Iodide Ion Catalysis in the Benzylation of Cotton Cellulose

Abstract

The presence of alkali metal iodides accelerated the reaction of benzyl chloride with alkali cellulose. The alkali metal iodide was added to the mercerizing alkali used to activate the cotton yarn. The degree of benzylation observed with iodide present was 74% to 110% greater than with iodide absent. A D.S. of 0.7 could readily be obtained within a reaction period of thirty minutes at 115°C. The breaking strength retention at this D.S. was 93% to 119%, based on unmercerized, untreated yarn. Other salts tended to retard benzylation. Borax and neutralized boric acid were ineffective as catalysts, contrary to previous reports. Catalysis by iodide salts is considered to be due to the in situ formation of benzyl iodide from benzyl chloride within the cellulose fibers, the organic iodide being a more active alkylating agent than the chloride. Hydrotropic effects of the alkali iodides appear to be of secondary importance in the catalysis.