N,N-Dimethylcyclohexylamine (DMCHA): A Comprehensive Overview

Introduction

N,N-Dimethylcyclohexylamine (DMCHA), also known as 1-Cyclohexyl-N,N-dimethylamine, is a tertiary amine with the chemical formula C₈H₁₇N. It is a colorless to pale yellow liquid with a characteristic amine odor. DMCHA finds widespread application as a catalyst in the production of polyurethane foams, a starting material for various organic syntheses, and as a corrosion inhibitor. This article provides a comprehensive overview of DMCHA, encompassing its physical and chemical properties, synthesis methods, applications, safety considerations, and global manufacturers. The information presented aims to provide a detailed understanding of this important chemical compound.

1. Chemical and Physical Properties

DMCHA exhibits a range of characteristic physical and chemical properties that dictate its behavior and applications. Understanding these properties is crucial for handling, storage, and utilization of the compound.

1.1 Physical Properties

Property	Value	Unit	Reference
Molecular Weight	127.23	g/mol	[1]
Appearance	Colorless to pale yellow liquid	–	[2]
Odor	Amine-like	–	[2]
Density (at 20°C)	0.845 – 0.855	g/cm3	[3]
Boiling Point	158 – 162	°C	[3]
Melting Point	-60	°C	[4]
Flash Point	41 – 43	°C	[3]
Refractive Index (nD20)	1.445 – 1.450	–	[3]
Solubility in Water	Slightly soluble (approx. 1 g/100 mL)	g/100 mL	[5]
Vapor Pressure (at 20°C)	0.7 kPa	kPa	[6]

1.2 Chemical Properties

• Basicity: DMCHA, being a tertiary amine, is a base and can react with acids to form salts. This property is crucial for its role as a catalyst in polyurethane foam production.
• Reactivity with Isocyanates: DMCHA catalyzes the reaction between polyols and isocyanates, the core process in polyurethane formation. It acts as a nucleophile, facilitating the addition of the polyol to the isocyanate group.
• Corrosion Inhibition: DMCHA can act as a corrosion inhibitor by forming a protective layer on metal surfaces, preventing oxidation and degradation.
• Stability: DMCHA is generally stable under normal storage conditions. However, it should be stored in tightly sealed containers to prevent absorption of moisture and carbon dioxide from the air.
• Flammability: DMCHA is a flammable liquid and should be handled with appropriate precautions.

2. Synthesis Methods

Several methods exist for the synthesis of DMCHA, each with its own advantages and disadvantages in terms of yield, cost, and environmental impact.

2.1 Reductive Amination of Cyclohexanone:

This is a common and widely used method. It involves the reaction of cyclohexanone with dimethylamine in the presence of a reducing agent, such as hydrogen gas and a catalyst (e.g., nickel or palladium), or a hydride reducing agent (e.g., sodium borohydride).

Cyclohexanone + Dimethylamine + Reducing Agent → DMCHA + Water

Advantages: Relatively high yield, readily available starting materials.
Disadvantages: Requires specialized equipment for handling hydrogen gas or requires careful control when using hydride reducing agents.

2.2 Alkylation of Cyclohexylamine:

This method involves the alkylation of cyclohexylamine with methylating agents, such as dimethyl sulfate or methyl iodide. This process typically requires multiple steps to introduce two methyl groups.

Cyclohexylamine + Methylating Agent → N-Methylcyclohexylamine
N-Methylcyclohexylamine + Methylating Agent → DMCHA

Advantages: Can be tailored to produce specific amine derivatives.
Disadvantages: Can be more complex than reductive amination, may require multiple purification steps.

2.3 Reaction of Cyclohexanol with Dimethylamine and a Catalyst:

This method involves the reaction of cyclohexanol with dimethylamine in the presence of a suitable catalyst, such as a metal oxide or a zeolitic catalyst, at elevated temperatures.

Cyclohexanol + Dimethylamine → DMCHA + Water

Advantages: Utilizes a less hazardous starting material (cyclohexanol).
Disadvantages: May require higher temperatures and specialized catalysts. Lower yields compared to reductive amination.

2.4 Grignard Reaction (Less Common):

While less common for industrial production, a Grignard reaction involving a cyclohexyl Grignard reagent and dimethylformamide (DMF) followed by hydrolysis can yield DMCHA.

Cyclohexyl-MgX + DMF → Intermediate
Intermediate + H2O → DMCHA + ...

Advantages: Useful for small-scale synthesis or specific research applications.
Disadvantages: Grignard reagents are highly reactive and moisture-sensitive, making this method less practical for large-scale production.

3. Applications

DMCHA boasts a wide array of applications, primarily driven by its catalytic activity and amine functionality.

3.1 Polyurethane Foam Production:

This is the dominant application of DMCHA. It acts as a catalyst in the reaction between polyols and isocyanates, which are the building blocks of polyurethane foams. DMCHA promotes both the urethane (polyol-isocyanate) reaction and the blowing reaction (isocyanate-water), leading to the formation of a foamed polymer structure. It is particularly effective in rigid polyurethane foams.

