TETHMP·Na₁₂ is a highly phosphonated, multi-functional scale and corrosion inhibitor used in extreme conditions (high temperature, high hardness, oxidizing environments). Below is a step-by-step synthesis and formulation process flow.
1. Raw Materials Preparation
Key Chemicals Required:
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Hexamethylenediamine (HMDA) – Primary amine source.
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Phosphorous acid (H₃PO₃) – Phosphonation agent.
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Formaldehyde (CH₂O, 37% solution) – Crosslinking agent.
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Sodium hydroxide (NaOH, 50%) – Neutralization/pH adjustment.
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Hydrochloric acid (HCl, 30%) – Catalyst (optional).
2. Synthesis Process Flow
Step 1: Phosphonation Reaction (Formation of TETHMP Acid Form)
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Reactor Setup: Stainless steel or glass-lined reactor with reflux condenser.
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Reaction Conditions:
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Temperature: 90–110°C (controlled heating).
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Pressure: Atmospheric.
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pH: 1.5–2.5 (acidic, maintained with HCl if needed).
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Reaction Steps:
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Charge HMDA + H₃PO₃ + H₂O into reactor.
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Slowly add formaldehyde (exothermic, controlled addition).
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Stir for 4–6 hrs until complete phosphonation.
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Cool to 50°C before neutralization.
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Step 2: Neutralization (Conversion to Sodium Salt, TETHMP·Na₁₂)
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NaOH Addition:
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Slowly add 50% NaOH to adjust pH to 9–11.
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Temperature maintained at <60°C to prevent degradation.
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Final Product:
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TETHMP·Na₁₂ (liquid, ~40–50% active).
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Step 3: Purification & Filtration
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Impurity Removal:
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Filter through 5–10 µm cartridge to remove insoluble residues.
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Optional: Activated carbon treatment for color improvement.
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Step 4: Concentration & Drying (For Solid Form, Optional)
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Evaporation: Rotary evaporator to concentrate to ~70% solids.
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Spray Drying: If powder form is needed (final product: ~90% purity).
3. Quality Control & Testing
| Parameter | Specification | Test Method |
|---|---|---|
| Active Content | ≥40% (liquid), ≥85% (solid) | ICP-OES (Phosphorus analysis) |
| pH (1% solution) | 9–11 | pH meter |
| Density (25°C) | 1.25–1.35 g/cm³ (liquid) | Hydrometer |
| Fe³⁺ Chelation | ≥300 mg/g | Titration with FeCl₃ |
4. Packaging & Storage
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Liquid Form:
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Stored in HDPE drums (avoid metal contact).
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Shelf life: 12–18 months at 5–40°C.
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Solid Form:
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Packed in moisture-proof bags.
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Shelf life: 24+ months if kept dry.
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5. Environmental & Safety Considerations
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Waste Treatment:
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Neutralize acidic byproducts before disposal.
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Phosphorus content may require precipitation (e.g., Ca₃(PO₄)₂) for wastewater.
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Handling PPE:
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Gloves, goggles (NaOH/formaldehyde hazards).
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Summary: TETHMP·Na₁₂ Production Flow
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Phosphonation (HMDA + H₃PO₃ + CH₂O → TETHMP acid).
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Neutralization (TETHMP + NaOH → TETHMP·Na₁₂).
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Purification (Filtration/carbon treatment).
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Concentration (Optional drying for solid form).
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QC & Packaging.
This process yields a high-performance phosphonate for demanding water treatment applications (e.g., oilfield, boilers, RO membranes).