Ternary mixed ethers

摘要

Methylhydroxyethylhydroxypropylcellulose (MHEHPC) has degree of substitution by methyl groups (DS M) of 1.15-1.80, degree of substitution by hydroxyethyl groups (MS HE) of 0.10-0.70, and degree of substitution by hydroxypropyl groups (MS HP) of 0.30-1.00. An independent claim is included for preparation of MHEHPC. Cellulose is alkalified with 1.5-5.5 equivalents of alkali metal hydroxide per anhydroglucose unit (AGU). The alkalified cellulose is then reacted with ethylene oxide and propylene oxide at a temperature greater than 65[deg] C in the presence of a suspension medium which comprises alkyl halide in an amount A of (equivalents of alkali metal hydroxide per AGU minus 1.4) to (equivalents of alkali metal hydroxide per AGU plus 0.8). Further, alkyl halide is added in an amount B of at least the difference between the amount A of equivalents of alkyl halide per AGU and the amount of alkali metal hydroxide per AGU, where the amount B is not less than 0.2 equivalents per AGU. Subsequently, alkali metal hydroxide is added at more than 65[deg] C, and the resulting alkylhydroxyalkylcellulose is isolated from the reaction product mixture and is optionally cleaned.