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CAS 99-50-3 may appear across multiple EU annex records. The CAS lookup page shows all Annex II–VI entries sharing this identifier, useful for identifying cross-annex regulatory status of the same chemical substance.

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InventoryRef 5420115/10/2010

3,4-DIHYDROXYBENZOIC ACID

3,4-Dihydroxybenzoic acid

3,4-DIHYDROXYBENZOIC ACID is listed in the EU CosIng inventory, but no direct annex records are linked on this page yet.

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Regulatory evidence by market

No rule for this ingredient has been imported for any of the 13 markets tracked here.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 99-50-3

CAS 99-50-3PubChem CID 72

Protocatechuic Acid

3,4-dihydroxybenzoic acid is a dihydroxybenzoic acid in which the hydroxy groups are located at positions 3 and 4. It has a role as an EC 1.14.11.2 (procollagen-proline dioxygenase) inhibitor, an antineoplastic agent, a plant metabolite, a human xenobiotic metabolite and an EC 1.1.1.25 (shikimate dehydrogenase) inhibitor. It is a dihydroxybenzoic acid and a member of catechols. It is functionally related to a benzoic acid. It is a conjugate acid of a 3,4-dihydroxybenzoate. — ChEBI

IUPAC name: 3,4-dihydroxybenzoic acid

Molecular formula: C7H6O4
Molecular weight: 154.12 g/mol
Exact mass: 154.02660867 Da
XLogP3: 1.1
Topological polar surface area: 77.8 Å²
Hydrogen-bond donors: 3
Hydrogen-bond acceptors: 4
Covalent units: 1
Defined stereocentres: 0

Also known as

4-Carboxy-1,2-dihydroxybenzeneProtocatehuic acid4,5-Dihydroxybenzoic acid36R5QJ8L4BNSC-16631FEMA NO. 4430CHEBI:36062RefChem:25857

16 more reported names

202-760-0protocatechuateBenzoic acid, 3,4-dihydroxy-3,4-Dihydroxybenzoicacid3,4-Dihydroxy Benzoic AcidprotocatechuicacidCarbohydroquinonic acidCCRIS 62913,4-dihydroxy-benzoic acidEINECS 202-760-0NSC 16631Catechol-4-carboxylic AcidBRN 14488411ykp3, 4-Dihydroxybenzoic acidUNII-36R5QJ8L4B

Open full PubChem record PubChem annotations 3D structure image

External database identifiers

ChEBI:CHEBI:36062
ChEMBL:CHEMBL37537
EPA DTXSID:DTXSID4021212
PubMed:42004505
PubMed:40754433
PubMed:40228806
PubMed:37105472
PubMed:36807594
PubMed:36593721
PubMed:33497687
PubMed:32758512
PubMed:32461003
PubMed:32392679
PubMed:31850806
PubMed:31306686

Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Inventory details for 3,4-DIHYDROXYBENZOIC ACID

INCI name

3,4-DIHYDROXYBENZOIC ACID

Description

3,4-Dihydroxybenzoic acid

Record provenance

Inventory reference: 54201
Imported identity: 3,4-DIHYDROXYBENZOIC ACID
Source update: 15/10/2010

European Commission CosIng source notes

Annex records for 3,4-DIHYDROXYBENZOIC ACID

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Key data

CAS

99-50-3

202-760-0

Restriction

—

Function

SKIN PROTECTING: Helping to avoid harmful effects to the skin from external factors.

Official EU ingredient-name evidence

The ingredient name exactly matches the official 2025 EU glossary of common ingredient names.

#260 · 3,4-DIHYDROXYBENZOIC ACID

Ingredients with overlapping formulation functions

2-CAPRYLOYL CAPRYLOYL DIMETHYL ASPARTATEHAIR CONDITIONING; SKIN PROTECTING; SKIN CONDITIONING - MISCELLANEOUS

2-CAPRYLOYL CAPRYLOYL METHYL ALANINATEANTI-SEBUM, HAIR CONDITIONING, SKIN CONDITIONING, SKIN CONDITIONING - EMOLLIENT, SKIN PROTECTING

2-HYDROXYSTEARIC ACIDHAIR CONDITIONING; SKIN PROTECTING; SURFACTANT - CLEANSING; SKIN CONDITIONING - MISCELLANEOUS

2-METHYL 5-CYCLOHEXYLPENTANOLDEODORANT, SKIN CONDITIONING, SKIN PROTECTING

3,4-DIHYDROXYBENZOYL DIPEPTIDE-49 AMIDEHUMECTANT, SKIN CONDITIONING, SKIN CONDITIONING - EMOLLIENT, SKIN PROTECTING

3-ASCORBYLMETHYLCARBONYL GLYCYL TRI-T-BUTYL TRYPTOPHANAMIDEHAIR CONDITIONING; SKIN PROTECTING; SKIN CONDITIONING - MISCELLANEOUS

3-HYDROXYPROPYL SUNFLOWERAMIDESKIN CONDITIONING - EMOLLIENT; SKIN PROTECTING; SKIN CONDITIONING - HUMECTANT; SKIN CONDITIONING - …

6,8-DIMERCAPTOCAPRYLOYL TRIPEPTIDE-102ANTIOXIDANT; SKIN PROTECTING; SKIN CONDITIONING - MISCELLANEOUS

Additional official and scientific sources

11 external databases to check this identity in

Each link searches that source for this identity. What each source is, and its legal weight

ECHA CHEM / Information on chemicals PubChem PUG REST EU Safety Gate cosmetic product alerts ECHA CHEM US EPA CompTox Cosmetic Ingredient Review safety assessments FDA Global Substance Registration System ILO/WHO International Chemical Safety Cards Japan NITE-CHRIP NIOSH Pocket Guide to Chemical Hazards OECD eChemPortal

How 3,4-DIHYDROXYBENZOIC ACID appears in the CosIng inventory

The CosIng inventory lists 3,4-DIHYDROXYBENZOIC ACID as a cosmetic ingredient and this page links it to 0 annex records. The inventory entry captures names and identifiers, while the annex records show where the substance is prohibited, restricted or positively listed in EU cosmetics law.

3,4-DIHYDROXYBENZOIC ACID is also tagged with 1 cosmetic function in the official data. Function labels describe intended use, but they do not replace regulatory review of linked annex records before formulation or labelling work.

Frequently asked questions

3,4-DIHYDROXYBENZOIC ACID is listed in the EU CosIng ingredient inventory with no direct annex restriction records linked at this time. Absence of an annex link does not guarantee unrestricted use — always verify against the current official CosIng database before formulating.

According to the EU CosIng inventory, 3,4-DIHYDROXYBENZOIC ACID carries the following function designation(s):

SKIN PROTECTING

CAS 99-50-3 may appear across multiple EU annex records. Viewing the CAS lookup page shows all Annex II–VI entries sharing this identifier, which is useful for identifying cross-annex regulatory status of the same chemical substance.

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Source note for 3,4-DIHYDROXYBENZOIC ACID

This page reproduces the CosIng inventory entry for 3,4-DIHYDROXYBENZOIC ACID from public European Commission cosmetic ingredient materials and shows linked identifiers even when no direct annex match is currently attached.

Use this inventory page to research 3,4-DIHYDROXYBENZOIC ACID and compare linked records, but verify restrictions and legal status against the current official source text and law before making regulatory decisions.

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