( 176 ) 
be regarded as glucosides, derived from methylenglyeol CH, (OH), », 
which is unknown in the free state. Two of the alcoholic hydroxyl 
groups of the sugar-molecule have also taken part in the formation 
of the diformal-derivatives. A hydroxyl group is no longer present 
in formalmethylenexyloside and -arabinoside, for acetic anhydride 
and benzoyl chloride do not act on these substances. As, according 
to the analysis, two mols. of water have been eliminated, the following 
constitutional formulae, for instance, may be drawn up for the said 
pentose derivatives. 
O 
HCD ERGs 
eo CH, HC SH, 
/ HC—0/ hele“ 
Oo. ait CH 
ee) or | 
en HC—ON 
OE MOE: OE HED 
renee \ HC—0/ 
H,C—O oF 
CH, 
Diformalxylose (C, H,, O,) erystallises very neatly from benzene 
or light petroleum; melting point 56°—57°,[a@|p(2°/, solution in 
methylalcohol) — + 25°,7; may be readily ~ sublimed. 
Diformalarabinose is a somewhat oily, colorless liquid which may 
be distilled in vacuum without decomposition. Boiling point 155° 
at about 32 m.m. pressure; [alp (2°/, solution in methylaleohol) 
= — 16°. 
With glucose a syrupy diformalderivative may be separated from a 
solid mono-compound by taking advantage of the said difference 
in solubility. Neither of these substances have any reducing 
power or react with phenylhydrazine. They are probably mixtures; 
the white substance, although crystalline, does not possess a definite 
melting point (140—150°) and on analysis gives no satisfactory figures, 
but it could not up to the present be resolved by recrystallisation 
into components. The diformal-derivative, left in contact with solvents 
for many months, remained syrupy. 
Both compounds still contain one or more free hydroxyl groups ; 
10 
1) The methyleneglucose obtained by Torens (1.c.) has still a strong reducing 
action; it appears to us that it should not be regarded as a glucoside (which 
Tottens does); apparently two alcoholic groups of the glucose have taken part 
in its formation, 
