Quinaldinic acid

Bromination of quinaldine (I) (Section V,2) with bromine in glacial acetic acid in the presence of anhydrous sodium acetate aflFords o-tribromoqulnaldlne or 2-(tribromomethyl)-quinaldine (II) hydrolysis of the latter by boiling with dilute sulphuric acid gives quinaltiinic acid (III). 

Girard s reagent T is carbohydrazidomethyltrimethylammonium chloride (I) and is prepared by the reaction of the quaternary ammonium salt formed from ethyl chloroacetate and trimethylamine with hydrazine hydrate in alco-hoUc solution  

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Quinaldinic acid. Zinc > 100 mg in a solution acidified with acetic ( ethanoic) acid to pH 3-4. Heat to boiling and add 3 per cent sodium quinaldate solution with stirring until precipitation is complete (25 per cent excess should be used). Cool to room temperature, filter and wash the precipitate with cold water and then a little ethanol. Dry at 105-110 °C and weigh as Zn(C10H6O2N)2,H2O (Section 11.50). 

A hydrogen attached to a pyridine or pyridine 1-oxide nucleus cannot be replaced directly by cyanide however, addition of cyanide to various quaternary salts constitutes an important class of reactions of synthetic importance. Before surveying these reactions in detail, the four main classes are outlined. In 1905, Reissert reported the first example, the reaction of quinoline with benzoyl chloride in aqueous potassium cyanide (Scheme 111) (05CB1603). This yielded a crystalline product, C17H12N2O, a Reissert compound (176) which afforded benzaldehyde and quinaldinic acid on acid hydrolysis (Scheme 111). Kaufmann (09CB3776) treated a 1 -methylquinolinium salt with aqueous potassium cyanide and observed 1,4-rather than 1,2-addition (Scheme 112), the Reissert-Kaufmann reaction. Reissert compounds are well known in the quinoline and isoquinoline series, but only rarely have even small yields been found in the pyridine series. On the other hand, cyanide ions add 1,4 with ease to pyridinium salts that have an electron withdrawing substituent at C-3. 

The possibility of forming a five-membered ring through N and O shown by 8-hydroxyquinoline (7) is shared by quinaldinic acid (2) which forms well defined complexes Cu(C oH6N02)2 H20 from relatively acid solutions whence the more soluble complexes of Cd and Zn can be separated. Like oxine it is unselective and reacts with very many cations so that pH and other reaction conditions must be carefully controlled. Anthranilic acid (8) is so unselective that its use is confined to the quantitative precipitation of a single cation from a solution containing only Cd, Co, Cu, Ni or Zn. 

Experiment 6.152 describes a synthesis of quinaldinic acid from quinaldine (2-methylquinoline). The method depends upon the reactive nature of the 2-methyl group in quinaldine which can readily be brominated using bromine in acetic acid. Hydrolysis of the resulting tribromo derivative by boiling with dilute sulphuric acid occurs smoothly to give the corresponding carboxylic acid in good yield. 

Experiment 6.152 QUINALDINIC ACID (Quinoline-2-carboxylic acid)... 

However, the zwitterion mechanism appears attractive for picolinic and related acids. The volumes of activation for decarboxylation of picolinic are large and positive. This is consistent with release of solvent in going to the transition state as is indicated in reaction (4) of the zwitterion mechanism. The rate data for the decarboxylation of quinaldinic acids fits attractively into the zwitterion mechanism. The ratio of rate coefficients for the decarboxylation of zwitteron ion (I) to that of quinaldinic acid (II) shows a minimum value of 57 in quinoline solvent at 145.8 The anion of quinaldinic acid shows no detectable decomposition in... 

Nicotinamide, nitrilotriacetic acid, EDTA, quinaldinic acid, imidazole, sulfanilamide, diamox, and zincon did not inhibit the oxidation of alcohol significantly in concentrations of 5 X 10 M, 0° C., 1 hour preincubation, pH 6.0 to 9.5. 

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