Sodium bisulfite

Sodium bisulfite
Sodium bisulfite
CAS number 7631-90-5 YesY
PubChem 656672
RTECS number VZ2000000
Molecular formula NaHSO3
Molar mass 104.061 g/mol
Appearance White solid
Density 1.48 g/cm3
Melting point

150 °C, 423 K, 302 °F

Solubility in water 42 g/100 mL
EU Index 016-064-00-8
EU classification Harmful (Xn)
R-phrases R22 R31
S-phrases (S2), S25, S46
NFPA 704
NFPA 704.svg
Flash point Non-flammable
Related compounds
Other anions Sodium sulfite
Sodium metabisulfite
Other cations Potassium bisulfite
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Sodium bisulfite (sodium hydrogen sulfite) is a chemical compound with the chemical formula NaHSO3. Sodium bisulfite is a food additive with E number E222. This salt of bisulfite can be prepared by bubbling sulfur dioxide in a solution of sodium carbonate in water. Sodium bisulfite in contact with chlorine bleach (aqueous solution of sodium hypochlorite) will release harmful fumes.


Uses in chemistry

In organic chemistry sodium bisulfite has several uses. It forms a bisulfite adduct with aldehyde groups and with certain cyclic ketones to a sulfonic acid.[1]

Bisulfite reaction

This reaction has limited synthetic value(s) but it is used in purification procedures. Contaminated aldehydes in a solution precipitate as the bisulfite adduct which can be isolated by filtration. The reverse reaction takes place in presence of a base such as sodium bicarbonate or sodium hydroxide and the bisulfite is liberated as sulfur dioxide.[2]

Bisulfite adduct

Examples of such procedures are described for benzaldehyde,[3] tetralone,[4] citral,[5] the ethyl ester of pyruvic acid[6] and glyoxal.[7] In the ring-expansion reaction of cyclohexanone with diazald, the bisulfite reaction is reported to be able to differentiate between the primary reaction product cycloheptanone and the main contaminant cyclooctanone.[8]

The other main use of sodium bisulfite is as a mild reducing agent in organic synthesis in particular in purification procedures. It can efficiently remove traces or excess amounts of chlorine, bromine, iodine, hypochlorite salts, osmate esters, chromium trioxide and potassium permanganate.

A third use of sodium bisulfite is as a decoloration agent in purification procedures because it can reduce strongly coloured oxidizing agents, conjugated alkenes and carbonyl compounds.

Sodium bisulfite is also the key ingredient in the Bucherer reaction. In this reaction an aromatic hydroxyl group is replaced by an aromatic amine group and vice versa because it is a reversible reaction. The first step in this reaction is an addition reaction of sodium bisulfite to an aromatic double bond. The Bucherer carbazole synthesis is a related organic reaction.

Uses in food

While the related compound, sodium metabisulfite, is used in almost all commercial wines to prevent oxidation and preserve flavor, sodium bisulfite is sold by some home winemaking suppliers for the same purpose[9]. In fruit canning, sodium bisulfite is used to prevent browning (caused by oxidation) and to kill microbes.

In the case of wine making, sodium bisulfite releases sulfur dioxide gas when added to water or products containing water. The sulfur dioxide kills yeasts, fungi, and bacteria in the grape juice before fermentation. When the sulfur dioxide levels have subsided (about 24 hours), fresh yeast is added for fermentation.

It is later added to bottled wine to prevent the formation of vinegar if bacteria are present, and to protect the color, aroma and flavor of the wine from oxidation, which causes browning and other chemical changes. The sulfur dioxide quickly reacts with oxidation by-products and prevents them from causing further deterioration.

Sodium bisulfite is also added to leafy green vegetables in salad bars and elsewhere, to preserve apparent freshness, under names like LeafGreen. The concentration is sometimes high enough to cause severe allergic reactions.[citation needed]

In the 1980s, sodium bisulfite was banned from use on raw fruits and vegetables in the United States following the deaths of 13 people who unknowingly consumed produce treated with excessive amounts of the substance[10].

Industrial uses

Sodium bisulfite is a common reducing agent in the chemical industries. As it readily reacts with dissolved oxygen:

2 NaHSO3 + O2 → 2 NaHSO4

It is usually added to large piping systems to prevent oxidative corrosion. In biochemical engineering applications, it is helpful to maintain anaerobic conditions within a reactor. Sodium bisulfite should not be confused with sodium bisulfate which is used as a pH lowering chemical for swimming pools.

In wastewater treatment, sodium bisufite is often added following disinfection with a chlorine solution to neutralize the residual chlorine before discharging the treated effluent.

Bisulfite DNA sequencing

The chemical reaction that underlies the bisulfite-mediated conversion of cytosine to uracil.

Sodium bisulfite is used in the analysis of methylation status of cytosines in DNA.

