Synthesis of potassium tetrathionate

Preparation of potassium tetrathionate

78 g of potassium thiosulfate are ground in a large mortar with 52g of iodine and 10ml water until a smooth light yellow-brown paste results. The mass is allowed to stand for 15 minutes, then rinsed with 100ml of alcohol into a flask which is to be stoppered. When the mixture has stood for 2-3 hours, the residue of product is filtered off and washed with 25ml portions of alcohol until the rinsings are virtually colorless. The crude product is dissolved in 40ml of water at 40 °C, then cooled in ice while a total of 100ml of alcohol is added in 20ml portions with good swirling. The flask containing the reaction mixture is stoppered and allowed to stand overnight in the refrigerator (room temperature may be used, but the yield is slightly lower) . The well-formed crystals are filtered off, washed with 50ml of alcohol, and dried in vacuo.

Alternatively, potassium tetrathionate (anhydrous) is prepared by dissolving the sodium tetrathionate in its own weight of water at 40°C, adding 200% of the calculated amount of potassium acetate, and 1-2 volumes of alcohol.

Inorganic laboratory preparations, by G. G. Schlessinger, 65-66, 1962

100 ml of water are placed in a 500ml suction flask fitted with a stopper and a delivery tube leading to the bottom of the flask. The latter is cooled in an ice bath to 0°C and a stream of sulfur dioxide is passed in (hood) at this temperature until the water has been saturated with the gas. Saturation is indicated when, on interrupting the gas flow, the liquid no longer rises to an appreciable extent in the delivery tube. The latter is now replaced by a dropping funnel fitted with a drying tube. A solution of 10g (6ml) of freshly distilled sulfur chloride (b.p. 138°C) in 70ml of petroleum ether (60-80 °C fraction) is placed in the funnel. The temperature of the aqueous sulfur dioxide solution is maintained at 0°C or below while the sulfur chloride-petroleum ether mixture is added from the funnel in approximately 10ml portions. After each addition, the flask is shaken in the cooling bath until all the yellow color has disappeared from the layer of organic solvent. As the exhausted solvent accumulates in the reaction mixture, it dilutes the fresh incoming sulfur chloride solution and therefore the coloration of the petroleum ether persists somewhat longer during the shaking toward the close of the reaction. The contents of the flask may now be allowed to warm up to room temperature and the organic layer is separated from the aqueous mixture of hydrochloric and tetrathionic acids in a funnel. The water layer is returned to the original filter flask with a stopper and a glass tube ending in a coarse capillary (1mm diameter) which leads well under the surface of the liquid. The flask is attached to the water pump and all the excess sulfur dioxide is removed by partial evacuation over a period of about two hours until the residual liquid has practically no odor of the dissolved gas. A brisk stream of air may now be passed through the solution for about one hour to ensure removal of the sulfur dioxide. During the process of evacuation, a solution of 25g of potassium hydroxide in 10ml of warm water is prepared and mixed with 50ml of 95% alcohol. 120ml more of 95% alcohol are added, the entire solution is filtered if necessary and cooled in ice. The cold alkaline solution is now run slowly from a funnel into the acid mixture which is also immersed in an ice bath. Good swirling is essential during the neutralization. The mixture is allowed to stand in a stoppered vessel overnight (preferably at 5-10°C), the product is then filtered by suction, washed with 95% alcohol, and dried in vacuo.

Inorganic laboratory preparations, by G. G. Schlessinger, 67-68, 1962



InChI Key


Canonical SMILES


MeSH Synonyms

Potassium Tetrathionate, Sodium Tetrathionate, Tetrathionate, Potassium, Tetrathionate, Sodium, Tetrathionic Acid, Tetrathionic Acid, Calcium Salt (1:1), Tetrathionic Acid, Dipotassium Salt, Tetrathionic Acid, Disodium Salt, Tetrathionic Acid, Disodium Salt, Dihydrate

Depositor-Supplied Synonyms

Potassium tetrathionate, Dipotassium tetrathionate, 13932-13-3, Caswell No. 702A, Tetrathionic acid, dipotassium salt, Potassium tetrathionate [K2S406], EINECS 237-702-3, EPA Pesticide Chemical Code 075903, Tetrathionic acid, potassium salt (1:2), AC1L1VRD, DSSTox_CID_27043, DSSTox_RID_82064, UNII-8X6V5C8FZ9, DSSTox_GSID_47043, KSC492G0L, 2-isopropyl-5-methyl-pyrazine, 8X6V5C8FZ9, CHEMBL3187989, CHEBI:86466, CTK3J2305, MolPort-028-746-214, Tetrathionic acid dipotassium salt, EBD87405, Tox21_302315, AKOS015898995, POTASSIUM TETRATHIONATE, K2S4O6, dipotassium (sulfonatodisulfanyl)sulfonate, NCGC00256144-01, IN004744, CAS-13932-13-3, LS-149013, RT-000493, K-4503, I14-12067, 3B3-055175

Removed Synonyms

2-methyl-5-propan-2-ylpyrazine, 13760-29-7 (Parent), CID61701

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