2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7): Properties, Uses, and Safety
Introduction:
2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane, identified by its Chemical Abstracts Service (CAS) number 78-63-7, is a significant industrial chemical belonging to the class of organic peroxides. This compound is also widely recognized by its trade names, most notably Trigonox 101 and Luperox 101. Its primary industrial importance lies in its role as a highly effective free radical initiator in the production of various polymers. Additionally, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) serves as a crucial crosslinking agent for both synthetic and natural rubbers, as well as polyolefins. This article aims to provide a comprehensive overview of the chemical properties, diverse applications, key benefits, potential hazards, necessary precautions, and the manufacturing process associated with 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7). While its direct use as a pharmaceutical ingredient is not evident, its applications in the production of polymers may have relevance in the manufacturing of pharmaceutical packaging, medical devices, and other related materials.
Chemical Properties of 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7):
The molecular formula of 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) is C16H34O4 , and it has a molecular weight of 290.44 g/mol. At room temperature, it typically presents as a clear to light yellow liquid. It is important to note that for enhanced safety during storage and transportation, this chemical may be mixed with an inert solid.
The melting point of 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) is reported to be around 6°C , with some sources indicating a slightly higher value of 8°C. The boiling point exhibits variability depending on the pressure at which it is measured. A range of 55-57°C at a reduced pressure of 7 mmHg has been reported, as well as 122 to 126 °F at an even lower pressure of 0.1 mmHg. Notably, at atmospheric pressure (760 Torr), the boiling point is significantly higher, reported as 306.50 °C ± 25 °C. This substantial difference underscores the importance of specifying the pressure when discussing the boiling point of this compound. The density is approximately 0.87 g/mL at 25°C , and its specific gravity is also around 0.87.
The flash point, an indicator of flammability, also varies across different reports, possibly due to different testing methodologies. Values reported include 68°C , 36°C (closed cup) and 58°C (open cup) , 149 °F (65°C) , and 185 °F (85°C). This range highlights the flammable nature of the compound and the need for careful handling. Regarding solubility, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) is immiscible or insoluble in water but demonstrates good solubility in organic solvents and alcohol. Specifically, it is soluble in chloroform and sparingly soluble in methanol. The viscosity of the compound is reported as 6.4 mPa.s at 20°C or 7.35 mPa.s at 12 rpm (20°C).
In terms of stability and reactivity, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) is considered unstable and may contain an inhibitor to prevent premature decomposition. It exhibits incompatibility with strong oxidizing agents, acids, reducing agents, organic materials, and powdered metals. Furthermore, it acts as a strong oxidizing agent. Heating the compound can lead to fire. A critical safety parameter is its self-accelerating decomposition temperature (SADT), which is around 80°C. Exceeding this temperature can result in a hazardous exothermic reaction. There is also a significant danger of explosion if the compound is allowed to dry.
| Property | Value(s) | |
|---|---|---|
| Molecular Formula | C16H34O4 | |
| Molecular Weight | 290.44 g/mol | |
| Physical State | Clear to light yellow liquid | |
| Melting Point | ~6-8°C | |
| Boiling Point | 55-57°C at 7 mmHg; 122-126 °F at 0.1 mmHg; 306.50 °C ± 25 °C @ 760Torr | |
| Density | ~0.87 g/mL at 25°C | |
| Flash Point | 68°C, 36°C/58°C, 65°C, 85°C | |
| Solubility in Water | Immiscible/Insoluble | |
| Solubility in Other Solvents | Soluble in organic solvents and alcohol, chloroform; sparingly soluble in methanol | |
| Viscosity | 6.4 mPa.s at 20°C; 7.35 mPa.s at 12 rpm (20°C) | |
| Stability | Unstable, may contain inhibitor | |
| Reactivity | Strong oxidizing agent, incompatible with various substances, heating may cause fire, danger of explosion when dry | |
| SADT | ~80°C |
Uses and Applications of 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7):
2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) finds extensive use in the polymer industry. It is a primary free radical initiator in the polymerization processes of various monomers, including polypropylene (PP) , polyethylene (PE) , polystyrene , as well as acrylates and methacrylates. Its ability to initiate polymerization across a range of monomers highlights its broad applicability in creating diverse polymer materials.
Furthermore, this compound is highly effective as a crosslinking agent for both natural and synthetic rubbers, such as vinyl silicone rubber, polyurethane rubber, ethylene propylene rubber, EPDM, FKM, and HNBR , and polyolefins. A notable application is in the production of cross-linked polyethylene (XLPE), which is used in the manufacturing of power cables and pipes. The crosslinking process enhances the thermal and mechanical properties of these materials, making them more durable and suitable for demanding applications.
Another significant application of 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) is in the controlled rheology of polypropylene (CR-PP). It is used to initiate the degradation of polypropylene in a controlled manner, thereby adjusting its melt flow index (MFI). This is crucial for tailoring the properties of the final polypropylene product, including recycled polypropylene. This controlled modification allows for the production of polypropylene with specific performance characteristics required for various end uses.
Beyond these primary applications, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) is also utilized as a chaser catalyst to effectively reduce residual monomer levels during styrene polymerization. Additionally, it functions as a curing agent for unsaturated polyester and vinyl ester resins. Its applications extend to thermoset composites and acrylics , and there is potential for its use in the production of medical articles and O-rings. The compound’s ability to readily generate free radicals under specific conditions likely contributes to its wide range of applications in polymer chemistry.
