Opt. substd. and alkali-treated cellulose etherification - in organic soln. contg. quat. nitrogen or phosphorus organic salt opt. prepd. in situ

摘要

Cellulose ethers are prepd. by reacting a cellulose, opt. treated with an aq. alkali hydroxide soln., with an etherifying agent, in the presence of an aq. alkali hydroxide soln., an organic water-immiscible solvent capable of dissolving the etherifying agent, and of a quat. salt having formula (R1R2R3R4M)X (I) (where M is N or P; R1,R2,R3 and R4 each is an organic gp., esp. 1-4C alkyl or benzyl, and X is an anion). The pref. etherifying agent is a 1-4C alkyl halide or a benzyl halide. Carboxymethyl ethyl cellulose can be used as a coating for enteric pharmaceuticals. The substituents introduced by eetherification are evenly distributed. High grade low-viscous carboxymethyl ethyl cellulose can be prepd. having high whiteness, transparency and even degree of depolymerisation.