GB554477A - Improvements in or relating to the production of cellulose ethers - Google Patents

Abstract

554,477. Cellulose ethers. DREYFUS, H. Jan. 2, 1942, No. 68. [Class 2 (ii)] Cellulosic material is etherified in presence of both an inorganic base and an organic amine containing at least two amino groups. The amine may contain two or more tertiary amino groups, e.g. tetraethyl or tetramethyl ethylene diamine, tetraethyl-trimethylene diamine, or tetramethyl-tetramethylene diamine. It may be a primary or secondary, amine e.g. ethylene or propylene diamine but such a substance is converted into a tertiary amine during the reaction, with consumption of etherifying agent, and it is preferable to start with a tertiary amine. The etherifying agent may be an alkyl halide or dimethyl, diethyl, or other alkyl sulphate. The inorganic base may be sodium hydroxide. The amount of water present in the alkali-cellulose at the beginning of the etherification process is preferably restricted so that the alkali-water ratio is high, e.g. 60 per cent. or - more. The alkali may beconcentrated by azeotropic distillation in presence of nitrogen or other inert gas. After the preparation of the alkali cellulose, it may be mixed with the amine and etherifying .agent. Etherification may be carried out in presence of a diluent such as toluene, xylene, acetone, or dioxane. Etherification may be carried out in stages, a proportion of the total alkali and etherifying agent being added at each stage. The amine may be added at the beginning of etherification, or in portions at each stage. In an example, alkali-cellulose is prepared by soaking cellulose with a 60 per cent. solution of caustic soda and pressing. The alkali-cellulose is mixed, with toluene, diethyl sulphate, and tetraethyl ethylene diamine and etherification is effected at the boiling point of the toluene. A further quantity of caustic soda in the form of a 70 per cent. aqueous solution is added and then a further amount of diethyl sulphate is added and further etherification is effected. Further stages of etherification follow. Specification 546,647 is referred to.