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Nitriles, nitro and azo compounds

4-Nitrosophenol

Also known as p-Nitrosophenol, Phenol, 4-nitroso-, Quinone monoxime

CAS 104-91-6Formula C6H5NO2Molar mass 123.11 g/molEC 203-251-6
GHS signal word: Danger. Pictograms: Corrosive, Harmful or irritant, Serious health hazard, Hazardous to the environment 6 suppliers listed
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4-Nitrosophenol chemical structure, C6H5NO2, CAS 104-91-6
2D chemical structure

Key facts

What buyers check first

All properties
Appearance
Pale yellow orthorhombic needles, browns @ 126 °c
Melting point
132.2 to 143.9
Solubility
MODERATELY SOL IN WATER, SOL IN DILUTE ALKALIES GIVING GREEN TO BROWNISH GREEN SOLUTIONS…
HS code
290899
Category
Nitriles, nitro and azo compounds
UN number
UN 3236
Illustrative photo, off-white crystalline powder in fibre drums in a warehouse
Typical packagingIllustrative packaging image, not the actual product

What is 4-Nitrosophenol?

Plain description, key identifiers and synonyms

P-benzoquinone monoxime is a black solid. (NTP, 1992)

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
4-nitrosophenol
CAS number
104-91-6 CAS number cross-checkedOther or deprecated CAS: 637-62-7
EC number
203-251-6
Molecular formula
C6H5NO2
UNII
55EB58H2UP
MDL number
MFCD00002329
InChIKey
JSTCPNFNKICNNO-UHFFFAOYSA-N
InChI
InChI=1S/C6H5NO2/c8-6-3-1-5(7-9)2-4-6/h1-4,8H
SMILES (canonical and isomeric)
C1=CC(=CC=C1N=O)O

Synonyms

  • p-Nitrosophenol
  • Phenol, 4-nitroso-
  • Quinone monoxime
  • Nitrosophenol
  • Quinone oxime
  • Phenol, p-nitroso-
  • 1,4-Benzoquinone monoxime
  • para-Nitrosophenol
  • 4-Benzoquinone Monoxime
  • p-Quinone monoxime
  • Quinone monooxime
  • 1,4-Benzoquinone 4-oxime
  • p-Quinone monooxime
  • 4-Nitrosofenol
  • Quinone 4-oxime
  • p-Benzoquinone 4-oxime
  • p-Benzoquinone, monooxime
  • p-Chinonmonoxim
  • p-Benzoquinone monoxime
  • 4-(hydroxyimino)cyclohexa-2,5-dien-1-one
  • 4-Hydroxyimino-2,5-cyclohexadiene-1-one
  • 4-07-00-02073 (Beilstein Handbook Reference)
  • 2,5-Cyclohexadiene-1,4-dione 1-Oxime
  • 2,5-Cyclohexadiene-1,4-dione, monooxime
  • 2,5-Cyclohexadien-1-one, 4-hydroxyimino-
Show all 34 synonyms
  • benzoquinone oxime
  • mono-nitroso phenol
  • 2,5-Cyclohexadiene-1,4-dione 1-Oxime, 1,4-Benzoquinone 4-Oxime, Quinone Monooxime, NSC 239647,
  • benzoquinone monooxime
  • 2, 4-hydroxyimino-
  • 2,4-dione, monooxime
  • benzoquinone imine N-oxide
  • Nitrosophenol, 4-
  • 1,4-Benzoquinone, 1-oxime-

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
Pale yellow orthorhombic needles, browns @ 126 °cexp.
Melting point
132.2 to 143.9exp.
Solubility
MODERATELY SOL IN WATER, SOL IN DILUTE ALKALIES GIVING GREEN TO BROWNISH GREEN SOLUTIONS, SOL IN ALC, ETHER, ACETONEexp.

