Potassium bisulphite

Magnesium fluorosilicate Mercuric chloride Nickel chloride Nickel sulphate Potassium bisulphate Potassium bisulphite Potassium sulphite Silver nitrate... 

Method B. This is an improved modification of method A, effecting the debromination in a catalytic cycle by means of potassium bisulphite and catalytic amounts of diaryl tel-luride. 

No reaction with 1,1-dialkyl, 1,1,5,5-tetralkyl and 1,5-diisopropyl dioxopentane. The obtained dichlorides are easily reduced to the corresponding 3,5-dioxotellurane by treatment with aqueous potassium bisulphite. 

The filtrate from the iodide on evaporation in a desiccator yields a colourless crystalline solid (1 3 grams). Extraction with small quantities of hot water gradually removes any remaining iodide, a white powder remaining as residue. This is an anhydride of methyl hydroocytellurium oxide (telluracetic acid), CH3.TeO.OH, which cannot be obtained pure. In aqueous solution it is neutral to litmus, gives no precipitate with silver nitrate, and is reduced by potassium bisulphite to dimethyl ditelluride. It has a persistent odour, and gradually blackens above 230° C. 

Salts of the metals are thus present in equilibrium with the violet tellurium compounds, and in the case of the dibisulphate the balance is controlled by the proportion of wrater present. This is rendered visible in the action of iron upon phenoxtellurine dibisulphate, for the violet mixture becomes red when dried on clay in a desiccator, but the violet colour is restored on exposure to moist air. The method of examining a coloured complex consists in treating it with water, when the acceptor 55 is set free and can be extracted by ether the residual salt can then be reduced by adding potassium bisulphite, and the nucleus of the donor again extracted by ether. The products are insoluble in water, so that fresh equilibria cannot presumably be set up. 

Benzaldehyde.—Kauffmann,3 by electrolyzing benzaldehyde in a 12-15% solution of potassium bisulphite, obtained at the cathode a mixture of hydrobenzoin and isohydrobenzion. According to his statements,4 an alcoholic solution of sodium hydroxide is more suitable for the reaction than the aqueous solution of bisulphite. Other aldehydes and ketones show a behavior similar to that of benzaldehyde, as will be explained under the individual substances. 

Synonyms E228 potassium acid sulfite potassium bisulphite potassium hydrogen sulfite. 

Aurin ciystallizes in fine, red needles from its solution in HOI. It is insoluble iu H.O, but soluble iu HCl, alcohol, and glacial acetic acid. It forms a colorless compound with potassium bisulphite. 

Sulphite may be added to food as the gas sulphur dioxide, sodium bisulphite, potassium bisulphite, sodium metabisulphite, potassium metabisulphite and sodium sulphite. There has been much public debate about the safety of sulphite in foods, nowhere more so than in the USA. 

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