Dicyclohexylamine, Dicyclo Hexyl Amine, Dicyclo Hexyl Amine, Dodecahydro Diphenyl Amine, DCHA, 101-83-7

DICYCLOHEXYLAMINE (DCHA)

Dicyclohexylamine / Dicyclo Hexyl Amine / Dodecahydro Diphenyl Amine / DCHA
CAS Number: 101-83-7
EC Number: 202-980-7

1. PRODUCT IDENTIFICATION AND CHEMICAL IDENTITY

Dicyclohexylamine (DCHA) is a secondary alicyclic amine consisting of two cyclohexyl groups attached to a nitrogen atom. It is a colorless to pale yellow liquid at room temperature with a strong, penetrating, ammonia-like amine odor. Due to its relatively high melting point (-0.1 to -2°C), it can solidify at slightly below room temperature, appearing as a white to off-white crystalline mass. It is a strongly basic compound with a pKa of 10.4, making it a useful reagent for salt formation and as a catalyst in various organic reactions. DCHA is an important industrial chemical with applications in rubber and plastics, corrosion inhibition, agrochemicals, textiles, and the production of artificial sweeteners. Its common name "boiler protection amine" reflects its widespread use as a corrosion inhibitor in steam boiler systems.

2. PHYSICAL AND CHEMICAL PROPERTIES

Dicyclohexylamine is a pale yellow liquid at room temperature with a strong, penetrating, ammonia-like amine odor. It has a density of 0.912 g/mL at 20°C, making it slightly lighter than water. The melting point ranges from -2°C to -0.1°C, meaning it can solidify at slightly below room temperature and appear as a white to off-white crystalline mass. The boiling point is 255-256°C, with decomposition occurring at this temperature. The flash point is 96°C (205°F), indicating that it is a combustible liquid but has a relatively high flash point compared to many other organic solvents. The vapor pressure at 37.7°C is 12 mm Hg, indicating moderate volatility. The vapor density of 6 (air=1) means its vapor is approximately 6 times heavier than air and may accumulate in low-lying areas. It is slightly soluble in water (~0.8-1 g/L at 20°C) but soluble in most organic solvents including ethanol, ether, benzene, chloroform, and other organic solvents. The pH of a 1 g/L aqueous solution is 11, indicating strong basicity, consistent with its pKa of 10.4. The lower explosive limit is 0.8% and the upper explosive limit is 4.6% by volume in air.

3. CHEMICAL PROPERTIES AND REACTIONS

As a secondary amine, dicyclohexylamine exhibits the characteristic reactions of amines, including salt formation, alkylation, acylation, and complexation with metal ions.

Salt Formation with Acids:

Dicyclohexylamine reacts with acids to form salts. The most important salts include:

• Dicyclohexylamine Hydrochloride (DCHA·HCl): Formed by reaction with hydrochloric acid. Used in the production of dicyclohexylamine salts for various applications.

DCHA + HCl → DCHA·HCl

• Dicyclohexylamine Nitrite: Formed by reaction with nitrous acid. Used as a corrosion inhibitor.

DCHA + HNO₂ → DCHA·HNO₂

• Dicyclohexylamine Sulfamate: Formed by reaction with sulfamic acid. Used in the production of artificial sweeteners (cyclamate).

DCHA + HSO₃NH₂ → DCHA·HSO₃NH₂

Alkylation:

The secondary amine group can undergo alkylation reactions to form tertiary amines:

DCHA + R-X → N-alkyl dicyclohexylamine + HX

Acylation:

Dicyclohexylamine reacts with acid chlorides and anhydrides to form amides:

DCHA + R-COCl → R-CON(C₆H₁₁)₂ + HCl

Reaction with Carbon Disulfide:

Dicyclohexylamine reacts with carbon disulfide to form dicyclohexylammonium dithiocarbamates, which are important as rubber accelerators and antioxidants:

2 DCHA + CS₂ → (DCHA-H)⁺(S₂CN(C₆H₁₁)₂)⁻

Complex Formation:

Dicyclohexylamine forms complexes with metal ions and can act as a ligand in coordination chemistry. This property is utilized in its corrosion inhibition applications.

Oxidation:

Dicyclohexylamine can be oxidized to form N,N-dicyclohexylhydroxylamine or other oxidation products under strong oxidizing conditions.

4. PRODUCTION METHODS

Dicyclohexylamine is produced industrially by several methods, all based on the hydrogenation of suitable aromatic precursors or reductive amination of cyclohexanone.

