Methylene Diphenyl Diisocyanate (MDI) is a chemical compound used in the production of polyurethane foams, coatings, and adhesives. It has various industrial applications due to its reactivity and versatility.
| IUPAC Name | 4,4′-Methylenebis(phenyl isocyanate) |
| Molecular Formula | C15H10N2O2 |
| CAS Number | 101-68-8 |
| Synonyms | MDI, Diphenylmethane-4,4′-diisocyanate, 4,4′-Methylenebis(cyclohexyl isocyanate) |
| InChI | InChI=1S/C15H10N2O2/c18-14-8-6-13(7-9-14)16-12-17-15-10-4-2-1-3-5-11-15/h1-11H |
Methylene Diphenyl Properties
Methylene Diphenyl Diisocyanate Formula
The formula of Methylene Diphenyl Diisocyanate is C15H10N2O2. It represents the chemical composition of the compound, indicating the number and type of atoms present in each molecule.
Methylene Diphenyl Diisocyanate Molar Mass
The molar mass of Diphenylmethane-4,4’-diisocyanate is calculated by adding up the atomic masses of its constituent elements. It is approximately 250.25 grams per mole (g/mol).
Methylene Diphenyl Diisocyanate Boiling Point
The boiling point of Diphenylmethane-4,4’-diisocyanate is a temperature at which it changes from a liquid to a gas phase. It has a boiling point of around 267 to 270 degrees Celsius (513 to 518 degrees Fahrenheit).
Methylene Diphenyl Diisocyanate Melting Point
The melting point of Diphenylmethane-4,4’-diisocyanate is the temperature at which it changes from a solid to a liquid phase. It typically melts between 39 to 42 degrees Celsius (102 to 108 degrees Fahrenheit).
Methylene Diphenyl Diisocyanate Density g/mL
The density of Diphenylmethane-4,4’-diisocyanate refers to its mass per unit volume. It has a density of about 1.24 to 1.26 grams per milliliter (g/mL).
Methylene Diphenyl Diisocyanate Molecular Weight
The molecular weight of Diphenylmethane-4,4’-diisocyanate is the sum of the atomic weights of its constituent atoms. It is approximately 250.25 grams per mole (g/mol).
Methylene Diphenyl Diisocyanate Structure
The structure of Diphenylmethane-4,4’-diisocyanate consists of two phenyl groups connected by a methylene bridge (-CH2-) with two isocyanate (-NCO) functional groups. This arrangement gives it its unique chemical properties.
Methylene Diphenyl Diisocyanate Solubility
Diphenylmethane-4,4’-diisocyanate has limited solubility in water, but it is soluble in many organic solvents such as acetone, ethyl acetate, and toluene. Its solubility varies depending on the temperature and solvent used.
| Appearance | Colorless to light yellow liquid |
| Specific Gravity | 1.24 – 1.26 g/mL |
| Color | Colorless to light yellow |
| Odor | Pungent |
| Molar Mass | 250.25 g/mol |
| Density | 1.24 – 1.26 g/mL |
| Melting Point | 39 – 42 °C (102 – 108 °F) |
| Boiling Point | 267 – 270 °C (513 – 518 °F) |
| Flash Point | 160 °C (320 °F) |
| Water Solubility | Limited |
| Solubility | Soluble in organic solvents |
| Vapour Pressure | 0.1 mmHg at 25 °C |
| Vapour Density | 8.6 (air = 1) |
| pKa | ~ 14.0 |
| pH | Not applicable |
Methylene Diphenyl Diisocyanate Safety and Hazards
Diphenylmethane-4,4’-diisocyanate poses several safety and hazard concerns. It is a potent skin and respiratory sensitizer, causing allergic reactions in some individuals upon contact or inhalation. Direct exposure can lead to skin irritation, redness, and chemical burns. Inhalation of its vapors may cause respiratory tract irritation, coughing, and difficulty breathing. It is crucial to handle MDI with caution, wearing appropriate protective equipment such as gloves, goggles, and respiratory masks. Proper ventilation should be ensured in areas where MDI is used to prevent the accumulation of vapors. Spills should be promptly cleaned up, and waste disposal must comply with relevant regulations to prevent environmental contamination.
