| Revision as of 18:00, 6 September 2011 editEdgar181 (talk | contribs)Extended confirmed users196,325 edits salt of dithionous acid← Previous edit |
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{{redirect|Sodium hydrosulfite|sodium hydrogen sulfite (NaHSO<sub>3</sub>), sometimes erroneously referred to as sodium hydrosulfite|Sodium bisulfite}} |
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{{not to be confused with|Sodium hydrosulfide|Sodium dithionate}} |
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{{redirect|D-Ox|other uses|dox (disambiguation)}} |
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{{chembox |
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{{chembox |
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|Verifiedfields = changed |
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| verifiedrevid = 414061121 |
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|Watchedfields = changed |
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| Name = Sodium dithionite |
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|verifiedrevid = 448784510 |
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| ImageFile = Sodium-dithionite-2D.png |
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| ImageName = Sodium dithionite |
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|Name = Sodium dithionite |
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| ImageFile1 = Sodium-dithionite-xtal-1992-3D-balls.png |
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|ImageFile = Sodium-dithionite-2D.png |
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|ImageName = Sodium dithionite |
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| OtherNames =<small>D-Ox<br/>Hydrolin<br/>Reductone<br/>Sodium hydrosulfite<br/>Sodium sulfoxylate<br/>Sulfoxylate<br/>Vatrolite<br/>Virtex L</small> |
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|ImageFile2 = Sample of sodium dithionite.jpg |
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| Section1 = {{Chembox Identifiers |
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|OtherNames =D-Ox, Hydrolin, Reductone<br/>sodium hydrosulfite, sodium sulfoxylate, Sulfoxylate<br/>Vatrolite, Virtex L<br/>Hydrosulfit, Prayon<br/>Blankit, Albite A, Konite<br/>Zepar, Burmol, Arostit |
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| CASNo = 7775-14-6 |
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|Section1={{Chembox Identifiers |
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| CASNo_Ref = {{cascite}} |
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|CASNo = 7775-14-6 |
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| PubChem = 24489 |
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|CASNo_Ref = {{cascite|correct|CAS}} |
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| RTECS = JP2100000 |
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|UNII_Ref = {{fdacite|correct|FDA}} |
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| EINECS = 231-890-0 |
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|UNII = 2K5B8F6ES1 |
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}} |
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|PubChem = 24489 |
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| Section2 = {{Chembox Properties |
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|ChEBI_Ref = {{ebicite|changed|EBI}} |
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| Formula = Na<sub>2</sub>S<sub>2</sub>O<sub>4</sub> |
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|ChEBI = 66870 |
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| MolarMass = 174.107 g/mol |
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|RTECS = JP2100000 |
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| Appearance = white to grayish crystalline powder |
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|ChemSpiderID = 22897 |
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| Density = 2.19 g/cm<sup>3</sup>, solid |
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|EINECS = 231-890-0 |
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| Solubility = very soluble |
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|StdInChI = 1S/2Na.H2O4S2/c;;1-5(2)6(3)4/h;;(H,1,2)(H,3,4)/q2*+1;/p-2 |
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| MeltingPtC = 52 |
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|StdInChIKey = JVBXVOWTABLYPX-UHFFFAOYSA-L |
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| BoilingPt = Decomposes |
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|SMILES = S(=O)S(=O).. |
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|UNNumber = 1384 |
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| Section7 = {{Chembox Hazards |
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| ExternalMSDS = |
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|Section2={{Chembox Properties |
