13047-13-7Relevant articles and documents
Method for stabilizing synthetic thermoplastic materials against thermal degradation
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, (2008/06/13)
The present invention relates to a novel method for stabilizing synthetic thermoplastic materials against thermal degradation, which comprises incorporating in said materials one or more compounds of the formula (I) STR1 in which R1 is unsubstituted or substituted phenyl, n is e.g. 1, 2 or 3, and, when n is 1, R2 is e.g. --COR3, --COOR4 or --CO-N(R5)R6 in which R3 is e.g. C4 -C17 alkyl, R4 is e.g. C4 -C18 alkyl, cyclohexyl or t-butylcyclohexyl, R5 and R6 which can be identical or different are e.g. C2 -C8 alkyl or cyclohexyl, and, when n is 2, R2 is e.g. --CO--R10 --OC, --COO-R11 --OOC-- or --CONH--R12 --NHCO- in which R10 is e.g. C2 -C8 alkylene, R11 is e.g. C4 -C6 alkylene and R12 is e.g. C4 -C6 alkylene, and, when n is 3, R2 is e.g. benzenetricarbonyl. Several compounds of the formula (I) are new.
Kinetics of Electron-Transfer Reactions of Hydroquinones and Ascorbic Acid with 1-Phenyl-3-pyrazolidone Radicals
Youngblood, Michael P.
, p. 1843 - 1849 (2007/10/02)
The kinetics of oxidation of four hydroquinones and ascorbic acid by 1-phenyl-3-pyrazolidone radicals have been examined in aqueous solution from pH 6.5 to 9.5.For the hydroquinones, the kinetics are markedly autocatalytic unless sulfite is present in the solutions.The autocatalysis is apparently due to accumulation of a significant quantity of semiquinone formed via reproportionation of the quinone product with unreacted hydroquinone.If present in sufficient concentration, sulfite eliminates autocatalysis by scavenging quinone, and the kinetics are first-order in each reactant.The kinetic results suggest that the electron transfer from hydroquinone to the radical to form semiquinone is rate-limiting.In the case of ascorbic acid, autocatalysis is not observed, and the kinetics are first-order in oxidant and reductant.The kinetic dependence on pH permits the resolution of bimolecular rate constants for oxidation of the fully ionized and the singly protonated reductants.The correlation of these rate constants with thermodynamic driving force is in agreement with the Marcus theory.