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Sulfates and sulfur salts

Sodium dithionite

Also known as Sodium hydrosulfite, Sodium hydrosulphite, Vatrolite

CAS 7775-14-6Formula Na2O4S2Molar mass 174.11 g/molEC 231-890-0
GHS signal word: Danger. Pictograms: Flammable, Harmful or irritant 211 suppliers listed
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Sodium dithionite chemical structure, Na2O4S2, CAS 7775-14-6
2D chemical structure

Key facts

What buyers check first

All properties
Appearance
White or grayish-white crystalline powder
Melting point
52 °C
Density
2.38 g/cm³
Flash point
Ca. 100
Solubility
Slightly sol in alcohol, very soluble in water
HS code
283110
Category
Sulfates and sulfur salts
UN number
UN 1384
Illustrative photo, off-white crystalline powder in an HDPE jar on a laboratory bench
Typical packagingIllustrative packaging image, not the actual product

What is Sodium dithionite?

Plain description, key identifiers and synonyms

Sodium dithionite is an inorganic sodium salt that is the disodium salt of dithionous acid. It has a role as a bleaching agent and a reducing agent. It contains a dithionite(2-).

Identifiers

Registry numbers, names and line notations, tap to copy

CAS number
7775-14-6 CAS number cross-checked
EC number
231-890-0
Molecular formula
Na2O4S2
UNII
2K5B8F6ES1
MDL number
MFCD00011640
INCI name
SODIUM HYDROSULFITE
InChIKey
JVBXVOWTABLYPX-UHFFFAOYSA-L
InChI
InChI=1S/2Na.H2O4S2/c;;1-5(2)6(3)4/h;;(H,1,2)(H,3,4)/q2*+1;/p-2
SMILES (canonical and isomeric)
[O-]S(=O)S(=O)[O-].[Na+].[Na+]

Synonyms

  • Sodium hydrosulfite
  • Sodium hydrosulphite
  • Vatrolite
  • Sodium sulfoxylate
  • Disodium dithionite
  • Dithionous acid, disodium salt
  • Blankit
  • Burmol
  • Hydros
  • Blankit IN
  • V-Brite B
  • Hydrosulfite R Conc
  • Disodium hydrosulfite
  • Sodium hydrosulfite (Na2S2O4)
  • Sodium dithionite (Na2(S2O4))
  • Dithionite, Sodium
  • Sodium hypodisulfite
  • Sodium Hydrosulfite, 85%
  • sodium dithionit
  • sodiumdithionite
  • sodiumhydrosulfite
  • Sodiumhydrosulphite
  • sodium hydro sulfite
  • Dithionous acid, sodium salt (1:2)
  • sodium sodium hydrosulfite
Show all 32 synonyms
  • Dithionous aciddisodiuMsalt
  • Na2O4S2
  • Na2S2O4
  • Sodium dithionite (Na2S2O4)
  • Na2 (S2 O4)
  • Sodium dithionite or sodium hydrosulfite
  • Sodium dithionite or sodium hydrosulfite [UN1384] [Spontaneously combustible]

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 or grayish-white crystalline powderexp.
Odour
Faint sulfurousexp.
Melting point
52 °Cexp.
Density
2.38 g/cm³exp.
Flash point
Ca. 100exp.
Autoignition temperature
Ca. 190exp.
Solubility
Slightly sol in alcohol, very soluble in waterexp.

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
174.11 g/molcalc.
Exact mass
173.9033 Dacalc.
LogP (octanol/water)
-7.33calc.
Topological polar surface area
80.26 Ųcalc.
Hydrogen bond donors
0calc.
Hydrogen bond acceptors
4calc.
Rotatable bonds
1calc.
Heavy atoms
8calc.
Rings
0calc.
Aromatic rings
0calc.
Fraction sp3 carbons
0calc.
Formal charge
0calc.
Stereocentres
2calc.
Components
3calc.

Calculated for screening. Confirm critical figures with the supplier.

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS02: Flammable
Flammable
GHS07: Harmful or irritant
Harmful or irritant
122WNFPA 704 rating

Hazard statements

  • H251Self-heating, may catch fire.
  • H302Harmful if swallowed.
Precautionary statements (11)
  • P235Keep cool.
  • P264Wash skin thoroughly after handling.
  • P270Do not eat, drink or smoke when using this product.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P301 + P317If swallowed: Get medical help.
  • P330Rinse mouth.
  • P407Maintain air gap between stacks or pallets.
  • P410Protect from sunlight.
  • P413Store bulk masses at temperatures not exceeding the specified limit.
  • P420Store separately.
  • P501Dispose of contents and container in accordance with local regulations.
UN number
UN 1384
Transport hazard class
4.2
Packing group
II

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

Sodium dithionite suppliers

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All 211 suppliers
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Where suppliers are based

211 suppliers in 40 countries

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Sodium dithionite 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

Reducing agent to strip certain dyes from fabrics and in vat dyeing, bleaching agent for ground wood pulp, soap, straws, sugar reducing agent to strip certain dyes from fabrics and in vat dyeing, bleaching agent for ground wood pulp, soap, straws, sugar.

