Driving force for participation

Both the hydroxyl group and the alkoxyl group have low driving forces for participation, and it is not surprising that, in sugar chemistry, only a... 

When (40) was heated in W,W-dimethylformamide with a powerful nucleophile, sodium azide, there was no evidence for intervention of the ion (41) the Sn2 reaction leading to the 4-azido-3-0-benzoyl-4-deoxy-D-talitol derivative was quite efficient. It is clear that, in the open-chain system of (40), there is only a moderate driving force for participation by the benzoyl group, and that it is easy to divert the reactions of (40) to the direct displacement tsqje. 

The driving force for participation also more than offsets the transition-state strain in the case of 2-chloromethylthiirane (24). The acetolysis of (24) proceeds 1000 times faster than cyclopropylmethyl chloride and gives, as one product, 3-acetoxythietane via the sulfonium ion (25) [Eq. (8)]. The oxygen analog of (24), epichlorohydrin, reacts 3 times as fast as cyclopropylmethyl chloride, which is already accelerated relative to primary derivatives (see Chapter 2). 

The differences in solvation of the reactants and the products constitute in general the major difference between the driving force for the equilibrium reaction in solution and that in the gas phase. The molar Gibbs free energy of solvation for any species I that participates in the equilibrium in a given solvent S can be written as... 

This work showed that the driving forces for the decisive interfacial electron-transfer reactions in DSSCs are not necessarily fixed by the chemical identity of the participants, but can vary depending on the spatial location of the dye in the electrochemical double layer. 

Catalysis appears to proceed simply by positioning an ionized carboxyl group within 3.0 A of a reactive methyl group on SAM. The predominant driving force for transmethylation appears to be proximity rather then the active participation of SAMT active site residues in preparing the methyl acceptor atom. 

In the second type of interaction, the components of the immune system are active participants in that the xenobiotic or some fraction of a xenobiotic is recognized as nonself and therefore provides the driving force for the response. Drugs and chemicals which are capable of triggering an immune response are generally low-molecular-weight substances possessing some inherent reactivity. For the most part, the xenobiotic... 

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