364 
Mr Fenton , Oxidation in Presence of Iron. 
Synthesis of Hexoses. 
[Trans. Chem. Soc. 1897. 375.] 
When glycollic aldehyde is heated in a vacuum to about 100° 
it partly vaporizes unchanged, as previously mentioned ; the 
remainder is found on cooling as a solid transparent gum which is 
somewhat brittle and has a sweet taste. Analyses and molecular 
weight determinations by the freezing-point method shew that 
this product has the formula C 6 H 12 0 6 . Its aqueous solution 
reduces Feh ling’s solution and gives various colour reactions 
characteristic of sugars, and when heated with water to 140° it 
yields furfural. After purification by treatment with alcohol it 
gives with phenylhydrazine acetate a normal hexosazone 
CjsH^NA. 
If the product obtained from condensation of glycollic alde- 
hyde by heat, and purification with alcohol as above described, be 
further heated for several hours in a vacuum to 100 — 106°, it 
becomes more brittle and its composition then approximates to 
the formula C 6 H 10 O 5 . 
The synthetical formation of sugars in the manner here 
described is of especial interest as tending to throw light on the 
natural formation of carbohydrates, more particularly when the 
following facts are considered. 
When tartaric acid or its salts are exposed to sunlight and air 
in presence of small quantities of ferrous salts, a notable quantity 
of dioxymaleic acid is produced. For this experiment to succeed 
the three conditions presence of iron, oxygen and sunlight are 
absolutely necessary ; in absence of any one of these conditions 
the change does not occur. Since dioxymaleic acid spontaneously 
decomposes, even at ordinary temperatures, in aqueous solution 
giving glycollic aldehyde, and the latter readily undergoes con- 
densation to hexose (and probably to hexose ‘anhydrides’ also) it 
is evident that a theory as to the natural formation of carbo- 
hydrates may be formulated which perhaps compares favourably 
in some respects with the popular ‘formaldehyde hypothesis’ of 
Baeyer. [Compare Fenton, B. A. Report , 1895.] 
With regard to the chemical nature of the sugar obtained in 
the manner here described it may be remarked that it closely 
resembles the condensation products obtained by Loew and by 
Fischer from formaldehyde and by Fischer and Tafel from 
‘glycerose.’ In order to throw further light upon the matter 
glycollic aldehyde was afterwards condensed in presence of dilute 
alkalis instead of by heat, and from this product a hexosazone 
was obtained which corresponds exactly in melting point and 