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| EUIndex = 016-028-00-1 |
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|Formula = Na<sub>2</sub>S<sub>2</sub>O<sub>4</sub> |
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| EUClass = Harmful ('''Xn''') |
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|MolarMass = 174.107 g/mol (anhydrous) <br/> 210.146 g/mol (dihydrate) |
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| RPhrases = {{R7}}, {{R22}}, {{R31}} |
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|Appearance = white to grayish crystalline powder <br/> light-lemon colored flakes |
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| SPhrases = {{S2}}, {{S7/8}}, {{S26}}, {{S28}}, {{S43}} |
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|Odor = faint sulfur odor |
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| NFPA-H = 2 |
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|Density = 2.38 g/cm<sup>3</sup> (anhydrous) <br/> 1.58 g/cm<sup>3</sup> (dihydrate) |
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| NFPA-F = 3 |
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|Solubility = 18.2 g/100 mL (anhydrous, 20 °C) <br/> 21.9 g/100 mL (Dihydrate, 20 °C) |
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| NFPA-R = 1 |
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|SolubleOther = slightly soluble in ] |
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| NFPA-O = |
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|MeltingPtC = 52 |
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| FlashPt = 100 °C |
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|BoilingPt = Decomposes |
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| Autoignition = 200 °C |
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| PEL = |
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|Section3={{Chembox Hazards |
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|ExternalSDS = |
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| Section8 = {{Chembox Related |
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|GHSPictograms = {{GHS02}}{{GHS07}} |
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| OtherAnions = ]<br/>] |
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|GHSSignalWord = Danger |
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| OtherCations = |
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|HPhrases = {{H-phrases|251|302}} |
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| OtherFunctn = |
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|PPhrases = {{P-phrases|235+410|264|270|280|301+312|330|407|413|420|501}} |
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| Function = |
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|NFPA-H = 2 |
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| OtherCpds = ]<br/>]<br/>]<br/>] |
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|NFPA-F = 3 |
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|NFPA-R = 1 |
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|FlashPtC = 100 |
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|AutoignitionPtC = 200 |
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|Section4={{Chembox Related |
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|OtherAnions = ]<br/>] |
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|OtherCompounds = ]<br/>]<br/>]<br/>] |
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'''Sodium dithionite''' (also known as '''sodium hydrosulfite''') is a white ]line powder with a weak ]ous odor. It is a sodium ] of ]. Although it is ] under most conditions, it will ] in hot ] and in ] ]s. It can be obtained from ] by the following ]:<ref>{{cite doi|10.1021/ie50175a006}}</ref> |
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'''Sodium dithionite''' (also known as '''sodium hydrosulfite''') is a white ]line powder with a sulfurous odor. Although it is stable in dry air, it ] in hot ] and in ] ]s. |
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:2 NaHSO<sub>3</sub> + Zn → Na<sub>2</sub>S<sub>2</sub>O<sub>4</sub> + Zn(OH)<sub>2</sub> |
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==Structure== |
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==Structure== |
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] |
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The structure has been examined by ] and ]. The dithionite dianion has C{{su|b=2}} ], with almost eclipsed with a 16° O-S-S-O torsional angle. In the ] form ({{chem|Na|2|S|2|O|4|·2H|2|O}}), the dithionite anion has ] 56° O-S-S-O torsional angle.<ref>{{cite journal| first1 = J. B.| first2 = D. R.| first3 = J. T.| first4 = P. E.| first5 = K. L.| last1 = Weinrach| first6 = D. S.| first7 = D. W.| title = A structural study of sodium dithionite and its ephemeral dihydrate: A new conformation for the dithionite ion| journal = Journal of Crystallographic and Spectroscopic Research| volume = 22| issue = 3| pages = 291–301| year = 1992| doi = 10.1007/BF01199531| last2 = Meyer| last3 = Guy| last4 = Michalski| last5 = Carter| last6 = Grubisha| last7 = Bennett| s2cid = 97124638}}</ref> |
