is not a restricted substance under normal industrial use.

Q9: Do you offer free samples?
Aozunchem provides complimentary small samples (10–20 g) for qualified R&D purposes. Sample policy requires a brief application description. Shipping costs may apply. Contact us to request a sample.

Q10: What is the typical impurity profile of your product?
Our standard grade contains ≤0.5% total related substances (mainly o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, and p-hydroxybenzoic acid). High-purity grade has ≤0.1% individual impurities.

Contact Us

For pricing, technical data sheets (TDS/MSDS), sample requests, or to discuss custom synthesis and bulk supply, please contact:

Email: lisa@aozunchem.com
WeChat / WhatsApp: +86 186 5121 5887