Cellulose acetate phthalate

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Schematic (simplified) formula presentation from the polymer chain of cellulose acetate phthalate with an acetyl residue ( marked in blue ) from acetic acid and two further acyl residues ( marked in green ), which are derived from phthalic acid. The distribution of the ester functions can vary within the polymer chain.

Cellulose acetate phthalate is a biopolymer based on cellulose . Like cellulose acetate , cellulose propionate, cellulose acetate propionate and cellulose acetate butyrate, it is an ester of cellulose with carboxylic acids . While in the case of cellulose acetate the esterification only took place through acetic acid , in the pharmaceutical grade cellulose acetate phthalate statistically 21.5 to 26.0% of the hydroxyl groups of the cellulose are esterified by acetic acid and 30.0 to 36.0% by phthalic acid. Cellulose acetate phthalate therefore contains acetyl groups (C 2 H 3 O) and phthalyl groups (C 8 H 5 O 3 ).

Manufacturing

Cellulose acetate phthalate can be made by reacting cellulose triacetate with phthalic anhydride in organic bases such as pyridine .

properties

Cellulose acetate phthalate is a white to almost white hygroscopic solid. It is practically insoluble in water, slightly soluble in acetone and soluble in diethylene glycol .

use

Cellulose acetate phthalate is used in the pharmaceutical industry as a coating for tablets and capsules, for example, since such a coating is enteric-coated.

Individual evidence

  1. ↑ a b European Pharmacopoeia , Deutscher Apotheker Verlag Stuttgart, 6th edition, 2008, ISBN 978-3-7692-3962-1 , pp. 2039-2040.
  2. ↑ a b Oliver Türk: Material use of renewable raw materials . 1st edition. Springer Vieweg, Wiesbaden 2014, ISBN 978-3-8348-1763-1 , p. 200-203 .