Hydrogen transfer in molecular system

Force Field Treatment of Proton and Hydrogen Transfer in Molecular Systems... 

Figure C3.2.7. A series of electron transfer model compounds with the donor and acceptor moieties linked by (from top to bottom) (a) a hydrogen bond bridge (b) all sigma-bond bridge (c) partially unsaturated bridge. Studies with these compounds showed that hydrogen bonds can provide efficient donor-acceptor interactions. From Piotrowiak P 1999 Photoinduced electron transfer in molecular systems recent developments Chem. Soc. Rev. 28 143-50.

The photoinduced electron transfer (PET) is especially important in the case of large or giant molecules (supermolecules), ie systems made up of molecular components in the same way as molecules are made up of atoms [11-19], As the systems are made up of a number of discrete components held together by different but not always exactly specified forces (covalent bonds, electrostatic interactions, hydrogen bonds, or other intermolecular interactions), the photoinduced electron transfer or energy transfer in these systems may be formally treated as intermolecular [20],... 

In conclusion, molecular charge transfer concepts and theory such as overviewed above and much more comprehensively in refs. 28,62,63,68 broadly frame proton and hydrogen atom transfer in biological systems and in interfacial bioelectrochemistry. Highly challenging incorporation of all the composite physical system properties, however, approach the boundaries of present state-of-the-art in condensed matter chemical rate theory. 

There is no definite knowledge of the mechanism of hydrogen transfer in the diamine oxidase system. Zeller et al. 170) postulate that the reaction involves a transfer of the hydrogen from the substrate to an acceptor on diamine oxidase followed by the transfer of this hydrogen to molecular oxygen under the influence of a second enzyme. 

Scheme 8.1 Molecular fragments that are known or expected to include resonance-assisted hydrogen bonding (RAHB). The proton transfer in these systems will be facilitated by the extensive electron conjugation. Adapted from [3],...

In step one, conversion of coal to a THF soluble product is rapid. The THF solubles are unstable in the presence of a coal derived solvent, but in the absence of hydrogen. In step two, the addition of molecular hydrogen to the system or of Tetralin to the solvent to increase hydrogen transfer to the coal increases the THF soluble conversion but does not lower the sulfur... 

Water-soluble complexes constitute an important class of rhodium catalysts as they permit hydrogenation using either molecular hydrogen or transfer hydrogenation with formic acid or propan-2-ol. The advantages of these catalysts are that they combine high reactivity and selectivity with an ability to perform the reactions in a biphasic system. This allows the product to be kept separate from the catalyst and allows for an ease of work-up and cost-effective catalyst recycling. The water-soluble Rh-TPPTS catalysts can easily be prepared in situ from the reaction of [RhCl(COD)]2 with the sulfonated phosphine (Fig. 15.4) in water [17]. 

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