Zinc ferrocyanide

Ferrocyan-kaUum, n. potassium ferrocyanide. -kupfer, n. cupric ferrocyanide. -natrium, n. sodium ferrocyanide. -silber, n. silver ferrocyanide. -verbindung, /. ferrocyanide. -wasserstoff, m., -wasserstoffsMure, /. ferro-cyanic acid, -zink, n. zinc ferrocyanide. -zinn, n. tin ferrocyanide. 

II. The use of the zinc, ferrocyanide, ferricyanide redox system. Analy-... 

Fogg and Wood [196] have separated sulphonamides by TLC using 0.03—3.33 M acetic acid on layers of zinc ferrocyanide which they had prepared themselves. 

Procedure. A drop of a 1 AT solution of potassium ferrocyanide is added to a drop of a cold saturated solution of zinc sulfate (or nitrate) and then a drop of 1 % sodium nitroprusside is added. White zinc ferrocyanide precipitates. A drop of the neutral test solution is introduced. The precipitate becomes red if sulfite is present. 

Alkali ferricyanides oxidize acid solutions of diethylaniline and other aromatic amines, as well as certain monoazo dyestuffs a change of color results and ferrocyanide is formed. This reversible redox reaction, proceeds very slowly and incompletely. However, if the ferrocyanide ions are removed as insoluble white zinc ferrocyanide, the oxidation proceeds rapidly. This acceleration is a result of raising the oxidation potential of ferricyanide ions through removal of ferrocyanide ions. The white zinc ferrocyanide is deeply tinted by adsorption of the colored quinoidal oxidation products of the amines, and thus affords a sensitive test for zinc. The test is especially useful in the presence of chromium and aluminum. It can also be used in other instances provided no other cations are present, which form colored precipitates with potassium ferrocyanide (Co+, Ni+, Fe+, Mn+ , Cu+ ). Traces of iron, which in practice are always to be reckoned with, do not interfere with the zinc test. Anions which oxidize the amines must be absent, e.g., permanganate, chromate, vanadate, persulfate, iodate. 

D. F.. Swinehart . "Stannous GMonide-Iodine and Zinc-Ferrocyanide. Titrations. Application of the Dead-Stop End Point" Anal. Chem. 23,. 380-81(1951). 

Antwerp Bl ue n Essentially, zinc ferrocyanide with a pale greenish-blue color. It is characterized by good opacity and almost complete absence of floating tendency. 

Another example, interesting for analytical chemistry, is that of the couple hexa-cyanoferrate(III) (ferricyanide)/hexacyanoferrate(II) (ferrocyanide), whose standard potential is E° = 0.36 V. The ferrocyanide ion, in the presence of zinc ions and in some conditions, gives the zinc ferrocyanide Zn2[Fe (CN)6]. The zinc ferrocyanide... 

We have investigated copper preparations (Raney s and others), Raney nickel, zinc oxide, iron oxide, vanadium quin-toxide (VjOg), silica gel (SiOj) and some varieties of silicon dioxide applied as carriers, zinc ferrocyanide pure, and with Fe + and Cu + ions, a cobalt-thorium contact for Fischer and Tropsch s s5mthesis, zinc hydroxide with Co + ions, and silica gel with nickel sulphate (II) fixed on it. We have investigated contact fixed on a carrier and without a carrier, with additions of an activator, etc. For example, Co + ions on Zn(0H)2 could be clearly detected potentiometrically and still in the quantity of 3.10 g Co + to a powder electrode. 

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