In this technique, sodium bisulfite deaminates cytosine into uracil, but does not affect 5-methylcytosine, a methylated form of cytosine with a methyl group attached to carbon 5.

When the bisulfite-treated DNA is amplified via polymerase chain reaction, the uracil is amplified as thymine and the methylated cytosines are amplified as cytosine. DNA sequencing techniques are then used to read the sequence of the bisulfite-treated DNA. Those cytosines that are read as cytosines after sequencing represent methylated cytosines, while those that are read as thymines represent unmethylated cytosines in the genomic DNA.[11]

See also


  1. ^ Steven D. Young, Charles T. Buse, and Clayton H. Heathcock (1990), "2-Methyl-2-(Trimethylsiloxy)pentan-3-one", Org. Synth., ; Coll. Vol. 7: 381 
  2. ^ S. A. Buntin and Richard F. Heck (1990), "2-Methyl-3-phenylpropanal", Org. Synth., ; Coll. Vol. 7: 361 
  3. ^ Harold M. Taylor and Charles R. Hauser (1973), "α-(N,N-Dimethylamino)phenylacetonitrile", Org. Synth., ; Coll. Vol. 5: 437 
  4. ^ M. D. Soffer, M. P. Bellis, Hilda E. Gellerson, and Roberta A. Stewart (1963), "β-Tetralone", Org. Synth., ; Coll. Vol. 4: 903 
  5. ^ Alfred Russell and R. L. Kenyon (1955), "Pseudoionone", Org. Synth., ; Coll. Vol. 3: 747 
  6. ^ J. W. Cornforth (1963), "Ethyl Pyruvate", Org. Synth., ; Coll. Vol. 4: 467 
  7. ^ Anthony R. Ronzio and T. D. Waugh (1955), "Glyoxal Bisulfite", Org. Synth., ; Coll. Vol. 3: 438 
  8. ^ Hyp J. Dauben, Jr., Howard J. Ringold, Robert H. Wade, David L. Pearson, and Arthur G. Anderson, Jr., "Cycloheptanone", Org. Synth., ; Coll. Vol. 4: 221 
  9. ^ The Many Uses Of Sodium Bisulfite
  10. ^ van der Leun, Justine (July 2009). "What's In Your Food?". AOL Health. Retrieved August 2009. 
  11. ^ Frommer, M.; McDonald, L. E.; Millar, D. S.; Collis, C.M.; Watt, F.; Grigg, G.W.; Molloy P.L.; Paul, C.L. (1992). "A genomic sequencing protocol that yields a positive display of 5-methylcytosine residues in individual DNA strands" (free full text). PNAS 89 (5): 1827–31. doi:10.1073/pnas.89.5.1827. PMC 48546. PMID 1542678. 

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Look at other dictionaries:

  • sodium bisulfite — noun also sodium acid sulfite : either of two salts usually obtained by passing sulfur dioxide through a solution of sodium carbonate: a. : an unstable crystalline salt NaHSO3 that is known especially in solution and forms sodium metabisulfite on …   Useful english dictionary

  • sodium bisulfite — noun The mono sodium salt of sulfurous acid, NaHSO, used as a food preservative and as a reagent in organic synthesis. Syn: sodium hydrogen sulfite …   Wiktionary

  • sodium bisulfite — the monosodium salt of sulfurous acid, HNaO3S, used as an antioxidant and stabilizing agent in pharmaceutical preparations …   Medical dictionary

  • Bisulfite de sodium — Général Synonymes Sulfite acide de sodium, hydrogénosulfite de sodium No CAS …   Wikipédia en Français

  • Sodium sulfite — anhydrous …   Wikipedia

  • Sodium dithionite — Sodium dithionite …   Wikipedia

  • Bisulfite — ion (IUPAC recommended nomenclature: hydrogen sulfite) is the ion HSO3−. Salts containing the HSO3− ion are termed bisulfites also known as sulfite lyes. For example, sodium bisulfite is NaHSO3.ReactionsBisulfite salts are typically prepared by… …   Wikipedia

  • sodium hydrosulfite — noun : a crystalline salt Na2S2O4 made by reduction (as of sodium bisulfite or sulfur dioxide with zinc) and used as a reducing agent especially in dyeing, printing, and stripping textiles and as a bleaching agent; sodium dithionite not used… …   Useful english dictionary

  • sodium sulfite — noun : a sulfite of sodium: as a. : the crystalline normal salt Na2SO3 used chiefly as a reducing agent, bleaching agent, and antichlor, in photographic developing and fixing baths, and in preserving foods b. : sodium bisulfite a c …   Useful english dictionary

  • bisulfite — /buy sul fuyt/, n. Chem. a salt of sulfurous acid, containing the HSO3 group; an acid sulfite; a hydrogen sulfite, as sodium bisulfite, NaHSO3. Also, bisulphite. [1885 90; BI 1 + SULFITE] * * * …   Universalium

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