Aromatic acid salts

The exchange of protons a to a carboxylic acid salt (R—CH2—COOR -> R—CD2 COOR ) is known to proceed satisfactorily with various aliphatic and aromatic acid salts under strongly alkaline conditions.7,43 This reaction is presumably applicable to steroid derivatives (e.g. bile acids) as well, but examples are lacking in this field. 

The adoption of an eluent having a very low conductivity, which can be passed directly through the conductometric detector. Typical eluents used are benzoate, phthalate, or other aromatic acid salts, with low limiting equivalent conductances (leading to direct detection) or potassium hydroxide eluent, with high conduc-... 

Aromatic acid salts, ArC02 1605-1525 6.23-6.56 s, br w asym C02 str. (a, -unsat.compds. 

Figure 8.3 (a) The layered structure of aromatic acid salts. The cleavage plane exposes the apolar side of the molecules. The polar parts, with the acid moieties and M cations, are bnried. The cleavage plane properties (e.g., hydrophobicity) and unit-cell parameters can be modulated to some extent by the nature (f-butyl, chlorine, etc.) and also by the position (ortho, meta, or para) of the substituent X. Reproduced from Reference [11] with permission of Pergamon Press, (b) Combined diffraction pattern of poly(ethylene terephthalate) and the sodium salt of p-chlorobenzoic acid. The salt reflections are sharp spots the PET reflections are more arced. The contact plane of PET is (100) the chain axis is vertical. 

This conversion cannot easily be carried out on a semi-micro scale by ordinary chemical means. Liberation of an acid from one of its salts by dil. H SO is feasible when the organic acid is insoluble in water (e.g. an aromatic acid) or... 

A) Adds. The ammonium salts of aromatic acids when acidified in cold aqueous solution will deposit the crystalline acid. 

The Perkin reaction, uti1i2ing an aromatic aldehyde, an acid anhydride, and a base such as an acid salt or amine, produces the corresponding a,P-unsaturated acid. 

As a dibasic acid, malic acid forms the usual salts, esters, amides, and acyl chlorides. Monoesters can be prepared easily by refluxing malic acid, an alcohol, and boron trifluoride as a catalyst (9). With polyhydric alcohols and polycarboxyUc aromatic acids, malic acid yields alkyd polyester resins (10) (see Alcohols, polyhydric Alkyd resins). Complete esterification results from the reaction of the diester of maUc acid with an acid chloride, eg, acetyl or stearoyl chloride (11). 

Aromatic amines form addition compounds and complexes with many inorganic substances, such as ziac chloride, copper chloride, uranium tetrachloride, or boron trifluoride. Various metals react with the amino group to form metal anilides and hydrochloric, sulfuric, or phosphoric acid salts of aniline are important intermediates in the dye industry. 

Tellurium perchlorate, iodate, and methylthiosulfate, as weU as Te(IV) salts of aUphatic and aromatic acids, have been prepared. 

Aiomatic aisonic acids aie generally prepared by tiie Bart reaction from an aromatic diazonium salt and sodium arsenite ... 

The conversion of c>-hydroxyaryl ketones la to chromones 2a and/or coumarins 3a with aliphatic acid anhydrides in the presence of the sodium or potassium salt of the corresponding acid and the reaction between lb and aromatic acid anhydrides and the salt of the corresponding acid to form flavones 2b (Allan-Robinson) is called the Kostanecki-Robinson (K-R) reaction. ... 

Flavone formation is believed to proceed through a similar mechanism as the synthesis of chromones, albeit aromatic acid anhydrides and their corresponding salts are used. The first step is benzoylation of 12 to give the ester 14. Enolization and o-alkylation then affords the enolbenzoate 15. Enolbenzoate 15 then undergoes an acyl transfer to yield... 

This material can be prepared, e.g, by reaction of prednisolone-21-chloroacetate in solvent with the sodium or potassium salt of the corresponding aliphatic or aromatic acid, or by reaction of prednisolone with the chloride of the corresponding acyl-glycolic acid, in the presence of a hydrochloric acid acceptor. 

