Rate-limiting steps in bromide-free TEMPO-mediated oxidation of cellulose—Quantification of the N -Oxoammonium cation by iodometric titration and UV–vis spectroscopy

•Iodometric titration can be applied to determine TEMPO+.•UV–vis spectrometry with MCR can be utilized to analyze TEMPO and TEMPO+.•The conversion of TEMPO to TEMPO+ can be monitored with iodometric titration.•HOBr is a more effective activator than HOCl.•Preactivation of TEMPO enhances bromide-free TEMPO-mediated oxidation of pulp.