Monocarboxylate complexation

The ionization state of a drag may be affected by factors other than pH. When citrate, a tricarboxylic acid, chelates metals such as aluminum, the tetravalent citrate-aluminum complex leaves a free non-complexed monocarboxylic acid which is a substrate for the monocarboxylic acid or lactate carrier in the brain endothelium. When citrate is not chelated, it has no affinity for these carriers and, as there is no di- or tricarboxylic acid carrier within the BBB, citrate is not significantly transported through the BBB via carrier-mediated transport. 

Aluminum salts of carboxylic acids, aluminum carboxylates, may occur as aluminum tricarboxylates (normal aluminum carboxylates), Al(OOCR)2 monohydroxy (monobasic) aluminum dicarboxylates, (RCOO)2Al(OH) and dihydroxy (dibasic) aluminum monocarboxylates, RCOOAl(OH)2. Aluminum carboxylates are used in three general areas textiles, gelling, and pharmaceuticals. Derivatives of low molecular weight carboxyUc acids have been mainly associated with textile appHcations those of fatty carboxyUc acids are associated with gelling salts and more complex carboxylates find appHcations in pharmaceuticals. 

Carboxylates, Oxalates, and Catecholates. Complexes of Th(IV) with mono-, di-, tri-, and polycarboxylates have been extensively studied. Monocarboxylates, RCOO , have been complexed with Th(IV), eg, Th(RCOO)4, where R = H, CH, CCl, or and M Th(HC02)4, ... 

Transplutonium(VI) complexes aqua,3,1220 carbonates, 3, 1220 carboxylates chelating, 3, 1220 halogens, 3,1220 monocarboxylates, 3,1220 nitrato, 3,1220 oxides, 3,1220 oxoanions, 3, 1220 Transport cations... 

Acetic anhydride is the only monocarboxylic acid anhydride that is important in modification reactions. The acetylation of the amino groups of proteins can be made relatively specific if the reaction is done in saturated sodium acetate, since the o-acetyltyrosine derivative is unstable to an excess of acetate ions (Fraenkel-Conrat, 1959). The tyrosine derivative rapidly hydrolyzes in alkaline reaction conditions, even in the absence of added acetate buffer (Uraki et al., 1957 Smyth, 1967). Treatment with hydroxylamine also cleaves any o-acetyltyrosine modifications, forming acetylhydroxamate, which can be followed by its purple complex with Fe3+ at 540 nm... 

Published equilibrium constants for monocarboxylato complexes are summarized in Table VII. All that can be deduced with certainty from these data is that the anions derived from monocarboxylic acids form rather weak complexes with beryllium. In all probability they act as monodentate ligands. The possibility of bidentate chelation using both carboxylate oxygen atoms can be ruled out on the grounds... 

Scheme 8. 1 1 complex 37 formed from a hydro-phobic modified polyethyl-eneimine 35 and HBC monocarboxylic acid derivative 36. 

Esters for lubricant applications are divided into five groups monocarboxylic acid esters (monoesters), dicarboxylic acid esters (diesters), glycerol esters, polyol esters, and complex esters. 

The major structural units of naturally occurring forms of both simple and complex lipids are the aliphatic, long chain monocarboxylic acids. These are of great importance because of their contribution to the physical and chemical characteristics of the compounds of which they are constituents. In the investigation of the structure of a lipid it may be necessary to determine not only the identity and amount of any fatty acids present but also their position within the molecule. 

Figure 23 shows a biphasic toluene/perfluoro-2-butyltetrahydrofuran (Fluoro-inert FC-75) mixture containing dendrimer-encapsulated Pd nanoparticles complexed with poly(hexafluoropropylene oxide-co-difluoromethylene oxide) monocarboxylic acid prepared via the type of electrostatic modification de-... 

Fig. 23. This photograph shows a two-phase system consisting of (top phase) toluene and (bottom phase) perfluoro-2-butyltetrahydrofuran (Fluoroinert FC-75).The dark color (brown) in the bottom phase indicates that the dendrimer-encapsulated Pd nanoparticles, complexed with poly (hexafluoropropylene oxide-co-difluoromethylene oxide) monocarboxylic acid, are selectively extracted into the fluorous phase. No detectable color was observed in the organic phase. Reprinted with permission from Ref. 103 Copyright 2000 American Chemical Society...

Reductions of anhydrides of monocarboxylic acids to alcohols are very rare but can be accomplished by complex hydrides [55, 99]. More frequent are reductions of cyclic anhydrides of dicarboxylic acids, which give lactones. Such reductions were carried out by catalytic hydrogenation, by complex hydrides and by metals. 

We used our computationally based model to design and assess a series of chiral rho-dium(II) carboxylates. It was quickly apparent that although others achieved some success with chiral monocarboxylates [24, 25], designs based on simple monocarboxylates were too flexible to allow rational design. We are therefore pursuing two complementary strategies (1) the use of ortho-metallated head-to-tail triarylphosphine complexes, and (2) the use of bridging diacids. 

Naphthenic Acids Acids derived from crude oil which are usually monocarboxylic, monocyclic, and completely saturated. Many are derivatives of cyclopentane and more complex alicyclic ring systems. 

Composition. Rosin is primarily a complex mixture of monocarboxylic acids of alkylated hydrophenanthrene nuclei. These constituents, known as resin acids, represent about 90% of rosin. The resin acids are subdivided into two types, based on their skeletal structure. The abietic-type acids contain an isopropyl group pendent from the carbon numbered 13. The pimaric-type acids have a methyl and vinyl group pendent from the same carbon atom. Figure 1 shows the structure of typical resin acids abietic acid, C20H30O2 (1) is predominant. The remaining 10% of commercial rosin consists of neutral materials that are either hydrocarbons or saponifiable esters. These materials are derived from resin acids by decarboxylation or esterification. 

Metal ions will not catalyze the decarboxylation of monocarboxylic acids, presumably because metal ion complexation with the ground state is more stable than complexation with the transition state. A reversal of this argument indicates... 

There have been several reports on monocarboxylate complexes although different formulae and various structures have been produced. After boiling VC13 with anhydrous formic acid, a... 

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