Key Benefits of Using 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane:
The use of 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) offers several key benefits in various industrial applications. In rubber products, it enhances tensile strength and hardness. When used as a crosslinking agent for polyolefins, it improves their thermal stability and mechanical properties. This results in materials that are more durable and resistant to demanding conditions.
In the processing of polypropylene, this compound allows for precise control of the melt flow index , providing manufacturers with the flexibility to tailor the polymer’s properties for specific applications. It can also be used to produce polypropylene with a low molecular weight and a narrow molecular weight distribution , which is beneficial for certain high-performance applications.
As a crosslinking agent, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) acts as an effective high-temperature vulcanizer for a variety of rubbers, including vinyl silicone rubber. Notably, it offers excellent scorch safety in rubber compounds. Scorch refers to the premature vulcanization of rubber, which can lead to processing difficulties and material waste. The excellent scorch safety provided by this compound allows for a longer processing window before curing begins, improving manufacturing efficiency.
Furthermore, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) is a versatile free radical initiator suitable for a wide range of polymerization reactions. In certain applications, its decomposition produces volatile, odor-free byproducts , which is advantageous when the odor of the final product is a concern, such as in consumer goods or medical devices. Additionally, it does not cause blooming on the vulcanization surface of rubber , ensuring a high-quality finish. This compound is also effective in curing engineered rubber compounds that contain fillers like carbon black , making it suitable for a broad range of industrial rubber products. The high scorch times associated with its use in some applications further contribute to safer processing.
Potential Side Effects and Important Precautions:
2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) is classified as an organic peroxide and is considered a hazardous material. It presents several potential hazards that necessitate careful handling and storage. Heating the compound can cause a fire , and it may explode if exposed to heat or contamination. There is a significant danger of explosion if the compound is allowed to dry. It is a flammable liquid and can readily ignite combustible materials.
Exposure to 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) can have adverse health effects. It is known to cause skin irritation and eye irritation. It may also be harmful if inhaled or absorbed through the skin. Studies have indicated moderate toxicity through the intraperitoneal route , and there is suspicion that it may cause genetic defects.
To ensure safety when handling and storing 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7), several precautions must be strictly followed. It should be kept away from heat, sparks, open flames, and other ignition sources , and smoking should be prohibited in areas where it is handled. The compound must be stored away from clothing and other combustible materials. Appropriate personal protective equipment (PPE), including gloves, protective clothing, eye protection, and face protection, should be worn when handling this chemical. Storage should be in a well-ventilated place, and the compound should be kept cool in a tightly closed container. It is also crucial to store it away from reducing agents, acids, alkalis, and heavy metal compounds , and to avoid shock and friction. Protection from sunlight is also recommended , and the compound should not be allowed to dry. In case of skin contact, wash thoroughly with soap and water. For eye contact, flush with plenty of water for at least 15 minutes and seek medical attention. If inhaled, move to fresh air. If ingested, do not induce vomiting and seek immediate medical help. Disposal of the compound and its container should be carried out in accordance with applicable local, regional, and national regulations.
Manufacturing Process of 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane:
The industrial manufacturing of 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) typically involves the chemical reaction between 2,5-dimethyl-1,5-hexadiene and tert-butyl hydroperoxide. This reaction is generally conducted under acid catalysis in a solvent that is substantially anhydrous. The use of an acid catalyst facilitates the reaction by protonating the peroxide, making it more electrophilic and reactive towards the olefin.
In some manufacturing processes, an electron pair acceptor Lewis acid may also be employed to further enhance the reaction. Examples of such Lewis acid catalysts include boron trifluoride etherate and zinc chloride-ether. These catalysts can coordinate with the peroxide oxygen, further activating it. If the tert-butyl hydroperoxide used in the process is of technical grade and contains water, a preliminary step to remove the water may be necessary. This can be achieved by mixing it with the 2,5-dimethyl-1,5-hexadiene and then adding a dehydrating agent such as sulfuric acid or calcium chloride, followed by the addition of the electron pair acceptor Lewis acid.
The chemical reaction between 2,5-dimethyl-1,5-hexadiene and tert-butyl hydroperoxide results in the formation of 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) and water as a byproduct. The reported reaction yield for this process is approximately 79% in some industrial settings. Following the initial reaction, the crude product typically undergoes purification steps to achieve the desired high level of purity. Common purification methods include vacuum distillation and distillation with air purging. Vacuum distillation is used to lower the boiling point of the product, allowing for purification at lower temperatures, which helps to prevent thermal decomposition. Air purging during distillation can also be employed to remove volatile impurities. The choice of purification method may depend on factors such as cost-effectiveness, scalability, and the specific purity requirements for the intended applications.
Conclusion:
2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) is a chemically significant compound primarily utilized in the polymer industry for its properties as a free radical initiator and a crosslinking agent. Its key chemical and physical properties, including its molecular formula, molecular weight, physical state, and reactivity, dictate its applications in the production of a wide range of polymers and rubbers. While offering numerous benefits such as improved material properties, controlled polymer modification, and efficient crosslinking, it is crucial to acknowledge and carefully manage its potential hazards. Strict adherence to safety precautions during handling, storage, and disposal is paramount due to its flammability, potential for explosion, and irritant effects. The manufacturing process typically involves the reaction of 2,5-dimethyl-1,5-hexadiene with tert-butyl hydroperoxide under acid catalysis, followed by purification. Although not a direct pharmaceutical ingredient, 2,5-Dimethyl-2,5-di(tert-butylperoxy)hexane (CAS 78-63-7) plays an indirect role in the pharmaceutical industry through its use in the production of various materials such as medical devices and packaging, highlighting its broader industrial importance.