Sodium Chlorite Bleaching

Hefti, Heinz

doi:10.1177/004051756003001107

Cited by 17 publications

(2 citation statements)

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“…A problem with the latter method, is the formation of chlorinated organic compounds during delignification. 52,53 In contrast, PAA is chlorine-free, environmentally friendly, yields non-toxic decomposition products and is directly produced from two renewable chemicals, acetic acid and hydrogen peroxide. 54,55 The partial PAA delignification leads to approximately 34% mass loss; and in the present study the resulting DW scaffold is used as bio-composite reinforcement where a thermoplastic polymer matrix is filling the pore space.…”

Section: Resultsmentioning

confidence: 99%

Interface tailoring by a versatile functionalization platform for nanostructured wood biocomposites

2020

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Section: Resultsmentioning

confidence: 99%

Interface tailoring by a versatile functionalization platform for nanostructured wood biocomposites

2020

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“…As will be shown, the strong oxidant chlorite (ClO 2 – ) is an important common reactant in mixtures that maximize the advantage of chlorine dioxide reactivity with certain functional groups (alkenes in the present case). Chlorite ion has a rich oxidative chemistry with organic compounds, most notably in the conversion of aldehydes to carboxylic acids. − Chlorite is also used in the textile bleaching industry, where it offers several advantages over chlorine bleach, but the chemistry of chlorite bleaching has not been investigated in appreciable detail to our knowledge. − Chlorite is not a direct oxidant for epoxidation of alkenes but can serve as a source of oxidizing equivalents. − One goal in the present work was to demonstrate how the selectivity and utility of chlorite can be enhanced as an oxidant in epoxidation applications via a thorough understanding of the reaction mechanism. We will show how the high oxidizing power of the chlorite ion can be successfully coupled to the selectivity of ClO 2 for the epoxidation of alkenes.…”

Section: Introductionmentioning

confidence: 98%

Kinetics and Mechanism of Styrene Epoxidation by Chlorite: Role of Chlorine Dioxide

2014

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An investigation of the kinetics and mechanism for epoxidation of styrene and para-substituted styrenes by chlorite at 25 °C in the pH range of 5-6 is described. The proposed mechanism in water and water/acetonitrile includes seven oxidation states of chlorine (-I, 0, I, II, III, IV, and V) to account for the observed kinetics and product distributions. The model provides an unusually detailed quantitative mechanism for the complex reactions that occur in mixtures of chlorine species and organic substrates, particularly when the strong oxidant chlorite is employed. Kinetic control of the reaction is achieved by the addition of chlorine dioxide to the reaction mixture, thereby eliminating a substantial induction period observed when chlorite is used alone. The epoxidation agent is identified as chlorine dioxide, which is continually formed by the reaction of chlorite with hypochlorous acid that results from ClO produced by the epoxidation reaction. The overall stoichiometry is the result of two competing chain reactions in which the reactive intermediate ClO reacts with either chlorine dioxide or chlorite ion to produce hypochlorous acid and chlorate or chloride, respectively. At high chlorite ion concentrations, HOCl is rapidly eliminated by reaction with chlorite, minimizing side reactions between HOCl and Cl2 with the starting material. Epoxide selectivity (>90% under optimal conditions) is accurately predicted by the kinetic model. The model rate constant for direct reaction of styrene with ClO2(aq) to produce epoxide is (1.16 ± 0.07) × 10(-2) M(-1) s(-1) for 60:40 water/acetonitrile with 0.20 M acetate buffer. Rate constants for para substituted styrenes (R = -SO3(-), -OMe, -Me, -Cl, -H, and -NO2) with ClO2 were determined. The results support the radical addition/elimination mechanism originally proposed by Kolar and Lindgren to account for the formation of styrene oxide in the reaction of styrene with chlorine dioxide.

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