366 
Mr Fenton , Oxidation in Presence of Iron. 
is effected at a low temperature and the intermediate compound 
subsequently decomposed by heating. 
Ruff [ Ber . 1898. 1573 et seqi] has since applied this method 
with much success to several other processes of similar degradation 
in the case of monobasic acids and brings about the operation in 
a single stage. He modifies the method by using a ferric salt 
instead of a ferrous salt, and operates at a higher temperature at 
starting, without isolation of an intermediate product. In this 
way, for example, he obtains d. arabinose from gluconic acid, and 
d. tetrose from d. arabonic acid. 
Oxidation of Polyhydric Alcohols. 
[Fenton and Jackson, Trans. Chem. Soc. 1899. 1.] 
The influence of ferrous iron in assisting and regulating oxida- 
tion is again illustrated to a marked degree in the case of poly- 
hydric alcohols. These substances when treated with hydrogen 
dioxide alone are either unaffected or very slowly and incompletely 
oxidized, but in presence of a small quantity of ferrous iron a 
vigorous oxidation immediately ensues with considerable evolu- 
tion of heat. In this manner glycollic aldehyde is formed from 
glycol, glyceraldehyde from glycerol, tetrose from erythritol and 
mannose from mannitol. Hexoses are also obtained from dulcitol 
and sorbitol. This method probably affords the simplest and 
most direct method of oxidizing the polyhydric alcohols. Mono- 
hydric alcohols of the C w H^ n+1 OH series appear to be unaffected. 
In the cases of glycol, glycerol, and erythritol the oxidations 
may, as in the case of tartaric acid, be effected by atmospheric 
oxygen in presence of iron when exposed to sunlight. 
Oxidation of Acids. 
[Fenton and Jones, Trans. Chem. Soc. 1900. 69. Fenton, B. A. 
Report, 1899.] 
As in the case of tartaric acid and the polyhydric alcohols the 
presence of ferrous iron is found to exert a similar remarkable 
influence in the oxidation of all hydroxy-acids, in addition to 
many cyclic and unsaturated acids. Owing to the selective 
character of this oxidation-process it is possible in many cases to 
obtain products which cannot be directly prepared in any other 
way. Some of the more important results obtained may be 
briefly summarised as follows — 
Saturated aliphatic acids which do not contain hydroxyl or 
