Dicarboxylic acids aromatic, acidity

Polycarbonates. Polyarjiates are aromatic polyesters commonly prepared from aromatic dicarboxylic acids and diphenols. One of the most important polyarylates is polycarbonate, a polyester of carbonic acid. Polycarbonate composite is extensively used in the automotive industry because the resin is a tough, corrosion-resistant material. Polycarbonates (qv) can be prepared from aUphatic or aromatic materials by two routes reaction of a dihydroxy compound with phosgene accompanied by Hberation ofHCl(eq. 5) ... 

PolybenZimidaZoles. The polyben2imida2oles (PBIs) are generally produced by the high temperature, melt polycondensation reaction of aromatic bis-ortho-diamines and aromatic dicarboxylates (acids, esters, or amides) in a reaction such as that shown in equation 11 to form ben2imida2ole [51-17-2] as the repeating unit. 

Isothiazole-4,5-dicarboxylic acid, 3-phenyl-dimethyl ester synthesis, S, 150 Isothiazole-5-glyoxylic acid ethyl ester reduction, 6, 156 Isothiazole-4-mercurioacetate reactions, 6, 164 Isothiazole-5-mercurioacetate reactions, 6, 164 Isothiazoles, 6, I3I-I75 acidity, 6, 141 alkylation, 6, 148 aromaticity, S, 32 6, 144-145 basicity, 6, I4I biological activity, 6, 175 boiling points, 6, I43-I44, 144 bond fixation, 6, 145 bond orders, 6, I32-I34 calculated, 6, 133 bromination, S, 58 6, 147 charge densities, 6, 132-134 cycloaddition reactions, 6, 152 desulfurization, S, 75 6, 152 deuteration, S, 70... 

Oxepin, 4-ethoxycarbonyl-2,3,6,7-tetrahydro-synthesis, 7, 578 Oxepin, 2-methyl-enthalpy of isomerization, 7, 555 Oxepin, 2,3,4,5-tetrahydro-reduction, 7, 563 synthesis, 7, 578 Oxepin, 2,3,4,7-tetrahydro-synthesis, 7, 578 Oxepin, 2,3,6,7-tetrahydro-oxidation, 7, 563 reduction, 7, 563 Oxepin-2,6-dicarboxylic acid stability, 7, 565 Oxepinium ions synthesis, 7, 559 Oxepins, 7, 547-592 antiaromaticity, 4, 535 applications, 7, 590-591 aromatization, 7, 566 bond lengths and angles, 7, 550, 551 cycloaddition reactions, 7, 27, 569 deoxygenation, 7, 570 dipole moment, 7, 553 disubstituted synthesis, 7, 584... 

The present method for preparing aromatic dicarboxylic acids has been used to convert phthalic or isophthalic acid to tereph-thalic acid (90-95%) 2,2 -biphenyldicarboxylic acid to 4,4 -biphenyldicarboxylic acid 3,4-pyrroledicarboxylic acid to 2,5-pyr-roledicarboxylic acid and 2,3-pyridinedicarboxylic acid to 2,5-pyridinedicarboxylic acid. A closely related method for preparing aromatic dicarboxylic acids is the thermal disproportionation of the potassium salt of an aromatic monocarboxylic acid to an equimolar mixture of the corresponding aromatic hydrocarbon and the dipotassium salt of an aromatic dicarboxylic acid. The disproportionation method has been used to convert benzoic acid to terephthalic acid (90-95%) pyridine-carboxylic acids to 2,5-pyridinedicarboxylic acid (30-50%) 2-furoic acid to 2,5-furandicarboxylic acid 2-thiophenecar-boxylic acid to 2,5-thiophenedicarboxylic acid and 2-quinoline-carboxylic acid to 2,4-quinolinedicarboxylic acid. One or the other of these two methods is often the best way to make otherwise inaccessible aromatic dicarboxylic acids. The two methods were recently reviewed. ... 

Some of the typical conditions of polycondensations used for aliphatic and aromatic monomers are not suitable for furan derivatives, e.g., the melt polycondensation of 2,5-furan dicarboxylic acid chloride with 2,5-b/s(hydroxymethyl) furan at about 80 °C only yields a black insoluble product5. The hydrochloric acid liberated in the reaction is clearly responsible for the charring of the furanic diol which like its simpler homologue furfuryl alcohol, resinifies rapidly in acidic media (see below). 

From the preceding discussion, it is easily understood that direct polyesterifications between dicarboxylic acids and aliphatic diols (Scheme 2.8, R3 = H) and polymerizations involving aliphatic or aromatic esters, acids, and alcohols (Scheme 2.8, R3 = alkyl group, and Scheme 2.9, R3 = H) are rather slow at room temperature. These reactions must be carried out in the melt at high temperature in the presence of catalysts, usually metal salts, metal oxides, or metal alkoxides. Vacuum is generally applied during the last steps of the reaction in order to eliminate the last traces of reaction by-product (water or low-molar-mass alcohol, diol, or carboxylic acid such as acetic acid) and to shift the reaction toward the... 

