Butadiene (C4H6) is a versatile chemical compound. It is used in the production of synthetic rubber, plastics, and various other products due to its elasticity and strength.
| IUPAC Name | buta-1,3-diene |
| Molecular Formula | C4H6 |
| CAS Number | 106-99-0 |
| Synonyms | Divinyl, Biethylene, Buta-1,3-diene, Vinyl ethylene, Erythrene |
| InChI | InChI=1S/C4H6/c1-3-4-2/h3-4H,1-2H2 |
Butadiene Properties
Butadiene Formula
The formula of butadiene is C4H6. It consists of four carbon atoms and six hydrogen atoms. This molecular formula represents the arrangement of atoms in butadiene and gives insight into its chemical composition.
Butadiene Molar Mass
The molar mass of Buta-1,3-diene can be calculated by adding the atomic masses of its constituent elements. Carbon has a molar mass of approximately 12.01 g/mol, and hydrogen has a molar mass of around 1.01 g/mol. Therefore, the molar mass of Buta-1,3-diene is approximately 54.09 g/mol.
Butadiene Boiling Point
Buta-1,3-diene has a relatively low boiling point compared to many other compounds. It boils at approximately -4.4 degrees Celsius or 24.1 degrees Fahrenheit. This low boiling point allows for easy conversion of liquid Buta-1,3-diene into its gaseous state.
Butadiene Melting Point
Unlike many organic compounds, Buta-1,3-diene does not have a distinct melting point due to its highly reactive nature and tendency to polymerize. Instead, it exists as a colorless gas at room temperature and atmospheric pressure.
Butadiene Density g/mL
The density of Buta-1,3-diene is around 0.63 g/mL. This value indicates that Buta-1,3-diene is less dense than water, which has a density of 1 g/mL. The low density of Buta-1,3-diene contributes to its buoyancy and its ability to form vapors easily.
Butadiene Molecular Weight
The molecular weight of Buta-1,3-diene is approximately 54.09 g/mol. This value represents the average mass of a molecule of Buta-1,3-diene, taking into account the atomic masses of carbon and hydrogen atoms present in its chemical structure.
Butadiene Structure
The structure of Buta-1,3-diene consists of a chain of four carbon atoms bonded together with alternating single and double bonds. Each carbon atom is also bonded to two hydrogen atoms. This linear structure gives Buta-1,3-diene its characteristic properties and reactivity.
Butadiene Solubility
Buta-1,3-diene is sparingly soluble in water but readily dissolves in organic solvents such as benzene and toluene. Its low solubility in water is due to the differences in polarity between Buta-1,3-diene and water molecules.
| Appearance | Colorless gas |
| Specific Gravity | 0.62 – 0.63 |
| Color | Colorless |
| Odor | Mild, aromatic odor |
| Molar Mass | 54.09 g/mol |
| Density | 0.62 – 0.63 g/mL |
| Melting Point | -138.4°C (-217.1°F) |
| Boiling Point | -4.4°C (24.1°F) |
| Flash Point | -76°C (-105°F) |
| Water Solubility | Insoluble |
| Solubility | Soluble in organic solvents (e.g., benzene, toluene) |
| Vapor Pressure | 448 mmHg at 20°C |
| Vapor Density | 1.9 (Air = 1) |
| pKa | ~43 (estimated) |
| pH | Neutral |
Butadiene Safety and Hazards
Buta-1,3-diene poses certain safety hazards and precautions should be taken when handling it. It is flammable and can form explosive mixtures with air. Therefore, proper ventilation and fire prevention measures are crucial. Prolonged exposure to Buta-1,3-diene may cause irritation to the eyes, skin, and respiratory system. It is also considered a potential carcinogen and exposure should be minimized. Protective equipment like gloves, goggles, and respirators should be used when working with Buta-1,3-diene. Spills should be contained and cleaned up promptly. It is important to follow safety guidelines, such as those provided by regulatory agencies, to ensure safe handling and storage of Buta-1,3-diene.
| Hazard Symbols | Flammable (F), Harmful (Xn), Carcinogenic (C) |
| Safety Description | Keep away from heat/sparks/open flames. Use in well-ventilated areas. Avoid prolonged exposure. Handle with gloves and protective clothing. |
| UN IDs | UN 1010 |
| HS Code | 2903.14.00 |
| Hazard Class | 2.1 – Flammable Gas |
| Packing Group | PG II |
| Toxicity | Considered a potential carcinogen and may cause respiratory and skin irritation. |
Butadiene Synthesis Methods
There are several synthesis methods for Buta-1,3-diene, each with its own advantages and limitations. One common method is the steam cracking of hydrocarbons, such as naphtha or natural gas liquids.
