Aliquat 336 is a trade name for a series of quaternary ammonium salts, most commonly the chloride salt of methyltrioctylammonium (tricaprylylmethylammonium chloride). It functions primarily as a phase‑transfer catalyst and is widely employed in organic synthesis, industrial separations, and oil‑field applications.
Chemical identity
- Systematic name: methyltrioctylammonium chloride
- Molecular formula: C₂₆H₅₈ClN
- Molar mass: 425.22 g mol⁻¹
- CAS Registry Number: 133-77-5 (for the chloride salt)
- Physical state: Viscous, colorless to pale yellow liquid at ambient temperature
- Solubility: Practically insoluble in water; miscible with many organic solvents such as benzene, toluene, chloroform, and kerosene.
Structure and properties
Aliquat 336 consists of a quaternary nitrogen center bearing one methyl group and three octyl (C₈) alkyl chains, balanced by a chloride anion. The long hydrophobic alkyl groups provide strong affinity for non‑polar phases, while the positively charged nitrogen enables interaction with anionic species in aqueous media, thereby facilitating the transport of ions across immiscible phase boundaries.
Key physicochemical parameters (reported for the chloride salt) include:
- Density: ≈ 0.94 g cm⁻³ at 20 °C
- Viscosity: 30–50 cP (varies with temperature)
- Flash point: > 150 °C (no flash point reported under standard test conditions)
Applications
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Phase‑transfer catalysis (PTC)
Aliquat 336 is employed to accelerate reactions between reagents located in separate phases, such as the nucleophilic substitution of alkyl halides, the condensation of nitriles, and the synthesis of heterocycles. By forming ion pairs with inorganic anions (e.g., OH⁻, CN⁻, SCN⁻), it transports these species into the organic phase where they react with organic substrates. -
Solvent extraction and metal ion recovery
Its ability to form lipophilic ion pairs makes it useful for extracting metal ions (e.g., Au³⁺, Pt⁴⁺, Pd²⁺, rare‑earth elements) from aqueous solutions into organic diluents. It is employed in hydrometallurgical processes and in the treatment of industrial waste streams. -
Oil‑field chemistry
In enhanced oil recovery, Aliquat 336 is added to drilling fluids or surfactant formulations to improve emulsification, inhibit scale formation, and facilitate the transport of corrosion inhibitors. -
Analytical chemistry
The reagent is used in certain titrimetric and spectrophotometric methods for the determination of halides and other anions, where it enhances the extraction of the analyte into an organic phase for measurement.
Manufacture
Aliquat 336 is typically produced by quaternization of trimethylamine with a mixture of 1‑bromo‑octane (or 1‑chlorooctane) under controlled conditions, followed by chloride ion exchange and purification steps to remove residual halides and low‑molecular‑weight by‑products. Commercial preparations may contain a distribution of alkyl chain lengths due to the use of technical octyl halide mixtures.
Safety and environmental information
- Hazard classification: According to the Globally Harmonized System (GHS), Aliquat 336 is classified as a skin and eye irritant (Category 2) and may cause respiratory irritation.
- Toxicity: Acute oral LD₅₀ values for rodents are in the range of 1,200–2,500 mg kg⁻¹, indicating moderate toxicity. Chronic exposure data are limited.
- Handling precautions: Use personal protective equipment (gloves, goggles, lab coat) and work in a well‑ventilated area or fume hood. Avoid release into waterways; the compound exhibits low biodegradability and may persist in aquatic environments.
- Regulatory status: Listed in various chemical inventories (e.g., TSCA, REACH). Specific restrictions may apply in certain jurisdictions when used in large‑scale industrial processes.
Related compounds
- Aliquat 336 bromide (the bromide salt)
- Aliquat 336 nitrate (nitrate salt)
- Other quaternary ammonium phase‑transfer catalysts such as tetrabutylammonium bromide (TBAB) and benzyltriethylammonium chloride (BTEAC).
References
(References are typically drawn from peer‑reviewed journals, safety data sheets, and chemical supplier catalogs; specific citations are omitted here per the instruction to avoid fabrication.)
