Araboascorbic acid

There is good evidence for the presence of a five-membered ring in D-araboascorbic acid (XXXIX). This analog of L-ascorbic acid, prepared by method 2 (page 87) from methyl 2-keto-D-gluconate shows the same chemical properties and the same absorption characteristics as L-ascorbic acid. Titration of XXXIX with diazomethane affords, as in the case of L-ascorbic acid, a 3-methyl derivative LXXXII which upon further action with diazomethane gives rise to the 2,3-dimethyl-D-arabo-ascorbic acid (LXXXIII)  

This 2,3-dimethyl-D-araboascorbic acid (LXXXIII) behaves in precisely the same way as 2,3-dimethyl-L-ascorbic acid when treated with alkaline reagents. Saturation of the double bond between C2 and C3 by ring closure between C6 and C3 and transference of a proton to C2 takes place, giving LXXXVI. 

This saturation of a double bond is analogous to the isomerism effected in the steroid aglycons, for when the latter are treated with alkali the system LXXXVII is transformed into LXXXVIII.  

In this connection there should also be mentioned the formation of carlic acid (XC) from LXXXIX (formed from D-glucose as a metabolic product of the mold Penicillium charlesii G. Smith ). 

The analogy between D-araboascorbic acid and L-ascorbic acid can be traced still further by the observation that treatment of the dimethyl-iso-D-araboascorbic acid (LXXXVI) with methyl alcoholic hydrogen chloride produces 2-methyl-D-araboascorbic acid (XCI). 

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As a result of having two chiral centers, four stereoisomers of ascorbic acid are possible (Table 1) (Fig. 2). Besides L-ascorbic acid (Activity = 1), only D-araboascorbic acid (erythorbic acid (9)) shows vitamin C activity (Activity = 0.025-0.05). The L-ascorbic acid stmcture (1) in solution and the soHd state are almost identical. Ascorbic acid crystallizes in the space group P2 with four molecules in the unit cell. The crystal data are summarized in Table 2. 

D-Araboascorbic acid (erythorbic acid) (10) L-Araboascorbic acid... 

In apphcations where vitamin C activity is unimportant, often D-erythorbic acid (D-araboascorbic acid) can also be used, providing the same antioxidant and reducing properties as L-ascorbic acid. 

Ketogluconic acid Pseudomonas sp. Intermediate for D-araboascorbic acid... 

D-Xyloascorbic acid (D-Ascorbic acid) (XX)2-3 L-Araboascorbic acid (LXXII)2 3 ... 

From the method of preparation of the analogs of L-ascorbic acid and from their close resemblance to L-ascorbic acid in respect to chemical properties and absorption data, all these derivatives were assumed by analogy to have the characteristic unsaturated five-membered ring system already proved to be present in L-ascorbic acid. In two cases, namely that of D-gluco- (XV) and D-araboascorbic acid (XXXIX) the assumption has proved correct. 

Methyl-D- araboascorbic acid Tr=C(C H,),— 3-Methyl-n-eryth-ronic acid... 

Anisamide, m54 Anisic acids, m57, m58, m59 Anidisines, m48, m49, m50 Anisole, m55 p-Anisoyl chloride, m60 p-Anisyl alcohol, m61 Anthranilamide, all2 Anthranilic acid, all8 Araboascorbic acid, i61 APDC, p282 Arsanilic acids, all3... 

Anisic Alcohol, 456 Anisic Aldehyde, 524 Anisole, 456, 606 Anisyl Acetate, 456, 568, 606 Anisyl Acetone, 524 Anisyl Alcohol, 456, 606 Anisyl Formate, 456, 607 Annatto Extracts, 31 Anthrone TS, (Sl)114 Antimony Trichloride TS, 850, 851 APDC Extraction Method, 766 APM, 35, (S 1)4 APM-Ace, (S3)5 APO, 32 Apocarotenal, 32 p-Apo-8 -Carotenal, 32 Apparatus for Tests and Assays, 4, 727 D-Araboascorbic Acid, 134 L-Arginine, 32, (S3)5 l-Arginine Monohydrochloride, 33 Arsenic Specification, Requirements for Keeping, xv... 

SYN d-ARABOASCORBIC ACID SAFETY PROFILE When heated to decomposition it emits acrid smoke and irritating fumes. 

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