Acids aromatic polycarboxylic

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... 

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... 

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]. 

The diacids are characterized by two carboxyHc acid groups attached to a linear or branched hydrocarbon chain. AUphatic, linear dicarboxyhc acids of the general formula HOOC(CH2) COOH, and branched dicarboxyhc acids are the subject of this article. The more common aUphatic diacids (oxaUc, malonic, succinic, and adipic) as weU as the common unsaturated diacids (maleic acid, fumaric acid), the dimer acids (qv), and the aromatic diacids (phthaUc acids) are not discussed here (see Adipic acid Maleic anhydride, maleic acid, and fumaric acid Malonic acid and derivatives Oxalic acid Phthalic acid and OTHERBENZENE-POLYCARBOXYLIC ACIDS SucciNic ACID AND SUCCINIC ANHYDRIDE). The bihinctionahty of the diacids makes them versatile materials, ideally suited for a variety of condensation polymerization reactions. Several diacids are commercially important chemicals that are produced in multimillion kg quantities and find appHcation in a myriad of uses. 

Additionally to phenolic intermediates, upon the aromatic ring opening, a series of carboxylic acids can be formed. Maleic acid, for instance, has been detected in the oxidation of byphenyls (Bouquet-Somrani et al., 1996), 1,2,4-THB (Li et al., 1991a), 1,2-dimethoxybenzene (Pichat, 1997), and acid orange 7 (Stylidi et al., 2003). Similarly, muconic acid has been reported as an intermediate of byphenyls oxidation (Bouquet-Sormani et al., 1996), while succinic and malonic acids were identified in polycarboxylic benzoic acid oxidation (Assabane et al., 2000). It is therefore expected that these or similar acids be formed during phenol oxidation. 

In a stndy of retention of aromatic carboxylic acids under IPC conditions, linear free energy relationships were observed between the capacity factors and the extraction eqnilibrinm constants of benzoic acid and naphthalene carboxylic acid. The capacity factor of benzene polycarboxylic acids was directly related to then-association constants and qnatemary ammonium ions calculated on the basis of an electrostatic interaction model [27,28],... 

As coalification progresses, cross-linking increases and the lignin-derived polymers become more aromatic. Phenolic polycarboxylic acids and hydroxynaphthalene dicarboxylic acids which were identified are not found in the CuO-NaOH oxidation products of lignins and plant materials. 

Polycarboxylic acid anhydrides by oxidation of aromatic compounds, e.g.—phthalic anhydride from naphthalene or o-xylene and also maleic anhydride from benzene... 

---