Process for preparing alkylhydroxyalkyl cellulose

Details Process for preparing alkylhydroxyalkyl cellulose Process for preparing alkylhydroxyalkyl cellulose

2005-05-10

2005-05-10

Wilson, James O. (Department: 1623)

Organic compounds -- part of the class 532-570 series

Organic compounds

Carbohydrates or derivatives

C536S090000, C536S091000, C536S095000, C536S096000, C536S099000, C536S100000

Reexamination Certificate

active

06891034

ABSTRACT:
Described is a process of preparing alkylhydroxyalkyl cellulose, e.g., methylhydroxypropyl cellulose (MHPC). The process includes: (a) alkylating cellulose with an aqueous caustic solution containing from 1.5 to 5.5 equivalents of alkali metal hydroxide, e.g., NaOH, per anhydroglucose unit (AGU) of said cellulose, in the presence of a suspension agent, e.g., dimethyl ether, which contains alkyl halide, e.g., methyl chloride, in an amount of from (equivalents of alkali metal hydroxide per AGU minus 1.4) to (equivalents of alkali metal hydroxide per AGU plus 0.8); (b) reacting the alkalised cellulose of step (a) with one or more alkylene oxides, e.g., propylene oxide, at a temperature higher than 65° C., e.g., 85° C.; (c) adding alkyl halide, to the product of step (b), in an amount of at least the difference between (i) the equivalents of alkyl halide per AGU in step a) and (ii) the equivalents of alkali metal hydroxide added per AGU in step (a), provided that the amount of additionally added alkyl halide is at least 0.2 equivalents per AGU; and (d) isolating alkylhydroxyalkyl cellulose from the reaction mixture of step (c). Optionally the isolated alkylhydroxyalkyl cellulose may be purified.

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Houben-Weyl, Methoden der Organischen Chemie, Makromolekulare Stoffe, 4thedition (month unavailable) 1987, vol. 3 20, pp. 2042-2043, Polysaccharid-Derivate Dr. Konrad Engelskirchen.

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