Diacetone sorbose

In the modern industrial manufacturing proce.ss, the reduction to d-sorbitol is accomplished either electrolytically or by catalytic hydrogenation (Ha/CuCrOa). Additionally, it has been found that the reaction of sorbose with acidified acetone at low temperature (— 5 °C) gives a greatly increased yield of the di-O-isopropylidenyl (as opposed to the 2,3-mono-O-isopropylidenyl) derivative. The oxidation of this protected sorbose (2,3 4,6-di-0-isopropylidene-L-sorbofuranose or diacetone sorbose ) to the corresponding 2,3 4,6-di-0-isopropylidene-2-... 

Diacetone sorbose to diketogluconic acid C Hoffmann-LaRoche Seiler and Robertson (1982)... 

Most current industrial vitamin C production is based on the efficient second synthesis developed by Reichstein and Grbssner in 1934 (15). Various attempts to develop a superior, more economical L-ascorbic acid process have been reported since 1934. These approaches, which have met with htde success, ate summarized in Crawford s comprehensive review (46). Currently, all chemical syntheses of vitamin C involve modifications of the Reichstein and Grbssner approach (Fig. 5). In the first step, D-glucose (4) is catalytically (Ni-catalyst) hydrogenated to D-sorbitol (20). Oxidation to L-sotbose (21) occurs microhiologicaRy with The isolated L-sotbose is reacted with acetone and sulfuric acid to yield 2,3 4,6 diacetone-L-sorbose,... 

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... 

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... 

Nickel oxide anodes are another example for a relatively simple oxide electrocatalyst used rather widely in the oxidation of organic substances (alcohols, amines, etc.) in alkaline solutions at relatively low anodic potentials (about +0.6 V RHE). These processes, which occur at an oxidized nickel surface, are rather highly selective. As an example, we mention the industrial oxidation of diacetone-L-sorbose to the corresponding acid in vitamin C synthesis. This reaction occurs at nickel oxide electrodes with chemical yields close to 100%. 

Fig. 17. Schematic diagram of the flow system used for batch and continuous oxidation of DAS (Diacetone-L-sorbose) with a swiss roll cell with an anode area of 3 m2...

Versuche zu Totalsynthesen in der Prostaglandinreihe, by P. de Roche (1973). Oxydation von D-Glucose und von Diaceton-L-sorbose mit Sauerstoff, by F. Bacber (1976). 

Diacetone 2-sorbose 2-keto-2-gulonic acid 2-Ascorbic acid ... 

Diacetone-L-sorbose Reject Reject Accept Accept Reject Reject... 

The heterogeneously catalyzed Mn02-mediated oxidation of diacetone-L sorbose to diacetone-2keto-L sorbic acid, the latter being a precursor to vitamin C, at nickel anodes and based on the chemical oxidation of the substrate by NiOOH is of technical relevance. The limiting current density in 1 M KOH solution is under operation conditions only 10 A/cm2 leading to relatively poor space-time yields. Robertson and Ibl showed that acceptable space-time yields can by obtained by using thin layer cells of Swiss roll type (193, 194), which leads to an efficient compression of the cell width to fractions of a millimeter. 

In the synthesis of vitamin C, the oxidation of diacetone L-sorbose to diacetone 2-keto-L-gulonic acid proceeds at an Ni-anode in the presence of hydroxide. Under these conditions, the nickel hydroxide surface is anodically transformed to NiOOH, the nickel peroxide, which acts as chemical oxidant via hydrogen atom abstraction. Thus, a chemically modified redox-active electrode acts as a heterogeneous redox catalyst [13] ... 

The yield of diacetone-L-sorbose in the presence of0.1-0.35% of H3PW12O40 or H4SiWi204o is 85% under reflux. 

