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Skin conditioning agents and actives

Protocatechuic acid

Also known as 3,4-Dihydroxybenzoic acid, 4-Carboxy-1,2-dihydroxybenzene, Protocatehuic acid

CAS 99-50-3Formula C7H6O4Molar mass 154.12 g/molEC 202-760-0
GHS signal word: Warning. Pictograms: Harmful or irritant 121 suppliers listed
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Protocatechuic acid chemical structure, C7H6O4, CAS 99-50-3
2D chemical structure

Key facts

What buyers check first

All properties
CAS number
99-50-3
Formula
C7H6O4
Molar mass
154.12 g/mol
EC number
202-760-0
HS code
291829
Category
Skin conditioning agents and actives

What is Protocatechuic acid?

Plain description, key identifiers and synonyms

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.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
3,4-dihydroxybenzoic acid
CAS number
99-50-3 CAS number cross-checkedOther or deprecated CAS: 1225528-47-1
EC number
202-760-0
Molecular formula
C7H6O4
UNII
36R5QJ8L4B
MDL number
MFCD00002509
INCI name
3,4-DIHYDROXYBENZOIC ACID
InChIKey
YQUVCSBJEUQKSH-UHFFFAOYSA-N
InChI
InChI=1S/C7H6O4/c8-5-2-1-4(7(10)11)3-6(5)9/h1-3,8-9H,(H,10,11)
SMILES (canonical and isomeric)
C1=CC(=C(C=C1C(=O)O)O)O

Synonyms

  • 3,4-Dihydroxybenzoic acid
  • 4-Carboxy-1,2-dihydroxybenzene
  • Protocatehuic acid
  • 4,5-Dihydroxybenzoic acid
  • protocatechuate
  • Benzoic acid, 3,4-dihydroxy-
  • 3,4-Dihydroxy Benzoic Acid
  • Carbohydroquinonic acid
  • 3,4-dihydroxy-benzoic acid
  • Catechol-4-carboxylic Acid
  • 1ykp
  • 3, 4-Dihydroxybenzoic acid
  • protocatechuicacid
  • b-Resorcylate
  • beta-Resorcylate
  • procatechuic acid
  • ProtocatechicAcid
  • 4fht
  • protoeatechuic acid
  • protocatechulic acid
  • 3,4-dihydrobenzonic acid
  • Protocatechoic acid
  • Protocatechuic acid (M1)
  • 3,4-dihodroxybenzoic acid
  • 3,4-dihydoxy benzoic acid
Show all 34 synonyms
  • 3,4-Dihydroxybenzoate, VIII
  • Protocatechuic acid (Standard)
  • Pyrocatechol-4-carboxylic Acid
  • Protocatechuic acid (pca)
  • Dihydroxybenzoic acid, 3,4-
  • 1,2-Dihydroxybenzene-4-carboxylic acid
  • 3,4-Dihydroxybenzoic Acid (See P6857)
  • 3,4-Dihydroxybenzoic acid, >=97.0% (T)
  • 3,4-Dihydroxybenzoic acid, analytical standard

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

No measured properties are recorded for this substance yet. Ask suppliers for a technical data sheet.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
154.12 g/molcalc.
Exact mass
154.0266 Dacalc.
LogP (octanol/water)
0.8calc.
Topological polar surface area
77.76 Ųcalc.
Hydrogen bond donors
3calc.
Hydrogen bond acceptors
3calc.
Rotatable bonds
1calc.
Heavy atoms
11calc.
Rings
1calc.
Aromatic rings
1calc.
Fraction sp3 carbons
0calc.
Formal charge
0calc.
Stereocentres
0calc.
Lipinski rule of five
Passes (0 violations)calc.

Calculated for screening. Confirm critical figures with the supplier.

Murcko scaffold

The ring system that remains when every side chain is removed

Murcko scaffold of this chemical, c1ccccc1

c1ccccc1

1 ring, 6 atoms, the Benzene ring system.

