Degradation alkaline

Alkaline Degradation. At high pH, sucrose is relatively stable however, prolonged exposure to strong alkaU and heat converts sucrose to a mixture of organic acids (mainly lactate), ketones, and cycHc condensation products. The mechanism of alkaline degradation is uncertain however, initial formation of glucose and fructose apparendy does not occur (31). In aqueous solutions, sucrose is most stable at —pH 9.0. 

Chrysin (17) was the first flavone to be isolated in a pure form, and its stmcture was elucidated by identification of its alkaline degradation products (72—74). The stmcture was confirmed by synthesis (75,76). The same procedures were used to estabflsh the stmcture of other flavones and in so doing the foundation of flavone chemistry was laid (77). 

Alkaline degradation was used to determine the stmcture of pelargonidin [134-04-3] cyanidin [528-58-5] and delphenidin [528-53-0] by treating each of them with concentrated potassium hydroxide at 140—150°C (89). Each of them produced phloroglucinol (27) and the corresponding phenoHc ben2oic acid ... 

Clemo, Perkin and Robinson have recorded the production of indole and carbazole when methylstrychnine is heated with caustic potash, and more recently a series of simple bases has been obtained by the alkaline degradation of strychnine. Of these, tryptamine (j8-3-indolylethylamine), 3-ethylindole, indole and 4-methyl-3-ethylpyridine have been identified, and a fifth purified as the picrate, CjoHuN. CgH30,N3, m.p. 192°, has been described by Clemo and by Siddiqui, but has not been identified. Tryptamine is to be expected as the Robinson formula includes the tryptamine skeleton. ... 

Although there has been interest recently in phthalazine quaternary salts, no work has been reported on the position of quatemization since the classic studies of Gabriel and co-workers. For the sake of completeness, it may be noted that 4-methylphthalazine (59) and methyl iodide gave the salt 60 alkaline degradation of 60 gave a... 

Trimethyloxazolo[4,5-/]quinoline prepared from 2,7-dimethyl-6-methoxyquinoline using nitration, demethylation (or reversed), reduction, and cy-clization with acetic anhydride confirms unambigously the structure of the aromatic part of the antibiotic X-537A after nitration and alkaline degradation (71JOC3621). 

The Nucleotide Sequence in Deoxypentosenucleic Acids. Part II. The Alkaline Degradation of Calf-thymus aldehydo Apurinic Acid Di(carboxymethyl) Dithioacetal, A. S. Jones, D. S. Letham, and M. Stacey, J. Chem. Soc., (1956) 2579-2583. 

Carbohydrate Components of Antibiotics. Part II. Alkaline Degradation of Mycaminose and Synthesis of 3,6-Dideoxy-3-dimethylammo-L-altrose and Derivatives Therefrom, A. B. Foster, J. Lehmann, and M. Stacey, /. Chem. Soc., (1962) 1396-1401. 

Richards et al.23-24 proposed that the alkaline degradation reaction proceeds via a slow, rate-determining SJCB mechanism, where the substitution at the C-l of the D-glucose moiety by oxyanions derived from l -OH or 3 -OH resulted in 1- or 3-O-P-D-glucopyranosyl-D-fructose (see Fig. 4) the mechanism implies that T - time thyl sucrose is degraded via 3 -displacement and 3 -(3-methylsucrose via the 1 -displacement. The 1- or 3-<3-[3-D-glucopyranosyl-D-fructose intermediates are then... 

Fig. 9.—Reaction model for alkaline degradation of reducing sugars.

Because alkali degradation of sucrose does not result in inversion products, in slightly alkaline solution (pH < 8.5), the loss of sucrose to invert sugar (glucose + fructose) is a consequence of the acid hydrolysis mechanism, which provides D-glucose and D-fructose for further alkaline degradation. 

Mills depiction, cyclic monosaccharides, 63 Monosaccharides, see also Aldoses acid degradation, 457-459 alkaline degradation, 449-455 mechanisms, 451... 

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