New Better Oxidizing Chemical
AndersHoveland
Acolyte
There is a seldom known of chemical which is safer, easier to make, and more powerful than potassium permanganate, which is often used in organic chemistry.
Potassium, sodium, or calcium ferrate is a strong oxidizer when acidified. Since it contains no manganese, it is envirormentally friendly. Some drug users have developed "manganism", in which they experience permanent neurological damage causing parkinson's like symptoms with "intention tremors", because of traces of permanganate which have not been fully neutralized in the injected drugs.
K2FeO4, Na2FeO4, CaFeO4
These are unusual examples of iron in a +6 oxidation state; normally it is only in +2 or +3.
Solutions of ferrate are purplish-brown (burgundy) color, in contrast to the bright pink-violet of permanganate.
Preparation
Ferrate salts can easily be prepared from iron salts, hypochlorite, and a base. The formation and stability of ferrate requires a high pH, and the anion is not stable at neutral or low pH.
(2) Fe+3 + (3) OCl‾ + (4) OH‾ --> (2) FeO4-2 + (3) Cl‾ + (2) H2O
Preparation of Sodium Ferrate free from Chloride
Twenty-four parts of Fe2O3 and 40 parts of Na2O by weight were well mixed in a porcelain mortar in the absence of water or carbon dioxide. The mixture was transferred to a refractory vessel and placed in a furnace at 150°C through which dry oxygen flowed. In the next 30 minutes the temperature was increased to 450°C and yielded sodium ferrate(IV) after one hour.
(4) Na2O + Fe2O3 + (½) O2 —> (2) Na4FeO4
The product contained only around fifty percent sodium ferrate(lV). Sodium ferrate(lV) disproportionates in water or alkaline solutions to form sodium ferrate(VI), according to the reaction:
(3) Na4FeO4 + (8) H2O —> Na2FeO4 + (2) Fe[OH]3 + (10) NaOH
Uses
Unlike permanganates, ferrates are potentially envirormentally safe. However, unlike permanganate, ferrate requires a much more alkaline solution for stability. Potassium ferrate decomposes above 198 °C. Being more powerful than permanganate and even persulfate, ferrate would be expected to oxidize soluble silver salts to
silver(I,III) oxide (Ag2O2), which will precipitate once the pH is no longer alkaline u
Like permanganate, addition of concentrated sulfuric acid to potassium ferrate would be expected to produce traces of ozone (1.5%). (possibly the ozone/oxygen mixture could be bubbled through more conc H2SO4 to dry it, then allowed to pass into a glass reaction vessel, while also passing in a gaseous mixture containing chlorine dioxide. The two should react, causing the condensation of a volatile red liquid, dichlorine hexoxide Cl2O6. )
Sodium ferrate can even be used to oxidize chlorate (or a limited quantity of chloride) to perchlorate. Note that the usual method of preparing ferrate from hypochlorite is problematic, as the sodium ferrate must then be separated from the chloride ions, and the sodium salt is harder to isolate from this solution than the potassium salt.
Comparison of Oxidizing Strength
To see how powerful ferrate is in relation to other common oxidizers, see the table of reduction potentials, in which fluorine is the strongest oxidizer:
Fluorine 2.87v
Chlorine (aqueous) 1.36v
Hypochlorite (alkaline) 0.8v
Hypochlorite (acidified) 1.49v
Persulfate (acidified) 2.01v
Persulfate (heat or catalyst) 2.6v
Hydrogen Peroxide (acidified) 1.78v
Ozone (aqueous acidic solution) 2.08v
Ozone (aqueous neutral solution) 1.24v
Hydroxyl Radical3 2.80v
Permanganate (acidified) 1.68v
Ferrate (acidified) 2.20v
Ferrate (alkaline) 0.72v
reduction potential for perchlorate is +1.23 V; and for periodate +1.64V
Summary: Ferrate, as it is being acidified, is more powerful than permanganate or even ozone (but not mixtures of ozone and H2O2).
Ferrate is a stronger oxidizer than persulfate, unless the persulfate is heated or the solution contains iron ions. Mixtures of ferrate with persulfate together appear to more rapidly oxidize other chemicals than either alone.
Potassium, sodium, or calcium ferrate is a strong oxidizer when acidified. Since it contains no manganese, it is envirormentally friendly. Some drug users have developed "manganism", in which they experience permanent neurological damage causing parkinson's like symptoms with "intention tremors", because of traces of permanganate which have not been fully neutralized in the injected drugs.
