Rongalite

Chembox new
Name = Rongalite
ImageFile = Rongalite.png ImageName = Rongalite
IUPACName = Sodium hydroxymethanesulfinate
OtherNames = Rongalite
Sodium formaldehydesulfoxylate
Section1 = Chembox Identifiers
SMILES = C(O)S(=O) [O-] . [Na+]
CASOther = [149-44-0]
[6035-47-8] dihydrate
RTECS = PB0380000
Section2 = Chembox Properties
Formula = CH₃NaO₃S
MolarMass = 118.10 g/mol
154.14 g/mol, dihydrate
Appearance = colorless crystals
Density = 1.75 g/cm³, dihydrate
Solubility = 600 g/L, dihydrate (approximate)
MeltingPt = 64.5 °C, dihydrate
pKa = decomp. at low pH
Section3 = Chembox Structure
MolShape = pyramidal at S
Section7 = Chembox Hazards
ExternalMSDS =
MainHazards = non-toxic
RSPhrases = R: 36/37/38 S:26-36
Section8 = Chembox Related
Function = compounds
OtherFunctn = SO₃^2-, CH₂O

Rongalite, also called Rongalit (registered trademark of BASF) is sodium hydroxymethylsulfinate, or Na⁺HOCH₂SO₂^-. The salt has many names, including also sodium formaldehyde sulfoxylate and Bruggolite. It is water-soluble and generally sold as the dihydrate.

Reactions

This salt is prepared from sodium dithionite:::Na₂S₂O₄ + 2 CH₂O + H₂O → NaHOCH₂SO₃ + NaHOCH₂SO₂This reaction proceeds quantitatively, such that dithionite can be determined by its conversion to rongalite, which is far less O₂-sensitive and thus easier to handle.

NaHOCH₂SO₂ can essentially be considered to be a source of SO₂^2-. As such it is used both as a reducing agent and as a reagent to introduce SO₂ groups into organic molecules. Treatment of elemental Se and Te with NaHOCH₂SO₂ gives solutions containing the corresponding Na₂Se_x and Na₂Te_x, where x is approximately 2. As a nucleophile, NaHOCH₂SO₂ reacts with alkylating agents to give sulfones.::NaHOCH₂SO₂ + 2 C₆H₅CH₂Br → [C₆H₅CH₂] ₂SO₂ + NaBr + CH₂O + HBrOccasionally, alkylation will occur also at oxygen, thus α,α' dibromoxylene gives both the sulfone and the isomeric sulfinate ester.

Use

The original use of the compound was as industrial bleaching agent and in textile dying. The other dominating use today is the application as reducing agent in redox-initiator systems for emulsion polymerization.

Zinc formaldehyde sulfoxylate

The zinc complex Zn(HOCH₂SO₂] ₂ is marketed under the trademarks Decroline, Decolin, and Safolin. This compound is an additive in polymers and textiles. [Masciocchi, N.; Rigamonti, C. and Maspero, A., "Poly [di-μ3-hydroxymethanesulfinato-zinc(II)] ", Acta Crystallographica Section E: Structure Reports Online, 2005, volume E61, m2683-m2685.]

References

*Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
*L. Tschugaeff und W. Chlopin: Beiträge zur Kenntnis des Reduktionsvermögens der schwefligen Säure. I. Einwirkung von Natriumhydrosulfit auf Tellur und Selen" Chemische Berichte 1914, volume 47, pages 1269-1275.
*R. Steudel, V. Munchow "Determination of dithionite (S₂O₂^2- and Hydroxymethanesulphinate (HOCH₂SO₂^-; Rongalite) by Ion-Pair Chromatography" Journal of Chromatography, (1992) volume 623 174-I 77.