No abstract

Second-order rate constants are reported for the reaction between a series of esteric bleach activators with different acyl substituents, namely, acetyloxybenzenesulfonate, n-butanoyloxybenzenesulfonate, n-nonanoyloxybenzenesulfonate and isononanoyloxybenzenesulfonate, and a set of peroxide nucleophiles whose basicity ranges from below that of the oxybenzenesulfonate leaving group to above it. The results conform to a Brønsted-type relationship with nuc , 0.42 ± 0.01 for acetyloxybenzenesulfonate, very similar to the value of 0.40 ± 0.01 for para-nitrophenyl acetate and a range of peroxide nucleophiles. A significantly larger value of nuc , 0.56 ± 0.05 is obtained with n-nonanoyloxybenzenesulfonate. This increase in nuc is interpreted in terms of steric and polar interactions between the acyl substituent and the attacking nucleophile. The reactivity of n-butanoyloxybenzenesulfonate is similar to that of n-nonanoyloxybenzenesulfonate whilst that of isononanoyloxybenzenesulfonate is less. These results are discussed in terms of the practical consequences for bleach activation and with regard to the mechanism of acyl transfer from esters to peroxides.

No abstract

The complex of NiII with nitrilotriacetic acid (NTA) (but not other aminocarboxylate complexes) autocatalyses the hydrogen peroxide bleaching of amaranth, although the reaction is inhibited by the absence of light or presence of alcohol, suggesting a radical-based mechanism.

The complex of Ni II with nitrilotriacetic acid (NTA) (but not other aminocarboxylate complexes) autocatalyses the hydrogen peroxide bleaching of amaranth, although the reaction is inhibited by the absence of light or presence of alcohol, suggesting a radical-based mechanism.