Application	Role of DMCHA	Benefits
Rigid Polyurethane Foams	Catalyst for urethane and blowing reactions	Controlled cell structure, improved foam stability, faster cure rates
Flexible Polyurethane Foams	Co-catalyst with other amine or organometallic catalysts	Enhanced foam properties, improved processing characteristics
Polyurethane Coatings & Elastomers	Catalyst for chain extension and crosslinking reactions	Improved mechanical properties, faster cure times, enhanced chemical resistance

3.2 Catalyst in Other Reactions:

DMCHA can catalyze other chemical reactions beyond polyurethane formation, including:

• Epoxy Resin Curing: It can act as an accelerator in the curing of epoxy resins, promoting the crosslinking reaction between the epoxy resin and the curing agent.
• Transesterification Reactions: DMCHA can catalyze transesterification reactions, which are important in the production of biodiesel and other esters.

3.3 Corrosion Inhibitor:

DMCHA can be used as a corrosion inhibitor, particularly in aqueous systems. It forms a protective layer on metal surfaces, preventing oxidation and corrosion. It is often used in cooling water systems and metalworking fluids.

3.4 Intermediate in Organic Synthesis:

DMCHA serves as a versatile building block in organic synthesis for the preparation of various chemical compounds, including pharmaceuticals, agrochemicals, and other specialty chemicals. It can be used to introduce a cyclohexyl group or a dimethylamino group into a molecule.

3.5 Pharmaceutical Applications (Limited):

While less common, DMCHA derivatives have been explored for potential pharmaceutical applications. For example, quaternary ammonium salts derived from DMCHA have shown some biological activity. Research in this area is ongoing.

4. Safety Considerations

DMCHA is a chemical compound that requires careful handling and storage due to its potential hazards.

4.1 Health Hazards:

• Skin and Eye Irritation: DMCHA is a strong irritant to the skin and eyes. Contact can cause redness, pain, and burns.
• Respiratory Irritation: Inhalation of DMCHA vapors can cause irritation of the respiratory tract, leading to coughing, shortness of breath, and sore throat.
• Ingestion: Ingestion of DMCHA can cause gastrointestinal irritation, nausea, vomiting, and diarrhea.
• Sensitization: Prolonged or repeated exposure to DMCHA may cause skin sensitization in some individuals.

4.2 Flammability Hazards:

DMCHA is a flammable liquid and its vapors can form explosive mixtures with air. It should be kept away from heat, sparks, and open flames.

4.3 Environmental Hazards:

The environmental impact of DMCHA is not fully characterized. However, it is important to prevent its release into the environment. It should be disposed of properly in accordance with local regulations.

4.4 Handling and Storage Precautions:

• Wear appropriate personal protective equipment (PPE), including gloves, safety glasses, and a respirator when handling DMCHA.
• Work in a well-ventilated area.
• Avoid contact with skin, eyes, and clothing.
• Do not ingest or inhale DMCHA.
• Store DMCHA in tightly sealed containers in a cool, dry, and well-ventilated area.
• Keep away from heat, sparks, and open flames.
• Avoid contact with strong oxidizing agents, strong acids, and isocyanates.
• Dispose of DMCHA waste in accordance with local regulations.

4.5 First Aid Measures:

• Eye Contact: Immediately flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids. Seek medical attention.
• Skin Contact: Immediately wash skin with soap and water for at least 15 minutes. Remove contaminated clothing and shoes. Seek medical attention if irritation persists.
• Inhalation: Remove to fresh air. If breathing is difficult, administer oxygen. Seek medical attention.
• Ingestion: Do not induce vomiting. Rinse mouth with water. Seek medical attention immediately.

5. Global Manufacturers

Several global manufacturers produce DMCHA for various applications. This list is not exhaustive, and specific manufacturers may vary depending on geographic location and market conditions.

Manufacturer	Location	Product Grade Information (Example)
Huntsman Corporation	The Woodlands, Texas, USA	PURELAST® DMCHA (typically >99% purity, low water content)
Evonik Industries AG	Essen, Germany	TEGOAMIN® DMCHA (specification sheets detail purity, water content, and other relevant parameters)
Tosoh Corporation	Tokyo, Japan	Various grades, potentially with specific modifications for different polyurethane applications
Lanxess AG	Cologne, Germany	Actively involved in polyurethane raw materials, may produce or distribute DMCHA
BASF SE	Ludwigshafen, Germany	Supplier of polyurethane raw materials, potentially producing or distributing DMCHA
Wanhua Chemical Group Co., Ltd.	Yantai, China	Major polyurethane producer, likely a significant producer of DMCHA for internal and external use
Luxi Chemical Group Co., Ltd.	Liaocheng, China	Producer of various chemical products, including amines and potentially DMCHA
Shandong Dongda Chemical Co., Ltd.	Zibo, China	Specializes in the production of amine catalysts, including DMCHA

Note: Product grade information can vary significantly between manufacturers. It is essential to consult the manufacturer’s specification sheet for detailed information on purity, water content, and other relevant parameters. Contacting the manufacturer directly is always recommended for the most up-to-date product information and availability.