Detailed Production Process (Aniline Hydrogenation Method):

1. Aniline Hydrogenation: Aniline is reacted with hydrogen in the presence of a catalyst (nickel, cobalt, or ruthenium-based) at temperatures of 150-250°C and pressures of 10-50 atm to produce cyclohexylamine.

C₆H₅NH₂ + 3 H₂ → C₆H₁₁NH₂ (cyclohexylamine)

2. Alkylation: The cyclohexylamine is further reacted with additional cyclohexylamine or cyclohexanol to produce dicyclohexylamine. This can be achieved by:

   • Reaction with Cyclohexylamine: Cyclohexylamine is reacted with itself in the presence of a dehydrogenation catalyst.

   2 C₆H₁₁NH₂ → (C₆H₁₁)₂NH + NH₃

   • Reaction with Cyclohexanol: Cyclohexylamine is reacted with cyclohexanol in the presence of a catalyst.

   C₆H₁₁NH₂ + C₆H₁₁OH → (C₆H₁₁)₂NH + H₂O

3. Purification: The crude dicyclohexylamine is purified by distillation under reduced pressure to remove unreacted starting materials and byproducts. The product is obtained as a pale yellow liquid with a typical amine odor.

Detailed Production Process (Cyclohexanone Reductive Amination Method):

1. Imine Formation: Cyclohexanone is reacted with cyclohexylamine to form the imine intermediate (N-cyclohexylidenecyclohexylamine).

   C₆H₁₀O + C₆H₁₁NH₂ → C₆H₁₀=NC₆H₁₁ + H₂O

2. Hydrogenation: The imine is hydrogenated in the presence of a catalyst (Pd/C or Raney nickel) at moderate temperature and pressure to yield dicyclohexylamine.

   C₆H₁₀=NC₆H₁₁ + H₂ → (C₆H₁₁)₂NH

3. Purification: The product is purified by distillation to obtain high-purity dicyclohexylamine.

5. APPLICATIONS AND INDUSTRIAL USES

Dicyclohexylamine is a versatile chemical intermediate with applications in multiple industries. Its strong basicity, ability to form salts, and reactivity make it useful in a wide range of applications.

5.1. Rubber and Plastics Industry

Dicyclohexylamine is a key raw material in the production of rubber vulcanization accelerators, particularly dithiocarbamate and thiuram accelerators. These accelerators improve the efficiency of the vulcanization process, reducing cure time and improving the physical properties of the final rubber product. DCHA-based accelerators provide good processing safety and moderate cure rates, making them suitable for a wide range of rubber applications including tires, conveyor belts, hoses, and molded goods. Typical usage levels in rubber formulations range from 0.5-2% in accelerator systems.

5.2. Corrosion Inhibition

Dicyclohexylamine is widely used as a corrosion inhibitor, particularly in steam boiler systems and steam condensate return lines. In steam boiler systems, CO₂ present in the steam dissolves in condensate to form carbonic acid, which is corrosive to metal surfaces. DCHA, being volatile, is carried with the steam and condenses with the water, neutralizing the carbonic acid and forming a protective film on metal surfaces. Its common name "boiler protection amine" reflects this important application. It is also used as a vapor phase corrosion inhibitor for protecting metal surfaces in closed systems such as pipelines and storage tanks. Typical usage levels in corrosion inhibition applications are at the ppm level.

5.3. Agrochemicals

Dicyclohexylamine is an important intermediate in the synthesis of various agrochemicals, including pesticides, herbicides, and fungicides. Its strong basicity and reactivity make it useful for the production of active ingredients that contain amine or amide functional groups. Several commercial agrochemicals are synthesized from dicyclohexylamine or its derivatives.

5.4. Artificial Sweetener Production (Cyclamate)

Dicyclohexylamine is a key raw material in the production of sodium cyclamate, a widely used artificial sweetener. The production process involves the reaction of DCHA with sulfamic acid to form dicyclohexylamine sulfamate, which is then converted to sodium cyclamate through a neutralization reaction. Cyclamate is used as a low-calorie sweetener in beverages, foods, and pharmaceuticals. This application represents a significant use of dicyclohexylamine.

Cyclamate Production Reaction:

DCHA + HSO₃NH₂ → DCHA·HSO₃NH₂ (dicyclohexylamine sulfamate)

DCHA·HSO₃NH₂ + NaOH → NaSO₃NH₂ (sodium cyclamate) + DCHA + H₂O

5.5. Polyurethane Production

Dicyclohexylamine can be used as a catalyst in polyurethane production, particularly in the production of flexible polyurethane foams. It acts as a tertiary amine catalyst for the reaction between isocyanates and polyols, promoting the formation of urethane linkages. Its catalytic activity and volatility profile can be tailored for specific foam formulations. However, other amines and catalysts are more commonly used in modern polyurethane production.

