I.G.Farbenind.
Patent: DE696773 , 1936 ;
DRP/DRBP Org.Chem.
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Reppe et al.
Justus Liebigs Annalen der Chemie, 1956 , vol. 601, p. 81,104
in acetic acid 20percent acetic acid, 380°C, stirring until a pH of 5.5 results, treatment of soln. with activated coal, further treatment at 30°C with activated coal and salicylic acid, thiosalicylic acid or thiocyanates;; product contains less than 5E-6percent Fe(3+);;
