Nicotinic acid, hydrogenation

What are the concentrations of nicotinic acid, hydrogen ion, and nicotinate ion in a solntion of O.IOM nicotinic acid, HC6H4NO2, at 25°C What is the pH of the solntion What is the degree of ionization of nicotinic acid The acid-ionization constant, K, was determined in the previous example to be 1.4 X 10. ... 

Trifluoromethylpyridine can be prepared ia 25—65% yield from nicotinic acid and sulfur tetrafluoride (434,439). An alternative method is the passage of chlorine iato a mixture of ( -picoline and hydrogen fluoride ia an autoclave (190°C, 3 MPa) (440). 4-Trifluoromethylpyridine is prepared ia 57% yield from isonicotinic acid and sulfur tetrafluoride. 

Condensation of ethyl acetoacetate with phenyl hydrazine gives the pyrazolone, 58. Methylation by means of methyl iodide affords the prototype of this series, antipyrine (59). Reaction of that compound with nitrous acid gives the product of substitution at the only available position, the nitroso derivative (60) reduction affords another antiinflammatory agent, aminopyrine (61). Reductive alkylation of 61 with acetone in the presence of hydrogen and platinum gives isopyrine (62). Acylation of 61 with the acid chloride from nicotinic acid affords nifenazone (63). Acylation of 61 with 2-chloropropionyl chloride gives the amide, 64 displacement of the halogen with dimethylamine leads to aminopropylon (65). ... 

Nicotinic acid derivatives occur in biologic materials as the free acid, as nicotinamide, and in two coenzymatic forms nicotinamide adenine dinucleotide (NAD), and nicotinamide adenine dinucleotide phosphate (NADP). These coenzymes act in series with flavoprotein enzymes and, like them, are hydrogen acceptors or, when reduced, donors. Several plants and bacteria use a metabolic pathway for the formation of nicotinic acid that is different from the tryptophan pathway used by animals and man (B39). 

The antagonists of nicotinic acid are 6-aminonicotinamide and, less potent, 3-acetylpyridine and pyridine-3-sulfonic acid (H15, J4). Nicotinamide has also been reported to be effective in experimental cancer (S3). It is supposedly converted to nonphysiological nucleotide analogs of NAD and NADP because it becomes attached to available apo-dehydrogenase the resulting enzyme cannot function in hydrogen and electron-transfer reactions essential to normal cellular metabolism (D7). 

Hydroxycynnclidine (14.1.17) is synthesized from the methyl ester of wo-nicotinic acid, which is reacted with the ethyl ester of bromoacetic acid to give the piridinium salt (14.1.14). This is rednced by hydrogen nsing a platinnm catalyst, giving 1-carbethoxymethyl-... 

Nicotinic acid forms some piperidine as well as nipecotic acid when it is reduced with hydrogen over ruthenium, rhodium or platinum oxide presumably decarboxylation involves the intermediate 3,6-dihydro compound (265), which behaves like a j8-keto acid (Scheme 189). 

Nicotinamide (8.45) and nicotinic acid (8.46, niacin)—which have also been referred to as vitamin B3 or B5—are simple pyridine-3-carboxylic acid derivatives occurring in liver, yeast, and meat. In the form of nicotinamide-adenine dinucleotide (NAD" ) or its phosphorylated form (NADP+), nicotinamide is the most important electron carrier in intermediary metabolism. Unlike FAD, it adds a hydride ion (i.e., one pair of electrons and one hydrogen) only. 

Jellinek and Gordon propose a mechanism in which a rapid protonation of the amide nitrogen is followed by a slow attack by a hydroxonium ion to give nicotinic acid, an ammonium ion and a hydrogen ion. Such a mechanism accords with their observation that the experimental rate coefficients increase more rapidly than would be the case if they were proportional to the first... 

Two vitamins, nicotinamide and pyridoxine (vitamin B6), are pyridine derivatives. Nicotinamide participates in two coenzymes, coenzyme I (65 R = H) which is known variously as nicotinamide adenine dinucleotide (NAD) or diphosphopyridine nucleotide (DPN), and coenzyme II (65 R = P03H2) also called triphosphopyridine nucleotide (TPN) or nicotinamide adenine dinucleotide phosphate (NADP). These are involved in many oxidation-reduction processes, the quaternized pyridine system acting as a hydrogen acceptor and hydrogen donor. Deficiency of nicotinamide causes pellagra, a disease associated with an inadequately supplemented maize diet. Nicotinic acid (niacin) and its amide are... 

Nicotinic acid can be converted to nicotinamide in Ihe body and, in this form, is found as a component of two oxidation-reduction coenzymes (Fig. 2) nh olimiinide adenine dinuclentide (NAD) and nicotinamide adenine dinucleolide phosphine NADP). The nicotinamide portion of the coenzyme iransfers hydrogens by alternating between an oxidized quaternary nitrogen and a reduced tertiary nitrogen. See Fig. 3. 

Figure6.32 Structure of the cationic cluster complex [Eu4(p.3-0H)4(nic)6(H20)8]2 + (nic= nicoti-nate). Hydrogen atoms are removed for clarity [57]. (Redrawn from X. Kong et al., Hydrolytic synthesis and structural characterization of lanthanide hydroxide clusters supported by nicotinic acid, Inorganic Chemistry, 48, 3268-3273, 2009.)...

SYNS (S)-3-(l-METHYL-2-P RROLIDINYL-PYRIDINE (R)-(R,R))-2,3-DIHYDROXYBUTANEDIOATE (1 2) NICOTINE ACID TARTRATE NICOTINE BITARTRATE NICOTINE HYDROGEN TARTRATE (-)-NICOTINE HYDROGEN TARTRATE NICOTINE... 

A new route to prepare nicotinic acid starts from 2-methylglutaronitrile, a major side-product in the adiponitrile process and, as such, a readily available starting-material. It is easily hydrogenated to 2-methylpentanediamine, which is then condensed to methyl piperidine and dehydrogenated to 3-picoline. The gas-phase ammoxidation of the latter to cyanopyridine is followed by hydrolysis to either nicotinamide or nicotinic acid (Scheme 20.4). The cyanopyridine route for the production of nicotinic acid has the advantage of a significantly better selectivity with respect to the direct oxidation route from 3-picoline owing to the easy decar-... 

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