Dithionous acid

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Dithionous acid
Dithionous acid.svg
Dithionous-acid-3D-balls.png
Names
IUPAC name
Dithionous acid
Other names
Hydrosulfurous acid; Hyposulfurous acid
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
PubChem CID
  • InChI=1S/H2O4S2/c1-5(2)6(3)4/h(H,1,2)(H,3,4) Yes check.svgY
    Key: GRWZHXKQBITJKP-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/H2O4S2/c1-5(2)6(3)4/h(H,1,2)(H,3,4)
    Key: GRWZHXKQBITJKP-UHFFFAOYAX
  • O=S(O)S(=O)O
Properties
H2S2O4
Molar mass 130.144 g/mol
Acidity (pKa)0.35, 2.45 [1]
Conjugate base Dithionite
Related compounds
Related compounds
Oxalic acid
Sodium dithionite
Potassium dithionite
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)
Infobox references

Dithionous acid is a sulfur oxoacid with the chemical formula H2S2O4. It is unstable in pure form, [2] but its salts, known as dithionites, are stable.

It was initially assumed that the C2 symmetric structure HOS(=O)-S(=O)OH is the most stable among molecules with the formula H
2
S
2
O
4
using ab initio calculations. [2] The reason for this is the existence of intermolecular hydrogen bonds. It is now known that dithionous acid spontaneously decomposes to SO2 and S(OH)2.

Sodium dithionite is a white powder used as a reductant and a bleaching agent. It is also used to reduce the nitro group to an amino group in organic reactions.

Related Research Articles

Alcohol Type of organic compound

In chemistry, alcohol is an organic compound that carries at least one hydroxyl functional group (−OH) bound to a saturated carbon atom. The term alcohol originally referred to the primary alcohol ethanol (ethyl alcohol), which is used as a drug and is the main alcohol present in alcoholic drinks. An important class of alcohols, of which methanol and ethanol are the simplest members, includes all compounds for which the general formula is CnH2n+1OH. Simple monoalcohols that are the subject of this article include primary (RCH2OH), secondary (R2CHOH) and tertiary (R3COH) alcohols.

A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus (+) and minus (−) signs. These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a chemical name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulae can fully specify the structure of only the simplest of molecules and chemical substances, and are generally more limited in power than chemical names and structural formulae.

Hydroxide Chemical compound

Hydroxide is a diatomic anion with chemical formula OH. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, a ligand, a nucleophile, and a catalyst. The hydroxide ion forms salts, some of which dissociate in aqueous solution, liberating solvated hydroxide ions. Sodium hydroxide is a multi-million-ton per annum commodity chemical. A hydroxide attached to a strongly electropositive center may itself ionize, liberating a hydrogen cation (H+), making the parent compound an acid.

Monosaccharides, also called simple sugars, are the simplest form of sugar and the most basic units (monomers) of carbohydrates. The general formula is C
n
H
2n
O
n
, or [Cn(H2O)n] or { CH2O}n albeit not all molecules fitting this formula are carbohydrates. They are usually colorless, water-soluble, and crystalline solids. Contrary to their name (sugars), only some monosaccharides have a sweet taste.

Silicate Class of chemical compounds

In chemistry, a silicate is any member of a family of anions consisting of silicon and oxygen, usually with the general formula [SiO(4−2x)−
4−x
]
n
, where 0 ≤ x < 2. The family includes orthosilicate SiO4−
4
, metasilicate SiO2−
3
, and pyrosilicate Si
2
O6−
7
. The name is also used for any salt of such anions, such as sodium metasilicate; or any ester containing the corresponding chemical group, such as tetramethyl orthosilicate.

Borates are boron-oxygen compounds, which form boron oxyanions. These can be trigonal or tetrahedral in structure, or more loosely can consist of chemical mixtures which contain borate anions of either description. The element boron most often occurs in nature as borates, such as borate minerals and borosilicates.

An oxyanion, or oxoanion, is an ion with the generic formula A
x
Oz
y
. Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determined by the octet rule. The corresponding oxyacid of an oxyanion is the compound H
z
A
x
O
y
. The structures of condensed oxyanions can be rationalized in terms of AOn polyhedral units with sharing of corners or edges between polyhedra. The oxyanions adenosine monophosphate (AMP), adenosine diphosphate (ADP) and adenosine triphosphate (ATP) are important in biology.

Sulfonic acid

A sulfonic acid (or sulphonic acid) refers to a member of the class of organosulfur compounds with the general formula R−S(=O)2−OH, where R is an organic alkyl or aryl group and the S(=O)2(OH) group a sulfonyl hydroxide. As a substituent, it is known as a sulfo group. A sulfonic acid can be thought of as sulfuric acid with one hydroxyl group replaced by an organic substituent. The parent compound (with the organic substituent replaced by hydrogen) is the parent sulfonic acid, HS(=O)2(OH), a tautomer of sulfurous acid, S(=O)(OH)2. Salts or esters of sulfonic acids are called sulfonates.