Sulfur compounds have also been widely studied as activating agents for polyesterification reactions. p-Toluenesulfonyl chloride (tosyl chloride) reacts with DMF in pyridine to form a Vilsmeir adduct which easily reacts with carboxylic acids at 100-120° C, giving highly reactive mixed carboxylic-sulfonic anhydrides.312 The reaction is efficient both for aromatic dicarboxylic acid-bisphenol312 and hydroxybenzoic acid314 polyesterifications (Scheme 2.31). The formation of phenyl tosylates as significant side products of this reaction has been reported.315... 

Bu2Sn(lV)] complexes formed for pyridine mono- and dicarboxylic acids (Figure 20) containing -COO group(s) and aromatic N donor atom were prepared. 

N-Substituted amides can be prepared by direct attack of isocyanates on aromatic rings.The R group may be alkyl or aryl, but if the latter, dimers and trimers are also obtained. Isothiocyanates similarly give thioamides. The reaction has been carried out intramolecularly both with aralkyl isothiocyanates and acyl isothiocyanates.In the latter case, the product is easily hydrolyzable to a dicarboxylic acid this is a way of putting a carboxyl group on a ring ortho to one already there (34 is... 

The dimethylbenzenes (xylenes) are very important industrial chemicals recovered during the refining of petroleum. All three xylenes are used to produce the corresponding aromatic dicarboxylic acids by reaction with oxygen over a catalyst. 

Branched polyesters contain oxalkylated primary fatty amines or oxalkyl-ated polyamines together with at least trivalent oxalkylated alkanol that is responsible for branching. The condensation is achieved with a dicarboxylic acid or a dicarboxylic acid anhydride [216]. In this way, branched polyoxyalkylene mixed polyesters are formed. Suitable solvents are water or organic solvents, such as methanol, isopropanol, butanol, or aromatic hydrocarbons (e.g., toluene, xylene). 

Dicarboxylic acids were converted in a one-pot procedure with CDI (boiling THF, 15 min) into the bisimidazolides, and then by subsequent treatment with aliphatic, aromatic, or heteroaromatic primary amines into imides (piperazine-2,6-diones) in excellent yields [131]... 

Now and then, projectiles from outer space cause excitement and surprises, as in January 2000, when a meteorite impacted the frozen surface of Lake Targish in Canada. It was a new type of C-chondrite with a carbon concentration of 4-5%, and probably came from a D-type asteroid (Hiroi et al., 2001). More exact analysis of the Targish meteorite showed the presence of a series of mono- and dicarboxylic acids as well as aliphatic and aromatic hydrocarbons (Pizzarello et al., 2001). Aromatic compounds and fullerenes were detected in the insoluble fraction from the extraction this contained planetary helium and argon, i.e., the 3He/36Ar ratio was... 

Polyesters containing aromatic moiety in the main chain were synthesized by lipase CA-catalyzed polymerization of dicarboxylic acid divinyl esters and gly-... 

Several novel biodegradable polyesters of different compositions have been developed during the last decade, e.g., an aliphatic copolymer of various glycols and dicarboxylic acids (Bionolle) or copolymers of aliphatic diols and aromatic monomers [119-121]. 

Synthesis of polyanhydrides from the aromatic dicarboxylic acids (isophthalic and terephthalic acids) by melt polycondensation was first... 

For example, such attempts were undertaken in a body of work [60] dealing with the preparation (through acceptor-catalytic copolyesterification) of triple copolyesters composed from the residues of aromatic dicarboxylic acids, bisphenols and N-methyldielhanolamine (NMDEA). Scheme 7 illustrates the principle of such a syntheses the upper part shows the chemical... 

Electrophilic substitution of the ring hydrogen atom in 1,3,4-oxadiazoles is uncommon. In contrast, several reactions of electrophiles with C-linked substituents of 1,3,4-oxadiazole have been reported. 2,5-Diaryl-l,3,4-oxadiazoles are bromi-nated and nitrated on aryl substituents. Oxidation of 2,5-ditolyl-l,3,4-oxadiazole afforded the corresponding dialdehydes or dicarboxylic acids. 2-Methyl-5-phenyl-l,3,4-oxadiazole treated with butyllithium and then with isoamyl nitrite yielded the oxime of 5-phenyl-l,3,4-oxadiazol-2-carbaldehyde. 2-Chloromethyl-5-phenyl-l,3,4-oxadiazole under the action of sulfur and methyl iodide followed by amines affords the respective thioamides. 2-Chloromethyl-5-methyl-l,3,4-oxadia-zole and triethyl phosphite gave a product, which underwent a Wittig reation with aromatic aldehydes to form alkenes. Alkyl l,3,4-oxadiazole-2-carboxylates undergo typical reactions with ammonia, amines, and hydrazines to afford amides or hydrazides. It has been shown that 5-amino-l,3,4-oxadiazole-2-carboxylic acids and their esters decarboxylate. 

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