Patent GB-149320-A (GB)
Title: Improvements in and relating to the manufacture of ethers of cellulose or of its conversion products and derivatives
IPC: C08B11/00
Filed: 1920-05-17
Abstract: The more highly etherified ethyl, methyl, benzyl, and other alkyl and aralkyl ethers of cellulose, or of its conversion products or derivatives, are prepared from the lower ethers by conducting the further etherification in the absence of water or in the presence of an amount of water not exceeding five times the weight of the cellulose used as the primary material.  For the further etherification, a large excess of alkali is not required, and a quantity calculated on the amount of etherifying-agent present is sufficient; an excess of alkali may, however, be employed, in which case the amount of etherifying-agent required is less than that necessary when considerable quantities of water are present.  The products obtained are distinguished by their resistance to cold water and by their solubility in a large number of volatile solvents.  The lower ethers may first be isolated from the primary reaction mixtures, as for example by precipitation with hot water, alcohol, alcohol-ether, or acetone; or the further etherification may be carried out in the primary mixture after complete or partial removal of the excess of water; and if only a small excess of alkali is to be employed this may be incorporated in the mixture before the water is driven off, provided that care is taken, as by the use of a low temperature, not to damage the ether.  The removal of the water may be effected at atmospheric or reduced pressure, with or without heating, and it is facilitated by energetic stirring or kneading; depending on the proportion of water driven off, a paste or powdery mass is obtained.  For the further etherification, the finely-divided or pasty material is mixed if necessary with an additional quantity of alkali hydroxide, added at once or in small quantities; the etherifying-agent is added and the mixture heated, or it is added slowly with heating; the ether is separated by the addition of water, acidified if necessary, collected, washed with dilute acid if necessary, and then with water, and dried.  By-products such as alcohols, ethers, &c. may be distilled off during or after the etherification, or may be recovered from the reaction mixture either by steam distillation or by extraction with suitable solvents.  In an example, the preparation of an ethyl ether of cellulose is described in which a viscose or an alkali- or hydro-cellulose and diethyl sulphate are the primary reacting materials.  Specifications 12854/12, 6035/13, and 14339/14 are referred to.ALSO:The Specification as open to inspection under Sect. 91 (3) (a) includes the preparation of the more highly etherified ethyl, methyl, benzyl and other alkyl and aralkyl ethers of carbohydrates of the general formula (t6H10O5) such as starch, dextrin, lichenin, and inulin, by conducting the further etherification of the lower ethers in the absence of water or in the presence of only moderate amounts of water.  For the further etherification a large excess of alkali is not required, and a quantity calculated on the amount of etherifying-agent present is sufficient; an excess of alkali may, however, be employed, in which case the amount of etherifying-agent required is less than that necessary when considerable quantities of water are present. The products obtained are distinguished by their resistance to cold water and by their solubility in a large number of volatile solvents.  The lower ethers may first be isolated from the primary reaction mixtures, as, for example, by precipitation with hot water, alcohol, alcohol-ether, or acetone; or the further etherification may be carried out in the primary reaction mixture after complete or partial removal of the excess of water; and if only a small excess of alkali is to be employed this may be incorporated in the mixture before the water is driven on, provided that care is taken as by the use of a low temperature, not to damage the ether. The removal of the water may be effected at atmospheric or reduced pressure, with or without heating, and it is facilitated by energetic stirring or kneading; depending on the proportion of water driven off, a paste or powdery mass is obtained.  For the further etherification, the finely-divided or pasty material is mixed if necessary with an additional quantity of alkali hydroxide, added at once or in small quantities; the etherifying-agent is added and the mixture heated, or it is added slowly with heating; the ether is separated by the addition of water, acidified if necessary, collected, washed with dilute acid if necessary and then with water, and dried.  By-products such as alcohols, ethers, &c. may be distilled off during or after the etherification, or may be recovered from the reaction mixture either by steam distillation or by extraction with suitable solvents.  Specifications 12854/12, 6035/13, and 14339/14, [all in Class 2 (ii), Cellulose &c.], are referred to. This subject-matter does not appear in the Specification as accepted.