Pyridine carboxylates

Pyridine carboxamide [98-92-0] (nicotinamide) (1) and 3-pyridine carboxylic acid [59-67-6] (nicotinic acid) (2) have a rich history and their early significance stems not from their importance as a vitamin but rather as products derived from the oxidation of nicotine. In 1867, Huber prepared nicotinic acid from the potassium dichromate oxidation of nicotine. Many years later, Engler prepared nicotinamide. Workers at the turn of the twentieth century isolated nicotinic acid from several natural sources. In 1894, Su2uki isolated nicotinic acid from rice bran, and in 1912 Funk isolated the same substance from yeast (1). 

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. ... 

Chemical Name Myo-lnositol hexa-3-pyridine carboxylate Common Name Inositol hexanicotinate Structural Formula ... 

Chemical Name 2-[ [3-(Trifluoromethyl)phenyl] amino]-3-pyridine carboxylic acid 1,3-di-hydro-3-0X0-1 -isobenzofuranyl ester... 

Chemical Name 3-Pyridine carboxylic acid compounded with 3,7-dihydro-7-[2-hydroxy-3-[(2-hydroxymethyl)methylamino] propyl] -1,3-dimethyl-1 H-purlne-2,6-dlone(1 1)... 

Fluorinated derivatives of 191 have been prepared from chlorofluoro-pyridine carboxylic acids (92JMC518). 

Hydroxylation is also involved in the degradation of all the pyridine carboxylates and the interrelations of these pathways are shown (Fignre 10.11) ... 

Chloro-2-hydroxypyridine-3-carboxylate is a terminal metabolite in the degradation of 3-chloroquinoline-8-carboxylate, but can be degraded by Mycobacterium sp. strain BA to chlorofumarate by reactions analogous to those described above for pyridine carboxylates (Figure 10.18) (Tibbies et al. 1989a). 

With N,0 mixed donor ligands several complexes have been reported with ligands such as 4,5-dichloro-2-cyano-3,6-dione-l,4-cyclohexen-l-ol,1445 isonicotinic acid,1446 p-aminobenzoic acid,1447 alanine, histidine or histamine derivatives,1448-1450 [N(0)C(CN)2]-,1451 pyridine-carboxylate derivatives, 1452 1454 [N(pph20)2] (263),1455 bis(sulfonyl)amide derivatives,1456,1457 tris(pyridyl)-... 

Soldenhoff, K. H. Solvent extraction of copper(II) from chloride solutions by some pyridine carboxylate esters. 

Burgess, A. Dalton, R. F. Solvent extraction of palladium by pyridine carboxylic esters. Process Metallurgy 1992 pp 1087-1092. 

The observed hyperbolic dependences suggest a mechanism that involves a pre-equilibrium binding of two pyridine carboxylates to the Fem of lm, followed by the intramolecular proton transfer from the coordinated acid (Scheme 3). This option has been supported by measurements of the binding constants for py and related ligands. The data in Fig. 8 agree with the mechanism in Scheme 3. The reactive intermediate for robust lm is the diaxially coordinated species, one of the two ligands being picolinic acid (L). 

Scheme 4. Proposed general mechanism of demetalation of 1 by picolinic acid accounting for first (la, in the box) and second (lm) orders in the buffer acid concentration. The charge of the Fem-TAML complex is shown outside the bracket and localized charges are shown for the deprotonated pyridine carboxylates. From Ref. (27).

Kinetics and mechanisms of substitution at Pt(II) and Pd(II) have been reviewed and compared with respect to reactions of nitrogen bases such as imidazole, pyrazole, inosine, adenosine, and guanosine-5 -monophosphate with ammine, amine, pyridine carboxylate, and... 

Reviewed here are surface electrochemical studies of organic molecules adsorbed at well-defined Pt(lll) electrode surfaces from aqueous solution. Emphasis is placed upon studies of nicotinic acid (NA), pyridine (PYR), and nine related pyridine carboxylic acids. 

Nicotinic acid and related meta-carboxylic acids display the remarkable characteristic that coordination of the pendant carboxylic acid moieties to the Pt surface is controlled by electrode potential. Oxidative coordination of the carboxylate pendant occurs at positive electrode potentials, resulting in disappearance of the 0-H vibration and loss of surface acidity as judged by absence of reactivity towards KOH. Carboxylate in the 4-position of pyridine (as in INA) is virtually independent of electrode potential, whereas strong coordination of ortho-carboxylates to the Pt surface is present at most electrode potentials. Adsorbed pyridine carboxylic acids are stable in vacuum when returned to solution the adsorbed material displays the same chemical and electrochemical properties as prior to evacuation. 

