On the chemical fate of propyl gallate as stabilizer in Lyocell spinning dopes

Abstract Propyl gallate (PG, gallic acid propyl ester, Tenox®) is a very frequently used stabilizer and antioxidant in food material applications, also on large scale the Lyocell process to stabilize cellulose spinning dopes. In present study we have investigated fate of PG under classical conditions (cellulose dissolved N -methylmorpholine- -oxide monohydrate at temperatures above 80 °C) by means multiple analytical techniques, including NMR, GPC, MS-hyphenated chromatography. It demonstrated that quickly hydrolyzed or, as side reaction, aminolyzed morpholide. The products antioxidative action gallate, namely ellagic its bis( ortho -quinone), are easily adsorbed cellulosic surfaces chiefly responsible for discoloration dopes resulting fibers. However, morpholide parent compound amide, while both having good activity similar itself, do neither form nor -quinone) thus significantly superior conventionally with regard chromophore generation brightness loss. Also moieties tannins can be converted into amide or further stabilizers, which might open way new stabilizers niche utilization tannins. Graphical abstract