Ethanolamine, complexes with

ELECTROCHEMICAL ACTIVITY OF CARBONS MODIFIED BY d-METAL COMPLEXES WITH ETHANOLAMINES... 

Bilayers are preferentially formed for Ns = 0.5...1. Lipids that form bilayers cannot pack into micellar or cylindrical structures because of their small head group area and because their alkyl chains are too bulky to fit into a micelle. For bilayer-forming lipids this requires that for the same head group area a a, and chain length Lc, the alkyl chains must have twice the volume. For this reason lipids with two alkyl chains are likely to form bilayers. Examples are double-chained phospholipids such as phophatidyl choline or phophatidyl ethanolamine. Lipids with surfactant parameters slightly below 1 tend to form flexible bilayers or vesicles. Lipids with Ns = 1 form real planar bilayers. At high lipid concentration this leads to a so-called lamellar phase. A lamellar phase consist of stacks of roughly parallel planar bilayers. In some cases more complex, bicontinuous structures are also formed. As indicated by the name, bicontinuous structures consist of two continuous phases. 

Unlike ethylene glycol, a-hydroxycarboxylic acids, and p-mercaptoethanol, ligands such as ethanolamine, ethylenediamine, amino acids, and 2-aminoethanethiol do not form V2L2 complexes with vanadate [46], However, weakly formed products of VL stoichiometry (—546 ppm, —556 ppm) are observed with a number of a-amino acids [47], Because the amine functionality in amino acids is not suitable for formation of the cyclic [VN]2 core expected for a dimer, then one or the other of these VL compounds may correspond to the monomeric precursor to such a dimeric product. Certainly, with the a-hydroxycarboxylic acids, the monomeric complex can be a major component in solution. Similar VL complexes have not been reported for the amino alcohols. Perusal of the available reports suggests that the amine derivatives were studied under conditions where the nitrogen functionality was protonated, so the results may be somewhat misleading. 

The importance of the chelate effect combined with the construction of multidentate ligands is well known in lanthanide chemistry. This is expressed in the rich coordination chemistry of / -diketonates [88] or complexes with Schiff bases [89] and macrocyclic polyethers [90] where lanthanide cations achieve steric saturation by high coordination numbers. Entrapment of the cation in a macrocyclic cavity results in greater complex stability. However, simply functionalized ligands such as ethanolamines can also supply a suitable ligand sphere [91-93],... 

The complexes of zinc and cadmium with Schiff bases derived from salicylaldehyde and propan-2-olamine or 2-aminomethylpropanol have been reported,57 as well as their complexes with ethanolamine and propan-2-olamine.58,59 Zinc complexes of stoicheiometry ZnL2X2 have been obtained where L = benzoyl- and salicyl-hydra-zones of vanilline. furfural, and cinnamaldehyde. Zinc complexes of several substituted o-bydroxybutyrophenones and their oximes have been reported.60-62 Complexes of stoicheiometery ZnL2U have been reported where L = the a-nitroketonato-anion obtained from nitroacetone, 3,3-dimethyl-l-nitrobutan-2-one or 3-nitrocam-phor and L — bipyridyl or 1,10-phenanthroline.63... 

Lipids also can be beneficial for cells in culture, since some substances absorbed by the cells need to be solubilized in lipids, or in some cases the toxicity of compounds may be reduced by complexation with lipids. The absence of essential lipids such as linoleic acid, lecithin, cholesterol, ethanolamine, or phosphorylcholine can result in the decrease of cloning efficiency and in reduction in the size of colonies, as shown for insect cells by Echalier (1997). However, one of the difficulties in supplying lipids at reasonable concentrations is their low solubility. To circumvent this limitation, lipids can be emulsified with complexing agents such as Pluronic F68 or cyclodextrin (Maiorella et al., 1998). 

Of examinations with commercially available chiral monoalkylamines and ethanolamines, complexation of chiral acerand 53 (RRRR and SSSS having four chiral carbons of R and S configurations, respectively) and norpseudoephedrine 63 (having two chiral carbons of. -configuration) in chloroform is shown as a representative example in Fig. 16. The (SSSS)-53 63 complex reveals a higher intensity of the absorption maximum near 550 nm compared to that of (RRRR)-53 63. This means that norpseudoephedrine is more easily accommodated in the cavity of (SSSS)-53 than that of (RRRR)-53, in accord with CPK molecular model examinations. 

Carbon dioxide, 4 an important green house gas,45 is obtained in combustion of carbon and hydrocarbons, calcination of CaC03, and so on. It forms complexes with transition metals (Section 7-14) and inserts into MH and other bonds (Section 21-3). The gas is very soluble in ethanolamines, which are used to scrub C02 from gas streams. Liquid C02 at pressures up to 400 bar is a solvent for some organic compounds and is used to extract caffeine from coffee beans many studies of other applications of supercritical C02 have been conducted.46... 

The reactions may be run on a large scale but is advisable to cool the reaction to 0 "C or 25 "C since the reduction may become exothermic. Usually an excess of organoborane is used since the bimolecular process becomes very slow towards the end of the reduction. Excess organoborane is destroyed by the addition of a low-boiling aldehyde such as acetaldehyde. This helps prevent contamination of the desired product with isopinocampheol. The borane component may be removed by precipitation as an ethanolamine complex or by an oxidative workup using hydrogen peroxide and base. Alternatively, these two steps may be combined, with the majority of the borane removed with ethanolamine and any remaining boron components removed by oxidation. 

Not only complexes but also metal salts that complex with the compounds to be separated can be used as selective complexing stationary phases. For example, Phillips [91] described the use of zinc and copper stearates and nickel oleate for the selective separation of amines. The retentions of aliphatic amines decrease in the order primary > secondary > tertiary. The separation of 7-picoline and 2,6-lutidine on a zinc stearate column is possible if the column efficiency is only 4 theoretical plates and the column is 1 cm long. To effect this separation on a non-selective silicone stationary phase a column with an efficiency of 250,000 theoretical plates is required. Some amines (e.g., ethanolamine... 

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