Characteristics of Dodecyl Trimethyl Ammonium Chloride (DTAC)

Dodecyl Trimethyl Ammonium Chloride (DTAC) is a versatile cationic surfactant belonging to the quaternary ammonium compound (QAC) family. Its characteristics are defined by its chemical structure, physicochemical properties, and broad range of functionalities.

Core Physicochemical Properties

DTAC is a quaternary ammonium salt with the chemical formula C₁₅H₃₄ClN and a molecular weight of 263.89. Key physical properties include:

Appearance: The physical form of DTAC varies. Pure (≥98%) material is typically a white to off-white solid or powder, while lower concentration commercial solutions (e.g., 30-50%) appear as colorless to yellow transparent liquids or colloids.

Solubility: It is highly soluble in water and also dissolves well in polar organic solvents like ethanol, acetone, methanol, and chloroform. However, it is insoluble in non-polar solvents like ether and benzene.

Acidity (pH): A 50 g/L aqueous solution of DTAC typically has a pH between 4.0 and 7.5.

Hygroscopic Nature: DTAC is hygroscopic, meaning it readily absorbs moisture from the air. It should be stored in a dry, sealed environment to prevent clumping and degradation.

Functional Characteristics & Applications

As a cationic surfactant, the DTAC molecule possesses a positively charged quaternary ammonium head and a long hydrophobic dodecyl tail. This structure gives it several key functional characteristics:

Surfactant & Emulsifier: It effectively reduces surface tension and can stabilize emulsions. This makes it useful in emulsion polymerization for synthetic rubber and resins, architectural waterproof coatings, and as a pigment dispersant.

Antistatic Agent: The cationic nature of DTAC allows it to adsorb onto surfaces like fabrics and fibers, neutralizing static charges. This makes it suitable as a softener and antistatic finishing agent in the textile industry.

Biocide / Disinfectant: DTAC exhibits antimicrobial properties, making it effective as a bactericide and algicide. It is used in industrial water treatment systems, oilfield injection water, and as a disinfectant in food processing and healthcare environments.

Phase Transfer Catalyst: In organic synthesis, DTAC can act as a phase transfer catalyst to facilitate reactions between compounds in different phases.

Biotechnology Reagent: It is used as a hemolytic agent in automated blood analyzers, where it selectively lyses red blood cells while preserving white blood cells.

Stability, Compatibility & Safety

Stability: DTAC demonstrates good chemical stability, maintaining its surfactant properties under acidic and alkaline conditions and at temperatures below 100°C. It is also stable to heat and light.

Compatibility: It shows excellent compatibility with other cationic and nonionic surfactants, but it is incompatible with anionic surfactants and should not be mixed with them.

Safety & Hazards: DTAC is an irritant, causing skin and eye irritation. It is also very toxic to aquatic life with long-lasting effects. It should be handled with appropriate protective equipment, and contact with skin and eyes should be avoided.