3- Pyridine carboxylic acid

Pyridine-3-carboxylic acid (nicotinic acid) (CHON) (Values on 76BC,79JAa 

Pyridine-4-carboxylic acid (isonicotinic acid) (C.H 0 (H values 76BC 

3-Hydroxy-5-hydroxymethy1-2-methylpyridine-4-carboxylic acid 79FL 

3-Hydroxy-2-methylpyridine-4,5-dicarboxylic acid (2-methyl-3- 79FL 

Pyridine-2,3-dicarboxylic acid (quinolinic acid) (C H O.N) (Values on 73CB,78BPG,78SJ, Vol.l, p.375) 79BPG,79S,79SJa, 

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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 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). 

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.

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]. 

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. 

The first inhibitors of flavin-dependent MAO that were developed for clinical use were hydrazines and hydrazides. The chance discovery that the antitubercular drug, 4-pyridine carboxylic acid hydrazide (isoniazid, 40), was also a potent MAO inhibitor led to the development of the related drug, iproniazid (41), used for the treatment of depressive illness. Although this compound demonstrated remarkable antidepressant action, its clinical value was seriously compromised by side effects [19]. 

D. E. Peters Dr. Taube and Dr. Gould have presented evidence for electron transfer at a nitrogen site (5). Using pentaamminecobalt(III) complexes of various pyridine carboxylic acids these workers found two paths in the rate expression which they call the acidic and basic paths. For the alkylpyridinium complexes, namely the iV-methyl derivatives, only one term in the rate was found. 

Aminonicotinic or Amino- pyridine carboxylic Acids(Aminonicotinsaure or Amino pytidin carbons dure in Ger),HaN-(CjNH,) COOH. Aminonicotinic acids are aminopyridinecar-boxylic acids in which the carboxyl group is attached to position 3(if it is attached to position 2 the compd is called ami no pi colin ic acid). Four isomers of aminonicotinic acid with the amino groups in 2,4,5 or 6 positions are known. There is also an isonicotinic acid in which the carboxyl group is in position 4 and the amino group in position 3 (See also Aminopicolinic Acid)... 

Other reported chromium(III) complexes containing py and related ligands are listed in Table 58. Complexes of 2-pyridylmethylamine are dealt with in Section 35.4.2.3 and of pyridine carboxylic acids in Section 35.4.8. 

Pyridine and quinoline /V-oxides react with phosphorus oxychloride or sulfuryl chloride to form mixtures of the corresponding a- and y-chloropyridines. The reaction sequence involves first formation of a nucleophilic complex (e.g. 270), then attack of chloride ions on this, followed by rearomatization (see also Section 3.2.3.12.5) involving the loss of the /V-oxide oxygen. Treatment of pyridazine 1-oxides with phosphorus oxychloride also results in an a-chlorination with respect to the /V-oxide groups with simultaneous deoxygenation. If the a-position is blocked substitution occurs at the y-position. Thionyl chloride chlorinates the nucleus of certain pyridine carboxylic acids, e.g. picolinic acid — (271), probably by a similar mechanism. 

The involvement of zinc in nicotinamide-based hydride-transfer reactions has led to numerous studies of Group IIB complexes of pyridine carboxylic acid derivatives. Cadmium complexes of 2-pyridinecarboxylic acid, 5 3-pyridinecarboxylic add497 and 3-pyridinecarboxamide498 have been reported. The crystal structure of [Cd(HC02)2L2(H20)2] (L = 3-pyridinecarboxamide) has also been described the metal is in an octahedral environment in which the amide acts as a monodentate N donor.498... 

D-Arg h2N.cooh L-NyNH2 NH Isonicotinic acid Cl XOOH 3-Benzoyl-2-pyridine carboxylic acid o CP COOH ... 

The tunneling spectrum of a doped junction can be seen in Fig. 4. In this case we have an Al-A10x-4-pyridine-carboxylic acid-Ag sample, with approximately monolayer coverage, run at 1.4 K. Fig. 4a shows the modulation ( first harmonic ) voltage Vw across the junction as a function of applied bias. Since the modulation current Iu is kept constant, Vu is proportional to the dynamic resistance of the sample. The second harmonic voltage V2U ( Fig. 4b ), proportional to d V/dl, shows the vibrational spectrum of the absorbed molecules. As we shall see below, a quantity which is more closely related to the density of vibrational oscillator strengths D(r) is d I/dV. We show in Fig.4c the quantity... 

The vibrational spectrum of 4-pyridine-carboxylic acid on alumina in Fig. 4d is equivalent to an infrared or Raman spectrum and can provide a great deal of information about the structure and bonding characteristics of the molecular layer on the oxide surface. For example, the absence of the characteristic > q mode at 1680 cm 1 and the presence of the symmetric and anti-symmetric O-C-O stretching frequencies at 1380 and 1550 cm indicate that 4-pyridine-carboxylic acid loses a proton and bonds to the aluminum oxide as a carboxylate ion. 

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