Toluene diisocyanate (TDI) is a chemical compound used in the production of polyurethane foams and coatings. It reacts with other chemicals to create durable and versatile materials.
| IUPAC Name | Toluene diisocyanate |
| Molecular Formula | C9H6N2O2 |
| CAS Number | 584-84-9, 91-08-7 |
| Synonyms | TDI; 2,4-Diisocyanato-1-methylbenzene; Toluene-2,4-diisocyanate; Toluenediisocyanate; Toluene-2,6-diisocyanate; Toluene-2,4-DIISOCYANATE; Methyl-1,3-diisocyanatobenzene |
| InChI | InChI=1S/C9H6N2O2/c1-7-3-4-8(10-6-7)5-9(11)12-2/h3-6H,1-2H3 |
Toluene Diisocyanate Properties
Toluene Diisocyanate Formula
The formula of TDI is C9H6N2O2. It consists of nine carbon atoms, six hydrogen atoms, two nitrogen atoms, and two oxygen atoms. The arrangement of these atoms in the molecule contributes to its unique properties and reactivity.
Toluene Diisocyanate Molar Mass
The molar mass of TDI is calculated by adding up the atomic masses of its constituent elements. With a formula of C9H6N2O2, the molar mass is approximately 174.16 grams per mole. Molar mass is an essential parameter for various calculations and determining the amount of substance present.
Toluene Diisocyanate Boiling Point
TDI has a boiling point of approximately 251-253 degrees Celsius. This temperature represents the point at which the liquid compound undergoes a phase change and turns into a gas. The boiling point is influenced by intermolecular forces and molecular structure.
Toluene Diisocyanate Melting Point
The melting point of TDI is around -10 degrees Celsius. It is the temperature at which the solid compound changes to a liquid state. The melting point is determined by factors like molecular symmetry, packing arrangement, and intermolecular forces.
Toluene Diisocyanate Density g/mL
TDI has a density of approximately 1.22 grams per milliliter. Density is a measure of mass per unit volume and provides insights into the compactness of the substance. The density of TDI is influenced by the arrangement and size of its constituent atoms.
Toluene Diisocyanate Molecular Weight
The molecular weight of TDI is approximately 174.16 grams per mole. It is the sum of the atomic weights of the atoms present in the molecule. The molecular weight is significant for various calculations, including stoichiometry and determining the amount of substance.
Toluene Diisocyanate Structure
TDI has a distinct structure. It consists of a toluene ring with two isocyanate functional groups (-NCO) attached to it. The arrangement of these functional groups and the carbon skeleton determines its chemical behavior and reactivity.
Toluene Diisocyanate Solubility
TDI is sparingly soluble in water but dissolves well in organic solvents like acetone, ethyl acetate, and toluene. Its solubility characteristics arise from the polarity of the molecule and its ability to form interactions with solvents through hydrogen bonding or dipole-dipole interactions.
| Appearance | Clear, colorless to pale yellow liquid |
| Specific Gravity | 1.22 |
| Color | Colorless to pale yellow |
| Odor | Pungent, aromatic |
| Molar Mass | 174.16 g/mol |
| Density | 1.22 g/mL |
| Melting Point | -10 °C |
| Boiling Point | 251-253 °C |
| Flash Point | 118 °C |
| Water Solubility | Low, sparingly soluble in water |
| Solubility | Soluble in organic solvents (acetone, toluene) |
| Vapor Pressure | 0.2 mmHg at 25 °C |
| Vapor Density | 6.0 |
| pKa | 10.6 |
| pH | Not applicable (pH depends on the solution medium) |
Toluene Diisocyanate Safety and Hazards
TDI poses potential safety hazards and requires careful handling. It is irritating to the skin, eyes, and respiratory system, causing irritation, redness, and coughing. Prolonged or repeated exposure can lead to sensitization, resulting in allergic reactions. The compound is flammable and can form explosive mixtures with air. Adequate ventilation and protective equipment, such as gloves and goggles, should be used when working with it. Proper storage and handling are crucial to prevent spills and minimize the risk of exposure. It is important to follow safety guidelines and consult safety data sheets for detailed information on handling and emergency procedures.
| Hazard Symbols | Corrosive, Toxic |
| Safety Description | Toxic; Irritant; Flammable |
| UN IDs | UN 2078 |
| HS Code | 2929.10.00 |
| Hazard Class | 6.1 (Toxic); 3 (Flammable) |
| Packing Group | II |
| Toxicity | Acute toxicity, sensitization, irritation |
Toluene Diisocyanate Synthesis Methods
There are several methods to synthesize TDI.
