GB190407397A - Improvements in the Manufacture and Production of Stable, Dry Hydrosulphites. - Google Patents

Abstract

7397. Johnson, J. Y., [Badische Anilin & Soda Fabrik]. March 28. Ammonium, potassium, sodium, zinc, &c. hyposulphites.-Stable dry hyposulphites are prepared by heating the precipitated salts with a fluid which absorbs water, such as methyl, ethyl, amyl, and other alcohols, glycerine, ketones, ethyl acetate and other esters &c. The liquid or -its vapour is dried during the process by a suitable drying-agent, such as quicklime, calcium chloride, caustic soda or potash, sodium or potassium carbonate, sodium sulphate, &c. The hyposulphite is afterwards dried at a temperature of from 60‹ to 80‹ C. The extraction may be carried out under a pressure greater than that of the atmosphere. The following examples are given : -(1) Sodium hyposulphite is washed with alcohol and extracted with boiling ethyl alcohol, which is kept dry by quick lime. The salt is then filtered and pressed, or the alcohol is distilled off under reduced pressure, after which the salt is dried in vacuo over sulphuric acid. Methyl alcohol, ethyl acetate, amyl alcohol under reduced pressure, or ether under increased pressure, may also be used. (2) Potassium hyposulphite, made into a paste with methyl alcohol, is extracted with boiling methyl alcohol dried by quick lime. The salt is dried in vacuo and finally over sulphuric acid. (3) Zinc hyposulphite is washed with ethyl alcohol, and extracted with boiling ethyl alcohol dried by quick lime ; the salt is dried as before. Acetone dried by calcium chloride may be employed. (4) Sodium hyposulphite is heated with glycerine, and filtered. The glycerine paste may be used without further treatment, or it may be washed with alcohol and dried as before. The glycerine may also be removed by washing with methyl alcohol, acetone, ethyl acetate, benzene, ligroin, &c. Other hyposulphites, such as zinc-potassium, zinc-sodium, and zinc-ammonium &c. salts may be similarly treated. Reference is made to Specifications Nos. 901 and 18,852, A.D. 1900.