• IUPAC Name: Sodium O,O-diethyl dithiophosphate
• Synonyms:
  • Sodium diethyl dithiophosphate
  • NaDDTP (common abbreviation)
  • Diethyl dithiophosphate sodium salt
• CAS Number: 3338-24-7
• Molecular Formula: C₄H₁₀NaO₂PS₂
• Molecular Weight: 208.2 g/mol

2. Structure & Bonding

• Core Structure:
  • Central phosphorus atom (oxidation state +5) bonded to:
    • Two ethyl groups (-OCH₂CH₃) via oxygen atoms.
    • Two sulfur atoms (dithio group, replacing oxygen in phosphate).
    • A sodium ion (Na⁺) as the counterion.
• Hybridization: Phosphorus adopts a tetrahedral geometry (sp³ hybridization).

3. Physical Properties

• Appearance: yellowish to yellow-green liquid.
• Solubility:
  • Water: Highly soluble (ionic nature).
  • Organic Solvents: Soluble in ethanol, acetone, and dimethylformamide (DMF).
• Odor: Faint sulfurous odor.

4. Synthesis

1. Step 1: Reaction of phosphorus pentasulfide (P₂S₅) with ethanol to form diethyl dithiophosphoric acid: P2S5+4[CH3CH2OH→2](C2H5O)2PSSH+H2S↑P2S5+4CH3CH2OH→2(C2H5O)2PSSH+H2S↑
2. Step 2: Neutralization with sodium hydroxide: (C2H5O)2PSSH+NaOH→Na[(C2H5O)2PS2]+H2O(C2H5O)2PSSH+NaOH→Na[(C2H5O)2PS2]+H2O

5. Key Applications

• Mining Industry:
  • Flotation Collector: Selectively binds to sulfide minerals (e.g., Cu, Pb, Zn ores) in froth flotation processes.
• Lubricant Additives:
  • Extreme-Pressure (EP) Agent: Reduces wear in machinery under high-stress conditions.
• Agriculture:
  • Pesticide Intermediate: Precursor for organophosphate insecticides (e.g., malathion).
• Coordination Chemistry:
  • Ligand for metal complexes (e.g., zinc, copper).

6. Safety & Handling

• Health Hazards:
  • Irritation: Skin, eyes, and respiratory tract irritation upon exposure.
  • Toxicity: Moderately toxic (oral LD50 in rats: ~500 mg/kg).
• Environmental Risks:
  • Highly toxic to aquatic life; avoid release into waterways.
• Precautions:
  • Use PPE (gloves, goggles, respirator).
  • Store in airtight containers away from moisture, acids, and oxidizers.

7. Stability & Reactivity

• Stability: Hygroscopic (absorbs moisture); store in dry conditions.
• Incompatibilities:
  • Reacts with strong acids to release toxic H₂S gas.
  • Reacts with oxidizing agents (e.g., peroxides, chlorates).

8. Regulatory Status

• GHS Labeling:
  • Hazard Statements: H314 (skin irritation), H318 (eye irritation).
• Transport: Not classified as dangerous goods in small quantities.

9. Key Differences from Diisopropyl Analogs

• Solubility: More water-soluble than diisopropyl derivatives due to smaller alkyl groups.
• Reactivity: Ethyl groups offer slightly lower steric hindrance, enhancing ligand-metal binding in flotation.