| Hazard Symbols | Irritant, Health Hazard |
| Safety Description | Handle with caution. Avoid direct contact with skin and eyes. Use in well-ventilated areas. Dispose of properly. |
| UN IDs | UN 2278 |
| HS Code | 2929.10.00 |
| Hazard Class | 6.1 (Toxic substances) |
| Packing Group | III |
| Toxicity | May cause allergic reactions and irritate skin, eyes, and respiratory system. |
Methylene Diphenyl Diisocyanate Synthesis Methods
Different methods can synthesize Diphenylmethane-4,4’-diisocyanate (MDI).
One common method for synthesizing Diphenylmethane-4,4’-diisocyanate (MDI) involves the reaction between aniline and formaldehyde, followed by phosgenation. This reaction forms a mixture of 4,4′-methylenedianiline (MDA) and its isomers, which are then reacted with phosgene to yield MDI.
Another method directly combines aniline and phosgene to produce MDA as an intermediate. The MDA is then reacted with phosgene to obtain MDI, eliminating the need for formaldehyde in the synthesis.
An alternative approach involves the reaction between aniline and diphenyl carbonate, followed by phosgenation. This reaction forms a mixture of carbamic acid derivatives, which are then treated with phosgene, resulting in the formation of MDI.
Additionally, MDI can be obtained by reacting aniline with carbon monoxide in the presence of a catalyst, such as copper or palladium.
The synthesis of MDI requires careful handling of toxic and hazardous chemicals. Operators should follow appropriate safety precautions and protective measures throughout the process to ensure their well-being and minimize environmental impact.
Methylene Diphenyl Diisocyanate Uses
MDI plays a vital role in multiple industries due to its versatile properties. Its notable applications include:
- Polyurethane Foams: Manufacturers use MDI as a key component to produce polyurethane foams, which find uses in insulation materials, furniture cushions, mattresses, and automotive interiors.
- Coatings and Adhesives: MDI contributes to the formulation of coatings and adhesives, providing excellent durability, resistance to abrasion, and adhesion properties. Industries apply it in paints, varnishes, sealants, and structural adhesives.
- Insulation Materials: Builders incorporate MDI-based foams as insulation materials in buildings, refrigeration systems, and appliances. This helps enhance energy efficiency and reduce heat transfer.
- Automotive Applications: Manufacturers employ MDI in the production of automotive parts, such as bumpers, dashboards, door panels, and seat cushions. It offers lightweight yet robust solutions with excellent mechanical properties.
- Packaging Materials: Industries use MDI-based foams to package fragile items, providing cushioning and impact resistance during transport and storage.
- Textiles and Fibers: MDI contributes to the production of synthetic fibers, including elastane and spandex, which find applications in clothing, sportswear, and medical textiles.
- Construction Materials: Builders incorporate MDI into construction materials like adhesives, sealants, and coatings to enhance their durability, water resistance, and weatherability.
- Electronics and Appliances: MDI-based foams find use in electronic devices, appliances, and electrical enclosures to provide insulation, protection, and vibration dampening.
Questions:
Q: Is there a safety data sheet available for methylene diphenyl diisocyanate?
A: Yes, a safety data sheet (SDS) for diphenylmethane-4,4’-diisocyanate is available and provides essential information on its hazards, handling, and safety precautions.
Q: What are the hazards associated with methylene diphenyl diisocyanate?
A: Diphenylmethane-4,4’-diisocyanate poses hazards including skin and respiratory sensitization, skin irritation, and respiratory tract irritation. It should be handled with caution.
Q: Who are some manufacturers of methylene diphenyl diisocyanate?
A: Various manufacturers produce diphenylmethane-4,4’-diisocyanate, including major chemical companies and suppliers within the chemical industry.
Q: How is methylene diphenyl diisocyanate made?
A: Diphenylmethane-4,4’-diisocyanate is typically synthesized through reactions involving aniline, formaldehyde (or diphenyl carbonate), and phosgene, followed by purification processes.