372 Mr Fenton, Oxidation in Presence of Iron. 



This semi-aldehyde is of especial interest in consequence 

 of its relationship to uric acid, since its aldehyde-hydrate 

 CH (OH) 2 . CO . COOH may be regarded as tautomeric with 

 trihydroxy-acrylic acid C(OH) 2 = C(OH) . COOH. 



Oxidation of Carbohydrates. 



[Cross and Bevan, Trans. Chem. Soc. 1898. 463, 1899. 747. 

 Morrell and Crofts, ibid. 1899. 786, etc.] 



This branch of the research has hitherto been undertaken, in 

 communication with the author, especially by Messrs Cross and 

 Bevan, and Morrell and Crofts. Amongst the most important 

 results which have been obtained in this direction may be 

 mentioned the observations of the latter chemists, who shew that 

 both dextrose and lsevulose when oxidized by hydrogen dioxide in 

 presence of ferrous iron yield hexosone CH 2 OH(CHOH) 3 . CO . CHO, 

 and that similar results are obtained with arabinose and rhamnose, 

 which give pentosone and methyl-pentosone respectively. 



Galactose, presumably owing to its special configuration, gives 

 a different result, which is being further investigated. 



Messrs Cross and Bevan have also studied the action on 

 acetylene and benzene, which yield acetic acid and phenol respec- 

 tively. Furfural also yields a colour-giving substance, which is 

 probably hydroxy-furfural. 



Function of the Iron. 



In the present state of these researches, which are still in 

 active progress, it is somewhat premature to draw general con- 

 clusions as to the probable nature of the influence of iron in the 

 oxidations mentioned, but the following statements may be made 

 with considerable confidence : 



(a) The influence of the iron belongs to the class of chemical 

 changes usually described as catalytic, an almost infinitesimal 

 proportion being in many cases sufficient to determine the 

 oxidation. 



(b) It is probably essential in all cases that the iron should 

 be present in the fe?'7*ons state, and in the few instances where 

 a ferric salt has been successfully employed it is probable that 

 previous reduction to the ferrous state initially occurs. 



(c) Judging from the colour changes and other effects it is 

 highly probable that the iron undergoes alternate changes in 

 state of oxidation or valency ; the higher state may be the ferric 

 condition or it may correspond to a still higher form, such as FeO„. 

 (Compare Manchot, Zeit. Anorg. Chem., 1901, 420.) 