Phosphorous acid is the compound described by the formula H3PO3. This acid is diprotic (readily ionizes two protons), not triprotic as might be suggested by this formula. Phosphorous acid is an intermediate in the preparation of other phosphorus compounds. Organic derivatives of phosphorous acid, compounds with the formula RPO3H2, are called phosphonic acids.

Tin(II) chloride Chemical compound

Tin(II) chloride, also known as stannous chloride, is a white crystalline solid with the formula SnCl2. It forms a stable dihydrate, but aqueous solutions tend to undergo hydrolysis, particularly if hot. SnCl2 is widely used as a reducing agent (in acid solution), and in electrolytic baths for tin-plating. Tin(II) chloride should not be confused with the other chloride of tin; tin(IV) chloride or stannic chloride (SnCl4).

Phosphorus pentoxide Chemical compound

Phosphorus pentoxide is a chemical compound with molecular formula P4O10 (with its common name derived from its empirical formula, P2O5). This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desiccant and dehydrating agent.

Telluric acid Chemical compound

Telluric acid is a chemical compound with the formula Te(OH)6. It is a white solid made up of octahedral Te(OH)6 molecules which persist in aqueous solution. There are two forms, rhombohedral and monoclinic, and both contain octahedral Te(OH)6 molecules. Telluric acid is a weak acid which is dibasic, forming tellurate salts with strong bases and hydrogen tellurate salts with weaker bases or upon hydrolysis of tellurates in water.

Orthocarbonic acid Chemical compound

Orthocarbonic acid (methanetetrol) is the name given to a hypothetical compound with the chemical formula H4CO4 or C(OH)4. Its molecular structure consists of a single carbon atom bonded to four hydroxy groups. It would be therefore a fourfold alcohol. In theory it could lose four protons to give the hypothetical oxocarbon anion CO4−
4
(orthocarbonate), and is therefore considered an oxoacid of carbon.

Arsenous acid Chemical compound

Arsenous acid (or arsenious acid) is the inorganic compound with the formula H3AsO3. It is known to occur in aqueous solutions, but it has not been isolated as a pure material, although this fact does not detract from the significance of As(OH)3.

Sodium dithionite Chemical compound

Sodium dithionite is a white crystalline powder with a weak sulfurous odor. Although it is stable in the absence of air, it decomposes in hot water and in acid solutions.

Sodium dithionate Chemical compound

Sodium dithionate Na2S2O6 is an important compound for inorganic chemistry. It is also known under names disodium dithionate, sodium hyposulfate, and sodium metabisulfate. The sulfur can be considered to be in its +5 oxidation state.

An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce the H+ cation and the anion of the acid.

Dithionite Anion

The dithionite anion ([S2O4]2−), is an oxoanion of sulfur. It is commonly encountered as the salt sodium dithionite.

Rongalite Chemical compound

Rongalite is a chemical compound with the molecular formula Na+HOCH2SO2. This salt has many additional names, including Rongalit, sodium hydroxymethylsulfinate, sodium formaldehyde sulfoxylate, and Bruggolite. It is listed in the European Cosmetics Directive as sodium oxymethylene sulfoxylate (INCI). It is water-soluble and generally sold as the dihydrate. The compound and its derivatives are widely used in the dye industry.

Sulfoxylic acid Chemical compound

Sulfoxylic acid (H2SO2) (also known as hyposulfurous acid or sulfur dihydroxide) is an unstable oxoacid of sulfur in an intermediate oxidation state between hydrogen sulfide and dithionous acid. It consists of two hydroxy groups attached to a sulfur atom. Sulfoxylic acid contains sulfur in an oxidation state of +2. Sulfur monoxide (SO) can be considered as a theoretical anhydride for sulfoxylic acid, but it is not actually known to react with water.

References

  1. Catherine E. Housecroft; Alan G. Sharpe (2008). "Chapter 16: The group 16 elements". Inorganic Chemistry, 3rd Edition. Pearson. p. 520. ISBN   978-0-13-175553-6.
  2. 1 2 Drozdova, Yana; Steudel, Ralf; Hertwig, Roland H.; Koch, Wolfram; Steiger, Thomas (1998). "Structures and Energies of Various Isomers of Dithionous Acid, H2S2O4, and of Its Anion HS2O4- 1". The Journal of Physical Chemistry A. 102 (6): 990–996. Bibcode:1998JPCA..102..990D. doi:10.1021/jp972658d.