Noncross-linked polystyrene nanoencapsulation of ferric chloride: A novel and reusable heterogeneous macromolecular Lewis acid catalyst toward selective acetylation of alcohols, phenols, amines, and thiols

Abstract

Ferric chloride has been successfully nanoencapsulated for the first time on a non-cross-linked polystyrene matrix as the shell material via the coacervation technique. The resulting polystyrene nanoencapsulated ferric chloride was used as a novel and recyclable macromolecular Lewis acid catalyst for efficient and selective acetylation of various alcohols, phenols, amines, and thiols using acetic anhydride as the acetyl source at room temperature. The non-cross-linked polystyrene/ferric chloride composite nanocapsules were characterized by DR.-UV, ATR-FT-IR, FE-SEM, TEM, EDX, ICP, DLS, and TGA techniques. This polymeric nanocatalyst with the average particle size of 558 nm was stable and can be easily separated from the reaction mixture by simple filtration, recovered, and it is reusable with only minimal loss of Fe(III). The polystyrene-nanoencapsulated FeCl3 (PS-NC/FeCl3) was found to be stable and more active than its unencapsulated counterpart. Moreover, the nanocapsulated catalyst has relatively high TOF. The composite nanocapsules with multiple ferric chloride cores embedded in a non-cross-linked polystyrene shell showed excellent catalytic activity and reusability indicating the permeability of the shells of nanocapsules enabled catalytic reactions.