Patent GB-656285-A (GB)
Title: Improvements in or relating to the production of ethers of cellulose and other polysaccharides
IPC: C08B11/187
Filed: 1948-10-13
Abstract: A carboxyethyl ether of cellulose is obtained by treating a suspension of an alkali cellulose in an inert organic liquid with an ester of acrylic acid.  The alkali cellulose may be formed by mixing the cellulose with an alkali-metal hydroxide, ammonium hydroxide, or quaternary ammonium hydroxide.  Instead of forming the alkali cellulose in a separate step, it may be formed at the time of etherification.  A suspension of the cellulose in an p  inert organic liquid may thus be reacted with acrylic ester in presence of alkali. The etherification may be carried out at room temperature or at elevated temperature and at atmospheric or higher pressure.  In an example, cotton linters are suspended in dioxane, and to the mixture is added sodium hydroxide in the proportion of about 2 molecular equivalents per hydroxyl group in the glucose unit of the cellulose molecule.  Water is added to make up an 80 per cent alkali solution with the sodium hydroxide. The mixture is boiled under reflux, cooled, and then placed in a tumbling autoclave.  Methyl acrylate (2 moles per hydroxyl per glucose unit of the cellulose) is added and the mixture is heated at 140 DEG  C.  The fibrous product is washed with methanol and dried. The sodium salt of the carboxyethyl cellulose obtained is soluble in water and dilute aqueous alkalies. In another example, cotton linters are mixed with a 40 per cent aqueous sodium hydroxide solution and the alkali cellulose crumbs obtained are suspended in tert.-butanol.  The mixture is heated under reflux and the methyl acrylate (1 mole. per hydroxyl per glucose unit of the cellulose) is added.  The mixture is heated at 80 DEG  C. for 5 hours.  In another example, wood pulp is suspended in isopropanol and treated with caustic soda solution.  Methyl acrylate is added and the mixture is heated at 70 DEG  C. for 16 hours.  Instead of cotton linters or wood pulp, there may be used cellulose which has been regenerated from cellulose acetate by means of sodium methylate. Trimethyl benzyl ammonium hydroxide may be used instead of caustic soda.  Instead of methyl acrylate there may be used ethyl, propyl, isopropyl, butyl, amyl, hexyl, 2-ethyl hexyl, or benzyl acrylate. The acrylic ester may contain a polymerization inhibitor such as hydroquinone or b -phenyl naphthylamine.  Other inert organic liquids which may be used are tetrahydrofurane and the diethyl ether of ethylene glycol.  The amount of acrylic ester present in the reaction may be 0.5-2.0 molecular equivalents per etherifiable hydroxyl group in the cellulose molecule in order to obtain a water- and alkali-soluble product.  The carboxyethyl cellulose obtained may be used as a thickening agent in textile printing pastes, or in latex dispersions.  It may be used as a creaming agent for latex, or in oil drilling mud, or in adhesives.ALSO:A carboxyethyl ether of a polysaccharide is obtained by treating a suspension of an alkali polysaccharide in an inert organic liquid with an ester of acrylic acid.  The alkali polysaccharide may be obtained by the action of an alkali-metal hydroxide, ammonium hydroxide, or a quaternary ammonium hydroxide on the polysaccharide.  Etherification may be effected at room temperature or at elevated temperature and at atmospheric or higher pressure.  The polysaccharide may be starch, cellodextrin, pectin, or cellulose.  The formation of the alkali polysaccharide may take place at the time of etherification.  A suspension of the polysaccharide in an inert organic liquid may thus be reacted with an acrylic ester in the presence of an aqueous solution of the alkaline reagent.  The amount of acrylic ester present in the reaction may be 0.5-2.0 molecular equivalents per etherifiable hydroxyl group in the polysaccharide molecule in order to obtain a water-and-alkali-soluble product.  The inert organic liquid may be dioxane, tert.-butanol, tetrahydrofurane, or the diethyl ether of ethylene glycol.  The acrylic ester may be methyl acrylate or ethyl, propyl, isopropyl, butyl, amyl, hexyl, 2-ethyl hexyl, or benzyl acrylate.  The acrylic ester may contain a polymerization inhibitor such as hydroquinone or b -phenyl naphthylamine.