5.6. Textile Chemicals

Dicyclohexylamine is used in the textile industry as an intermediate in the production of cationic fabric softeners, processing aids, and dyeing assistants. Its strong basicity and ability to form salts make it useful for the production of quaternary ammonium compounds and other cationic surfactants used in textile processing.

5.7. Other Applications

6. SALTS AND DERIVATIVES

Dicyclohexylamine forms various salts and derivatives that have important industrial applications.

7. ALTERNATIVES AND COMPARABLE COMPOUNDS

8. HEALTH EFFECTS AND TOXICOLOGY

Dicyclohexylamine is classified as a highly toxic substance with significant health hazards. It has a strong penetrating odor, which makes it relatively easy to detect at low concentrations.

8.1. Toxicological Data

8.2. Health Effects

Acute Exposure:

Chronic Exposure:

• Skin Sensitization: Repeated or prolonged skin contact can cause allergic skin reactions and dermatitis.

• Nervous System Effects: Long-term exposure may cause neurological effects including headache, dizziness, and fatigue.

• Carcinogenicity: Limited evidence suggests potential carcinogenicity; handle with appropriate precautions.

8.3. First Aid Measures

9. SAFETY INFORMATION (GHS CLASSIFICATION)

Signal Word: DANGER

Hazard Statements (H-Codes):

Precautionary Statements (P-Codes):

10. FIREFIGHTING MEASURES

11. ACCIDENTAL RELEASE MEASURES

12. STORAGE AND HANDLING

Dicyclohexylamine should be stored below +30°C in cool, dry, well-ventilated areas, away from ignition sources and incompatible materials. Containers should be tightly closed to prevent absorption of CO₂ from air, which can lead to carbonate formation. It is sensitive to air and should be protected from prolonged exposure. It is incompatible with strong acids and strong oxidizing agents. Storage should be in a cool, ventilated, dry place, isolated from fire and oxidizing agents. For transportation, it should be sealed in iron drums with a net weight of 150 kg. Handling and transportation should be in accordance with the regulations for flammable and toxic chemicals.

Handling Notes:

• Use in well-ventilated areas

• Avoid skin contact (can be absorbed through skin)

• Avoid eye contact

• Avoid inhalation of vapors

• Use appropriate personal protective equipment

• Ground and bond containers when transferring

• Keep away from ignition sources

• Do not allow to freeze (melting point ~ -2°C to -0.1°C)

13. TRANSPORT INFORMATION

Dicyclohexylamine is classified as a dangerous good with UN number 2565. Hazard class is 8 (Corrosive) and Packing Group III. Transport should be in properly labeled, closed containers. It is classified as a marine pollutant. During transport, keep away from strong acids and strong oxidizing agents. Proper labeling and documentation are required.

14. REGULATORY INFORMATION

Regulatory Status:

15. OTHER NAMES AND DATABASE IDENTIFIERS

Database Identifiers:

16. PHYSICAL AND CHEMICAL PROPERTIES (ISOMERS AND COMPARABLE COMPOUNDS)

17. ENVIRONMENTAL INFORMATION

Dicyclohexylamine is very toxic to aquatic organisms and may cause long-term adverse effects in aquatic environments. It should not be released into the environment. It has a moderate potential for bioaccumulation (LogP ~3.9). It is expected to be biodegradable but should still be handled with care to prevent environmental contamination. Waste disposal should be carried out according to local, state, and federal regulations. Incineration at a permitted facility is recommended.

18. COMMON NAMES AND INDUSTRY TERMINOLOGY

19. DOWNSTREAM AND UPSTREAM PRODUCTS

19.1. Raw Materials (Upstream)

19.2. Derivative Products (Downstream)

20. SUMMARY AND CRITICAL WARNINGS

SUMMARY:

Dicyclohexylamine (DCHA, C₁₂H₂₃N, CAS 101-83-7) is a secondary alicyclic amine consisting of two cyclohexyl groups attached to a nitrogen atom. It appears as a pale yellow liquid or white to off-white crystalline powder, with a strong, penetrating amine odor. The molecular weight is 181.32 g/mol, density is 0.912 g/mL, melting point is -2°C to -0.1°C, boiling point is 256°C, and flash point is 96°C. It is slightly soluble in water (~1 g/L) but soluble in most organic solvents. It is strongly basic with a pKa of 10.4. It is produced by catalytic hydrogenation of aniline, reductive amination of cyclohexanone, or hydrogenation of diphenylamine. Major applications include rubber and plastic industry (vulcanization accelerators, antioxidants), corrosion inhibition (steam boiler systems, vapor phase inhibitors), agrochemicals (pesticide and herbicide intermediates), artificial sweetener production (cyclamate), polyurethane catalysts, textile chemicals, and organic synthesis. It is classified as a highly toxic substance with significant health hazards. It is a combustible liquid with a relatively high flash point (96°C) and moderately volatile. It is very toxic to aquatic organisms with long-lasting effects. Classified as UN 2565 (Class 8 - Corrosive, Packing Group III).

