Ribonic acid

A similar series of reactions applied to L-sorbose (once a rare sugar but now easily obtained from sorbitol by bacterial oxidation16) gives rise to 2-keto-L-gulonic acid.4 The method is not confined to keto-hexoses and has been employed in the preparation from L-erythropentulose (XXXI) of the 2-keto-L-ribonic acid (XXXV) which undergoes immediate transformation to the corresponding L-erythroascorbic acid (XXXVI).16... 

The extension of the salt-acid,27 phenylhydrazide,28 and amide rules29 to the derivatives of the 2-(hydroxymethyl) sugars by Schmidt and Weber-Molster30 indicated that the configuration of C2 in hamamelonic acid is the same as that of D-ribonic acid. Finally, the d-ribo configuration of the sugar was established by the synthesis of hamamelonic acid and its C2 epimer from D-ery/ftro-pentulose31 by the cyanohydrin reaction of Fischer and Kiliani. 

The pyrimidine nucleosides from ribonucleic acid (uridine and cytidine) present a more formidable problem, since they cannot be hydrolyzed by dilute mineral acid, and the use of concentrated acid usually destroys the sugar moiety. It was observed, however, that simultaneous bromination, hydrolysis, and oxidation of cytidine (with bromine-hydrobromic acid) yields 5-bromouracil plus D-ribonic acid.60 Since cytidine can be deaminated to uridine with nitrous acid,61 both of these pyrimidine nucleosides must... 

The cyclohexenone 16 would arise from the enol silyl ether containing the dimethyl acetal 15, which originates from one-step opening of the phenylsulfonylmethyl furanose 14. Thus, the starting material simplifies to commercially available D-ribonic acid y-lactone. 

Ribose may be identified through the benzimidazole from ribonic acid, 2-(D-n6o-tetrahydroxybutyl)benzimidazole52 53 54 and its picrate and hydrochloride. However, caution must be used at two points in this procedure. In the first place, the customary oxidation of ribose with alkaline hypoiodite produces both ribonic and arabonic acids, the latter being formed by the alkali-induced epimerization of the former. While this epimerization may be avoided by using a buffered oxidizing mixture such as bromine-barium benzoate,65 there is, in the second place, further risk of epimerization during the condensation of the aldonic acid with o-phenylenediamine, particularly if there is insufficient acid present.9 10-11... 

The oxidation of D-ribose to D-ribonic acid was first carried out by Levene and Jacobs78 who used bromine in an aqueous suspension of barium carbonate as an oxidant more recent work bearing upon the oxidation of ribose to ribonic acid with alkaline hypoiodite63 and with bromine-barium benzoate has already been mentioned. More vigorous oxidation gives n o-trihydroxyglutaric acid.3... 

The 3- and 5-phosphates of D-ribose have both been obtained through the hydrolysis of naturally occurring ribosides. In 1908 Levene and Jacobs122 subjected the barium salt of inosinic acid to acid hydrolysis and obtained a pentose phosphate as its barium salt. Shortly thereafter the same authors78 showed that, under the conditions which normally convert a pentose to a pentaric acid, this phosphate was oxidized only to a phosphorylated D-ribonic acid and it was evident, therefore, that... 

Some chemical fragments of DNA and RNA can also be found in meteorites (Tables 5.1 and 5.2). For example, some meteorites have been reported to contain small amounts of adenine, one of the nucleobases found in RNA and DNA. The current view is that the Murchison meteorite contained adenine, guanine, their hydrolysis products hypoxanthine and xanthine, and uracil. The reported concentration of all those substances, however, is low, about 1.3 ppm. The Murchison and other meteorites may also contain ribitol and ribonic acid, the reduced and oxidized forms of ribose, respectively, but ribose itself has not been found.6... 

C5H7N04 acrylamide glycolic acid, anhydrous 6737-24-2 25.00 1.2996 2 4960 C5H805 D(- -)-ribonic acid g-lactone 5336-08-3 25.00 1.2601 2... 

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