Process for preparing water-soluble phosphonomethyl ethers of cellulose

Abstract

Disclosed is a process for preparing water-soluble phosphonomethyl ethers of cellulose from cellulose and halogenomethane phosphonic acid or one of its salts or acid derivatives, in an aqueous, alkaline medium. The process is carried out in such a way that, for each mole of the cellulose, from about 2.1 to 15 moles of hydroxide ions and from about 0.4 to 3.0 moles of halogenomethane phosphonate ions as etherifying agent are caused to react in from about 3 to 50 parts by weight, per part by weight of the cellulose, of a mixture which is composed of an inert, preferably water-miscible organic solvent and water and in which the proportion of water ranges from about 2 to 60 percent by weight, the reaction is continued until the phosphonomethyl cellulose has a DS of at least about 0.13.

Dependencies are inferred from the claim text.