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A weak S-S bond is indicated by the S-S distance of 239 pm, which is elongated by ca. 30 pm relative to a typical S-S bond.<ref>{{Greenwood&Earnshaw2nd}}</ref> Because this bond is fragile, the dithionite anion dissociates in solution into the <sup>−</sup> radicals, as has been confirmed by ]. It is also observed that <sup>35</sup>S undergoes rapid exchange between S<sub>2</sub>O<sub>4</sub><sup>2−</sup> and SO<sub>2</sub> in neutral or acidic solution, consistent with the weak S-S bond in the anion.<ref name="InorgChem" /> |
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] and single-crystal X-ray diffraction studies of sodium dithionite in the solid state reveals that it exists in different forms. In one ] form, the dithionite ion has C{{su|b=2}} geometry, almost eclipsed with a 16° O-S-S-O torsional angle. In the ] form ({{chem|Na|2|S|2|O|4|.2H|2|O}}), the dithionite anion has a shorter S-S bond length and a ] 56° O-S-S-O torsional angle.<ref>{{cite doi|10.1007/BF01199531}}</ref> |
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==Applications== |
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==Preparation== |
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Sodium dithionite is produced industrially by reduction of ]. Approximately 300,000 tons were produced in 1990.<ref name=Ullmann>{{cite book |author1=José Jiménez Barberá |author2=Adolf Metzger |author3=Manfred Wolf |chapter=Sulfites, Thiosulfates, and Dithionites |title=Ullmann's Encyclopedia of Industrial Chemistry |date=15 June 2000 |publisher=Wiley Online Library |doi=10.1002/14356007.a25_477|isbn=978-3527306732 }}</ref> The route using zinc powder is a two-step process: |
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===Industry=== |
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:2{{nbsp}}SO<sub>2</sub> + Zn → ZnS<sub>2</sub>O<sub>4</sub> |
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This compound is a water-soluble ], and can be used as a ] in ] solutions. It is used as such in some industrial dying processes, where an otherwise water-insoluble dye can be reduced into a water-soluble ] salt. The reduction properties of sodium dithionite also eliminate excess dye, residual oxide, and unintended pigments, thereby improving overall colour quality. Reaction with ] produces ], which is used as a ], in, for instance, ], ], ], Leather, Chrome Tanning agent and ].<ref>{{cite book |
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:ZnS<sub>2</sub>O<sub>4</sub> + 2{{nbsp}}NaOH → Na<sub>2</sub>S<sub>2</sub>O<sub>4</sub> + Zn(OH)<sub>2</sub> |
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| title = Organic building blocks of the chemical industry |
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| author = Herman Harry Szmant |
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The ] method obeys the following stoichiometry: |
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| publisher = John Wiley and Sons |
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:NaBH<sub>4</sub> + 8{{nbsp}}NaOH + 8{{nbsp}}SO<sub>2</sub> → 4{{nbsp}}Na<sub>2</sub>S<sub>2</sub>O<sub>4</sub> + NaBO<sub>2</sub> + 6{{nbsp}}H<sub>2</sub>O |
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| year = 1989 |
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Each equivalent of H<sup>−</sup> reduces two equivalents of sulfur dioxide. ] has also been used as the reductant. |
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| isbn = 0471855456 |
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| page = 113 |
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==Properties and reactions== |
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===Hydrolysis=== |
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Sodium dithionite is stable when dry, but aqueous solutions deteriorate due to the following reaction: |
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: 2 S<sub>2</sub>O<sub>4</sub><sup>2−</sup> + H<sub>2</sub>O → S<sub>2</sub>O<sub>3</sub><sup>2−</sup> + 2 HSO<sub>3</sub><sup>−</sup> |
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This behavior is consistent with the instability of ]. Thus, solutions of sodium dithionite cannot be stored for a long period of time.<ref name="InorgChem">{{cite book |
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| title = Inorganic Chemistry, 3rd Edition |
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| chapter = Chapter 16: The group 16 elements |
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| author1 = Catherine E. Housecroft |
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| author2 = Alan G. Sharpe |
