Otsuji, Yoshio; Koda, Yoshiki; Kubo, Masaru; Furukawa, Masaaki; Imoto, Eiji published the artcile< Reactivities of the heterocyclic compounds. VI. Application of the Hammett equation to pyridine compounds>, Product Details of C19H34O2, the main research area is .
5-Ethylpyridine-2-carboxylic acid (I) (12 g.) dissolved in 100 ml. AcOH and 10 g. H2SO4, 11 g. CrO3 added at 15°, and the product purified through the Cu salt gave 42% 5-acetylpyridine-2-carboxylic acid (II), m. 179-80°. Et ester of II was prepared similarly in 72% yield, b5 143-5°; 2,4-dinitrophenylhydrazone m. 226°. H2O2 (30%) (20 ml.) added to 50 ml. H2SO4 at 0-5° and 5 g. 2-aminopyridine-5-carboxylic acid in 50 ml. H2SO4 added gave after 2 days 63% 2-nitropyridine-5-carboxylic acid (III), m. 187-8°. Compounds used in this study were picolinic acid (IV), I, 5-iodo-2-carboxylic acid, II, nicotinic acid, and their Et esters, 2-methylpyridine-5-carboxylic acid, 2-chloropyridine-5-carboxylic acid, and III. The hydrolysis rates of Et 5-substituted pyridine-2-carboxylates at 25° were studied and found to be linear with Hammett σp values except for Et ester of II. Deviation of the Ac group was attributed to enolization and ionization when the Ac group was attached to an electron-drawing group. ρ was obtained as 1.56 and the small ρ was attributed to the electronegativity of N. Hydrolysis rate of 3 Et pyridinecarboxylates was in good agreement with the π-electron distribution. Dissociation constants of 5-substituted pyridine-2-carboxylic acids (V) and 2-substituted pyridine-5-carboxylic acids (VI) were obtained. V gave always higher pKa than VI, indicating that IV and its derivatives existed as zwitterions. The Hammett equation was also applicable to the dissociation and ρ was obtained as 2.31 and 1.60 for V and VI, resp., while substituted benzoic acids had 1.60 under the similar conditions. Greater ρ than that expected from ester hydrolysis must be attributed to the existence of a zwitterion of which H+ on N influences the σ values. From the ρ value the ratio of zwitterion in V was estimated as 30% in 50% EtOH. The σ value was corrected by use of the above zwitterion content and better linear correlation was obtained.
Nippon Kagaku Zasshi published new progress about Activation energy. 112-63-0 belongs to class esters-buliding-blocks, and the molecular formula is C19H34O2, Product Details of C19H34O2.
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