The Dow Chemical Company

Christopher D Messelt

Carl P Strange

Clark W Gibson

Glen L Adams

Glenda P Townsend

Alkylene oxide is added as a vapor in preparing C.sub.2 or higher hydroxyalkylcellulose ethers and hydroxyalkylalkylcellulose ethers by continuously adding the reagents to alkali cellulose at elevated temperatures.

Process for preparing hydroxyalkylcellulose ethers

Higher reaction efficiencies are seen in cellulose etherification reactions when the reagents are continuously added to alkali cellulose at elevated temperatures. In particular, mixed hydroxyalkylcellulose ethers are prepared with higher reaction efficiencies using this process. In an especially preferred embodiment, hydroxypropylmethylcellulose is prepared by continuously adding propylene oxide to heated cellulose containing a small amount of caustic, adding more caustic and then continuously adding methyl chloride at elevated temperatures.

Mixed hydroxyalkyl cellulose ethers are prepared in a multi-stage etherification process, for example, hydroxyethylmethylcellulose is prepared by reacting alkali cellulose sequentially with ethylene oxide, methyl chloride, ethylene oxide and methyl chloride to form a product having uniform substitution. Products made by this process have improved solubility and other properties.

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Christopher D Messelt