Solvent modulation of the dynamics of hydride transfer
摘要:
A two-coordinate model is used to discuss hydride transfer between substituted acridans and substituted quinolinium ions. Both the donor and the acceptor can be regarded as analogues of the enzymatic cofactor, NAD+. One coordinate is used for solvent and heavy atom motions; the other is used for the hydrogenic motion which produces the covalency change. In hydroxylic solvents the primary kinetic isotope effect is maximized and constant, and the Bronsted a indicates a critical configuration equally resembling reactants and products. However, in certain polar, aprotic solvents, most notably dimethyl sulfoxide (DMSO), the isotope effect is sharply reduced and the Bronsted a indicates a productlike critical configuration. These changes are attributed to a barrier in the solvent coordinate. Solvents like DMSO, which are known to be relatively good Lewis bases, are thought to respond relatively slowly to the relocation of positive charge in the reacting molecules. This shifts the rate-limiting step to the solvent coordinate. Hydroxylic solvents, on the other hand, have a fast component in their dielectric relaxation spectrum, which permits them to respond quickly to the relocation of charge. Thus, the overall bottleneck is in the hydrogenic coordinate.
The Tightness Contribution to the Brønsted α for Hydride Transfer between NAD<sup>+</sup> Analogues
作者:In-Sook Han Lee、Kim-Hung Chow、Maurice M. Kreevoy
DOI:10.1021/ja011855u
日期:2002.7.1
It has been shown that the rate of symmetrical hydridetransfer reaction varies with the hydride affinity of the (identical) donor and acceptor. In that case, Marcus theory of atom and group transfer predicts that the Bronsted α depends on the location of the substituent, whether it is in the donor or the acceptor, and the tightness of the critical configuration, as well as the resemblance of the critical
9- Ý4- (AMINO) PHENYL¨-ACRIDINIUM SALZE ALS KATIONISCHE DIREKTZIEHER ZUM FÄRBEN VON KERATINHALTIGEN FASERN
申请人:Henkel AG & Co. KGaA
公开号:EP2245013A1
公开(公告)日:2010-11-03
[DE] 9- [4- (AMINO) PHENYL] -ACRIDINIUM SALZE ALS KATIONISCHE DIREKTZIEHER ZUM FÄRBEN VON KERATINHALTIGEN FASERN<br/>[EN] 9-[4-(AMINO) PHENYL] ACRIDINIUM SALTS AS CATIONIC DIRECT DYES FOR COLORING KERATINOUS FIBERS<br/>[FR] SELS DE 9- [4- (AMINO)PHÉNYL] -ACRIDINIUM UTILISÉS COMME COLORANTS DIRECTS CATIONIQUES POUR COLORER DES FIBRES CONTENANT DE LA KÉRATINE
申请人:HENKEL AG & CO KGAA
公开号:WO2009103798A1
公开(公告)日:2009-08-27
Die vorliegende Anmeldung betrifft kationische Verbindungen der Formel (Ia): mit den Definitionen für R1 bis R9 und X- wie in Anspruch 1, die sich zur Färbung von Keratinfasern, insbesondere menschlichen Haaren, eignen und zum Teil im Stand der Technik selber noch nicht beschrieben sind. In Ausfärbungen dieser Verbindungen werden extrem, intensive Farbnuancen, insbesondere im Blau- und Violettbereich mit sehr guten Echtheitseigenschaften erhalten. Diese Direktzieher liefern ebenfalls bei gleichzeitiger Anwendung von Oxidationsmitteln wie Wasserstoffperoxid oder einem Gemisch aus Wasserstoffperoxid und Peroxidisulfaten leuchtende Nuancen ohne Abschwächung von Farbintensität und Farbbrillanz.
[EN] HYDRIDE DONORS AS AN ADDITIVE FOR REDUCING LOW SPEED PRE-IGNITION EVENTS<br/>[FR] DONNEURS D'HYDRURE UTILISÉS EN TANT QU'ADDITIF POUR RÉDUIRE DES ÉVÉNEMENTS DE PRÉ-ALLUMAGE À FAIBLE VITESSE
申请人:CHEVRON ORONITE CO
公开号:WO2020070672A1
公开(公告)日:2020-04-09
Fuel and lubricant compositions are provided that contain an organic hydride-based reductant. Methods for preventing or reducing low speed pre-ignition events in an internal combustion engines using these compositions are also provided.