2-Pyridinecarboxylic acid, reaction with

Soluble, amphoteric ion exchange resins have been prepared by reaction of pyridinecarb-oxylic acids, especially 2-pyridinecarboxylic acid (215), with chloromethylated poly(styrene) (192 Scheme 104) (76IZV33). Resin (216) exhibited pronounced selectivity for Cu2+ and Ni2+ ions, and also, at pH 1.65, for the U022 ion. 

Pyridinecarboxylic acid with [Ru3(CO)i2l in toluene forms the chelate mononuclear complex 249 (99JOM(585)246). 2-Pyridinecarboxylic acid (HL) with [Ru(CO)2Cl2]n and further with tetraethylammonium perchlorate or tetra-n-butylammonium perchlorate yields (R4 N)LRu( 2 (N,0)-L)(C0)2C12] (R = Et, m-Bu) (03JOM(665)107). The reaction of the same ligand with [Ru(bipy)(CO)2Cl2] and silver nitrate in water and... 

Complexation with pyridine or 4-pyridinecarboxylic acid Reaction of CN" with Pd-dimethylglyoximate complex that releases dimethylglyoxime, isolated as the Ni derivative... 

In a similar manner, reaction of a mixture of triethylamine and benhydrazide or 4-pyridinecarboxylic acid hydrazide with PhPOCl2, PhNHPOClz and POCI3, gave spirophosphoranes (lOa-e) (Fig. 1). All of these structural rearrangements were supported by X-Ray analysis as well as NMR and IR experiments. 

In a similar manner, 2,4,6-trisubstituted 3-pyridinecarboxylic acid esters have been prepared using a mixture of a, 3-ketoesters, propargylic alcohols, ammonium acetate and Mn02. The reaction proceeds by oxidation of the propargylic alcohol to the corresponding ketone, which reacts with the enamine being formed from the like loos lor and ammonium acetate. For this domino process, normal heating at 70 °C was used. 

Oxidation of pyridinecarboxylic acids.1 Reaction of a pyridinecarboxylic acid or the ester with 10% F2 in N2 results in oxidation to the corresponding 2-pyridone in 50-75% yield. An N-fluoropyridinium salt is probably an intermediate. 

Preparative Methods the ligand can be obtained through reaction of 2 equiv of 2-pyridinecarboxylic acid with (1R,2R)-1,2-diaminocyclohexane using Mukaiyama s reagent or via the acid chloride. ... 

Pyridinecarboxylates (99) give photosubstitution products on irradiation with alcohols the products have alkyl or alkoxy substituents, and the product ratios depend on the absence or presence of added mineral acid. A mechanistic rationalization is presented, based on the involvement of a triplet excited state located largely on C==0 or a triplet located largely on the ring (for alkylation), and a singlet excited state (for alkoxylation). The reaction of pyridinecarboxylic acids in the presence of transition-metal ions is reported pyridine-2-carboxylic acid gives pyridine and 2,2 -bipyridyl with iron(iii), but 2-pyridone with copper(ii) pyridine-3-carboxylic acid (100) with Fe gives a dehydrodimer without decarboxylation. 

Numerous examples of acylation at C-3 have appeared. Reactions have been carried out with acid anhydrides <92CPB631>, acid halides <86CPB2833, 85MI 8l0-0i>, aryl sulfonyl chlorides <93JMC1425> and under Vilsmeier-Haack conditions <93H(35)915>. Yields were generally better, and the required conditions milder, when C-2 carried an electron-releasing group. No reaction occurred when ethyl 2-pyrazolo[l,5-a]pyridinecarboxylate was heated with benzoyl chloride <93H(35)915>. 

Another example of the Schmidt reaction was reported isomeric pyridinecarboxylic acids were treated with sodium azide in sulfuric acid at elevated temperatures to give 3-aminopyridine (69% yield) and 2- and 4-aminopyridines in less than 30% yield. " ... 

A reaction deals with the preparation of 4-halogenated pyridinecarboxylic acids (X-240) from 4-nitronicotinic acid-1-oxide (X-239) by explosive interaction with phosphorous trichloride or tribromide The requisite formation of nitrosyl chloride is not recorded. The 4-iodoacid (X-240, X = I) was prepared from the chloro-acid with hydrogen iodide. The authors also report... 

A new method for the conversion of an oxazoline into its parent carboxylic acid has been reported which involves treatment with NaOCl followed by hydrolysis with mild base yields between 60 and 93% are obtained for eight examples. 3-Acyl-pyridines (59) undergo a Minisci reaction to give 6-substituted products (60) in 20—82% yield Wolff-Kishner reduction then generates the pyridinecarboxylic acids (61) (Scheme 29). ... 

Oxidation at Benzylic Position. Nitric acid oxidizes many aromatic alkyl substituents to the carboxylic acid group. Thus toluene is oxidized to benzoic acid in 85-90% yield. Oxidation of ethylbenzene with 15% nitric acid also gives benzoic acid in 80% yield. The reaction is general and has also been applied to the oxidation of pyridine derivatives. When 4-methylpyridine is treated with 10% nitric acid in phosphoric acid at elevated temperature and pressure, 4-pyridinecarboxylic acid is obtained in 93% yield. The reaction of p-isopropyltoluene can be controlled to give the partially oxidized product, p-methylbenzoic acid, in 56-59% yield. Additional examples of selective benzylic oxidations are shown in eqs 13 and... 

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