N,N-Dimethylcyclohexylamine: Storage, Stability, and Handling Guidelines

Introduction

N,N-Dimethylcyclohexylamine (DMCHA), represented by the chemical formula C₈H₁₇N, is a tertiary amine widely used in various industrial applications, primarily as a catalyst in polyurethane foam production. Its reactivity and inherent chemical properties necessitate careful handling, storage, and adherence to specific stability guidelines to ensure product quality, safety, and efficacy. This article aims to provide comprehensive information on DMCHA, covering its properties, potential hazards, storage recommendations, stability considerations, and relevant safety protocols. The information presented is intended for professionals involved in the handling, storage, and use of DMCHA.

1. Chemical and Physical Properties

Understanding the fundamental properties of DMCHA is crucial for proper handling and storage.

Property	Value	Unit	Reference
Chemical Name	N,N-Dimethylcyclohexylamine	–
CAS Registry Number	98-94-2	–
Molecular Formula	C8H17N	–
Molecular Weight	127.23	g/mol
Appearance	Colorless to pale yellow liquid	–
Odor	Amine-like	–
Boiling Point	160-162	°C	[1, 2]
Melting Point	-60	°C	[1, 2]
Flash Point	43-46	°C (Closed Cup)	[1, 2]
Density	0.845-0.855	g/cm³ @ 20°C	[1, 2]
Refractive Index	1.447-1.451	–	[1, 2]
Vapor Pressure	1.3 hPa @ 20°C	–	[3]
Solubility in Water	Slightly soluble	–	[3]
Solubility in Organic Solvents	Soluble in most organic solvents (e.g., alcohols, ethers)	–	[3]
pKa	10.4	–	[4]

2. Potential Hazards and Safety Precautions

DMCHA, like other tertiary amines, presents certain hazards that require careful consideration and appropriate safety measures.

• Flammability: DMCHA is a flammable liquid and vapor. The low flash point necessitates keeping it away from ignition sources.
• Corrosivity: DMCHA is corrosive to skin and eyes. Direct contact can cause severe burns.
• Inhalation Hazard: Inhalation of DMCHA vapors can cause irritation of the respiratory tract, coughing, and difficulty breathing.
• Environmental Hazard: DMCHA can be harmful to aquatic life. Measures should be taken to prevent release into the environment.

Safety Precautions:

• Personal Protective Equipment (PPE): Always wear appropriate PPE when handling DMCHA, including:
  • Chemical-resistant gloves (e.g., nitrile, neoprene) 🧤
  • Safety goggles or face shield 🥽
  • Chemical-resistant apron or suit 🦺
  • Respiratory protection (if ventilation is inadequate) 😷
• Ventilation: Work with DMCHA in a well-ventilated area or under a fume hood.
• Handling: Avoid contact with skin, eyes, and clothing. Wash thoroughly after handling.
• Fire Safety: Keep DMCHA away from heat, sparks, open flames, and other ignition sources. Use explosion-proof equipment.
• Emergency Procedures:
  • Eye Contact: Immediately flush eyes with plenty of water for at least 15 minutes and seek medical attention.
  • Skin Contact: Immediately wash affected area with soap and water. Remove contaminated clothing and shoes. Seek medical attention if irritation persists.
  • Inhalation: Move to fresh air. If breathing is difficult, administer oxygen. Seek medical attention.
  • Ingestion: Do not induce vomiting. Rinse mouth with water and seek medical attention immediately.
• Spill Control: Contain spills with absorbent materials (e.g., sand, vermiculite). Dispose of contaminated materials properly according to local regulations.
• First Aid: Ensure readily available first aid kits and trained personnel are present in the work area.

3. Storage Recommendations

Proper storage of DMCHA is essential to maintain its quality, prevent degradation, and minimize potential hazards.

• Container Type: Store DMCHA in tightly closed, properly labeled containers made of compatible materials such as:
  • Stainless steel
  • Glass
  • High-density polyethylene (HDPE)
  • Avoid containers made of copper, aluminum, or other reactive metals.
• Storage Conditions:
  • Temperature: Store DMCHA in a cool, dry, well-ventilated area, away from direct sunlight and heat sources. The recommended storage temperature is between 15°C and 25°C.
  • Humidity: Keep the storage area dry to prevent moisture absorption.
  • Light: Protect DMCHA from direct sunlight and ultraviolet (UV) radiation, as these can accelerate degradation.
  • Incompatible Materials: Store DMCHA away from strong oxidizing agents, acids, and other incompatible materials.
  • Ventilation: Ensure adequate ventilation in the storage area to prevent the accumulation of vapors.
• Container Labeling: Clearly label all containers with the following information:
  • Chemical name: N,N-Dimethylcyclohexylamine
  • CAS Registry Number: 98-94-2
  • Hazard warnings
  • Storage instructions
  • Date of receipt or manufacture
• Storage Location:
  • Store DMCHA in a designated storage area specifically for flammable and corrosive materials.
  • The storage area should be equipped with appropriate fire suppression systems.
  • Restrict access to authorized personnel only.
• Inventory Management: Implement a proper inventory management system to track the quantity and age of DMCHA in storage. Use a "first-in, first-out" (FIFO) approach to minimize the risk of product degradation.

