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Impurities and reference standards

Rhein

Also known as Monorhein, Cassic acid, Rhubarb Yellow

CAS 478-43-3Formula C15H8O6Molar mass 284.22 g/molEC 207-521-4
GHS signal word: Warning. Pictograms: Harmful or irritant 83 suppliers listed
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Rhein chemical structure, C15H8O6, CAS 478-43-3
2D chemical structure

Key facts

What buyers check first

All properties
Physical form
Crystals
Melting point
321.1 °C
Boiling point
Sublimes
Solubility
Less than 1 mg/mL at 63 °F
HS code
291899
Category
Impurities and reference standards
Illustrative photo, closed blue fibre drums on a pallet in a warehouse
Typical packagingIllustrative packaging image, not the actual product

What is Rhein?

Plain description, key identifiers and synonyms

Rhein is a dihydroxyanthraquinone.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
4,5-dihydroxy-9,10-dioxoanthracene-2-carboxylic acid
CAS number
478-43-3 CAS number cross-checked
EC number
207-521-4
Molecular formula
C15H8O6
UNII
YM64C2P6UX
MDL number
MFCD00009618
INCI name
RHEIN
InChIKey
FCDLCPWAQCPTKC-UHFFFAOYSA-N
InChI
InChI=1S/C15H8O6/c16-9-3-1-2-7-11(9)14(19)12-8(13(7)18)4-6(15(20)21)5-10(12)17/h1-5,16-17H,(H,20,21)
SMILES (canonical and isomeric)
C1=CC2=C(C(=C1)O)C(=O)C3=C(C2=O)C=C(C=C3O)C(=O)O

Synonyms

  • Monorhein
  • Cassic acid
  • Rhubarb Yellow
  • Rheic acid
  • 4,5-Dihydroxyanthraquinone-2-carboxylic acid
  • Chrysazin-3-carboxylic acid
  • 1,8-Dihydroxyanthraquinone-3-carboxylic acid
  • 4,5-dihydroxy-9,10-dioxoanthracene-2-carboxylic acid
  • 9,10-Dihydro-4,5-dihydroxy-9,10-dioxo-2-anthracenecarboxylic acid
  • 2-Anthroic acid, 9,10-dihydro-4,5-dihydroxy-9,10-dioxo-
  • 1,8-dihydroxy-3-carboxyl-9,10-anthraquinone
  • 4,5-dihydroxy-9,10-dioxo-9,10-dihydroanthracene-2-carboxylic acid
  • 1,8-Dihydroxy-3-carboxyanthraquinone
  • Rhein (Standard)
  • 2-Anthracenecarboxylic acid, 9,10-dihydro-4,5-dihydroxy-9,10-dioxo-
  • 4,5-Dihydroxy-2-anthraquinonecarboxylic acid
  • 4,5-DiOH-anthraquinone-2-COOH
  • Rhein (1,8-dihydroxy-3-carboxyl anthraquinone)
  • 9,10-Dihydro-4,5-dihydroxy-9,10-dioxoanthracene-2-carboxylic acid
  • 4,5-dihydroxy-9,10-dioxo-anthracene-2-carboxylic acid
  • dipropionyl rhein
  • Chrysazin-3-carboxylicacid
  • Diacerein EP Impurity C, Rhein
  • 9,10-Dihydro-4,5-dihydroxy-9,10-dioxo-2-anthroic acid
  • Parietic acid
Show all 36 synonyms
  • Rhein(Monorhein)
  • Diacerein EP Impurity C
  • Monorhein,
  • Rhein CRS
  • RHN
  • Rhein, Rhubarb Yellow
  • Rhein, technical grade
  • Rheic acid (Standard)
  • 4ie7
  • Rhein, analytical standard
  • Chrysazin-3-carboxyli c 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

Physical form
Crystalsexp.
Melting point
321.1 °Cexp.
Boiling point
Sublimesexp.
Solubility
Less than 1 mg/mL at 63 °Fexp.

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
284.22 g/molcalc.
Exact mass
284.0321 Dacalc.
LogP (octanol/water)
1.57calc.
Topological polar surface area
111.9 Ųcalc.
Hydrogen bond donors
3calc.
Hydrogen bond acceptors
5calc.
Rotatable bonds
1calc.
Heavy atoms
21calc.
Rings
3calc.
Aromatic rings
2calc.
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, O=C1c2ccccc2C(=O)c2ccccc21

O=C1c2ccccc2C(=O)c2ccccc21

3 rings, 16 atoms, the Anthraquinone ring system.

2,059 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

Rhein suppliers

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

All 83 suppliers
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Where suppliers are based

83 suppliers in 12 countries

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Rhein price

Indicative price range per kg from live supplier offers

No published prices right now

Suppliers quote this chemical on request. Send one free request and compare quotes side by side.

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Uses and applications

What the substance is used for, by industry and function

Cosmetic ingredient, INCI name RHEIN(antimicrobial)

Pharmacological actions

  • Enzyme Inhibitors

Functional uses

  • Biocide

Cosmetic functions

  • Antimicrobial

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 Rhein is traded under.

HS 2918.99Indicative HS code

Carboxylic acids, with additional oxygen function (not alcohol, phenol, aldehyde or ketone)…

World exports in 2024
$1.46B
−1.1% vs 2023, imports $1.54B
2019 to 2024
Top exporters
  1. China40.0%
  2. India * partner reported26.6%
  3. Germany8.0%
Top importers
  1. United States25.6%
  2. Brazil6.7%
  3. Argentina5.9%

* Partner reported figures, a lower bound.

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

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

Frequently asked questions

Quick answers about Rhein, based on the data on this page

What is Rhein?

Rhein is a dihydroxyanthraquinone.

What is the CAS number of Rhein?

The CAS registry number of Rhein is 478-43-3.

What is the molecular formula and weight of Rhein?

The molecular formula of Rhein is C15H8O6 and its molar mass is 284.22 g/mol.

What is Rhein used for?

Known uses and roles of Rhein include preservatives in cosmetics and personal care, biochemical and pharmacological tools in research and laboratory, antimicrobial, biocide and enzyme inhibitors.

Is Rhein hazardous?

Rhein 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 Rhein?

Rhein is usually classified under HS code 291899 (Carboxylic acids with additional oxygen function and their anhydrides, halides…). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Rhein?

CompoundList lists 83 suppliers of Rhein in China, United States, Germany, United Kingdom and 8 more. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

What is the price of Rhein?

Suppliers quote Rhein 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 Rhein

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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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