The phosgenation method synthesizes TDI by reacting toluene with phosgene gas in the presence of a catalyst, such as a tertiary amine or metal chloride. The reaction occurs at elevated temperatures and pressures, producing TDI.
The nitration of toluene, followed by subsequent steps, constitutes another method. Toluene undergoes nitration to form dinitrotoluene, which then undergoes hydrogenation to yield toluene diamine. Toluene diamine reacts with phosgene to generate TDI.
The oxidative carbonylation method involves oxidizing toluene to produce benzyl chloride. The chemist combines this compound with carbon monoxide and a metal cyanide catalyst to generate a mixture of isocyanates. The mixture contains TDI, which the chemist separates and purifies.
The synthesis of TDI necessitates expertise and strict adherence to safety protocols. Handling hazardous chemicals and conducting reactions at high temperatures and pressures characterize the process. Monitoring and controlling reaction conditions carefully, along with employing proper equipment, ensure a safe and efficient synthesis process.
Toluene Diisocyanate Uses
TDI finds extensive use in various industries due to its versatile properties. Here are some of its common applications:
- TDI plays a vital role in producing flexible and rigid polyurethane foams, widely applied in furniture, bedding, automotive interiors, and insulation materials.
- Various industries utilize TDI in formulating coatings and adhesives, which offer excellent adhesion and durability, particularly in automotive, construction, and aerospace sectors.
- TDI contributes to manufacturing resilient and abrasion-resistant sealants and elastomeric materials used in gaskets, seals, and industrial components.
- TDI enhances the production of synthetic fibers by providing them with desirable properties such as strength, flexibility, and chemical resistance. These fibers find application in textiles, upholstery, and carpeting.
- Automotive components, such as seats, headrests, steering wheels, and interior trims, incorporate TDI-based polyurethane materials, enhancing comfort, aesthetics, and safety features.
- Manufacturers utilize TDI-based polyurethane foam to produce insulation panels for buildings, which offer excellent thermal insulation and contribute to energy efficiency.
- Industries in art, architecture, and prototyping use TDI for casting and molding processes, enabling the creation of intricate shapes and structures.
- TDI serves as a precursor for synthesizing various chemicals, including certain pesticides and pharmaceutical compounds.
Questions:
Q: How to make toluene diisocyanate?
A: TDI can be synthesized by reacting toluene with phosgene gas or by nitration and subsequent reactions.
Q: Does toluene contain toluene diisocyanate?
A: No, toluene does not naturally contain TDI. They are different chemical compounds.
Q: How to dispose of toluene diisocyanate?
A: TDI should be disposed of as hazardous waste following proper regulations and guidelines.
Q: How to pronounce toluene diisocyanate?
A: It is pronounced as “toh-leen dahy-soh-sahy-uh-neyt.”
Q: What is toluene diisocyanate used for?
A: TDI is used in the production of polyurethane foams, coatings, adhesives, sealants, synthetic fibers, and automotive components.
Q: What tools can be used to detect toluene diisocyanate?
A: Tools like gas chromatography, mass spectrometry, and infrared spectroscopy can be used to detect and analyze TDI.
Q: Is toluene diisocyanate a precursor chemical?
A: Yes, TDI is a precursor chemical used in the synthesis of other compounds, such as pesticides and pharmaceuticals.
Q: Is toluene diisocyanate an inorganic compound?
A: No, TDI is an organic compound composed of carbon, hydrogen, nitrogen, and oxygen atoms.