358 Mr Fenton, Oxidation in Presence of Iron. 



Oxidation in Presence of Iron. By Henry J. Horstman 

 Fenton, M.A., F.R.S. 



[Received 1 March 1902.] 



The remarkable influence which is exerted by traces of iron 

 salts in determining and regulating the oxidation of various 

 organic substances was first observed by the author in 1876, and 

 the observation has since opened up a very wide and fruitful field 

 for investigation. Since the researches which have been published 

 in this direction extend over a considerable period and have 

 appeared in various journals, it has been considered advisable to 

 communicate to the Society a brief summary of the work 

 together with an account of recent results not hitherto pub- 

 lished. 



The function of the iron in these reactions is twofold : in the 

 first place it increases the activity of the oxidizing agent to a 

 remarkable extent, and secondly it has a selective or regulating 

 influence so that certain groups are attacked and others left. 

 This second influence may be regarded as the essential and novel 

 feature of the actions referred to, oxidations being effected in this 

 way which are not possible by any other means ; the mere in- 

 crease of activity may of course be induced by other agents and 

 is not peculiar to iron. 



It has been considered necessary to emphasize this point and 

 also to draw attention to the dates of publication, since considerable 

 misconceptions with regard to these matters appear to exist. 

 [Compare G. Ollendorff, Inaugural Dissertation, Berlin, July 1900, 



11-] 



The first substance investigated in this direction was tartaric 



acid ; it was observed that this acid, or its salts, when treated 

 with certain oxidizing agents in presence of ferrous iron gave, on 

 addition of caustic alkali, a beautiful violet colour {Chemical 

 News, 1876, 33. 190; 1881, 43. 110]. The explanation of this 

 effect and the isolation and identification of the active product 

 was at first a matter of very considerable difficulty owing to the 

 unstable character of the substance in aqueous solution. In 1894 

 this product was isolated and proved to be the hitherto missing 

 dioxymaleic acid. From this acid a large number of interesting 

 derivatives have been obtained, and its decompositions and trans- 

 formations afford direct and simple means of preparing various 

 other compounds which can, by other methods, be obtained only 

 with great difficulty or not at all. 