485,677 other chemicals share this scaffold

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Warning
GHS07: Harmful or irritant
Harmful or irritant

Hazard statements

  • H315Causes skin irritation.
  • H319Causes serious eye irritation.
  • H335May cause respiratory irritation.
Precautionary statements (16)
  • P261Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P264Wash skin thoroughly after handling.
  • P264 + P265Wash skin thoroughly after handling. Do not touch eyes.
  • P271Use only outdoors or in a well-ventilated area.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P302 + P352If on skin: Wash with plenty of water.
  • P304 + P340If inhaled: Remove person to fresh air and keep comfortable for breathing.
  • P305 + P351 + P338If in eyes: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P319Get medical help if you feel unwell.
  • P321Specific treatment (see supplemental first aid instructions on the label).
  • P332 + P317If skin irritation occurs: Get medical help.
  • P337 + P317If eye irritation persists: Get medical help.
  • P362 + P364Take off contaminated clothing. And wash it before reuse.
  • P403 + P233Store in a well-ventilated place. Keep container tightly closed.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

Protocatechuic acid suppliers

Sponsored listings first, then the documented ranking: membership, verification, replies, completeness, freshness and ratings

All 121 suppliers
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Suppliers marked Unclaimed profile have not claimed their profile yet. They are not verified by CompoundList, their offers are price on request and details may have changed, so please confirm them with the supplier. Company representatives can claim a profile with a business email on the company's own website domain. Our team verifies each claim and sends the result by email.

Where suppliers are based

121 suppliers in 15 countries

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Protocatechuic acid price

Indicative price range per kg from live supplier offers

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Uses and applications

What the substance is used for, by industry and function

Cosmetic ingredient, INCI name 3,4-DIHYDROXYBENZOIC ACID(skin protecting)

Pharmacological actions

  • Anticarcinogenic Agents

Roles

  • animal metabolite
  • antineoplastic agent
  • enzyme inhibitor
  • eukaryotic metabolite
  • human metabolite
  • human xenobiotic metabolite
  • mammalian metabolite
  • metabolite
  • pharmaceutical
  • plant metabolite
  • xenobiotic metabolite

Functional uses

  • Flavouring and nutrient
  • Humectant

Cosmetic functions

  • Skin protecting

Regulatory status

Inventories, regulations and trade controls that list this substance

Health and food

  • EU cosmetic ingredient inventory

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Protocatechuic acid is traded under.

HS 2918.29Indicative HS code

Carboxylic acids, (with phenol function but without other oxygen function), their anhydrides, halides…

World exports in 2024
$861M
+0.9% vs 2023, imports $892M
2019 to 2024
Top exporters
  1. China30.5%
  2. South Korea18.3%
  3. Switzerland * partner reported13.3%
Top importers
  1. United States14.7%
  2. Germany13.3%
  3. Japan10.3%

* Partner reported figures, a lower bound.

Reported customs values in USD, not prices.Full trade data

The HS code shown for Protocatechuic acid is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Protocatechuic acid, based on the data on this page

What is Protocatechuic acid?

3,4-dihydroxybenzoic acid is a dihydroxybenzoic acid in which the hydroxy groups are located at positions 3 and 4.

What is the CAS number of Protocatechuic acid?

The CAS registry number of Protocatechuic acid is 99-50-3. Other or deprecated CAS numbers: 1225528-47-1.

What is the molecular formula and weight of Protocatechuic acid?

The molecular formula of Protocatechuic acid is C7H6O4 and its molar mass is 154.12 g/mol.

What is Protocatechuic acid used for?

Known uses and roles of Protocatechuic acid include skin conditioning agents in cosmetics and personal care, animal metabolite, antineoplastic agent, enzyme inhibitor, eukaryotic metabolite and 11 more.

Is Protocatechuic acid hazardous?

Protocatechuic acid carries the GHS signal word "Warning". Main hazards: causes skin irritation, causes serious eye irritation, may cause respiratory irritation. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Protocatechuic acid?

Protocatechuic acid is usually classified under HS code 291829 (Carboxylic acids with phenol function but without other oxygen function, their…). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Protocatechuic acid?

CompoundList lists 121 suppliers of Protocatechuic acid in China, United States, India, Germany and 11 more. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

Where can I buy Protocatechuic acid in India?

6 suppliers in India list Protocatechuic acid on CompoundList. Filter the suppliers list by country and send a request to compare prices, grades and delivery times.

What is the price of Protocatechuic acid?

Suppliers quote Protocatechuic acid on request because prices depend on grade, purity, quantity and destination. A free request on CompoundList gets you several quotes to compare.

Guides for buyers

Practical guides that help when you source, ship or handle Protocatechuic acid

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Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
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