 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.