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Cosmetic preservatives

4-Hydroxybenzoic acid

Also known as p-Hydroxybenzoic acid, p-Salicylic acid, 4-Carboxyphenol

CAS 99-96-7Formula C7H6O3Molar mass 138.12 g/molEC 202-804-9
GHS signal word: Danger. Pictograms: Corrosive, Harmful or irritant 130 suppliers listed
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4-Hydroxybenzoic acid chemical structure, C7H6O3, CAS 99-96-7
2D chemical structure

Key facts

What buyers check first

All properties
Appearance
White granular crystalline powder consisting of monoclinic prisms
Melting point
214.5 °C
Density
1.46 g/cm³ @ 25 °C
Solubility
Soluble in about 125 parts water, freely in alcohol, slightly in chloroform, soluble in…
HS code
291829
Category
Cosmetic preservatives
Illustrative photo, white granules in a woven sack in a warehouse
Typical packagingIllustrative packaging image, not the actual product

What is 4-Hydroxybenzoic acid?

Plain description, key identifiers and synonyms

4-hydroxybenzoic acid is a monohydroxybenzoic acid that is benzoic acid carrying a hydroxy substituent at C-4 of the benzene ring. It has a role as a plant metabolite and an algal metabolite. It is a conjugate acid of a 4-hydroxybenzoate.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
4-hydroxybenzoic acid
CAS number
99-96-7 CAS number cross-checkedOther or deprecated CAS: 30729-36-3
EC number
202-804-9
Molecular formula
C7H6O3
UNII
JG8Z55Y12H
MDL number
MFCD00002547
INCI name
4-HYDROXYBENZOIC ACID
InChIKey
FJKROLUGYXJWQN-UHFFFAOYSA-N
InChI
InChI=1S/C7H6O3/c8-6-3-1-5(2-4-6)7(9)10/h1-4,8H,(H,9,10)
SMILES (canonical and isomeric)
C1=CC(=CC=C1C(=O)O)O

Synonyms

  • p-Hydroxybenzoic acid
  • p-Salicylic acid
  • 4-Carboxyphenol
  • Benzoic acid, 4-hydroxy-
  • Benzoic acid, p-hydroxy-
  • para-Hydroxybenzoic acid
  • p-Oxybenzoesaure
  • 4-Hydroxybenzoate
  • p-carboxyphenol
  • 4-hydroxy benzoic acid
  • Hydroxybenzoic acid
  • 4-Hydroxybenzoesaeure
  • Paraben-acid
  • p-hydroxy benzoic acid
  • 4-hydroxy-benzoic acid
  • Acido p-idrossibenzoico
  • Kyselina 4-hydroxybenzoova
  • p-Salicyclic Acid
  • parahydroxybenzoic acid
  • Hydroxybenzoic acid, para
  • p-hydroxy-Benzoic acid
  • Benzoic acid, 4-hydroxy
  • Hydroxybenzenecarboxylic acid
  • p-Hydroxybenzoic
  • 3pcc
Show all 35 synonyms
  • 3pch
  • 4-hydroxy-benzoate
  • 4-Hydroxybenzoicacid
  • Benzoic acid, p-hydroxy
  • PHB
  • 4-Hydroxybenzenecarboxylic acid
  • p-Salicylate
  • p-hydroxy-Benzoate
  • Aspirin Impurity A
  • 4-OH benzoic acid

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

Appearance
White granular crystalline powder consisting of monoclinic prismsexp.
Melting point
214.5 °Cexp.
Density
1.46 g/cm³ @ 25 °Cexp.
Solubility
Soluble in about 125 parts water, freely in alcohol, slightly in chloroform, soluble in ether, acetone. Practically insoluble in carbon disulfide.exp.
Vapour pressure
1.9 × 10⁻⁷ mm Hg at 25 °C /Extrapolated/exp.

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
138.12 g/molcalc.
Exact mass
138.0317 Dacalc.
LogP (octanol/water)
1.09calc.
Topological polar surface area
57.53 Ųcalc.
Hydrogen bond donors
2calc.
Hydrogen bond acceptors
2calc.
Rotatable bonds
1calc.
Heavy atoms
10calc.
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
Danger
GHS05: Corrosive
Corrosive
GHS07: Harmful or irritant
Harmful or irritant

Hazard statements

  • H315Causes skin irritation.
  • H318Causes serious eye damage.
  • H319Causes serious eye irritation.
  • H335May cause respiratory irritation.
Precautionary statements (18)
  • 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.
  • P305 + P354 + P338If in eyes: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P317Get medical help.
  • 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

4-Hydroxybenzoic acid suppliers

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All 130 suppliers
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Where suppliers are based

130 suppliers in 21 countries

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4-Hydroxybenzoic 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

Intermediate, synthetic drugs, food preservative. Its methyl, propyl and butyl esters are used for cosmetics and pharmaceuticals.

