What is E337 and what is it used for ?

E337 Potassium sodium tartrate

What is E337

E337 is Potassium sodium tartrate tetrahydrate, commonly called Rochelle salt is an odourless, colourless to white crystalline solid with a salty taste. It is the double salt of tartaric acid. It is soluble in water but insoluble in alcohols. Potassium Sodium Tartrate is prepared from potassium bitartrate and sodium carbonate. Commercially it is produced as a by-product of the wine industry.

Properties and specification of E337

  • Synonyms: Potassium Sodium Tartrate; E337; Seignette’s salt; Rochelle salt; Potassium sodium tartrate tetrahydrate; Potassium sodium 2,3-dihydroxysuccinate; L(+)-Tartaric acid potassium Sodium salt; butanedioic acid, 2,3-dihydroxy-, potassium sodium salt
  • CAS number: 304–59–6
  • EINECS: 206–156–8
  • Purity: >99%
  • Appearance: colourless / white crystalline solid
  • Formula:KNaC4H4O6.4H2O

    potassium sodium tartrate structure

  • Molecular weight: 282.1
  • pH: 7–8.5
  • Density: 1.79
  • Specific gravity: 2.75 g/cm3
  • Solubility in water: soluble 630g/L @20C
  • Melting point: 75C
  • Boiling point: 220C
  • Refractive index: 1.59
  • Oil Absorption: 37g/100g

The chemical composition of Potassium sodium tartrate tetrahydrate consists of Water 24.53%, Potassium 13.85%, Sodium 8.15% and Tartaric acid 53.17%. When heated it melts at 70–80C; at 100C it loses 3 water molecules and eventually becomes anhydrous at 130–140C; at 220C it begins to decompose. Potassium Sodium Tartrate has the linear formula KOCOCH(OH)CH(OH)C­OONa.4H2O

How to make E337 Potassium Sodium Tartrate crystals

The salt is prepared by adding 0.5M sodium carbonate to a hot solution of 1M potassium bitartrate (cream of Tartar). The solution is mixed thoroughly and then filtered while hot. This solution is then dried to precipitate solid potassium sodium tartrate, as small crystals.

Uses for E337 Potassium Sodium Tartrate

As additive in food industry ( E337 ) where it acts as sequestrant, emulsifier, stabilizer, buffer and antioxidant in cheese products, margarine, jellies, jams, minced meat, and sausage casings.

In pharmacology it is used as saline cathartics (usual adult dose: 5–10g). potassium bitartrate is administered rectally as a suppository with sodium bicarbonate to produce carbon dioxide, which promotes defecation by distending the rectal ampulla; administered for relief of constipation, and evacuation of the colon before surgical or diagnostic procedures or childbirth. It is not to be used on persons with heart problems or those on low sodium diets.
Potassium Sodium Tartrate is also used for the removal of toxic materials in some cases of poisoning.

Other applications include the preparation of piezoelectric crystals used in electrical appliances; as a laxative; in the manufacture of mirrors; in the plating industry; as a laboratory reagent; in the preparation of Fehlings solution for the detection of aldehydes; and for delaying the quick-setting of gypsum .

Health & Safety

This substance is not classified as dangerous according to Directive 67/548/EEC.

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Where to Buy Potassium Sodium Tartrate GRG

Other Tartrate salts:

DiSodium Tartrate Dihydrate

Sodium hydrogen tartrate monohydrate – Sodium Bitartrate

Potassium Tartrate – Sodium Bitartrate

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About mistralhowto

formulation chemist

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