| 摘要 |
Dihydroxy aluminium alkali metal or ammonium carbonate of formula (HO)2AlOCO2X where X is an alkali metal or ammonium radical is prepared by reacting an aluminium compound as defined below with an alkali metal or ammonium bicarbonate in the presence of water to obtain a precipitate of the aluminium complex which is separated from the aqueous remainder of the mixture. Suitable aluminium compounds are water dispersable aluminium hydroxide or aluminium hydroxide gel, an aluminium acylate which is hydrolysable by water and water-soluble aluminium salts, the anions of which form a weaker bond with aluminium than does the -OH group, that is those anions which have a greater tendency to neutralize the alkali metal or ammonium cation than they have to remain bonded to the aluminium. Organic aluminium salts which may be used are aluminium acetate, acetotartrate, benzoate, boroformate, borotartrate, glycinate, lactate, glycolate, alaninate, paraphenolsulphonate, and beta-naphtholsulphonate. Aluminium oxalate, salicylate and aluminium salts of C8-C18 fatty acids such as the oleate, stearate, palmitate and myristate may also be used in the presence of organic solvents or basic reactants which increase their solubility. Inorganic aluminium salts include the borate, bromate, bromide, chloride, iodide, phosphate, sulphate, and nitrate. The aluminium compound and the bicarbonate may be admixed dry and added to the water or they may be added separately or they may be dissolved separately and the solutions mixed; heat may be applied to expedite their reaction. Normally, equimolecular proportions are employed, but excess bicarbonate may be used to ensure completion. Detailed examples relate to the reaction of sodium carbonate and bicarbonate with aluminium acetate, sulphate and hydroxide, the latter being in the form of a dried gel or a compressed gel containing 85-90 per cent of water. Specification 756,482 which relates to the preparation of the same compound by reacting an aluminium alcoholate with a bicarbonate, is referred to.ALSO:Dihydroxy aluminium alkali metal or ammonium carbonate of formula (HO)2AlOCO2X, where X is an alkali metal or ammonium radical (see Group III) is employed as an antacid. The compounds are the same as those described in Specification 756,482.
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