Monoacetone sorbose

In the third step, L-sorbose is reacted with acetone and excess sulfuric acid at low temperatures. The sorbose dissolves on conversion into the 2,3-mono-O-isopropjhdene-L-sorbose (2,3 monoacetone-L-sorbose) (MAS), and 2,3 4,6-bis-0-isoprop5hdene-a-L-sorbofuranose... 

Mono(2-aminoethyl) isocyanurate, 3 202 2,3-Monoacetone-L-sorbose (MAS) in ascorbic acid manufacture, 25 757 Monoacid chlorides, of maleic anhydride, 15 484-486... 

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... 

Oxidation of the monoacetone derivative, 2,3-isopropylidene-L-sorbose (XLIX), with air in the presence of platinum has reportedly given L-gulo-saccharoascorbic acid (LI), after treatment of the unstable intermediate 2,3-isopropylidene-2,5-furanose-L-gulosaccharic acid (L) with hydrochloric acid. 109... 

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