Gulonic acids

A Chinese pubHcation (47) with 17 references reviews the use of genetically engineered microorganisms for the production of L-ascorbic acid and its precursor, 2-KGA (49). For example, a 2-keto-L-gulonic acid fermentation process from sorbose has been pubUshed with reported yields over 80% (50). 

Diketo-gluconic acid (24) 2-Keto-L-gulonic acid (2-KGA)... 

Diacetone-L-sorbose (DAS) is oxidized at elevated temperatures in dilute sodium hydroxide in the presence of a catalyst (nickel chloride for bleach or palladium on carbon for air) or by electrolytic methods. After completion of the reaction, the mixture is worked up by acidification to 2,3 4,6-bis-0-isoptopyhdene-2-oxo-L-gulonic acid (2,3 4,6-diacetone-2-keto-L-gulonic acid) (DAG), which is isolated through filtration, washing, and drying. With sodium hypochlorite/nickel chloride, the reported DAG yields ate >90% (65). The oxidation with air has been reported, and a practical process was developed with palladium—carbon or platinum—carbon as catalyst (66,67). The electrolytic oxidation with nickel salts as the catalyst has also... 

Keto-L-gulonic acid [526-98-7] M 194.1, m 171 . Crystd from water and washed with acetone. 

Concentration in this manner allows sufficient time for the gulonic acid to be converted to the lactone in the presence of a trace of hydrochloric acid. The checkers observed also that an easily crystallized lactone was always obtained if concentration in mcuo were employed. 

DAG (-)-2,3 4,6-di-0-isopropylidene-2-keto-L-gulonic acid hydrate [L-a /Zo-2-hexulosonic acid, bis-O-(l-methylethylidine)-]... 

A. fi(-)-a-(l-Naphthyl)ethylamine. A mixture of 58.44 g. (0.20 mole) of (-)-2,3 4,6-di-0-isopropylidene-2-keto-L-gulonic acid hydrate [(-)-DAG] (Note 1) and 1.7 1. of acetone (Note 2) is placed in a 3-1. Erlenmeyer flask. A boiling chip is added, and the mixture is heated to a gentle boil. To the resulting hot solution is added cautiously but rapidly, over a 1 minute period, 34.24 g. (0.20 mole) of racemic y.- 1 -naphthyl)et hylamine (Note 3) in 100 ml. of acetone. The mixture is allowed to stand at room temperature for approximately 4 hours. The (-)-amine (-)-DAG salt is filtered with suction, washed with 100 ml. of acetone, and dried in a vacuum oven at 60° to constant weight. The yield of the crude (-)-amine (-)DAG salt is 73-76 g., m.p. 205-207° (decomp.) (Note 4), [a]p —14.2° (c 1.01%, methanol). For crystallization, the crude salt and 4.2 1. of ethanol (Note 5) are placed in a 5-1. round-bottomed flask fitted with a reflux condenser and a mechanical stirrer. The mixture is stirred and heated at reflux... 

CjjHjf.NsO 25146-54-7) see Fludarabine phosphate diacetone-2-oxo-L-gulonic acid (C 2H],07 18467-77-1) see Ascorbic acid diacetone-L-sorbose... 

An application to n-xylose (LXII) of the Fischer synthesis of 2-amino hexonic acids from pentoses would lead theoretically to a mixture of 2-amino-D-gulonic acid (LXIII) and 2-amino-D-idonic acid (LXIV). 

The 2-keto acids such as 2-keto-D-galactonic acid (XXIV) can be derived from the corresponding osone (XXIII) by oxidation with bromine.10 Oxidation of L-gulosone by the same method has provided 2-keto-L-gulonic acid. The success of this oxidation depends to a large extent upon the purity of the osone subjected to oxidation and this, as previously stated, is controlled by the purity of the osazone. 

Oxidation of Aldonic Acids. Preferential oxidation of the secondary alcoholic group adjacent to the carboxyl group in sugar acids or aldonic acids such as L-gulonic acid (XXV) can be carried out with chromic acid12 or with chlorates in the presence of a vanadium catalyst.13... 

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... 

D-Glucose — D-glucuronic acid — L-gulonic acid — L-ascorbic acid D-Galactose — D-galacturonic acid — L-galactonic acid — L-ascorbic acid... 

N-methyl-l,2-diphenylethylamine, 34, 64 tetraphenylarsonium chloride hydrochloride, 30, 97 Guanidine, 32, 96 Guanidine hydrochloride, 32, 45 Guanylthiourea, 35, 69 D-GuLONIC ACID, y-LACTONE, 36, 38... 

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