K2FeO4, Na2FeO4, CaFeO4
These are unusual examples of iron in a +6 oxidation state; normally it is only in +2 or +3.
Solutions of ferrate are purplish-brown (burgundy) color, in contrast to the bright pink-violet of permanganate.
Preparation
Ferrate salts can easily be prepared from iron salts, hypochlorite, and a base. The formation and stability of ferrate requires a high pH, and the anion is not stable at neutral or low pH.
(2) Fe+3 + (3) OCl‾ + (4) OH‾ --> (2) FeO4-2 + (3) Cl‾ + (2) H2O
Preparation of Sodium Ferrate free from Chloride
Twenty-four parts of Fe2O3 and 40 parts of Na2O by weight were well mixed in a porcelain mortar in the absence of water or carbon dioxide. The mixture was transferred to a refractory vessel and placed in a furnace at 150°C through which dry oxygen flowed. In the next 30 minutes the temperature was increased to 450°C and yielded sodium ferrate(IV) after one hour.
(4) Na2O + Fe2O3 + (½) O2 —> (2) Na4FeO4
The product contained only around fifty percent sodium ferrate(lV). Sodium ferrate(lV) disproportionates in water or alkaline solutions to form sodium ferrate(VI), according to the reaction:
(3) Na4FeO4 + (8) H2O —> Na2FeO4 + (2) Fe[OH]3 + (10) NaOH
Uses
Unlike permanganates, ferrates are potentially envirormentally safe. However, unlike permanganate, ferrate requires a much more alkaline solution for stability. Potassium ferrate decomposes above 198 °C. Being more powerful than permanganate and even persulfate, ferrate would be expected to oxidize soluble silver salts to
silver(I,III) oxide (Ag2O2), which will precipitate once the pH is no longer alkaline u
Like permanganate, addition of concentrated sulfuric acid to potassium ferrate would be expected to produce traces of ozone (1.5%). (possibly the ozone/oxygen mixture could be bubbled through more conc H2SO4 to dry it, then allowed to pass into a glass reaction vessel, while also passing in a gaseous mixture containing chlorine dioxide. The two should react, causing the condensation of a volatile red liquid, dichlorine hexoxide Cl2O6. )
Sodium ferrate can even be used to oxidize chlorate (or a limited quantity of chloride) to perchlorate. Note that the usual method of preparing ferrate from hypochlorite is problematic, as the sodium ferrate must then be separated from the chloride ions, and the sodium salt is harder to isolate from this solution than the potassium salt.
Comparison of Oxidizing Strength
To see how powerful ferrate is in relation to other common oxidizers, see the table of reduction potentials, in which fluorine is the strongest oxidizer:
Fluorine 2.87v
Chlorine (aqueous) 1.36v
Hypochlorite (alkaline) 0.8v
Hypochlorite (acidified) 1.49v
Persulfate (acidified) 2.01v
Persulfate (heat or catalyst) 2.6v
Hydrogen Peroxide (acidified) 1.78v
Ozone (aqueous acidic solution) 2.08v
Ozone (aqueous neutral solution) 1.24v
Hydroxyl Radical3 2.80v
Permanganate (acidified) 1.68v
Ferrate (acidified) 2.20v
Ferrate (alkaline) 0.72v
reduction potential for perchlorate is +1.23 V; and for periodate +1.64V
Summary: Ferrate, as it is being acidified, is more powerful than permanganate or even ozone (but not mixtures of ozone and H2O2).
Ferrate is a stronger oxidizer than persulfate, unless the persulfate is heated or the solution contains iron ions. Mixtures of ferrate with persulfate together appear to more rapidly oxidize other chemicals than either alone.
Comments
Interesting article put who bothers with making potassium permanganate when it is so easily purchased? I'd be far more inclined to purify a compound by removing KMnO4 than I would to construct or purchase a furnace for the purposes of manufacturing sodium ferrate.
Simply mix any iron compound (such as FeSO4, FeCl3, or even iron metal) with
an excess solution of concentrated sodium hydroxide (lye), and add in sodium hypochlorite (bleach). The brownish-purple color should be vissible after several minutes. This is dissolved ferrate.
The only reason one might not want any chloride ions is if one is using the ferrate to oxidize chlorate to perchlorate. If the proportion of chloride ions was too much, the ferrate would oxidize the chloride ions rather than the chlorate. Ferrate can be an extremely powerful oxidizer, but to realize its full oxidizing potential, one would need to separate it from the chloride ions.
With chloride ions, it is basically equivalent to permanganate for most organic reactions.