Patent GB-689623-A (GB)
Title: Improvements in manufacture of acids and salts from gums
IPC: C09F1/00
Filed: 1949-05-26
Abstract: Gum acids are prepared by subjecting a naturally occurring exudate gum which is a salt of a gum acid in aqueous medium to reaction with an ion-exchange material consisting only of a cation-exchange complex operating in the hydrogen cycle and thereby replacing the gum cation by hydrogen.  Specified gums are gum arabic, mesquite gum, ghatti gum, talha gum, brea gum and the soluble-constituents of those exudate gums which are only partially water-soluble, e.g. gum tragacanth or gum karaya.  The gums are normally treated in 5 to 30 per cent solution. Cation-exchange complexes include complex silica compounds such as hydrogen-providing zeolites, certain carbonaceous materials, such as lignite, peat and coal, treated with fuming sulphuric acid, and synthetic resins such as the phenol-formaldehyde-sulphonic acid resins, e.g. "Dowex" and "Amberlite."  In an example, a 20 per cent aqueous gum arabic solution is passed through a column of granular phenol-formaldehyde-sulphonic acid resin and the effluent is pure arabic acid solution of pH 2.  The exchange material is reactivated in the usual manner for re-use.  The arabic acid may be recovered by drying the solution and is capable of being readily redissolved.  The gum acids may be converted into salts by reaction with suitable metal compounds.  Iron, copper, silver and chromium salts are mentioned. The iron salts may be used in the preparation of light-sensitive papers, pigments and medicinal preparations.  The copper salts may be used in electroplating and in fungicidal uses.  The silver salt has antiseptic properties suitable for use in treatment of ophthalmic infections; they may also be used in light-sensitive applications. Specification 569,661 is referred to.ALSO:Gum acids are prepared by subjecting a naturally occurring exudate gum which is a salt of a gum acid in aqueous medium to reaction with an ion-exchange material consisting only of a cation-exchange complex operating in the hydrogen cycle and thereby replacing the gum cation by hydrogen. Specified gums are gum arabic, mesquite gum, ghatti gum, talha gum, brea gum and the soluble constituents of those exudate gums which are only partially water-soluble e.g., gum tragacanth or gum karaya.  The gums are usually employed in 5 to 30 per cent solution. Cation-exchange complexes include complex silica compounds such as hydrogen-providing zeolites, certain carbonaceous materials, such as lignite, peat and coal, treated with fuming sulphuric acid, and synthetic resins such as the phenol-formaldehyde sulphonic acid resins e.g. "Dowex" and "Amberlite."  In an example, a 20 per cent aqueous gum arabic solution is passed through a column of granular phenol-formaldehyde sulphonic acid resin and the resulting effluent is pure arabic acid solution of pH 2.  The ion exchanger is then reactivated in the usual manner. The arabic acid may be isolated by drying the solution and may be readily redissolved in water. The gum acids may be converted into metal salts; iron, copper, silver and chromium salts being mentioned.  The iron salts may be used in the preparation of light sensitive papers, pigments and medicinal compositions; the copper salts may be used in electro plating and have fungicidal uses; the silver salts have antiseptic properties and may be used in ophthalmic preparations and also in light sensitive applications. Specification 569,661 is referred to.