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| publisher = Pearson |
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| year = 2008 |
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| isbn = 978-0-13-175553-6 |
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| page = 520 |
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}}</ref> |
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}}</ref> |
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Anhydrous sodium dithionite decomposes to ] and ] above 90 °C in the air. In absence of air, it decomposes quickly above 150 °C to ], ], sulfur dioxide and trace amount of sulfur. |
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:{{chem|Na|2|S|2|O|4}} + 2 {{chem|CH|2|O}} → 2 {{chem|HOCH|2|SO}}{{su|b=2|p=−}} + 2 Na{{su|p=+}} |
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===Redox reactions=== |
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Sodium dithionite can also be used for water treatment, gas purification, cleaning, and stripping. It can also be used in industrial processes as a sulfonating agent or a sodium ion source. In addition to the textile industry, this compound is used in industries concerned with leather, foods, polymers, photography, and many others. Its wide use is attributable to its low toxicity {{LD50}} at 5 g/kg, and hence its wide range of applications. |
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Sodium dithionite is a reducing agent. At pH 7, the potential is -0.66 V compared to the ]. Redox occurs with formation of bisulfite:<ref>{{cite journal|author=Mayhew, S. G.|title=The Redox Potential of Dithionite and SO−2 from Equilibrium Reactions with Flavodoxins, Methyl Viologen and Hydrogen plus Hydrogenase|journal=European Journal of Biochemistry|year=2008|volume=85|issue=2|pages=535–547|doi=10.1111/j.1432-1033.1978.tb12269.x|pmid=648533|doi-access=free}}</ref> |
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:S<sub>2</sub>O<sub>4</sub><sup>2-</sup> + 2 H<sub>2</sub>O → 2 HSO<sub>3</sub><sup>−</sup> + 2 e<sup>−</sup> + 2 H<sup>+</sup> |
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Sodium dithionite reacts with oxygen: |
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===Biological sciences=== |
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:Na<sub>2</sub>S<sub>2</sub>O<sub>4</sub> + O<sub>2</sub> + H<sub>2</sub>O → NaHSO<sub>4</sub> + NaHSO<sub>3</sub> |
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Sodium dithionite is often used in ] experiments as a means of lowering solutions' ] (E<sup>o'</sup> -0.66 V vs NHE at pH 7<ref>S.G. Mayhew. Eur. J. Biochem. 85, 535-547 (1978)</ref>). ] is usually used as an oxidizing chemical in such experiments (E<sup>o'</sup> ~ 436 mV at pH 7). In addition, sodium dithionite is often used in ] experiments to determine the amount of ] that is not incorporated in primary ]s. Hence, iron extracted by sodium dithionite is also referred to as "free iron." The strong affinity of the dithionite ion for bi- and trivalent metal cations (M<sup>2+</sup>, M<sup>3+</sup>) allows it to enhance the solubility of iron, and therefore dithionite is a useful ]. When you heat the reaction, rainbow colors emerge due to the high transition states of energy. |
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These reactions exhibit complex pH-dependent equilibria involving bisulfite, thiosulfate, and sulfur dioxide. |
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===Geosciences=== |
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===With organic carbonyls=== |
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In the presence of aldehydes, sodium dithionite reacts either to form α-hydroxy-sulfinates at room temperature or to reduce the aldehyde to the corresponding alcohol above a temperature of 85 °C.<ref>J. Org. Chem., 1980, 45 (21), pp 4126–4129, http://pubs.acs.org/doi/abs/10.1021/jo01309a011</ref><ref>{{cite web|url=https://patents.google.com/patent/US5270058A/en|title=Aldehyde sulfoxylate systemic fungicides|website=google.com|access-date=27 April 2018|url-status=live|archive-url=https://web.archive.org/web/20180427175353/https://patents.google.com/patent/US5270058A/en|archive-date=27 April 2018}}</ref> Some ketones are also reduced under similar conditions. |
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Sodium dithionite has been used in chemical Enhanced Oil Recovery to stabilize polyacrylamide polymers against radical degradation in the presence of iron. It has also been used in environmental applications to propagate a low E<sub>h</sub> front in the subsurface in order to reduce pollutants such as chromium. |
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==Uses== |
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===Industry=== |
