370 Mr Fenton, Oxidation in Presence of Iron. 



repeated in a similar way several times, allowing the mixture to 

 stand for some hours between each saturation. The resulting 

 product now gives with phenylhydrazine a bright orange-yellow 

 precipitate, which when recrystallized from hot chloroform melts 

 at 222 — 224° and is shewn to be identical with Nastvogel's 

 osazone CHN ? HPh . CN 2 HPh . COOH which has been mentioned 

 above. [The investigation of this product was in the first instance 

 considerably retarded owing to the fact that all previous observers 

 have given a value to the melting-point of this osazone which is 

 far too low. A complete re-examination of the osazone has now 

 proved that the true melting-point is as here stated, 222 — 224°.] 



By concentrating the liquid under reduced pressure and allow- 

 ing the unaltered tartaric acid to crystallize out as far as possible, 

 a syrupy liquid is obtained, which however still retains some 

 tartaric acid, and which gives a very abundant yield of the above 

 osazone. The oxidation-product is shewn to contain no chlorine, 

 since it may be converted into a barium salt which is free from 

 chlorine, and which when decomposed with dilute sulphuric acid 

 gives the same osazone. Under these circumstances it is evident, 

 from the established constitution of the osazone (Nastvogel, 

 Annalen, 1888. 85 ; Will, Ber. 1891. 400, etc.), that the product 

 must be either hydroxypyruvic acid (or dihydroxyacrylic acid), 

 tartronic semi-aldehyde or mesoxalic semi-aldehyde. 



It gives no violet coloration with ferric chloride, so that it is 

 not identical with the glyceric acid oxidation-product above 

 referred to. 



In order further to decide the nature of the product the 

 following experiments were tried, and the results of these, apart 

 from other considerations, definitely prove its constitution. 



Action of Hydroxylamine. 



The tartaric acid-chlorine oxidation-product obtained as above 

 described . after removal of most of the unaltered tartaric acid was 

 mixed with excess of hydroxylamine hydrochloride in aqueous 

 solution and neutralized with sodium carbonate. After standing 

 over night it was acidified with dilute sulphuric acid and extracted 

 several times with ether. Most of the ether was distilled off and 

 the remaining liquid allowed to remain in a vacuum desiccator. 



The resulting solid reddish mass was dissolved in the least 

 possible ammonia solution and acidified with strong hydrochloric 

 acid, the operations being carried out with careful cooling. Long 

 colourless needles separated, which were purified by again dis- 

 solving in ammonia and acidifying with dilute sulphuric acid. 

 These melted at 178 — 180° and were found by analysis to have 

 the formula C 3 H 4 N 2 04. They are somewhat sparingly soluble in 

 cold water, and the aqueous solution gives with ferrous sulphate 



