dimethyl disulfide dmds
Molecular Composition and Formula
Dimethyl disulfide is represented by the molecular formula C2H6S2. This formula reveals its structure, consisting of two carbon atoms (C), six hydrogen atoms (H), and two sulfur atoms (S).
In simple terms, the molecule has a disulfide bond (S-S), which is sandwiched between two methyl groups (CH3). This distinct arrangement contributes to its reactive and sometimes volatile nature. Its unique composition is a key reason it’s widely used in applications like petrochemical refining and agricultural fumigation. For more details about the molecular structure, check out PubChem’s DMDS profile.
| Property | Details |
|---|
| Chemical Name | Dimethyl Disulfide (DMDS) |
| Chemical Formula | C₂H₆S₂ |
| Molecular Weight | 94.2 g/mol |
| CAS Number | 624-92-0 |
| Appearance | Colorless to pale yellow liquid |
| Odor | Strong sulfur-like odor |
| Density | 1.058 g/cm³ (at 20°C) |
| Boiling Point | 109°C |
| Melting Point | -85°C |
| Flash Point | 22°C (closed cup) |
| Solubility | Slightly soluble in water; soluble in organic solvents like ethanol, ether, and benzene |
| Stability | Stable under normal conditions; may decompose when exposed to high heat or oxidizing agents |
| Main Applications | – Used as a chemical intermediate for pesticides and pharmaceutical production |
| – Applied in petrochemical plants as a sulfiding agent and catalyst activator |
| – Intermediate in methanethiol production |
| Hazard Classification | Flammable liquid with irritant and toxic properties |
| Storage Requirements | Store in a cool, dry, and well-ventilated area, away from heat, flames, and oxidizing agents |
| Toxicity | Causes irritation to eyes, skin, and respiratory tract; inhaling high concentrations may result in poisoning |
| Environmental Information | Volatile in the environment; should not be discharged into natural water bodies |
Physical Characteristics
DMDS is a colorless to yellowish oily liquid, depending on its purity. While its appearance might seem benign, the odor is unmistakable. It has a strong, garlic-like smell that serves as a warning of its presence. This odor isn’t just descriptive—it highlights the compound’s sulfur content, often linked with pungent smells.
Here are some of its distinctive physical properties:
- Boiling Point: Around 109°C (228°F). This relatively low boiling point makes it easy to handle in industrial processes.
- Density: Heavier than water, which enhances its stability in certain applications.
- Solubility: Slightly soluble in water but mixes better with organic solvents like ethanol or methanol.
For more technical insights into its appearance and traits, refer to its Wikipedia profile.
These fundamental properties make DMDS versatile for industrial use but also demand careful handling to mitigate its risks. Let’s move forward to explore its applications and safety considerations in the broader context.
Production and Synthesis of DMDS
The production of dimethyl disulfide (DMDS) involves sourcing specific chemicals and employing well-controlled reactions to ensure high purity. Whether designed for petrochemical applications or agricultural use, the synthesis process is optimized for efficient output and minimal byproducts.
Raw Materials and Precursors
The production of DMDS begins with sourcing essential raw materials. These are the cornerstones for manufacturing a stable and efficient compound. The primary chemicals include:
- Methanol (CH3OH): A critical precursor, methanol provides the required methyl group.
- Sulfur or Sulfides: Sulfur is pivotal for forming the disulfide (S-S) bond within the molecule. Sources may include elemental sulfur or hydrogen sulfide (H2S).
- Catalysts: Industrial synthesis often employs catalysts (such as alumina) to speed up reactions and improve yields.
In addition to these, inert gases like nitrogen are sometimes used to maintain reaction stability and prevent unwanted oxidation.
Manufacturing Process
The synthesis of DMDS involves a series of controlled chemical steps. While methods may vary slightly depending on industrial requirements, the core process remains consistent:
- Preparation of Methyl Mercaptan: Methanol reacts with hydrogen sulfide (H2S) in the presence of a catalyst to produce methyl mercaptan (CH3SH). This is a crucial intermediate in DMDS formation.