In this process, the process heats the hydrocarbon feedstock to high temperatures, usually around 800-900°C, in the presence of steam. This leads to the breaking of carbon-carbon bonds and the formation of Buta-1,3-diene.
Another method involves the catalytic dehydrogenation of butene or butanes. By using specific catalysts, such as metal oxides or supported metals, the reaction selectively removes hydrogen atoms from the starting material, resulting in the production of Buta-1,3-diene.
The catalytic dimerization of acetylene yields Buta-1,3-diene as well. This process involves the reaction of two molecules of acetylene to form Buta-1,3-diene, usually in the presence of a metal catalyst like copper.
Catalysts such as alumina or zeolites facilitate the dehydration of ethanol at elevated temperatures. This process actively forms Buta-1,3-diene as a result.
Moreover, some plants produce Buta-1,3-diene as a byproduct of ethylene production through the naphtha or gas oil cracking process. This method takes advantage of the cracking reactions to generate a mixture of olefins, including Buta-1,3-diene.
These synthesis methods play a crucial role in the production of Buta-1,3-diene, providing various routes to meet the demand for this important chemical in industries such as rubber manufacturing, plastics, and synthetic fibers.
Butadiene Uses
Buta-1,3-diene finds application in a wide range of industries due to its versatile properties. Here are some key uses of Buta-1,3-diene:
- Synthetic Rubber: The production of synthetic rubber, such as styrene-Buta-1,3-diene rubber (SBR) and polyButa-1,3-diene rubber (PBR), primarily utilizes Buta-1,3-diene. These rubbers offer excellent elasticity, resilience, and abrasion resistance, making them ideal for tires, automotive components, conveyor belts, and footwear.
- Plastics: Buta-1,3-diene is a crucial monomer for the manufacture of various plastics, including acrylonitrile-Buta-1,3-diene-styrene (ABS) and styrene-Buta-1,3-diene (SB) plastics. These plastics exhibit enhanced impact strength, heat resistance, and dimensional stability, making them valuable for applications in consumer goods, appliances, and automotive parts.
- Adhesives: The strong bonding capabilities of Buta-1,3-diene-based polymers make them a valuable component in adhesive formulations. They provide adhesion to a wide range of substrates, making them useful for bonding applications in industries such as construction, woodworking, and packaging.
- Coatings: Buta-1,3-diene contributes to the production of coatings and paints with improved durability, flexibility, and adhesion properties. Resins, such as epoxy and alkyd resins, utilize it in their synthesis, constituting vital components of protective coatings for metals, concrete, and other surfaces.
- Textiles and Fibers: The production of synthetic fibers, such as acrylonitrile-Buta-1,3-diene (AB) fibers, utilizes Buta-1,3-diene. These fibers possess high strength, good dimensional stability, and resistance to chemicals, making them suitable for textiles, carpets, and industrial fabrics.
- Fuel Additives: Buta-1,3-diene enhances gasoline octane as a fuel additive used in its production. It improves the combustion properties of gasoline, leading to enhanced engine performance and reduced emissions.
These applications highlight the wide-ranging utility of Buta-1,3-diene across various industries, contributing to the development of diverse products that we encounter in our daily lives.
Questions:
Q: What is butadiene?
A: Buta-1,3-diene is a chemical compound with the molecular formula C4H6, consisting of a chain of four carbon atoms and two double bonds.
Q: What is the IUPAC name of the major product when 1,3-butadiene is reacted with equal amounts of HCl?
A: The major product, according to IUPAC nomenclature, is 3-chlorobut-1-ene.
Q: The molecule 1,3-butadiene contains how many H atoms?
A: Buta-1,3-diene contains six hydrogen (H) atoms in total.
Q: What is the relationship between the s-cis and s-trans forms of 1,3-butadiene?
A: The s-cis and s-trans forms of 1,3-butadiene are geometric isomers, differing in the arrangement of substituents around the double bonds.
Q: What is the total number of nodes in the ψ3 MO of 1,3-butadiene?
A: The ψ3 molecular orbital of 1,3-butadiene contains a total of three nodes.
Q: Butadiene has how many bonding MOs?
A: Butadiene has three bonding molecular orbitals (MOs) formed from the overlap of atomic orbitals.
Q: What is the expected absorption of butadiene?
A: Butadiene is expected to absorb ultraviolet (UV) light in the range of approximately 190-200 nm due to its conjugated system.