Antioxidants and Complexes

Antioxidant Mechanisms

• As reducing agent

• As inert atmosphere to prevent oxidation

Considerations in Selecting Antioxidants

• Inertness

• Solubility

• Toxicity

• Reaction with strong oxidizing agents

Sodium Thiosulfate (Na₂SO₃ × 5H₂O)

• Large, transparent, colorless crystals, cooling, bitter taste

• Iodimetric / Iodometric titration

• Treatment for CN^- poisoning

Sodium Nitrite (NaNO₂)

• White to slightly yellow granular powder

• Mild, saline taste, and deliquescent

• Antidote to CN^-

• Reducing Agent

• Oxidizing in acidic condition

• Neutral in alkaline condition

Hypophosphorus Acid (HPH₂O₂)

• Salts are used as food preservatives

• Prevents formation of Fe³ and I₂

Sodium Metabisulfite (Na₂SO₅)

• White crystal or white to yellowish crystalline
  powder

• Has odor of SO₂

• Source of bisulfite

Nitrogen (N₂)

• Protects chemicals, reagents, and pharmaceuticals from air oxidation

• Inert gas

• Production of inert atmosphere

Sulfur Dioxide (SO₂)

• Colorless, non-flammable gas

• Suffocating odor

• Strong reducing agent

• Antioxidant pharmaceutical aid

• For injectable preparations in single or multiple-dose containers

• Produces acidic solution in water

Calcium Disocium Edetate / CaNa₂EDTA

• White crystalline granule or powder

• Odorless, slightly hygroscopic, and has a faint saline taste

• Treat heavy metal poisoning lead (plumbism), copper, nickel, cadmium, zinc, chromium, manganese

Disodium Edetate / Na₂EDTA

• Same metals as CaNa₂EDTA

• Hypercalcemic diseases (Cardiac
  arrhythmias

Dimercaprol

• Arsenic, mercury, and gold poisoning

• Improves the excretion of lead and copper (Wilson’s disease)

• Contraindicated in iron, cadmium, and
  selenium poisoning

• Metal-dimercaprolcomplexes tend to
  dissociate in acid media

Penicillamine

• Capable of forming complexes with copper, iron, mercury, lead, gold

• Excretion of copper

• Treatment of gold dermatitis

Deferoxamine

• Produced naturally by Streptomyces pilosus as a ferric complex

• Does not have strong affinity with ferrous and
  other divalent metal ions