Of caiboxylic acids

The thennal decarboxylation of malonic acid derivatives is the last step in a multistep synthesis of caiboxylic acids known as the malonic ester synthesis. This synthetic method will be described in Section 21.7. 

The Kharasch-Sosnovsky reaction may be carried out in the presence of caiboxylic acids to introduce the acyloxy moiety of the acid used, and may also be conducted photochemically at room temperature using UV irradiation. Peroxy acids, diacyl peroxides, and peroxyphosphates and peroxyphospho-nates are alternative oxidants. r-Butyl hy operoxide may also be used in place of peroxy esters with broadly similar results, although formations of mixed peroxides and r-butyl ethers can then compete with allyl ester production. 

The Kolbe dimerization is believed to be favored by the following reaction conditions high concentration of caiboxylic acid, low pH value, absence of foreign anions, high cunent density and use of a platinum anode. 

Hydrogen atoms in labile positions, for example the hydrogen of caiboxylic acid, undergo rapid exchange and equilibration with tritiated water. These products are not veiy useful for biotransformation studies because the tritium label is veiy susceptible to exchange in aqueous solutions. 

Three-component condensation (3CC) of caiboxylic acids, C-isocyanides, and carbonyl compounds to afford a-acyloxycarboxamides. Also known as three-component reaction (3CR). C/i Ugi reaction. 

The extraction chemistry of caiboxylic acids with both conventional and complexing extractants has been reviewed by Kertes and King. A review of extraction chemistry of the low-molecular-weight chemistiy of the low-molecular-weight alcohols has been prepared by the same authors. ... 

The amination of the a-carbon atom of caiboxylic acid derivatives has been extensively studied by Ef-fenberger and cowoikers. Ethyl (5)-a-bromopropionate reacted with (/ )- -phenylethylamine to give (2RXR)- and (25,r )-/V-(l -phenylethyl)alanine ethyl ester, e.g. (2/ ,l / )-(4) and (2S,l / )-(4). Prolonged reaction time afforded the products in higher yields with decreasing stereospecificity (Scheme 5). 

One of the most useful variants of the Curtius reaction is the reaction of caiboxylic acids with diphenyl phosphorazidate (DPPA (I%0)2P(0)N3) in the presence of base, such as triethylamine (equation 2). ... 

Esters aie more easily reduced than caiboxylic acids. Two alcohols aie fonned from each ester molecule. The acyl group of the ester is cleaved, giving a primary alcohol. 

Electron delocalization in caiboxylate ions is nicely illustrated with the aid of electrostatic potential maps. As Figure 19.4 shows, the electrostatic potential is different for the two different oxygens of acetic acid, but is the same for the two equivalent oxygens of acetate ion. 

For many years, resonance in caiboxylate ions was emphasized when explaining the acidity of carboxylic acids. Recently, however, it has been suggested that the inductive effect of the carbonyl group may be more important. It seems clear that, even though then- relative contributions may be a matter of debate, both play major roles. 

Metal caiboxylates are ionic, and when the molecular weight isn t too high, the sodium and potassium salts of carboxylic acids are soluble in water. Carboxylic acids therefore may be extracted from ether solutions into aqueous sodium or potassium hydroxide. 

The answer to this question is critical because it tells us whether the caibon-oxygen bond of the alcohol or a caibon-oxygen of the caiboxylic acid is broken during esterification. 

Notice that the caiboxyl group that stays behind during the decarboxylation of malonic acid has a hydroxyl function that is not directly involved in the process. Compounds that have substituents other than hydroxyl groups at this position undergo an analogous decarboxylation. 

With p fa s of approximately 10, phenols aie stronger acids than alcohols, but weaker than caiboxylic acids. They aie converted quantitatively to phenoxide anions on treatment with aqueous sodium hydroxide. 

A key biochemical reaction of amino acids is their conversion to peptides, polypeptides, and proteins. In all these substances fflnino acids aie linked together by amide bonds. The amide bond between the fflnino group of one amino acid and the caiboxyl of another is called a peptide bond. Alanylglycine is a representative dipeptide. 

Abstract PAMAM types polyether based dendrimers were synthesized from three branched Jeffamines . Synthesized compounds bears metylester/ferf-butylester, caiboxylic acid or amine groups. In the synthesis iterative Micheal type of reaction paths were followed. Catalytic properties of the molecules were studied in homogenous phase. 

Reduction of the carboxylic acid group passes through the intermediate aldehyde. For a number of examples in the heterocyclic series, the aldehyde becomes a major product because it is trapped as the hydrated vfc.-diol form. Examples include imidazole-2-caiboxylic acid [139], thiazole-2-carboxylic acid [140] and pyridine-4-carboxylic acid [141] reduced in dilute aqueous acid solution. Reduction of imidazole-4-carboxylic acid proceeds to the primary alcohol stage, the aldehyde intermediate is not isolated. Addition of boric acid and sodium sulphite to the electrolyte may allow the aldehyde intermediate to be trapped as a non-reducible complex, Salicylaldehyde had been obtained on a pilot plant scale in this way by... 

Nicotinic acid and nicotinamide, members of the vitamin B group and used as additives for flour and bread enrichment, and as animal feed additive among other applications, are made to the extent of 24 million pounds (nearly 11 million kilograms) per year throughout the world. Nicotinic acid (pyridine-3-caiboxylic acid), also called niacin, has many uses. See also Niacin. Nicotinic acid is made by the oxidation of 3-picolme or 2-mcthyl-5-cthylpyridine (the isocinchomcnc acid produced is partially deearboxylated). Alternatively, quinoline (the intermediate quinolinic acid) is partially deearboxylated with sulfuric add in the presence of selenium dioxide at about 300° C or with nitric acid, or by electrochemical oxidation. Nicotinic acid also can be made from 3-picoline by catalytic ammoxidation to 3-cyanopyridine, followed by hydrolysis. 

