Tetrabutyl ammonium chloride hydrate
[CAS# 37451-68-6]

Identification

• Classification: Chemical reagent >> Organic reagent >> Amine salt (ammonium salt)
• Name: Tetrabutyl ammonium chloride hydrate
• Synonyms: Tetrabutylammonium chloride hydrate
• Molecular Formula: C₁₆H₃₆N.Cl.xH₂O
• CAS Registry Number: 37451-68-6
• EC Number: 670-485-7
• SMILES: CCCC[N+](CCCC)(CCCC)CCCC.O.[Cl-]

Properties

• Melting point: 41-44 °C (Expl.)
• Flash point: >110 °C

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335

Discovery and Applications

Tetrabutylammonium chloride hydrate (C16H36ClN·xH2O) is a chemical compound composed of a tetrabutylammonium cation (C16H36N+) and a chloride anion (Cl−), with a variable number of water molecules of crystallization (denoted as xH2O). It is a quaternary ammonium salt, similar to other ammonium salts that are often used in organic synthesis and industrial applications. Tetrabutylammonium chloride hydrate is commonly encountered in hydrated form, particularly in crystallized salts, where water molecules are integrated into its crystalline structure.

### Discovery and Synthesis

Tetrabutylammonium chloride was first synthesized by reacting n-butylamine with an alkyl halide, such as methyl chloride or ethyl chloride, in the presence of a base like sodium hydroxide. This reaction leads to the formation of the desired quaternary ammonium salt, with the chloride anion typically being supplied from hydrogen chloride gas or other chloride sources. The hydrate form of tetrabutylammonium chloride is commonly obtained as a crystalline solid when synthesized in aqueous solutions and is characterized by its solubility in water and organic solvents.

### Applications

Tetrabutylammonium chloride hydrate is widely used as a phase transfer catalyst (PTC). A phase transfer catalyst is a substance that facilitates the migration of a reactant between immiscible phases (e.g., an aqueous phase and an organic phase). Tetrabutylammonium chloride hydrate is particularly useful in reactions where ionic or polar reactants are poorly soluble in the organic phase. By transferring these reactants from the aqueous phase to the organic phase, the catalyst increases the rate of reactions, such as nucleophilic substitutions and other reactions involving ionic species.

In addition to its role as a phase transfer catalyst, tetrabutylammonium chloride hydrate has found applications in organic synthesis, particularly in the alkylation of various nucleophiles, including alcohols, phenols, and thiols. The compound has been used in the preparation of alkylated products in both academic research and industrial applications. Its ability to promote reactions that would otherwise be slow or inefficient makes it a valuable tool in synthetic organic chemistry.

Tetrabutylammonium chloride hydrate has also been employed in various separations and extractions, including the extraction of metal ions and organic compounds from aqueous solutions. It can enhance the solubility of metal complexes, improving the efficiency of extraction processes. Additionally, it has been used in ion-exchange processes, where it can alter the solubility of certain ions and facilitate their movement across membranes or into organic solvents.

Another important application of tetrabutylammonium chloride hydrate is in electrochemical studies, particularly in ion-pairing and ion transport processes. It has been used in the development of electrolyte systems for various electrochemical applications, such as batteries and capacitors. The compound’s ability to stabilize ionic species in nonpolar solvents has made it an essential component in studies involving ion conduction and transport.

Tetrabutylammonium chloride hydrate has also been applied in the preparation of surfactants and detergents. The large hydrophobic butyl groups make it effective in reducing surface tension between different phases, allowing for better emulsification and stabilization of colloidal systems. This property is valuable in the formulation of cleaning agents, emulsifiers, and other products that require effective phase stabilization.

### Safety and Handling

Like many quaternary ammonium compounds, tetrabutylammonium chloride hydrate should be handled with care. It is relatively stable under normal conditions, but it should be stored in tightly sealed containers to prevent the loss of water molecules and ensure the integrity of the hydrate. The compound can be toxic if ingested or inhaled in large amounts and may cause irritation to the skin, eyes, or respiratory system. Therefore, appropriate safety measures should be taken when handling the substance, including the use of protective clothing and adequate ventilation.

### Conclusion

Tetrabutylammonium chloride hydrate is a widely used quaternary ammonium salt with significant applications in organic synthesis, phase transfer catalysis, extractions, electrochemical studies, and the production of surfactants. Its ability to facilitate reactions between immiscible phases has made it invaluable in the synthesis of various chemical intermediates, while its solubility-enhancing properties make it useful in a variety of separation and extraction processes. As a well-established reagent in both laboratory and industrial settings, tetrabutylammonium chloride hydrate plays a key role in improving the efficiency of chemical reactions and processes.

References

2023 Decarboxylative Arylation of Pyrrole-Carboxylates. Science of Synthesis, 1, 315.

2003 Tetrabutylammonium Salts of Ruthenium(II) Nitroso Complexes. Journal of Structural Chemistry, 44, 1.
DOI: 10.1023/a:1024928913498

1995 A stability-indicating HPLC method for the determination of 17β-estradiol-3-phosphate in an ophthalmic solution. Chromatographia, 40, 2.
DOI: 10.1007/bf02272172