A-Acrose

D,L-Mannitol has been obtained by sodium amalgam reduction of D,L-mannose. The identical hexitol is formed from the formaldehyde polymer, acrose, by conversion through its osazone and osone to D,L-fmctose (a-acrose) followed by reduction (83). 

Fischer made use of 1 per cent, sodium hydroxide solution to polymerise a mixture of glyceric aldehyde and hydroxy-acetone, in the formation of a-acrose. After allowing the mixture to stand for four or five days the transformation was complete 3t... 

The above three syrups all appear to have contained a-acrose, which Emil Fischer isolated in a pnro stato in 1887, by tho action of baryta water upon acrolein bromide, when a mixture of a- and /3-acrose was obtained.17... 

Fischer subsequently obtained a-acrose alone, by tho polymerising influence of one per cent, sodinm hydroxide upon glycerose, an oxidation product of glycerol.18... 

Syrup. SoL >hot3 EtOH. Zn-t-AcOH— a-acrose. H.0 a%140°-k frufrital. 

Equilib. difficult to study, but an aq. soln. prob. contains approx. 70-75% p-Pyr, 20-23% P-Fur, 5% a-Fur, 0-2% a-Pyr and 0-0.7% open-chain forms. In Py and DM SO soln. there are higher proportions of furanose forms. a-Acrose was apparently an old synonym for the racemate. 

Fischer and Tafel s Complete Synthesis of Hexose Sugars a-ACROSE (from formaldehyde, glyceraldehyde, or acrolein dibromide) c H6NHNH2... 

DL-Mannitol (a-acritol) has been obtained by the reduction of a-acrose (see p. 104). Divinylglycol from acrolein was the starting point of Lespieau and Wiemann (4S). The glycol was obtained from acrolein by reduction with the zinc-copper couple and was then oxidized with silver chlorate and osmium tetroxide to DL-mannitol. Allitol was obtained simultaneously. It is apparent, therefore, that this divinylglycol must be a mixture of diols in which the hydroxyls are cis and trans. 

After the discovery of methylenitan by Butlerow and formose by Loew, from formaldehyde (see p. 8zi), Fischer and TafeF prepared what they called a- and )S-acrose by the action of baryta water on acrolein dibromide CH2 CH-CH0 CH20H CHOH-CHO -> C3Ht20e. a-acrose was shown... 

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