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Sodium dithionite is used as a water-soluble ] in some industrial dyeing processes. In the case of ]s and ]s, an otherwise water-insoluble dye can be reduced into its water-soluble ] ]. ] is sometimes processed in this way.<ref>{{cite journal|last1=Božič|first1=Mojca|last2=Kokol|first2=Vanja|title=Ecological alternatives to the reduction and oxidation processes in dyeing with vat and sulphur dyes|journal=Dyes and Pigments|date=2008|volume=76|issue=2|pages=299–309|doi=10.1016/j.dyepig.2006.05.041}}</ref> |
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===Domestic and hobby uses=== |
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Sodium dithionite can also be used for water treatment, aquarium water conditioners, gas purification, cleaning, and stripping.In addition to the textile industry, this compound is used in industries concerned with leather, foods, polymers, photography, and many others, often as a decolourising agent. It is even used domestically as a decoloring agent for white laundry, when it has been accidentally stained by way of a dyed item slipping into the high temperature washing cycle. It is usually available in 5 gram sachets termed ''hydrosulfite'' after the antiquated name of the salt. |
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It is the active ingredient in "Iron Out Rust Stain Remover", a commercial rust product.<ref>{{cite web | url=https://www.popularmechanics.com/home/tools/g2312/best-liquid-rust-removers-test/#product-13a4a293-8e39-4bbf-93b1-74a14dc07cfa-anchor | title=The Best Rust Removers for Restoring Every Surface | date=23 March 2023 }}</ref> |
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===Laboratory=== |
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Sodium dithionite is often used in ] experiments as a means of lowering solutions' ] (E<sup>o'</sup> -0.66 V vs ] at pH 7).<ref>{{cite journal|last1=MAYHEW|first1=Stephen G.|title=The Redox Potential of Dithionite and SO-2 from Equilibrium Reactions with Flavodoxins, Methyl Viologen and Hydrogen plus Hydrogenase|journal=European Journal of Biochemistry|volume=85|issue=2|year=1978|pages=535–547|issn=0014-2956|doi=10.1111/j.1432-1033.1978.tb12269.x|pmid=648533|doi-access=free}}</ref> ] is usually used as an oxidizing chemical in such experiments (E<sup>o'</sup> ~ .436 V at pH 7). In addition, sodium dithionite is often used in ] experiments to determine the amount of ] that is not incorporated in primary ]s. Hence, iron extracted by sodium dithionite is also referred to as "free iron." |
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Aqueous solutions of sodium dithionite were once used to produce '] solution' for the removal of oxygen from a gas stream.<ref>Kenneth L. Williamson "Reduction of Indigo: Sodium Hydrosulfite as a Reducing Agent" J. Chem. Educ., 1989, volume 66, p 359. {{doi|10.1021/ed066p359.2}}</ref> ] can be prepared in a two-step synthesis from ] by oxidation to the ''N''-oxide with a suitable ] followed by ] using sodium dithionite to introduce the ] ].<ref>{{cite encyclopedia|title = 1-Hydroxypyridine-2(1''H'')-thione|first1 = David W.|last1 = Knight|first2 = Jens|last2 = Hartung|date = 15 September 2006|doi = 10.1002/047084289X.rh067.pub2|publisher = ]|encyclopedia = ]|chapter = 1-Hydroxypyridine-2(1H)-thione|isbn = 978-0471936237}}</ref> |
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===Photography=== |
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It is used in Kodak fogging developer, FD-70. This is used in the second step in processing black and white positive images, for making slides. It is part of the ''Kodak Direct Positive Film Developing Outfit''.<ref>{{cite web |title=Kodak Direct Positive Film 5246 |url=https://125px.com/docs/techpubs/kodak/j6.pdf |website=125px.com |publisher=Kodak |access-date=6 November 2019}}</ref> |
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==Safety== |
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The wide use of sodium dithionite is attributable in part to its low toxicity {{LD50}} at 2.5 g/kg (rats, oral).<ref name=Ullmann/> |
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==See also== |
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==References== |
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==References== |
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{{reflist}} |
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{{Reflist}} |
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==External links== |
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*Sodium dithionite - ipcs inchem<ref name="inchem">{{cite web |title=Sodium dithionite - ipcs inchem |url=http://www.inchem.org/documents/sids/sids/7775146.pdf |website=www.inchem.org |access-date=15 June 2018 |location=Berliln, Germany |date=2004 |archive-date=17 April 2018 |archive-url=https://web.archive.org/web/20180417180337/http://www.inchem.org/documents/sids/sids/7775146.pdf |url-status=dead }}</ref> |
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