Oxygen scavenger for synthetic rubbers, vat dyeing of fibers and textiles, stripping agent for dyes, reagent, bleaching of sugar, soap, oils, and groundwood.

As reducing agent, particularly in dyeing with indigo and vat dyes, bleaching soaps, straw, removing dyes from dyed fabrics.

All uses of sodium dithionite are based on its reducing properties. In the textile industry, sodium dithionite is primarily used as reducing agent for vat dyes and sulfur containing dyes, and for the removal of pigments on textiles.

Read more

It is also used as a bleaching agent in reductive bleaching processes, for instance, in the bleaching of mechanical paper pulp, and the bleaching of cotton and wool, as well as sugar.

The use pattern is 50% textile bleaching, 35% pulp and paper bleaching, 5% kaolin bleaching, 10% other applications (e.g. household stain remover).

Industrial uses: Bleaching agent, Other, Dye, Oxidizing agent, Reducing agent.

Consumer uses: Reducing agent.

Use classes: Cosmetics.

Cosmetic ingredient, INCI name SODIUM HYDROSULFITE(reducing, viscosity controlling)

Roles

  • bleaching agent
  • reagent
  • reducing agent

Functional uses

  • Reducing agent
  • Viscosity modifier

Cosmetic functions

  • Reducing
  • Viscosity controlling

How it is made

Zinc dust process: ... An aqueous slurry of zinc dust is treated in a stirred reactor with cooling at ca. 40 °C with liquid or gaseous sulfur dioxide to give zinc dithionite. After completion of the reaction the solution is passed through a filter press to remove unreacted zinc dust and impurities from the zinc. The zinc is then precipitated from the zinc dithionite by adding sodium carbonate or sodium hydroxide in stirred vessels. The zinc carbonate or hydroxide is removed in filter presses.

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Anhydrous sodium dithionite is precipitated from the clarified sodium dithionite solution by concentration under vacuum and addition of sodium chloride at > 60 °C. It is filtered, washed with methanol, and dried at 90 - 100 °C. Besides the evaporation process the salting out process, which was more widely used previously, is still known. In this process the dithionite is obtained from the solution by the addition of sodium chloride and methanol.

Amalgam Process. In the amalgam process, sodium hydrogensulfite is reduced to sodium dithionite in aqueous solution in a cooled, stirred vessel using the sodium amalgam of a chloralkali electrolysis cell. The sodium-free mercury is returned to the electrolysis cell where it is recharged with sodium. During reaction of the amalgam with the hydrogensulfite solution a pH of 5 - 6 must be maintained. The product is obtained by precipitation with salts or methanol or both.

Regulatory status

Inventories, regulations and trade controls that list this substance

Europe

  • EU harmonised classification (CLP Annex VI)
    Index no: 016-028-00-1

Health and food

  • EU cosmetic ingredient inventory

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 Sodium dithionite is traded under.

HS 2831.10Indicative HS code

Dithionites and sulphoxylates of sodium

World exports in 2024
$159M
−26.1% vs 2023, imports $185M
2019 to 2024
Top exporters
  1. China53.5%
  2. India * partner reported18.2%
  3. Belgium17.8%
Top importers
  1. Turkey15.3%
  2. United States8.7%
  3. Vietnam * partner reported7.4%

* Partner reported figures, a lower bound.

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

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

Frequently asked questions

Quick answers about Sodium dithionite, based on the data on this page

What is Sodium dithionite?

Sodium dithionite is an inorganic sodium salt that is the disodium salt of dithionous acid. It has a role as a bleaching agent and a reducing agent. It contains a dithionite(2-).

What is the CAS number of Sodium dithionite?

The CAS registry number of Sodium dithionite is 7775-14-6.

What is the molecular formula and weight of Sodium dithionite?

The molecular formula of Sodium dithionite is Na2O4S2 and its molar mass is 174.11 g/mol.

What is Sodium dithionite used for?

Reducing agent to strip certain dyes from fabrics and in vat dyeing, bleaching agent for ground wood pulp, soap, straws, sugar reducing agent to strip certain dyes from fabrics and in vat dyeing, bleaching agent for ground wood pulp, soap, straws, sugar.

Is Sodium dithionite hazardous?

Sodium dithionite carries the GHS signal word "Danger". Main hazards: self-heating, may catch fire, harmful if swallowed. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Sodium dithionite?

Sodium dithionite is usually classified under HS code 283110 (Of sodium). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Sodium dithionite?

CompoundList lists 211 suppliers of Sodium dithionite in India, China, United States, Thailand and 36 more. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

Where can I buy Sodium dithionite in India?

45 suppliers in India list Sodium dithionite on CompoundList. Filter the suppliers list by country and send a request to compare prices, grades and delivery times.

What is the price of Sodium dithionite?

Suppliers quote Sodium dithionite 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 Sodium dithionite

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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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