Synthesis
The most common way to prepare cellulose acetate phthalate consists of the reaction of a partially substituted cellulose acetate (CA) with phthalic anhydride in the presence of an organic solvent and a basic catalyst. The organic solvents widely used as reaction media for the phthaloylation of cellulose acetate are acetic acid, acetone, or pyridine. The basic catalysts employed are anhydrous sodium acetate when using acetic acid, amines when using acetone, and the organic solvent itself when using pyridine as reaction medium.
Malm et al., records the preparation of phthalic acid derivatives of ethyl-cellulose and cellulose acetate without the use of pyridine by substituting sodium acetate as catalyst and acetic acid as a reaction solvent. Phthalyl content of the derivatives produced by this method is inversely dependent on the reaction temperature, although the rate of phthalyl introduction is faster at high temperatures. Phthalyl content also depends on proportions of acetic acid, as a reaction solvent
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