Key Properties:

Major Application Areas:

Key Safety Points:

• HIGHLY TOXIC: Toxic in contact with skin and if swallowed; causes severe burns

• CORROSIVE: Causes severe skin burns and eye damage

• ENVIRONMENTAL HAZARD: Very toxic to aquatic life with long-lasting effects

• COMBUSTIBLE: Flash point 96°C; keep away from ignition sources

• AIR SENSITIVE: Store under inert atmosphere if possible

• PENETRATING ODOR: Strong amine odor; good warning property

• CARCINOGENICITY: Limited evidence of carcinogenicity; handle with care

• STORAGE: Store below +30°C; cool, dry, well-ventilated area; separate from acids and oxidizers

• PPE REQUIRED: Chemical-resistant gloves, goggles, protective clothing, respiratory protection if ventilation is inadequate

CRITICAL WARNINGS:

Industrial Importance: Dicyclohexylamine is a versatile chemical intermediate with multiple industrial applications. Its most significant uses are in rubber vulcanization accelerator production, corrosion inhibition in steam boiler systems, and cyclamate production for artificial sweeteners. The rubber industry uses DCHA-based accelerators for tire and rubber product manufacturing. The corrosion inhibition application, where DCHA is known as "boiler protection amine," is crucial for maintaining the integrity of steam boiler systems and condensate return lines in power plants and industrial facilities. The cyclamate production application, while significant, has been affected by regulatory restrictions on artificial sweeteners in some regions.

Health Hazards: Dicyclohexylamine is highly toxic and corrosive. It is absorbed through the skin and can cause skin allergy and gangrene in severe cases. Vapors can cause nausea and anesthesia. Limited evidence suggests it may cause cancer. The maximum allowable concentration in workplace air is 10 mg/m³. Production equipment should be sealed to prevent leaks. The operation site should be force-ventilated, and operators should wear protective equipment. In case of contact with eyes or skin, rinse immediately with plenty of water and seek medical advice.

Corrosive Properties: Dicyclohexylamine is classified as a corrosive substance (Class 8). It can cause severe skin burns and eye damage. It reacts with acids to form salts, which can be corrosive as well. Contact with skin and eyes should be avoided at all costs. Proper personal protective equipment (PPE) is mandatory when handling this substance.

Environmental Impact: Dicyclohexylamine is very toxic to aquatic organisms and may cause long-term adverse effects in aquatic environments. Its release into the environment should be prevented. It has moderate potential for bioaccumulation (LogP ~3.9). Waste disposal should be carried out in accordance with local, state, and federal regulations. Incineration at a permitted facility is recommended.

Storage and Handling: Dicyclohexylamine should be stored below +30°C in cool, dry, well-ventilated areas, away from ignition sources and incompatible materials. It is sensitive to air and should be protected from prolonged exposure. It is incompatible with strong acids and strong oxidizing agents. Containers should be tightly closed to prevent absorption of CO₂ from air, which can lead to carbonate formation. For transportation, it should be sealed in iron drums with a net weight of 150 kg. Handling and transportation should be in accordance with the regulations for flammable and toxic chemicals.

Reactivity: As a secondary amine, dicyclohexylamine undergoes salt formation with acids, alkylation, acylation, and reaction with carbon disulfide. It forms complexes with metal ions. It should be kept away from strong acids and strong oxidizing agents, as it can react violently with them. It can absorb CO₂ from air to form carbonate salts, so containers should be kept tightly closed.

Important Disclaimer: This Technical Data Sheet (TDS) is for informational purposes only. The information provided is based on available data and is believed to be accurate. However, the user is solely responsible for determining the suitability of the product for their specific application and for complying with all applicable regulations and safety requirements. For complete safety, handling, storage, and regulatory compliance information, always refer to the official Safety Data Sheet (SDS/MSDS) provided by the manufacturer/supplier. Users are responsible for testing the product in their own processes and applications. All local, national, and international regulations must be followed when working with dicyclohexylamine.