Hydrogen peroxide activation with N-heterocycles

Use of optionally substituted hexagonal heterocycle with at least a nitrogen in the ring (A) for activating hydrogen peroxide, is claimed. Independent claims are included for: (1) agent (Q) for brightening keratin fibers comprising at least 8 pyridine derivatives e.g. of formula (Ia)-(Ie) and/or at least 15 pyrimidine derivatives e.g. of formula (IIa)-(IIe); and (2) the brightening of keratin fiber, preferably human hairs comprising applying an agent (M1), (M2) (M3) and (M4) on the fibers, and optionally washing after 5-30 minutes, where at least one of M1-M4 is (Q). R1>-R4>H, optionally substituted aryl, optionally substituted alkyl, optionally substituted alkylene or optionally substituted heterocycle, preferably H, CH3, CH2CH3, (CH2)2CH2, CH(CH3)2, (CH2)3CH3, CH(CH3)CH2CH3, CH2CH(CH3)2, F, Cl, Br, I, NH2, NO2, CN or CHO. [Image] [Image] [Image]. Sechsring-N-Heterocyclen lassen sich zur Aktivierung von Wasserstoffperoxid und insbesondere zur Verbesserung der Aufhellwirkung von Wasserstoffperoxid an keratinischen Fasern verwenden und können daher mit besonderem Vorteil in Haarfärbe- und -aufhellungsmittel eingearbeitet werden, wo sie zu einer Leistungssteigerung dieser Mittel führen.