Delignifying fibrous material, e.g. wood pulp, comprises contacting material with an active oxygen source and catalyst with iminium, oxaziridinium or sulfonylimine structure

摘要

Delignifying fibrous material with a kappa number of at least 5 comprises contacting the material with an aqueous medium containing an active oxygen source and a catalyst with an iminium, oxaziridinium or sulfonylimine structure. Delignifying fibrous material with a kappa number of at least 5 comprises contacting the material with an aqueous medium containing an active oxygen source in an amount of at least 0.5% by weight of dry fiber and a catalyst with an iminium, oxaziridinium or sulfonylimine structure of formula (I)-(IV) in an amount of at least 500 ppm by weight of dry fiber, whereby the kappa number is reduced by at least 2 units. [Image] [Image] R1, R4H or optionally substituted 1-30C aryl, heterocyclyl, alkyl, alkenyl, aralkyl, alkaryl or cycloalkyl; R2H, optionally substituted 1-30C aryl, heterocyclyl, acyl, alkyl, alkenyl, aralkyl, alkaryl or cycloalkyl, CN, NO2, F, Cl, Br, 1-20C alkoxy, COOH or 1-20C alkoxycarbonyl, or also C(R1)=NR3R4 in (I) or (II), C(R1)=NSO2R3 in (III) or C(R1)=NSO2QR3 in (IV); R3optionally substituted 1-30C aryl, heterocyclyl, aralkyl or alkaryl, or halo, CN or NO2; Q : O or NR1; X : anion or an anionic group bonded to R3; alternatively, R1+R2 and R2+R3 can form a mono- or polycyclic alicyclic, aromatic or heterocyclic ring system.