Product Overview
Tert dodecyl mercaptan is a branched-chain alkyl thiol serving as a critical chain transfer agent (CTA) and modifier in free-radical polymerization processes. As a clear, colorless to pale yellow liquid with a characteristic sulfurous odor, this specialty chemical plays an indispensable role in controlling polymer molecular weight and architecture. The unique structure of tert-dodecyl mercaptan makes it highly effective in regulating polymerization kinetics, directly impacting the final properties of synthetic rubbers, plastics, and resins. The reliable quality and consistent performance of tert dodecyl mercaptan are essential for manufacturers aiming to produce polymers with specific and repeatable characteristics.
Basic Information
| CAS No. | 25103-58-6 (Mixture of isomers, primarily tert-isomers) |
| UN No. | UN3071 (Mercaptans, liquid, toxic, n.o.s.) or UN3334 (Aviation regulated liquid, n.o.s.) – classification depends on specific shipping regulations and concentration. |
| Molecular Formula | C₁₂H₂₆S (typically a mixture of isomers, predominantly tertiary C12 thiols) |
| Hazard Classification | 6.1 (Toxic substance), 9 (Miscellaneous dangerous substance) |
Key Attributes & Parameters
| Purity | Typically 95-98% active content (as tert-alkyl mercaptans), with the balance being related isomers. |
| Physical State | Clear, colorless to pale yellow liquid. |
| Boiling Point/Range | Approximately 200-250°C (varies with isomer distribution) at 760 mmHg. |
| Flash Point | >80°C (typically, closed cup) – considered combustible. |
| Density | ~0.85 g/mL at 20°C. |
| Solubility | Insoluble in water; soluble in most organic solvents (alcohols, ethers, hydrocarbons). |
Features & Advantages
Highly Effective Chain Transfer Agent
The tertiary carbon atom adjacent to the thiol (-SH) group in tert dodecyl mercaptan makes it exceptionally efficient at terminating growing polymer chains and initiating new ones, allowing precise control over average molecular weight (MW) and polydispersity index (PDI).
Improved Polymer Processability
By lowering the molecular weight and viscosity of the polymer melt, it enhances flow characteristics, facilitating easier processing, molding, and extrusion.
Enhanced Product Consistency
Its reliable performance ensures batch-to-batch reproducibility in polymer production, leading to more uniform end-product properties.
Versatility Across Polymer Systems
Widely used in the production of various emulsion- and solution-polymerized polymers, including synthetic rubbers and certain thermoplastics.
Functional Characteristics
In free-radical polymerization, tert-dodecyl mercaptan functions by donating a hydrogen atom from its thiol group to a growing polymer radical. This terminates the growth of that chain while generating a new radical on the TDM molecule, which can then initiate a new polymer chain. This "chain transfer" activity effectively controls the average length of polymer chains. It is typically metered into the polymerization reactor in precise amounts, calculated as a percentage of the total monomer feed, to achieve the target molecular weight.
Primary Application Fields
Synthetic Rubber Production
The primary application is in the production of Styrene-Butadiene Rubber (SBR), both emulsion SBR (E-SBR) and solution SBR (S-SBR), where it is the dominant chain transfer agent.
Acrylonitrile Butadiene Styrene (ABS) Resins
Used to control molecular weight during the polymerization of the rubbery polybutadiene phase or the SAN matrix, impacting the toughness and processability of the final ABS.
Other Polymer Modifications
Employed in the manufacture of certain acrylic resins, methacrylate polymers, and other specialty copolymers where molecular weight regulation is critical.
Chemical Intermediate
Serves as a raw material for the synthesis of other specialty chemicals, such as certain surfactants or stabilizers.
Customer Collaboration Case
A major synthetic rubber manufacturer producing high-performance S-SBR for energy-efficient tire treads faced challenges in precisely controlling the Mooney viscosity and molecular weight distribution of their product, which directly affected rolling resistance and wet grip. We collaborated with their R&D team to optimize the use of our high-purity, low-color tert-dodecyl mercaptan. By fine-tuning the injection point and feed rate of the tert-dodecyl mercaptan in their continuous solution polymerization process, we helped them achieve a more uniform and narrower molecular weight distribution. This optimization resulted in a 15% improvement in the consistency of their polymer's viscoelastic properties. The reliable performance of our tert-dodecyl mercaptan was key to enabling the customer to meet the stringent specifications of a global tire manufacturer, securing a long-term supply contract and enhancing their market position in high-value rubber products.
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