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
123.11 g/molcalc.
Exact mass
123.032 Dacalc.
LogP (octanol/water)
1.79calc.
Topological polar surface area
49.66 Ųcalc.
Hydrogen bond donors
1calc.
Hydrogen bond acceptors
3calc.
Rotatable bonds
1calc.
Heavy atoms
9calc.
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
GHS08: Serious health hazard
Serious health hazard
GHS09: Hazardous to the environment
Hazardous to the environment

Hazard statements

  • H302Harmful if swallowed.
  • H318Causes serious eye damage.
  • H341Suspected of causing genetic defects.
  • H411Toxic to aquatic life with long lasting effects.
Precautionary statements (14)
  • P203Obtain, read and follow all safety instructions before use.
  • P264Wash skin thoroughly after handling.
  • P264 + P265Wash skin thoroughly after handling. Do not touch eyes.
  • P270Do not eat, drink or smoke when using this product.
  • P273Avoid release to the environment.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P301 + P317If swallowed: Get medical help.
  • 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.
  • P318If exposed or concerned, get medical advice.
  • P330Rinse mouth.
  • P391Collect spillage.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.
UN number
UN 3236

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-Nitrosophenol suppliers

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

All 6 suppliers
6 of 6 offers

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

6 suppliers in 3 countries

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4-Nitrosophenol 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

Manufacture of dyes.

Chemical intermediate for dyes.

Chemical intermediate for metal complex used as dye for camouflages.

Chemical intermediate, eg, for hydroquinone.

Industrial uses: Intermediate.

How it is made

From phenol by action of nitrous acid in the cold.

Probably by reaction of phenol with nitrous acid

Regulatory status

Inventories, regulations and trade controls that list this substance

Europe

  • EU harmonised classification (CLP Annex VI)
    Index no: 604-042-00-6

Health and food

  • EU Cosmetics Regulation Annex II, prohibited in cosmetics
    Name: 4-Nitrosophenol, Ref no: 995, Annex ref: II/995

United States

  • TSCA inventory (USA)
    Status: Active in US commerce, Regulatory flags: Proposed significant new use rule, proposed section 4 test rule

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code 4-Nitrosophenol is traded under.

HS 2908.99Indicative HS code

Halogenated, sulphonated, nitrated or nitrosated derivatives of phenols or…

World exports in 2024
$77.7M
+4.6% vs 2023, imports $83.7M
2019 to 2024
Top exporters
  1. China32.2%
  2. India * partner reported22.2%
  3. Spain8.5%
Top importers
  1. United States13.9%
  2. Spain10.6%
  3. Turkey8.3%

* Partner reported figures, a lower bound.

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

The HS code shown for 4-Nitrosophenol is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

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

What is 4-Nitrosophenol?

P-benzoquinone monoxime is a black solid. (NTP, 1992)

What is the CAS number of 4-Nitrosophenol?

The CAS registry number of 4-Nitrosophenol is 104-91-6. Other or deprecated CAS numbers: 637-62-7.

What is the molecular formula and weight of 4-Nitrosophenol?

The molecular formula of 4-Nitrosophenol is C6H5NO2 and its molar mass is 123.11 g/mol.

What is 4-Nitrosophenol used for?

Manufacture of dyes. Chemical intermediate for dyes. Chemical intermediate for metal complex used as dye for camouflages. Chemical intermediate, eg, for hydroquinone. Industrial uses: Intermediate.

Is 4-Nitrosophenol hazardous?

4-Nitrosophenol carries the GHS signal word "Danger". Main hazards: harmful if swallowed, causes serious eye damage, suspected of causing genetic defects. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of 4-Nitrosophenol?

4-Nitrosophenol is usually classified under HS code 290899 (Halogenated, sulphonated, nitrated or nitrosated derivatives of phenols or…). This is indicative, confirm it with your customs broker before shipping.

Where can I buy 4-Nitrosophenol?

CompoundList lists 6 suppliers of 4-Nitrosophenol in China, Japan and United States. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

What is the price of 4-Nitrosophenol?

Suppliers quote 4-Nitrosophenol 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-Nitrosophenol

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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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