Dicarboxylic acids neutralization

Ethylene—Dicarboxylic Acid Copolymers. Partial neutralization of copolymers containing carboxyls in pairs on adjacent carbons, eg, ethylene—maleic acid, has been described (11). Surprisingly, there is no increase in stiffness related to neutralization. Salts with divalent metal cations are not melt processible. The close spacing of the paired carboxyl groups has resulted in ionic cluster morphology which is distinct from that of the commercial ionomer family. 

C. i-Melhyllhiol-yphthalamidapropane-2,2,-dicarboxylic Acid. —A solution of 25 g. (0.066 mole) of the above ester in 30 cc. of 95 per cent alcohol is heated on the steam bath in a 200-cc. round-bottomed flask, and 70 cc. of 5 A sodium hydroxide is added. The cloudy liquid is heated until a sample gives a clear solution on dilution with water this occurs after about two hours. The solution is then chilled to 0 and cautiously neutralized to Congo red with 0.2 N hydrochloric acid, whereupon 75 cc. of 5 A hydrochloric acid is slowly added, the temperature being maintained at 0°. The acid separates as colorless crystals. This separation is completed by the slow addition of 60 cc. of concentrated hydrochloric acid (sp. gr. 1.19). The product is filtered by suction and v ashed free of salt with small quantities of ice-cold water. After drying in vacuo, the yield amounts to 21.5-22 g. (95.5-98 per cent of the theoretical amount) of a product melting at 141-143°. 

A mixture Df 3,7,8,12-tetraelhyl-2,13-dimethyltripyrrane-l, 14-dicarboxylic acid (1 e, 1 equiv), and 3,4-di-ethylpyrrole-2,5-dicarbaldehyde (2e, t equiv) was dissolved in 5% TFA/CH2C12 and stirred at rt for 2 h. The mixture was neutralized with Et3N and further reacted with DDQ (1 equiv) for 1 h. Column chromatography (neutral alumina) and recrystallization (CHCl3/MeOH) gave the title compound yield 60%. 

A dispersant that can be used in drilling fluids, spacer fluids, cement slurries, completion fluids, and mixtures of drilling fluids and cement slurries controls the rheologic properties of and enhances the filtrate control in these fluids. The dispersant consists of polymers derived from monomeric residues, including low-molecular-weight olefins that may be sulfonated or phosphonated, unsaturated dicarboxylic acids, ethylenically unsaturated anhydrides, unsaturated aliphatic monocarboxylic acids, vinyl alcohols and diols, and sulfonated or phosphonated styrene. The sulfonic acid, phosphonic acid, and carboxylic acid groups on the polymers may be present in neutralized form as alkali metal or ammonium salts [192,193]. 

Several examples of conjugate addition of carbanions carried out under aprotic conditions are given in Scheme 2.24. The reactions are typically quenched by addition of a proton source to neutralize the enolate. It is also possible to trap the adduct by silylation or, as we will see in Section 2.6.2, to carry out a tandem alkylation. Lithium enolates preformed by reaction with LDA in THF react with enones to give 1,4-diketones (Entries 1 and 2). Entries 3 and 4 involve addition of ester enolates to enones. The reaction in Entry 3 gives the 1,2-addition product at —78°C but isomerizes to the 1,4-product at 25° C. Esters of 1,5-dicarboxylic acids are obtained by addition of ester enolates to a,(3-unsaturated esters (Entry 5). Entries 6 to 8 show cases of... 

GC/MS has also been used to investigate acidic and neutral fractions (after alkaline hydrolysis, separation and trimethylsilylation) of a resinous sample collected from a flint flake dated back to the lower Palaeolithic (roughly 200 000 BC) and recovered near Arezzo in Italy [11]. The results show that the organic material recovered on the flint flake was a pitch obtained from birch bark by a pyrolysis type process. In fact, the main components of the acidic fraction are a series of linear a,oo-dicarboxylic acids ranging from 16 to 22 carbon atoms and a series of oo-hydroxycarboxylic acids ranging from 16 to 22 carbon... 

Unlike the urea- and melamine-formaldehyde resins, these wet strength agents are suitable for both neutral and alkaline pH. They are prepared by condensation of a dicarboxylic acid and bis (2-aminoethyl) amine, the free amino group is then alkylated with epichlorohydrin to give an aminochlorohydrin which exists in equilibrium with a 3-hydroxyazetidinium group (Figure 7.28). 