It is appropriate to refer here to the development of non-suppressed ion chromatography. A simple chromatographic system for anions which uses a conductivity detector but requires no suppressor column has been described by Fritz and co-workers.28 The anions are separated on a column of macroporous anion exchange resin which has a very low capacity, so that only a very dilute solution (ca 10 4M) of an aromatic organic acid salt (e.g. sodium phthalate) is required as the eluant. The low conductance of the eluant eliminates the need for a suppressor column and the separated anions can be detected by electrical conductance. In general, however, non-suppressed ion chromatography is an order of magnitude less sensitive than the suppressed mode. 

In the scientific sector, the understanding of the generally higher reactivity of heteroaromatic diazo components relative to that of aromatic diazonium salts has increased. The number of heterocyclic nitrogen atoms in azolediazonium ions has a marked influence on the N-H acidity of these ions. The pvalues of a series of such ions in aqueous solution at 0 °C (Scheme 12-4) indicate that the electrophilicity of the diazonio group in these compounds increases with the number of nitrogen atoms in the ring. ... 

This fully aromatic amide, based oil the amino acid p-aminobenzoic acid, can be spontaneously synthesized from p-aminobenzoic chloride.7 9 72 To prevent this occurring at an unwanted moment, the amine group is masked by forming the hydrochloric acid salt with hydrochloric acid. 

The various methods that are used for the production of aromatic acids from the corresponding substituted toluenes are outlined in Figure 1. The first two methods -chlorination/hydrolysis and nitric acid oxidation - have the disadvantage of relatively low atom utilization (ref. 13) with the concomitant inorganic salt production. Catalytic autoxidation, in contrast, has an atom utilization of 87% (for Ar=Ph) and produces no inorganic salts and no chlorinated or nitrated byproducts. It consumes only the cheap raw material, oxygen, and produces water as the only byproduct. 

The decarboxylation of aromatic acids is most often carried out by heating with copper and quinoline. However, two other methods can be used with certain substrates. In one method, the salt of the acid (ArCOO ) is heated, and in the other the carboxylic acid is heated with a strong acid, often sulfuric. The latter method is accelerated by the presence of electron-donating groups in ortho and para positions and by the steric effect of groups in the ortho positions in benzene systems it is... 

Despite its synthetic importance, the mechanism of the copper-quinoline method has been studied very little, but it has been shown that the actual catalyst is cuprous ion. In fact, the reaction proceeds much faster if the acid is heated in quinoline with cuprous oxide instead of copper, provided that atmospheric oxygen is rigorously excluded. A mechanism has been suggested in which it is the cuprous salt of the acid that actually undergoes the decarboxylation. It has been shown that cuprous salts of aromatic acids are easily decarboxylated by heating in quinoline and that arylcopper compounds are intermediates that can be isolated in some cases. Metallic silver has been used in place of copper, with higher yields. ... 

Incidentally, 31 contributes more to the hybrid than 32, as shown by bond-distance measurements. In benzenediazonium chloride, the C—N distance is 1.42 A, and the N—N distance 1.08 A, which values lit more closely to a single and a triple bond than to two double bonds (see Table 1.5). Even aromatic diazonium salts are stable only at low temperatures, usually only below 5°C, though more stable ones, such as the diazonium salt obtained from sulfanilic acid, are stable up to 10 or 15°C. Diazonium salts are usually prepared in aqueous solution and used without isolation, though it is possible to prepare solid diazonium salts if desired (see 13-20). The stability of aryl diazonium salts can be increased by crown ether complexion. ... 

The condensation of aromatic aldehydes with anhydrides is called the Perkin reaction When the anhydride has two a hydrogens (as shown), dehydration always occurs the P-hydroxy acid salt is never isolated. In some cases, anhydrides of the form (R2CHC0)20 have been used, and then the hydroxy compound is the product since dehydration cannot take place. The base in the Perkin reaction is nearly always the salt of the acid corresponding to the anhydride. Although the Na and K salts have been most frequently used, higher yields and shorter reaction times have been reported for the Cs salt. Besides aromatic aldehydes, their vinylogs ArCH=CHCHO also give the reaction. Otherwise, the reaction is not suitable for aliphatic aldehydes. ... 

Hui et al. 177) have investigated the inclusion compounds between carboxymethyl-amylose and the two aromatic keto-acid salts (30) and (31). The binding constants... 

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