Melibiose crystallization

Correct molecular formula for melibiose Discovery and crystallization of stachyose from Slachys Seheibler 1889 7 ... 

Reduction of epimelibiose was reported by French and associates23 73 to give crystalline epimelibiitol, of m.p. 157-8°, which on conversion to the acetate gave crystals of m.p. 122°, [a]21D + 104°(c 0.5, in chloroform). Epimelibiitol was similarly obtained by the reduction of planteobiose29 or of the alkaline-isomerization mixture from melibiose.73 Epimelibiitol and... 

The hydrogen bonding in melibiose monohydrate includes a homodromic cycle. Cyclic hydrogen-bonding schemes are not common in mono- and disaccharides, but in the crystal structure of the epimeric a,yS-melibiose monohydrate, 6-0-a-D-galactopyranosyl-cr,/ -D-glucopyranose-H20 [MELIBM01] (Fig. 13.49),... 

Only one tri-saccharose is important. It is known as raffinose and has the composition Ci8H320]6. It is found in beets and is present in the molasses after the sucrose sugar is crystallized out. It is also found in barley and in cotton seeds. When this tri-saccharose hydrolyzes it yields first a di-saccharose known as melibiose and a monosaccharose fructose. The di-saccharose is then further hydrolyzed and yields two molecules of mono-saccharose, viz., glucose and galactose. The complete hydrolysis of the tri-saccharose, therefore, is as follows. 

Dihydrate, monoclinic crystals from water or dil alcohol mp 84-85. Shows mutarotalion. [c ] +111.7 — 129.5 (c = 4), One gram dissolves in 0.4 ml water, 8.5 ml methanol, 220 ml abs alcohol. Dilute acids hydrolyze melibiose to D-glucose and i> -galactose Also split by emulsin and by bottom yeast. Reduces Fehling s soln. 3.5 g melibiose dihydrate are about as sweet as 1.0 g sucrose. 

Preparation. Hydrolysis of raffinose by invertase yields melibiose 80) and D-fructose. By the use of bakers yeast (top yeast), hydrolysis and simultaneous removal of the D-fructose by fermentation takes place. The sirup crystallizes directly or after purification through the octaacetate. 

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