6. Quality Control and Analysis

Ensuring the quality of DMCHA is crucial for its effective performance in various applications. Several analytical techniques are employed to assess its purity and other relevant properties.

6.1 Gas Chromatography (GC):

GC is a widely used technique for determining the purity of DMCHA. It separates the different components of the sample based on their boiling points and allows for the quantification of DMCHA and any impurities present.

6.2 Titration:

Titration with a standard acid solution can be used to determine the amine content of DMCHA. This provides a measure of the basicity of the compound.

6.3 Karl Fischer Titration:

This method is used to determine the water content of DMCHA. Low water content is often critical for its performance as a catalyst in polyurethane foam production.

6.4 Spectroscopic Methods:

• Infrared (IR) Spectroscopy: IR spectroscopy can be used to identify the characteristic functional groups present in DMCHA and to detect the presence of any impurities.
• Nuclear Magnetic Resonance (NMR) Spectroscopy: NMR spectroscopy provides detailed information about the structure of DMCHA and can be used to confirm its identity and purity.

6.5 Density Measurement:

Density measurement is a simple and quick method for assessing the quality of DMCHA. It can be used to detect any significant deviations from the expected value.

7. Market Trends and Future Outlook

The market for DMCHA is closely tied to the polyurethane industry, which is experiencing steady growth driven by increasing demand for polyurethane foams in various applications, including:

• Construction: Insulation materials, roofing, and flooring.
• Automotive: Seating, interior trim, and soundproofing.
• Furniture: Mattresses, upholstery, and cushioning.
• Appliances: Refrigerators, freezers, and washing machines.

7.1 Drivers of Market Growth:

• Increasing demand for polyurethane foams: This is the primary driver of market growth for DMCHA.
• Growing construction industry in developing countries: This is leading to increased demand for polyurethane insulation materials.
• Increasing demand for lightweight materials in the automotive industry: Polyurethane foams are used to reduce the weight of vehicles, improving fuel efficiency.
• Stringent energy efficiency regulations: This is driving demand for high-performance insulation materials, such as polyurethane foams.

7.2 Challenges and Opportunities:

• Environmental concerns: The use of DMCHA and other amine catalysts in polyurethane foam production can contribute to volatile organic compound (VOC) emissions. This is driving research into alternative catalysts with lower VOC emissions.
• Price volatility of raw materials: Fluctuations in the price of raw materials, such as cyclohexanone and dimethylamine, can impact the profitability of DMCHA production.
• Development of bio-based DMCHA alternatives: Research is underway to develop DMCHA alternatives derived from renewable resources, which could reduce the environmental impact of polyurethane foam production.
• Expanding applications in other industries: Exploring new applications for DMCHA in other industries, such as pharmaceuticals and agrochemicals, could drive future market growth.

8. Conclusion

N,N-Dimethylcyclohexylamine (DMCHA) is a versatile chemical compound with significant industrial importance, primarily as a catalyst in polyurethane foam production. Its properties, synthesis, applications, and safety considerations are well-defined. Understanding the global market trends and ongoing research efforts will be crucial for the continued development and application of DMCHA in the future. As environmental concerns become increasingly important, research into sustainable alternatives and methods to reduce VOC emissions will be critical for the long-term viability of DMCHA and the polyurethane industry as a whole.

Literature Sources

[1] CRC Handbook of Chemistry and Physics, 97th Edition, CRC Press, 2016.

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

[3] ChemicalBook: N,N-Dimethylcyclohexylamine.

[4] SciFinder database, American Chemical Society.

[5] Yalkowsky, S.H., Yan, H., Solubility and Solubilization in Aqueous Media, American Chemical Society, 1999.

[6] Daubert, T.E., Danner, R.P., Physical and Thermodynamic Properties of Pure Chemicals Data Compilation, Design Institute for Physical Property Data, AIChE, 1989.

[7] Oertel, G. Polyurethane Handbook, 2nd Edition, Hanser Gardner Publications, 1994.

[8] Rand, L., Thir, B.F., Stamberger, P., J. Appl. Polym. Sci., 1959, 2, 293. (Example of early research on amine catalysts)

[9] Ulrich, H. Introduction to Industrial Polymers, 2nd Edition, Hanser Publishers, 1993.

[10] Ashida, K. Polyurethane and Related Foams: Chemistry and Technology. CRC Press, 2006.

[11] Kirk-Othmer Encyclopedia of Chemical Technology, John Wiley & Sons. (General reference for chemical substances)

[12] Ullmann’s Encyclopedia of Industrial Chemistry, Wiley-VCH. (General reference for chemical substances)

[13] Patent Literature: Search for DMCHA synthesis and applications on databases like Google Patents and Espacenet. (Specific patents would be cited individually if referenced directly).

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