Amines hydrogen-bond affinity

It has been demonstrated that with the appropriate choice of membrane (hydro-phobic or hydrophilic polymers) the per-evaporation procedure can be efficiently applied for the quantitative and selective recovery of organic solutes, such as naphthalene, water, ethyl hexanoate and chlorobutane, from [C4CjIm]PF, IL [110]. It was also reported that the same ILs can be used as supported liquid membranes for the selective transport of secondary amines over tertiary amines with similar boiling points, and this was attributed to the higher hydrogen bond affinity of the secondary derivative with the imidazoHum cation [111,112]. 

In summary, the correlation of hydrogen-bond affinity and basicity scales exhibits a scatter caused by family-dependent relationships and steric effects. For unhindered bases, the scatter can be analysed into a series of nearly parallel lines for (i) amines, (ii) pyridines, (iii) polar bases and (iv) jt bases. 

The behavior of 3 toward ether or amines on the one hand and toward phosphines, carbon monoxide, and COD on the other (Scheme 2), can be qualitatively explained on the basis of the HSAB concept4 (58). The decomposition of 3 by ethers or amines is then seen as the displacement of the halide anion as a weak hard base from its acid-base complex (3). On the other hand, CO, PR3, and olefins are soft bases and do not decompose (3) instead, complexation to the nickel atom occurs. The behavior of complexes 3 and 4 toward different kinds of electron donors explains in part why they are highly active as catalysts for the oligomerization of olefins in contrast to the dimeric ir-allylnickel halides (1) which show low catalytic activity. One of the functions of the Lewis acid is to remove charge from the nickel, thereby increasing the affinity of the nickel atom for soft donors such as CO, PR3, etc., and for substrate olefin molecules. A second possibility, an increase in reactivity of the nickel-carbon and nickel-hydrogen bonds toward complexed olefins, has as yet found no direct experimental support. 

A broad range of functional monomers and cross-linkers has been used for the preparation of MIPs. The choice of the functional monomers depends on the nature and functionalities of the print molecule. The most widely used monomer is methacrylic acid, which has been shown to interact through ionic interactions and hydrogen bonds with amines, amides, carbamates and carboxylic acids [13-15]. The monomers and the print molecules self-assemble upon mixing and the strength of the complex is of importance for the selectivity of the polymer. For this reason, a considerable amount of research effort has focused on finding optimal monomers for various classes of print molecules and functionalities. For example, for some print molecules, polymers prepared with vinylpyridines [16,17], 2-(trifluoromethy-l)acrylic acid [18] or acrylamide [19] resulted in higher selectivities and affinities than polymers made from methacrylic acid. Mixtures of functional monomers... 

The N—H N hydrogen bond is responsible for the formation of the complexes between aniline and aliphatic amines (ammonia, methylamine, dimethylamine and tri-methylamine) which act as proton acceptors. Infrared photodissociation spectra and DFT calculation indicate208 that the clusters [aniline/ammonia]+ and [aniline/methylamine]+ have a non proton transferred (without the proton donation from the aniline moiety to the amine molecule) structure, while the complexes [aniline/dimethylamine]+, [aniline/ trimethylamine]+ possess a proton transferred structure. Reasonably, the proton transfer increases on increasing the proton affinity of the amine used as solvent. 

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