Aromatic polycarboxylates

Modern polyimides are most likely an outgrowth of trying to find increased utilization of aromatic polycarboxylic acids as prepared by oxidation of poly-methylbenzenes, a major component in petroleum feedstocks. Therefore, it is not too surprising that the first commercial application of these materials appeared... 

A one-pot reaction has been developed for the reduction of aldehydes, ketones, and primary, secondary and tertiary alcohols into their corresponding alkyl function using either diethylsilane or n-butylsilane as the reducing agent in the presence of the Lewis acid catalyst tris(pentafluorophenyl)borane carbon-carbon double bonds remain unaffected.366 Aliphatic and aromatic polycarboxylic acids are also conveniently reduced to their corresponding alkanes using the same reagents and catalyst.367... 

Aromatic polycarboxylates easily form 2D or 3D networks, for instance [Nd2(122)3(dmf)4]-H2O which present a 2D structure in which the 1,4-naphthalenedicarboxylate anions link Ndm ions of two adjacent double chains keeping them at a short distance of about 4.1 A (J. Yang et al., 2006). This allows up-conversion to take place, albeit with very low efficiency a blue emission is seen at 449.5 nm upon excitation at 580 nm (corresponding to the 4Gs/2 magnetic properties an energy-transfer up-conversion mechanism involving no excited state absorption is more likely. 

The aromatic polycarboxylates have generally been regarded as difficult to process at best. The sulfonate copolymer is similarly a high melt viscosity material. It can, however, be injection molded and extruded. In the interests of brevity we will not detail our experience in these areas, except to observe that only properly prepared and purified polysulfonates are stable to thermal processing, and predrying the resin prior to molding is preferred. 

Ramaswamy, S., M. Malalyandi, and G.W. Buchanan. 1985. Phase-transfer-catalyzed methylation of hydroxyaromatic adds, hydroxyaromatic aldehydes, and aromatic polycarboxylic acids. Environ. Sci. Technol. 19 507-512. 

Two substances that are frequently of concern in ion exchange demineralization are silica and organics. The organics are frequently present in natural waters as aromatic polycarboxylic acid derivatives known as humic and fulvic acids. Silica may be the limiting factor in the efficiency of the anionic resins, and (particularly in boiler feedwater applications) the lower the concentration before ion exchange demineralization, the better. Reverse osmosis will frequently produce 90% or greater reductions in total silica concentrations. However, performance should be tested on the specific water to be treated since trie results can be variable and the reason for differences between waters is not yet understood. 

Table 13.8 presents chemical compounds that have been identified as primary organic aerosol components (Rogge et al., 1991, 1993a-e) together with their annual average ambient mass concentrations in the Los Angeles air basin. These ambient concentrations are the cumulative results of a variety of primary sources and secondary aerosol production. Normal alkanoic acids, aliphatic dicarboxylic acids, and aromatic polycarboxylic acids are... 

As can be seen from Figure 6.63, very small and symmetric peaks result when a salt gradient is applied. Separations of this kind are not possible with either the ion-suppression technique or with ion-pair chromatography. This is especially true for aromatic polycarboxylic acids, which elute from a mixed-mode phase such as OmniPac PAX-500 according to their valency (Figure 6.64b). When separating on chemically bonded silica under ion-suppression conditions (Figure 6.64a), a shorter analysis time is observed but not all components of the test mixture are separated. Moreover, penta- and... 

Aromatic Polycarboxylic Acids, Mixed ether-ester triol... 

In recent years the availability of several aromatic polycarboxylic acids has been exploited in specialty alkyd resin preparations [57, 58]. For example, trimellitic acid-based alkyds are used in alkyd-melamine enamels and acrylic lacquers [57]. Isophthalic acid can be used alone or in conjunction with trimellitic anhydride or phthalic anhydride [59]. Pyromellitic acid and pyromellitic anhydride have also been suggested as partial replacements for phthalic anhydride in long or short oil alkyds to give more water-resistant (also caustic- and gasoline-resistant) coatings [60]. 

TABLE VII Preparation of Alkyd Resins Based on Aromatic Polycarboxylic Acids... 

The reaction of ciprofloxacin (cfH) with metal salts in the presence of aromatic polycarboxylate ligands (or under basic conditions) has been found to give original metal-cfH complexes, for example, [Ba2(cf)2(l,4-bdc)(H20)2] H20 and [Mn(cfH) (1,3-bdc)] (bdc=benzenedicarboxylate). The structure of [Ba2(cf)2(l,4-bdc)(H20)2]-H2O consists of unique two-dimensional arm-shaped layers (Fig. 6), while the second complex contains double-chain-Uke ribbons constructed from [Mn2(cfH)2(C02)2] dimers and 1,3-bdc (Fig. 7) [369],... 

Wen L, Wang F, Ftaig J, Lv K, Wang C, li D (2009) Structures, photoluminescence, and photocatalytic properties of six new metal—organic frameworks based on aromatic polycarboxylate acids and rigid imidazole-based synthons. Cryst Growth Des 9 3581—3589... 

Metal organic frameworks (MOFs) are crystalline porous materials whose structure is constituted by metal ions or clusters of metal ions held in places by coordination with bipodal or multipodal rigid organic linkers [1 ]. Typical organic compounds employed for the synthesis of MOFs are aromatic polycarboxylates that coordinate by electrostatic and coordinative bonds with metal ions or metal clusters. The aromatic ring provides conformational rigidity of the linker, making possible the directionality of the interaction of the carboxylic acids with the metallic nodes. There have been reported MOFs for virtually all the transition metals and also for alkali earth and other nontransition metals [5-7]. 

Another important characteristic of MOFs is the flexibility in the nature of linkers and metals that can be used in their preparation. Besides aromatic polycarboxylates, linkers having nitrogen or phosphorous atoms to coordinate with the metal site have also been reported. 

---