Ferric Nitrate Nonahydrate and NaCl

[kaos1]

Greetings,

In a recent situation in our process, we have noticed that when dispersing ferric nitrate nonahydrate, which is light purple or brownish depending on it's state, on sodium chloride it turns to a bright yellow. We have tried NaCl, KCl, dextrose, and calcium chloride as "carriers" for this compound and have found similar results.

Does anyone know what is happening here?

Kaos1

 

[moltenmetal]

Iron (III) chloride is yellow (intensely so at high concentrations, making it appear orange), and nitrate is a weaker ligand than chloride.

 

[kaos1]

Thanks moltenmetal,

I theorized that this was what was happening with the Cl-, but how does this explain this phenomenom when combined with dextrose and there is no chlorine present? What happens then?

Kaos1

 

[bchoate]

bchoate
A potential issue with the hexose dextrose is the aldehyde group in the sugar. Some studies have shown metal salt asssisted oxidation of dextrose in the absence of solvent.
Specifically iron III nonahydrate catalyzes the oxidation of dextrose to the carboxylic acid and iron III is reduced to iron II. The carboxyl groups may complex with some of the iron II species to stabilize them and prevent reoxidation to iron III. Dextrose is not an unreactive support.