Shown in Figure 6-A are EELS spectra of the entire series of pyridine carboxylic acids and diacids adsorbed at Pt(lll) from acidic solutions at negative electrode potential. Under these conditions all of the meta and para pyridine carboxylic acids and diacids exhibit prominent 0-H vibrations (OH/CH peak ratio near unity). In contrast, at positive potentials only the para-carboxylic acids display pronounced 0-H vibrations, Figure 6-B. All of the 0-H vibrations are absent under alkaline conditions, Figure 6-C. This situation is illustrated by the reactions of adsorbed 3,4-pyridine dicarboxylic acid ... 

Figure 6. EELS spectra of pyridine carboxylic acids adsorbed at Pt(lll). Experimental conditions (A and B) adsorption from 1 mM NA in 10 mM KF at pH 3, followed by rinsing with 2 mM HF (pH 3) (C) adsorption from 10 mM KF (pH 3), followed by rinsing with 0.1 mM KOH (pH 10) other conditions as in Figure 4. A. Adsorption at -0.2 V vs. Ag/AgCl (pH 3). Continued on next page.

Based on earlier experiences ring opening of the pyridine moiety in methyl 4-tetrazolo[l,5- ]pyridine carboxylate 70 on reaction with allylamine was predicted by Okawa et al. <1997T16061> (Scheme 19). Instead of the expected major structural change, however, a routine aminolysis was found to yield the allylamide 71. 

Glycosyl esters with remote functionality constitute a relatively new class of O-carbonyl glycosyl donors, which fulfill the prospect of mild and chemoselective activation protocols (Scheme 3.22). For example, Kobayashi and coworkers have developed a 2-pyridine carboxylate glycosyl donor 134 (Y = 2-pyridyl), which is activated by the coordination of metal Lewis acid (El+) to the Lewis basic pyridine nitrogen atom and ester carbonyl oxygen atom [324]. In the event, 2-pyridyl (carbonyl) donor 134 and the monosaccharide acceptor were treated with copper(II) triflate (2.2 equiv) in diethyl ether at —50 °C, providing the disaccharide 136 in 70% (a P,... 

Solid-liquid phase systems with no added solvent produce esters in high yield [e.g. 2, 3] and are particularly Useful when using less reactive alkyl halides [e.g. 15], for the preparation of sterically hindered esters [16], or where other basic sites within the molecule are susceptible to alkylation, e.g. anthranilic acid is converted into the esters with minimal A-alkylation and pyridine carboxylic acids do no undergo quat-emization [17]. Excellent yields of the esters in very short reaction times (2-7 minutes) are also obtained when the two-phase system is subjected to microwave irradiation [18]. Direct reaction of the carboxylic acids with 1,2-dichloroethane under reflux yields the chloroethyl ester [19], although generally higher yields of the esters are obtained under microwave conditions [20]. 

Copper(ii) complexes of 8-amino-7-hydroxy-4-methylcoumarin, 1,10-phenanthroline-2-carboxamide, 2-pyridone, 2,3-di-(2-pyridine N-oxide)-quinoxaline," pyridine carboxylates, l-(2 -pyridyl)-2-azonaphthol, and l-(2 -benzothiazolyl)-2-azonaphthol have also been reported. 

Reactions of c -[Ru(bpy)2Cl2] with ligands (86) or (87) (X = CH2) in EtOH(aq) lead to [Ru(bpy)2(86)] + and [Ru(bpy)2(87, X = CH2)] respectively. When X = 0 in ligand (87), the product is the pyridine carboxylate complex [Ru(bpy)2(pyC02)], the structure of which is confirmed by X-ray crystallography. Complexes of the type [Ru(bpy)2L] " in which L represents a series of mono- and dihydrazones have been prepared and characterized by spectroscopic methods (including variable temperature H NMR) and a structure determination for L = biacetyl di(phenylhydrazone). When L is 2-acetylpyridine hydrazone or 2-acetylpyridine phenylhydrazone, [Ru(bpy)2L] + shows an emission, but none is observed for the dihydrazone complexes. The pyrazoline complex [Ru(bpy)2L] (L = 5-(4-nitrophenyl)-l-phenyl-3-(2-pyridyl)-2-pyrazoline) can be isolated in two diastereoisomeric forms. At 298 K, these exhibit similar MLCT absorptions, but at 77 K, their emission maxima and lifetimes are significantly different. ... 

According to the figure below, reacting 2,6-dimethylanilme with the acid chloride of pyridine-carboxylic acid first gives the 2,6-xylidide of a-picoUnic acid (2.2.4). Then the aromatic pyridine ring is reduced to piperidine by hydrogen in the presence of a platinum on carbon catalyst. 

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