The gas-solid neutralizations found more interest than the solid-solid variant. The quantitative reactions of gaseous ammonia with solid benzoic and related acids were interpreted by a concept of gas permeability of the crystal in order to explain anisotropic reaction fronts in single crystals [24]. Also, the ammonium salts of the aromatic or aliphatic mono- and dicarboxylic acids 16-21 (Scheme 3) formed the corresponding salts with 100% yield. The need for molecular migrations immediately upon reaction was not considered at that... 

Fully aromatic polyamides are synthesized by interfacial polycondensation of diamines and dicarboxylic acid dichlorides or by solution condensation at low temperature. For the synthesis of poly(p-benzamide)s the low-temperature polycondensation of 4-aminobenzoyl chloride hydrochloride is applicable in a mixture of N-methylpyrrolidone and calcium chloride as solvent. The rate of the reaction and molecular weight are influenced by many factors, like the purity of monomers and solvents, the mode of monomer addition, temperature, stirring velocity, and chain terminators. Also, the type and amount of the neutralization agents which react with the hydrochloric acid from the condensation reaction, play an important role. Suitable are, e.g., calcium hydroxide or calcium oxide. 

An elegant variation of this procedure is to carry out the polycondensation with the salt of a diamine and a dicarboxylic acid (see Example 4-10). In this case, the formation of salt (which is also the first step in the direct polycondensation of a diamine and a dicarboxylic acid) and the polycondensation are carried out as two separate steps. The salts can be obtained in good crystalline form most simply by mixing equimolar amounts of diamine and dicarboxylic acid in a solvent in which the salt formed is insoluble (e.g., ethanol). In order to attain high molecular weights by such polycondensations the salts should be as neutral as possible (exactly equivalent amounts of diamine and dicarboxylic acid) and very pure (recrystallize, for example, from mixtures of ethanol/water). 

In 1994, Kunz et al. studied the oxidation of sucrose in the presence of Pt/C at 307 K and neutral pH [104]. Under these conditions, the positions 6, 6, and V of sucrose were mainly oxidized and a mixture of monocarboxylic and dicarboxylic acids (56/44) has been produced. Note that when the oxidized products were continuously removed by electrodialysis in order to avoid their subsequent... 

At neutral pH and using Pt/C as solid catalyst, Edye et al. have shown that the dicarboxylic acid of sucrose can be obtained with 68% yield at 373 K [106,107]. In contrast to the previous results obtained at pH 7.0, in this study the hydroxyl groups at C(6) and C(6 ) were oxidized and no oxidation of HOCH2(l ) had occurred. 

A, and the O H -0 length 2.53 A. The 2,6-dicarboxylic acid monohydrate exists in the neutral form, while the 3,5-isomer, dinicotinic acid, exists in the intermediate form, but here each molecule is joined by two kinds of hydrogen bond (O—H- O, 2.59 A O H- -N, 2.52 A) to four surrounding molecules. Pyridine-2,3-dicarboxylic acid exists in the zwitterionic form (38), as does cinchomeronic acid, the 3,4-dicarboxylic isomer (39), the N—H bond distances being 0.89 A and 1.09 A respectively. 

Base copolymers with dicarboxylic acid comonomers, even those in which one acid radical has been esterified, when neutralized with metal ions, which have two or more ionized valences, result in intractable ionic copolymers at the level of neutralization essential to obtain significant improvement in solid state properties. 

There are many other isomers in MS/MS analysis, such as several acyl-camitines that share the same mass, such as many of the hydroxyacylcami-tines and dicarboxylic acid acylcamitines. In addition, interfering products may, at times, share a common fragment ion or neutral loss and as a result will be detected in a profile. No method, however, is perfectly selective and a physician reviewing results from a newborn screen, whether analyzed using an immunoassay or MS, should be aware of the fact that in some cases, similar mass compounds may lead to potential sources of error. 

Consistent with the photolytic result, radiolysis of solutions of pyrazine gave only 1,4-dihydropyraziniumyl radical (17) in acidic or neutral conditions and no paramagnetic products in alkaline media.196 However, pyrazine-2,3-dicarboxylic acid gave the 1-hydropyrazinyl-2,3-dicarboxylate (63) in strongly alkaline solution.196... 

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