Alcohols can be converted electrochemically into the corresponding carboxylic acids in very good yields if Ni oxide anodes are used in alkaline electrolytes. This reaction was studied intensively in industry for the electrochemical oxidation of diacetone-L-sorbose to diacetone-2-ketogulonic acid (intermediates of the vitamin C synthesis). On the basis of Sowjet work 282 284) (initially Pt anodes and NaBr—NaCl—NiCl2— NaOH electrolytes subsequently Ni oxide anodes), Roche and Merck studied the synthesis on the laboratory and pilot scale. In cooperation with the ETH Zurich 285-286 a special cell 287 288) was developed for this reaction. 

D-Glucose was reduced to the D-sorbitol with a hydrogen over Ni Raney, then it was turned into the L-sorbose with the acetobacter suboxydans and the hydroxyl groups of L-sorbose were protected with acetone treatment yielded the diaceton-L-sorbose. Subsequent treatment with NaOCI/Raney Ni produced di-O-isopropylidene-2-oxo-L-gulonic acid. Partial hydrolysis with aqueous HCI gave deprotected 2-oxo-L-gulonic acid, which yielded ascorbinic acid by heating with HCI. 

Direct acetonation of L-sorbose is employed in the vitamin C synthesis. However, the diacetone-L-sorbose which is obtained is frequently contaminated by varying amounts of monoacetone-L-sorbose. The amount of monoacetone-L-sorbose87b in the diacetone derivative has been determined by petroleum ether extraction, followed by decomposition of the monoacetone derivative to acetone, which is determined iodimetrically. 

Studies have been made on the individual steps in this synthesis. Acetonation104 of L-sorbose was studied with respect to time, temperature and the presence of metal catalysts, among which aluminum and zinc were found beneficial. Solvent extraction105 was discovered as a means of separating the monoacetone derivative from the desired diacetone-L-sorbose (see page 117). Reichstein and Griissner103 condensed L-sorbose with formaldehyde, with 2-butanone and with benzaldehyde but they found the diacetone derivative to be the most satisfactory intermediate in their ascorbic acid synthesis. A crystalline dicyclohexylidene derivative has also been proposed in this connection.100... 

D-Ascorbic acid was prepared by Gatzi and Reichstein28 by oxidation of diacetone-D-sorbose to 2-keto-D-gulonic acid, and a desoxy derivative, 6-desoxy-L-a8corbic acid, with some vitamin activity, was synthesized from L-sorbomethylose.116... 

In works made under direction of N.M. Emanuel they showed that catalytic system [Cu2+... A. .. 02] where A" - the anion form of substrate (anion form of substrate was formed at the expense of its deprotonation under the action of bases introduced into the system) is extremely effective in reactions of oxidation of fluorinated alcohols with general formula H(CF2CF2)nCH2OH (where n=l-6) [2], camphor [3] and diacetone-L-sorbose [4] with... 

L-Allulose (LXI) was prepared by Steiger and Reichstein through the oxidative fermentation of allitol (LX) by the sorbose bacterium, Acetobacter xylinum. The product was isolated and purified by means of its crystalline diacetone derivative, of m. p. 57° and - -99 in... 

A nickel anode is in alkaline solution protected against corrosion by a layer of nickel oxides. oxide (NiOOH) is capable of oxidizing a number of functional groups primary alcohols may be oxidized to carboxylic acids [158-161], which is of interest for the technical production of an intermediate for vitamin C production [162]. NiOOH chemically oxidizes the substrate and is regenerated electrochemically a large anode surface, which is realized in the Swiss-roll cell (Chap. 31), is thus advantageous. NiOOH electrodes in form of nickel foam electrodes has been found to be useful for the oxidation of diacetone L-sorbose to diacetone 2-keto-L-gulonic acid in the vitamin C synthesis [163]. 

The oxidation of diacetone-L-sorbose to diacetone-2-ketogulonic acid is an indirect process using NiOOH as electrocatalyst (Scheme 13). The protection of the starting material with acetone to produce 2,3 4,6-di-(9-isopropylidene-a-L-sorbofuranose is done conventionally, as is the deprotection after the oxidation step. 

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