- Oxidation Reaction: Methyl mercaptan is oxidized under controlled conditions to form dimethyl disulfide. Oxygen or air is typically used as the oxidizing agent, ensuring that two methyl mercaptan molecules combine to create the (S-S) bond.
- Purification: The raw DMDS product is further purified to remove impurities and byproducts like dimethyl sulfide (DMS). This is often achieved using distillation.
Industries must maintain precise temperatures and pressures throughout the process to ensure a high yield and consistent product quality. Modern advancements in synthesis methods continue to improve efficiency, reducing costs and environmental impact.
Handling, Storage, and Transportation of DMDS
Proper handling, storage, and transportation of dimethyl disulfide (DMDS) are essential to ensure safety and compliance with regulatory standards. Taking shortcuts here can increase risks to health, the environment, and operational efficiency. Below, we’ll cover essential guidelines to help you manage this compound responsibly.
Storage Guidelines
Storing DMDS safely starts with the right conditions and materials. Without proper precautions, it can degrade, pose risks to personnel, and impact surroundings.
Key storage tips:
- Temperature: Keep DMDS in a controlled environment between 15°C and 25°C (59°F to 77°F). Extreme temperatures can cause it to vaporize or destabilize.
- Containers: Use sealed steel or high-density polyethylene (HDPE) drums specifically designed for chemical storage. These prevent leaks, interaction, or evaporation.
- Location: Place containers in well-ventilated areas, away from open flames, hot surfaces, or direct sunlight. Since DMDS is flammable, reducing ignition risks is critical.
- Secondary Containment: Use spill containment pallets or bund walls to prevent leaks from spreading if a container is compromised.
- Labeling: Clear, durable labels indicating “Flammable” and “Toxic” should always be visible. Proper labeling ensures first responders and staff understand the risks.
Pay attention to national and local regulations for chemical storage, as they might introduce additional requirements.
Transportation Requirements
Transporting DMDS requires attention to detail and adherence to safety laws. Mishandling during transit can lead to fines, accidents, or environmental hazards.
Follow these transportation best practices:
- Approved Vessels: Only move DMDS in chemical-grade tanker trucks, Intermediate Bulk Containers (IBCs), or certified drums with secure closures.
- Documentation: Ensure all shipments include Material Safety Data Sheets (MSDS) and proper shipping declarations. In the U.S., it’s classified under Hazard Class 3 (Flammable Liquid) per DOT regulations.
- Route Planning: Plan routes to avoid populated or environmentally sensitive areas. This minimizes public and ecological risks if an accident occurs.
- Temperature Control: Use insulated containers if traveling through extreme climates to maintain chemical stability.
- Labeling and Marking: Make sure tanks or containers are appropriately labeled with UN2053 and hazard icons for toxic and flammable substances.
Check specific guidelines for international transport if dealing with cross-border shipments. Compliance with frameworks like ADR (Europe) or IMDG (Maritime) might be necessary depending on the mode.
Emergency Procedures
Despite best efforts, accidents can happen. Knowing how to react promptly can make all the difference in limiting harm.
Steps to manage emergencies effectively:
- Spills and Leaks:
- Evacuate unnecessary personnel from the area immediately.
- Wear chemical-resistant gloves, goggles, and respirators before addressing spills.
- Use absorbent materials like sand or commercial spill kits to contain the liquid. Never use water to dilute—the reaction might worsen the situation.
- Place contaminated materials in approved disposal containers.
- Fire:
- Suppress flames using foam, dry chemical powder, or CO2 extinguishers. Avoid water, which can spread the oil.
- Call local emergency services and evacuate the area if the fire becomes uncontrollable.
- Exposure:
- Inhalation: Move the affected person into fresh air immediately. Seek medical attention if respiratory issues occur.
- Skin Contact: Rinse thoroughly with soap and lukewarm water. Remove contaminated clothing.
- Eye Contact: Rinse eyes gently with clean water for at least 15 minutes while keeping them open.