4. Stability Considerations

The stability of DMCHA can be affected by various factors, including temperature, light, air exposure, and the presence of impurities.

• Thermal Stability: DMCHA is relatively stable at room temperature. However, prolonged exposure to elevated temperatures can lead to degradation and the formation of undesirable byproducts.
• Photostability: Exposure to light, especially UV radiation, can cause DMCHA to degrade. Storing DMCHA in opaque containers or in a dark environment is recommended.
• Oxidative Stability: DMCHA can react with oxygen in the air, leading to the formation of N-oxides and other oxidation products. This process can be accelerated by the presence of catalysts such as metal ions. Proper storage in tightly closed containers under an inert atmosphere (e.g., nitrogen or argon) can minimize oxidation.
• Hydrolytic Stability: DMCHA is relatively stable in the presence of water under normal conditions. However, prolonged exposure to acidic or alkaline conditions can promote hydrolysis.
• Effect of Impurities: The presence of impurities, such as metal ions or other reactive compounds, can catalyze the degradation of DMCHA. Using high-purity DMCHA and storing it in clean containers can minimize this risk.

Stability Testing:

Regular stability testing is recommended to monitor the quality of DMCHA during storage. Common stability tests include:

• Appearance: Visual inspection for color changes, turbidity, or the formation of precipitates.
• Assay: Determination of the DMCHA content using titration, gas chromatography (GC), or other suitable analytical methods.
• Acidity: Measurement of the acidity of the DMCHA sample using titration or pH measurement.
• Water Content: Determination of the water content using Karl Fischer titration.
• Peroxide Content: Measurement of the peroxide content using iodometric titration or other suitable methods.
• Gas Chromatography (GC): GC analysis can identify and quantify any degradation products that may have formed.

Test Parameter	Acceptable Range	Test Method	Frequency
Appearance	Colorless to pale yellow, clear liquid	Visual Inspection	Every 3-6 months
Assay (GC)	≥ 99.0%	Gas Chromatography	Every 3-6 months
Acidity (as HCl)	≤ 0.1%	Titration	Every 3-6 months
Water Content (KF)	≤ 0.2%	Karl Fischer Titration	Every 3-6 months
Peroxide Content	≤ 10 ppm	Iodometric Titration	Every 3-6 months

5. Handling and Disposal

• Handling:
  • Minimize exposure to air and moisture during handling.
  • Use appropriate dispensing equipment to avoid spills and leaks.
  • Avoid generating aerosols or vapors.
  • Ensure adequate ventilation in the handling area.
• Waste Disposal:
  • Dispose of DMCHA and contaminated materials in accordance with local, state, and federal regulations.
  • Do not pour DMCHA down the drain.
  • Incineration is a common method for disposing of DMCHA.
  • Consult with a licensed waste disposal company for proper disposal procedures.

6. Applications and Considerations

DMCHA finds its primary application as a catalyst in the production of polyurethane foams. Its use is carefully managed to optimize the reaction kinetics and the final properties of the foam.

• Polyurethane Foam Production: DMCHA catalyzes the reaction between polyols and isocyanates, which are the main components of polyurethane foam. The concentration of DMCHA used affects the rate of the reaction and the properties of the resulting foam, such as density, hardness, and cell structure.
• Other Applications: DMCHA is also used as a building block in the synthesis of other organic compounds and as a corrosion inhibitor.
• Regulatory Considerations: DMCHA is subject to various regulations regarding its manufacture, handling, and use. It’s crucial to comply with all applicable regulations to ensure safety and environmental protection.

7. Conclusion

N,N-Dimethylcyclohexylamine is a valuable chemical compound with diverse industrial applications. However, its flammability, corrosivity, and potential environmental hazards necessitate careful handling, storage, and disposal practices. By adhering to the guidelines outlined in this article, professionals can ensure the safe and effective use of DMCHA while minimizing risks to human health and the environment. Regular monitoring of product quality through stability testing is crucial for maintaining its efficacy and preventing potential issues arising from degradation. Always consult the Safety Data Sheet (SDS) for the most up-to-date information and safety recommendations.

8. Future Directions

Research and development efforts are continuously focused on improving the stability and handling characteristics of DMCHA. This includes exploring new additives and stabilizers to enhance its resistance to oxidation, light, and heat, as well as developing more environmentally friendly alternatives. Furthermore, advancements in analytical techniques allow for more precise monitoring of DMCHA quality and degradation products.

References:

[1] Sigma-Aldrich. Safety Data Sheet for N,N-Dimethylcyclohexylamine.

[2] Alfa Aesar. Safety Data Sheet for N,N-Dimethylcyclohexylamine.

[3] PubChem. N,N-Dimethylcyclohexylamine. National Center for Biotechnology Information.

[4] Perrin, D. D. Dissociation Constants of Organic Bases in Aqueous Solution. Butterworths: London, 1965.

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