198 



SCIENCE PROGRESS 



type 4 : 4'-dimethyldiethyldiamino-triphenylmethane sulphonic 

 acid but without success. 



Organic Arsenic Compounds. — ^The number of organic 

 arsenic compounds synthesised increases rapidly, and an up- 

 to-date formula index of them would be of great use to workers 

 in this field. Two interesting cyclic arsenic compounds have 



recently been obtained, one, phenarsazine C^W^^ yC^W^ 



by Wieland and Rheinheimer {Ann., 1921, 423, i) and the 



As 



other arsanthrene 



030 



by Kalb {Ann., 1921, 423, 39). 



As 



The former is obtained by the following synthesis : 

 NH NH NH 



+ AsCL 



NaOMe 



♦ ax) 



AsOMe 



+ MeOH 



As 

 [XIV] 



Phenarsazine is very reactive and readily adds water, alcohol, 

 etc. ; the reactions are, however, reversible and on heating the 

 compound formed in a high boiling, inert solvent the phenar- 

 sazine is reformed ; with hydrochloric acid phenarsazine 

 chloride [XIV] is regenerated. 



Arsanthrene, the arsenic analogue of phenazine, is synthesised 

 from o-nitroaniline as follows : 



NO2.C6H4.NH2 

 NH,C«H..AsO,H, 



CgHg . AsO 



NO2.C6H4.ASO3H2 

 OH.N,.C«H,.AsOoH, 



> CgHg . AsO(OH) . CgH^ . AsOgHa 



AsCl 



\ 



AsClji 



o 



\As/ 



"n 



AsCl-^ 