Other Derivatives of SaUcylic Acid. p-Aminosalicylic acid and its salts have been used in the treatment of tuberculosis. / -Aminosalicylic add can be prepared by the caiboxylation of in-amiuoplienol. Metliylene-5,5-disalicylic acid, produced by heating two parts salicylic acid with 1-1.5 parts of 30-40 wt % formaldehyde in the presence of an add catalyst, is used as an intermediate in the production of bacitracin me thy le ne di salicy la te. 

One important group of condensation polymers is the polyesters. The most important commercial polyester is formed from the reaction of terephthalic acid (a diacid) with ethylene glycol (a diol). This polymerization occurs in a stepwise fashion (hence the name step growth polymerization). First, one carboxylic acid group of a diacid molecule and one hydroxy group of a diol molecule combine to form an ester, with the loss of water. Then a second diol molecule reacts with the unreacted caiboxylic group on the other end of the diacid molecule, or a second diacid molecule reacts with the unreacted hydroxy group of the diol. Continuation of this process adds a new monomer unit at... 

Cyclocondensation routes also provide access to pyrimidines. 2,3-Disubstituted pyrido[2,3-/i]-quinazolin-4(3//)-ones are obtained via cyclocondensation of 5-aminoquinoline-6-caiboxylic acid with acid chlorides <02SC235>. 5,6,8-Trialkyl-7-methoxy-2-aminoquinazolines are obtained from 1,3-dimethoxybenzenes via cyclocondensation of intermediate dihydrobenzenes with guanidine carbonate <02TL3295>. Diastereoselective intramolecular hetero Diels-Alder cyclization of a pyrazole carboxaldehyde condensed onto 1,3-dimethylbarbituric acid (101) gave polycyclic heterocycle 102 <02T531>. An efficient one-step synthesis of cyclobutene-annelated pyrimidinones 103 from methyl 2-chloro-2-cyclopropylideneacetate and amidines has been... 

The phenyl group became a practical protective group for carboxylic acids when Sharpless published a mild, effective one-step method for its conversion to a carboxylic acid.1 It has recently been used in a synthesis of the amino acid statine, where it served as a masked or caiboxylic acid equivalent.2... 

Caiboxylic acids, tetrahedral intermediates derived from, spectroscopic detection and investigation of their properties, 21, 37... 

The tetrahedral intermediate T can eliminate any one of the three -OH groups to reform either the original carboxylic acid or labeled caiboxylic acid. Further reaction of water with mono-labeled carboxylic acid leads to the doubly labeled product. 

Oxidation of primary alcdiols to aldehydes using these oxidants does not result in overoxidation to caiboxylic acids, in contrast to many other oxidants. This arises since the aldehydes are foimed under anhydrous conditions and are not capable of hydration, which is a necessary requirement for conversion to a carboxylic acid. 

Simple alcohols can be obtained from the decomposition of peroxy acids in cyclohexane or boizene at reflux. This chain reaction, which is efficient for adamantane-l-caiboxylic acid (equation 40), is unfortunately usually complicated by side reactions involving hydrogen abstraction firom the substrate or solvent. ... 

Nitriles can also be named as derivatives of carboxylic acids by replacing the -ic acid or -ok acid ending with -onitrile, or by replacing the -caiboxylic acid ending with -carbonitrile. The nitrile carbon atom is attached to Cl but is not itself numbered. 

Relatively few studies on the synthesis of mesoporous alumina have been reported to date [8]. One of the limitations of the reported synthetic strategies is that the rate of hydrolysis (and condensation) reaction of aluminum alkoxide are much faster than that of silicon alkoxide. In this study, we proposed a novel method to prepare bimodal porous aluminas with meso- and macropores with narrow pore size distribution and well-defined pore channels. The fiamewoik of the porous alumina is prepared via a chemical templating method using alkyl caiboxylates. Here, self-assemblied micelles of carboxylic acid were used as a chemical template. Mesoporous aluminas were prepared through carefiil control of the reactants pH, while the procedures are reported elsewhere [9]. 

Finally, some of the methods for carboxylic acid reduction (Section 1.12.2) have also been applied to esters. Thus, the ethyl ester of thiazole-2-caiboxylic acid has been reduced electrochemically to the corresponding aldehyde, and some of the high temperature metal oxide catalyzed hydrogenations have been used on esters. ... 

Other model or natural compounds which contained no free caiboxylic acid groups, showed significant and temperature-dependent chlorine release at pyrolysis or gasification between 300 °C and 500 °C when at least one of the following functional groups was frequent in the substance ... 

In the product-ion MS-MS spectra of dolasetron and metabolites (Ch. 10.3.2), an ion at m/z 166, representing the loss of the indole-3-caiboxylic acid, was found to be a common fragment ion. The precursor-ion analysis mode, with m/z 166 as common product ion, was applied to search for possible additional metabolites. All five previously identified metabolites were found, but no other compounds [9]. 

The reaction of activated aziridine-2-caiboxylic acid methyl esters (169) with ethoxycarbonylmethyl-enetriphenylphosphorane resulted in the formation of phosphorane (170) along with phosphorane (171) and aziridine (172), with the exception of (169d), where (172d) was obtained as the sole product (Scheme 74). Phosphorane (170b) was converted into 4-methylene-(2S)-glutamic acid (173). ... 

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