1-Butene (C4H8) is a colorless gas with a faint sweet odor. It is used in the production of polyethylene and as a starting material for other chemicals.
| IUPAC Name | But-1-ene |
| Molecular Formula | C4H8 |
| CAS Number | 106-98-9 |
| Synonyms | Butylene, Ethylethene, Vinylmethylethene |
| InChI | 1S/C4H8/c1-3-4-2/h3-4H,1-2H3 |
1-Butene Properties
1-Butene Formula
The chemical formula of 1-Butene is C4H8, which represents the number and types of atoms present in the molecule. The formula indicates that 1-Butene contains four carbon atoms and eight hydrogen atoms. The formula of 1-Butene is useful in determining its molecular weight and calculating its reactivity in chemical reactions.
1-Butene Molar Mass
1-Butene, also known as But-1-ene, has a molar mass of 56.11 g/mol. Molar mass refers to the mass of one mole of a substance and is calculated by adding the atomic masses of each atom in a molecule. In the case of but-1-ene, the molecule contains four carbon atoms and eight hydrogen atoms, each with its respective atomic mass.
1-Butene Boiling Point
But-1-ene has a boiling point of -6.3 °C or 20.7 °F. Boiling point refers to the temperature at which a liquid change to a gas at a fixed pressure. As but-1-ene is a gas at room temperature, it requires a low boiling point to maintain its gaseous state. but-1-ene’s boiling point is affected by factors such as pressure and the presence of other chemicals.
1-Butene Melting Point
But-1-ene has a melting point of -185.4 °C or -301.7 °F. Melting point refers to the temperature at which a solid change to a liquid at a fixed pressure. As but-1-ene is a gas at room temperature, it does not exist in a solid state. However, the melting point of but-1-ene is still a useful parameter for determining its physical and chemical properties.
1-Butene Density g/mL
But-1-ene has a density of 0.573 g/mL at room temperature. Density refers to the amount of mass per unit volume of a substance. The density of but-1-ene is lower than that of water, which has a density of 1 g/mL, indicating that but-1-ene is less dense than water. The density of but-1-ene is affected by factors such as temperature and pressure.
1-Butene Molecular Weight
But-1-ene has a molecular weight of 56.11 g/mol. Molecular weight is the sum of the atomic weights of all atoms in a molecule. The molecular weight of but-1-ene is an important factor in determining its physical and chemical properties, as well as its behavior in chemical reactions.
1-Butene Structure
But-1-ene has a linear structure, with four carbon atoms bonded to each other in a straight chain, and each carbon atom bonded to two hydrogen atoms. The molecular formula of but-1-ene is C4H8, and it belongs to the group of hydrocarbons known as alkenes. The double bond between the first and second carbon atoms in the molecule is responsible for its reactivity in chemical reactions.
| Appearance | Colorless gas |
| Specific Gravity | 0.573 |
| Color | Colorless |
| Odor | Faint sweet odor |
| Molar Mass | 56.11 g/mol |
| Density | 0.573 g/mL at room temperature |
| Melting Point | -185.4 °C or -301.7 °F |
| Boiling Point | -6.3 °C or 20.7 °F |
| Flash Point | -70 °C (-94 °F) |
| Water Solubility | Insoluble |
| Solubility | Soluble in organic solvents |
| Vapour Pressure | 278.4 kPa at 20°C |
| Vapour Density | 2.98 (air = 1) |
| pKa | 45.1 |
| pH | Neutral |
1-Butene Safety And Hazards
But-1-ene is a flammable gas and can form explosive mixtures with air. It is also an irritant to the eyes, skin, and respiratory system. Exposure to high concentrations of but-1-ene can cause dizziness, nausea, and headaches. Therefore, proper ventilation and protective equipment should be used when handling but-1-ene. It is important to store and handle but-1-ene away from sources of ignition and incompatible materials. In case of a leak or spill, the area should be immediately evacuated, and emergency response procedures should be followed. Additionally, proper disposal methods should be used to prevent environmental contamination.
| Hazard Symbols | F+ (Highly flammable) |
| Safety Description | Keep away from sources of ignition. Use only in well-ventilated areas. Wear protective equipment. |
| UN IDs | UN 1012 |
| HS Code | 290110 |
| Hazard Class | 2.1 (Flammable Gas) |
| Packing Group | Group II |
| Toxicity | Inhalation of high concentrations may cause central nervous system depression. |
1-Butene Synthesis Methods
Various methods can synthesize but-1-ene, including catalytic cracking of crude oil fractions or dehydration of butanol.
One common method is the catalytic dehydrogenation of butenes, which involves the removal of hydrogen atoms from butenes to form but-1-ene. Different catalysts, such as chromia-alumina, copper chromite, or platinum, can carry out this process.
Another method involves the selective dimerization of ethylene, followed by the dehydration of the resulting butenes to form but-1-ene. Zeolite catalysts, such as ZSM-5 or SAPO-11, can carry out this method.
A tungsten carbene complex can catalyze the metathesis reaction between propylene and ethylene to produce but-1-ene. This method is attractive as it allows for the production of but-1-ene from renewable resources, such as bio-based ethylene.
1-Butene Uses
But-1-ene is a versatile chemical compound that finds a wide range of industrial and commercial applications. Some common uses of but-1-ene include:
- Production of Polyethylene: Used as a co-monomer in the production of high-density and linear low-density polyethylene. The addition of 1-Butene helps to improve the polymer’s mechanical and thermal properties.
- Chemical Intermediates: Used as a chemical intermediate in the production of various chemicals, such as butadiene, butenes, butyraldehyde, and butanol.
- Fuel and Fuel Additives: Used as a fuel or fuel additive due to its high-octane rating and clean-burning properties.
- Refrigerants: Used as a refrigerant due to its low boiling point and non-flammable nature.
- Adhesives: Used in the production of hot-melt adhesives. These are commonly used in the packaging industry.
- Rubber and Plastics: Used as a feedstock for the production of synthetic rubber and plastics, such as polybutene.
- Lubricants: Used as a lubricant additive to improve the lubricity and anti-wear properties of lubricants.
- Pharmaceutical Industry: Used as a starting material in the synthesis of various pharmaceuticals.
Questions:
Q: Why might it be difficult to visualize the separation of cis- and trans-2-butene by TLC?
A: It might be difficult to visualize the separation of cis- and trans-2-butene by TLC because these isomers have very similar physical and chemical properties. This can result in overlapping spots on the TLC plate, making it challenging to distinguish between the two isomers.
Q: What is the molar mass of 1-butene if 5.38 × 1016 molecules of 1-butene weigh 5.00 μg?
A: The molar mass of but-1-ene can be calculated using the given number of molecules and the weight of the sample. The molar mass of but-1-ene is 56.11 g/mol.
Q: Your task is to convert 2-bromobutane to 1-butene in the highest yield. Which reagents would you use?
A: One possible method to convert 2-bromobutane to but-1-ene is through an E2 elimination reaction using a strong base, such as potassium tert-butoxide (KOtBu), in a polar aprotic solvent, such as dimethyl sulfoxide (DMSO) or tetrahydrofuran (THF).
Q: How to make 1-butene?
A: but-1-ene can be made through various methods, such as the catalytic dehydrogenation of butenes, the selective dimerization of ethylene followed by dehydration, or the metathesis reaction between propylene and ethylene. These methods involve different catalysts and reaction conditions, and careful consideration should be given to ensure high yield and purity of the final product.