Pyridine 2-carboxylic acid, from

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). 

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. 

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.

Cobalt(II) salts are effective catalysts for the oxidation of 1,2-glycols with molecular oxygen in aprotic polar solvents such as pyridine, 4-cyanopyridine, benzonitrile, DMF, anisole, chlorobenzene and sulfolane. Water, primary alcohols, fatty acids and nitrobenzene are not suitable as solvents. Aldehydic products are further oxidized under the reaction conditions. Thus, the oxidative fission of rram-cyclo-hexane-l,2-diol gives a mixture of aldehydes and acids. However, the method is of value in the preparation of carboxylic acids from vicinal diols on an industrial scale for example, decane-1,2-diol is cleaved by oxygen, catalyzed by cobalt(II) laurate, to produce nonanoic acid in 70% yield. ... 

Wt % was obtained from each benzene-ether extract. Determination was made from the gas chromatograms of their methyl esters. Thiophene- and pyridine carboxylic acids for Samples 2-6, and pyridine tricarboxylic acids for Sample 1. 

The Pesticide Manual describes 5 pyridine carboxylic acid derivatives, 3 benzoic acids, and 10 aryloxyalkanoic acids in current use as herbicides. 2,4,5-T seems to be banned worldwide and is not included in the current issue (Tomlin, 2000) but is described in earlier issues (e.g., Worthing, 1979). It was first registered in 1948 by Amchem Products, Inc., Pennsylvania, and the Dow Chemical Company, and was mainly used to control shrubs and trees, for example, in forests and along railways. Although the content of dioxin was eventually controlled, with a limit of <0.05 mg/kg in the preparation, it was banned soon after the termination of its use in Vietnam. Other products with 2,4,5-trichlorophenol were also banned or restricted after the Seveso accident (see Hay, 1978a, 1978b). 2,4-D is also produced from a chlo-rophenol and may contain dioxins, but of the much less toxic congeners. It... 

Beilstein Handbook Reference) Arecaidine Areoaine BRN 0112366 Methylguvacine N-Methylguvacine Nicotinic acid, 1,2,5,6-tetrahydro-1-methyl- NSC 76017 3-Pyridinecarboxylic acid, 1,2,5,6-tetrahydro-1-methyl- 1,2,6,6-Tetrahydro-1-methylnioo-tinic acid 1,2,5,6-Tetrahydro-1-methyl-3-pyridine-carboxylic acid. Isolated from betel nuts. Plates or tablets, mp = 232° (dec)insoluble in EtOH, Et20, CeHe, CHCI3, very soluble in H2O. 

Homologs of pyridine, quinoline, thiophen, and various other heterocycles can be oxidized to carboxylic acids generally without destruction of the hetero ring in the pyrrole series, however, this cannot be done directly but requires intervention of an intermediate (see Fischer et al.A05). More circuitous routes are also sometimes preferable in the quinoline series for instance, in their total synthesis of hydroquinine Rabe et a/.406 obtained the 4-carboxylic acid from 6-methoxy-4-methylquinoline by oxidizing the 4-styryl derivative (obtained by reaction with benzaldehyde) instead of oxidizing the methyl compound directly. Alkyl groups at positions 2 and 4 of pyridine are more easily oxidized than those at position 3. 

The organic ligands dealt with are the aminocarboxylic acids, iminodiacetic acid and its derivatives, peptides, aniline carobyxlic acids, pyridine carboxylic acids, peptides, and several other miscellaneous ligands. The data are critically selected from the literature rather than being simply compiled. 

Phosgene pyridine Carboxylic acid chlorides from sodium carboxylates s. 17, 857 cocyc H N COONa GOGl... 

Phosgene pyridine Carboxylic acid chlorides from sodium carboxylates... 

Cyanogen bromide pyridine Carboxylic acid anhydrides from carboxylic acids... 

Adams et al. 177a) prepared the hydroxypyrroline carboxylic acid from hydroxyproline and studied its metabolic reactions. Acetone powder extracts of liver were found to contain an enzyme (A -pyrroline dehydrogenase) which oxidized this compound to 7-hydroxyglutamate, utilizing either pyridine nucleotide as a hydrogen acceptor. Support for this step,... 

Pyridine hydrochloride Carboxylic acids from carboxylic acid esters... 

---