3,5-Dihydroxybenzoic Acid: Properties, Uses & FAQs

3,5-Dihydroxybenzoic acid is a naturally occurring phenolic acid bearing two hydroxyl groups at the 3- and 5-positions of the benzoic acid ring, widely used in analytical, biochemical, and materials research applications.

Chemical Name

3,5-Dihydroxybenzoic acid

CAS Number

99-10-5

Molecular Formula

C₇H₆O₄

Molecular Weight

154.12 g/mol

Aladdin SKU

D104386

Appearance

White to off-white crystalline powder

Key Applications

MALDI-TOF matrix, antioxidant assays, organic synthesis intermediate

What Is 3,5-Dihydroxybenzoic Acid?

3,5-Dihydroxybenzoic acid (3,5-DHBA; CAS 99-10-5) is a member of the hydroxybenzoic acid family of phenolic compounds. Its structure consists of a benzene ring bearing a carboxylic acid group at position 1 and hydroxyl substituents at positions 3 and 5, giving the molecule a symmetric, meta-substituted arrangement. The compound occurs naturally in certain plant species and is also readily accessible through chemical synthesis.

With a molecular formula of C₇H₆O₄ and a molecular weight of approximately 154.12 g/mol, 3,5-DHBA is a relatively small, water-soluble organic acid. Its two phenolic hydroxyl groups confer hydrogen-bonding capability and mild reducing character, properties that underpin many of its laboratory applications.

Key Laboratory Applications

MALDI-TOF Mass Spectrometry Matrix: 3,5-DHBA has been explored as a matrix compound in matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Its ability to absorb UV laser energy and co-crystallize with analytes makes it a candidate matrix for certain biomolecule and polymer analyses.

Antioxidant and Free-Radical Research: The phenolic hydroxyl groups enable 3,5-DHBA to act as a hydrogen-atom donor, making it relevant to studies of radical scavenging activity, oxidative stress, and structure–activity relationships among polyphenolic antioxidants.

Organic Synthesis Intermediate: 3,5-DHBA serves as a versatile building block for the synthesis of more complex phenolic natural products, pharmaceutically relevant scaffolds, and functional materials. Its symmetric substitution pattern simplifies regioselective transformations.

Biochemical Assays: The compound may be used as a reference standard or substrate in enzymatic assays involving phenol-oxidizing enzymes such as laccases and peroxidases.

Solubility, Storage, and Handling

Solubility: 3,5-Dihydroxybenzoic acid is soluble in polar solvents including water, ethanol, and methanol. Its solubility in water is moderate and is enhanced under alkaline conditions due to deprotonation of the phenolic and carboxylic groups. It has limited solubility in non-polar organic solvents.

Storage: The compound should be stored in a tightly sealed container in a cool, dry location away from light and moisture. Standard recommended storage is at room temperature or 2–8 °C under inert atmosphere where long-term stability is required. Avoid exposure to strong oxidising agents.

Handling Precautions: As with most fine chemical reagents, appropriate personal protective equipment (PPE) — including gloves, safety glasses, and a laboratory coat — should be worn. Consult the Safety Data Sheet (SDS) provided by Aladdin Scientific before use. Dispose of waste in accordance with local regulations.

Purity, Specifications, and Quality

Aladdin Scientific supplies 3,5-Dihydroxybenzoic acid (SKU D104386) as a research-grade reagent. Researchers should consult the product page or contact Aladdin's technical support team for the current certificate of analysis (CoA), which details purity grade, analytical test methods (e.g., HPLC or titration), and lot-specific results.

When selecting a grade for sensitive applications such as MALDI matrix preparation or reference standard use in quantitative assays, it is advisable to request a CoA confirming purity ≥98% and to check for the absence of interfering impurities. For routine synthetic applications, standard reagent grade is typically sufficient.

Aladdin Scientific's quality management processes include in-house analytical testing and traceability documentation to support reproducible research outcomes.

Ordering and Procurement

3,5-Dihydroxybenzoic acid is available from Aladdin Scientific under SKU D104386. Researchers and procurement teams can place orders directly through the Aladdin Scientific website or by contacting the sales team. Bulk quantities or custom packaging may be available upon request — please enquire with Aladdin's sales representatives for pricing and lead times.

For institutional or recurring orders, Aladdin Scientific offers account management options including volume pricing and invoice purchasing. Details on payment methods, shipping options, and return policies are available in the Help and Customer Service section of the Aladdin Scientific website.

Frequently asked questions

What is the CAS number for 3,5-Dihydroxybenzoic acid?

The CAS registry number for 3,5-Dihydroxybenzoic acid is 99-10-5. This number uniquely identifies the compound and can be used when searching databases or communicating with suppliers.

Is 3,5-Dihydroxybenzoic acid soluble in water?

3,5-Dihydroxybenzoic acid has moderate solubility in water. Solubility increases under alkaline conditions as the phenolic hydroxyl and carboxylic acid groups become deprotonated. It is also soluble in polar organic solvents such as ethanol and methanol.

What are the main uses of 3,5-Dihydroxybenzoic acid in the laboratory?

3,5-Dihydroxybenzoic acid is used as a potential MALDI-TOF mass spectrometry matrix, as a model substrate or standard in antioxidant and free-radical research, and as a synthetic building block for phenolic natural products and pharmaceutical intermediates. It may also serve as a substrate for phenol-oxidising enzyme assays.

How should 3,5-Dihydroxybenzoic acid be stored?

The compound should be stored in a tightly sealed container in a cool, dry place, protected from light and moisture. For long-term storage, keeping it at 2–8 °C under an inert atmosphere is advisable. Always consult the product's Safety Data Sheet for specific storage guidance.

What purity grade of 3,5-Dihydroxybenzoic acid does Aladdin Scientific supply?

Aladdin Scientific supplies 3,5-Dihydroxybenzoic acid (SKU D104386) as a research-grade reagent. For the exact purity specification and lot-specific analytical data, researchers should request the current Certificate of Analysis (CoA) from the product page or by contacting Aladdin's technical support.

Can I order 3,5-Dihydroxybenzoic acid in bulk quantities from Aladdin Scientific?

Bulk quantities or custom packaging of 3,5-Dihydroxybenzoic acid (SKU D104386) may be available upon request. Contact Aladdin Scientific's sales team directly to enquire about availability, pricing, and lead times for larger orders.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. Wiley-Interscience. (General reference for hydroxybenzoic acid chemistry.)
2. Aladdin Scientific. Product page: 3,5-Dihydroxybenzoic acid, SKU D104386. Aladdin Scientific official website.
3. Karas, M.; Hillenkamp, F. Laser desorption ionization of proteins with molecular masses exceeding 10,000 daltons. Analytical Chemistry, 1988, 60(20), 2299–2301. (Background reference for MALDI matrix principles.) doi:10.1021/ac00171a028

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.