Intermediate for dyes, fungicides.

Corrosion inhibitor, anti-oxidant and emulsifier.

Used in polymers as a component in the manufacture of polyester and as a constituent of liquid crystal polymers.

Industrial uses: Corrosion inhibitor, Intermediate, Monomers, Processing aids not otherwise specified.

Consumer uses: Processing aids not otherwise specified, Monomers, Surface modifier, Intermediate.

Use classes: Cosmetics.

Cosmetic ingredient, INCI name 4-HYDROXYBENZOIC ACID(fragrance, preservative)

Roles

  • algal metabolite
  • eukaryotic metabolite
  • metabolite
  • plant metabolite

Functional uses

  • Flavouring and nutrient
  • Fragrance
  • Preservative

Cosmetic functions

  • Fragrance
  • Preservative

How it is made

4-Hydroxybenzoic acid can... be obtained by isomerization of dipotassium salicylate at temperatures up to 240 °C and under carbon dioxide pressure (slightly above atmospheric pressure), or by oxidation of the alkali-metal salt of p-cresol on metal oxides at 260-270 °C. Reaction of phenol with tetrachloromethane in the presence of alkali produces salicylic acid as the main product and smaller amounts of 4-hydroxybenzoic acid.

4-Hydroxybenzoic acid is produced by carboxylation of potassium phenolate above 220 °C and with a carbon dioxide pressure of 0.45 MPa. The yield fo 4-hydroxybenzoic acid (partly present as the dipotassium salt) is 80% of the theoretical amount in which the conversion of phenolate is 60%.

Interaction of 1-aminobenzoic acid and nitrous acid.

Regulatory status

Inventories, regulations and trade controls that list this substance

Health and food

  • EU cosmetic ingredient inventory
  • EU Cosmetics Regulation Annex V, allowed preservative
    Name: 4-HYDROXYBENZOIC ACID / METHYLPARABEN /POTASSIUM ETHYLPARABEN /POTASSIUM PARABEN /SODIUM METHYLPARABEN /SODIUM ETHYLPARABEN /ETHYLPARABEN /SODIUM PARABEN…

United States

  • TSCA inventory (USA)
    Status: Active in US commerce

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code 4-Hydroxybenzoic 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 4-Hydroxybenzoic acid is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about 4-Hydroxybenzoic acid, based on the data on this page

What is 4-Hydroxybenzoic acid?

4-hydroxybenzoic acid is a monohydroxybenzoic acid that is benzoic acid carrying a hydroxy substituent at C-4 of the benzene ring. It has a role as a plant metabolite and an algal metabolite. It is a conjugate acid of a 4-hydroxybenzoate.

What is the CAS number of 4-Hydroxybenzoic acid?

The CAS registry number of 4-Hydroxybenzoic acid is 99-96-7. Other or deprecated CAS numbers: 30729-36-3.

What is the molecular formula and weight of 4-Hydroxybenzoic acid?

The molecular formula of 4-Hydroxybenzoic acid is C7H6O3 and its molar mass is 138.12 g/mol.

What is 4-Hydroxybenzoic acid used for?

Intermediate, synthetic drugs, food preservative. Its methyl, propyl and butyl esters are used for cosmetics and pharmaceuticals. Intermediate for dyes, fungicides. Corrosion inhibitor, anti-oxidant and emulsifier.

Is 4-Hydroxybenzoic acid hazardous?

4-Hydroxybenzoic acid carries the GHS signal word "Danger". Main hazards: causes skin irritation, causes serious eye damage, causes serious eye irritation. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of 4-Hydroxybenzoic acid?

4-Hydroxybenzoic 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 4-Hydroxybenzoic acid?

CompoundList lists 130 suppliers of 4-Hydroxybenzoic acid in China, United States, India, Germany and 17 more. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

Where can I buy 4-Hydroxybenzoic acid in India?

10 suppliers in India list 4-Hydroxybenzoic 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 4-Hydroxybenzoic acid?

Suppliers quote 4-Hydroxybenzoic 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 4-Hydroxybenzoic 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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