Butane

Butane, or n-butane, is the fourth member of the alkane group in hydrocarbons. Butane is one of the most useful organic compounds as it is heavily used by humans as a fuel source. It consists of 4 Carbon and 10 Hydrogen atoms, hence the name butane. Butane is found in natural gas and crude oil but is also produced in huge amounts during the refinement of petroleum to make gasoline. In this article, we will learn about the organic compound butane in detail with its formula, structure, isomers, properties including physical and chemical, and its use cases in the real world as well. So, let's start learning about this very useful compound named butane.

What is Butane?

Butane is a chemical compound under the category of Alkanes. Butane is the fourth member of the alkane family and it consists of 4 carbon atoms and 10 Hydrogen atoms.

Butane easily vaporizes at room temperature and it is a highly flammable and colorless easy liquifying gas. In butane, all the carbons with carbon and hydrogen are bonded with single covalent bonds (C – C and C – H). There is no electronegativity in C – C bond and little in C – H bond. This results in no charge separation and no dipole movement. Butane is under the group of Alkanes. Butane is also called Tetracarbane, Butyl hydride, and Quartane.

Chemical Formula and Structure of Butane

Butane consists of 4 carbon atoms and 10 Hydrogen atoms thus the chemical formula for butane is C₄H₁₀ and butane's structure is given as follows:

👁 Structure of Butane

Isomers of Butane

Butane (C₄H₁₀) shows two isomerism i.e., n-butane and Isobutane. These two are structural isomerism which means both have the same chemical formula but have different structures. We can see these two isomeric structures of butane as follows:

The image added below shows the normal structure of Butane in which all carbon atoms are connected to two carbon atoms except for the last ones.

👁 n-Butane

Whereas in isobutane a carbon atom is connected to three carbon atoms as mentioned in the image below,

👁 Iso-Butane

Preparation of Butane

There are various methods such as the dehalogenation of haloalkanes and hydrogenation of alkene and alkynes. Other than this, in Wurtz reaction, and Kolbe's Electrolysis butane is formed. Both of these reactions are given below.

Wurtz Reaction

Wurtz's reaction is an organic chemical coupling reaction in which sodium metal reacts with two alkyl halides in the presence of a dry ether solution to produce a higher alkane as well as a molecule containing sodium and the halogen. Butane is prepared by the reaction of bromoethane with metallic Na in the presence of dry ether as:

C₂H₅Br + 2Na + BrC₂H₅ (dry ether)⇢ C₂H₅ - C₂H₅

Kolbe's Electrolysis Process

During this reaction on electrolysis, sodium butanoate will give butane,

2CH₃CH₂CH₂-COONa  ⇢  CH₃CH₂CH₂CH₃   +  2CO₂  +  NaOH  +  H₂

Physical Properties of Butane

There are various physical properties of chemical compounds such as boiling point, melting point, density, odour and state. Some of these properties of butane are as follows:

• State: Butane is a colourless, odourless gas at room temperature and atmospheric pressure but can easily be liquified using moderate pressure or low temperature.
• Boiling Point: The boiling point of butane ranges from  -1°C to 1°C (30 to 34 °F or 272 to 274 K). At this temperature, it changes from a liquid to a gas.
• Melting Point: Butane does not have a distinct melting point because it is a gas at room temperature. However, under extremely low temperatures ranging from −140 to −134 °C (−220 to −209 °F or 133 to 139 K) it changes from crystalline form to liquid.
• Density: The density of butane is about 2.48 grams per litre (g/L) at standard temperature and pressure (STP) whereas the density of the liquid butane is significantly higher, around 573 kilograms per cubic meter (kg/m³) i.e., 573 grams per litre at its boiling point.
• Solubility: Butane is not very soluble in water. However, it is soluble in organic solvents such as ethanol, acetone, and benzene. The solubility of butane in water is 61mg/L at 20°C (68°F)
• Odour: Pure butane gas is odourless, but an odorant called ethanethiol (or thiophane) is often added to commercial butane to give it a distinctive smell due to safety concerns.
• Flammability: Butane is a highly flammable gas. It can ignite and burn in the presence of an ignition source such as a spark, flame, or heat and oxygen with ease. 
• Vapour Pressure: Butane has a relatively high vapour pressure. At room temperature, its vapour pressure is around 220 kPa (kilopascals), or about 2.2 times atmospheric pressure.
• Molecular Weight: The molar mass of butane is approximately 58.12 grams per mole (g/mol).

Chemical Properties of Butane

Some of the common chemical reactions or properties of butane are as follows:

Combustion of Butane

Butane readily undergoes combustion in the presence of oxygen. The balanced equation for the complete combustion of butane is:

2 C₄H₁₀ + 13 O₂→ 8 CO₂ + 10 H₂O

This reaction releases a large amount of heat energy and is commonly used as a fuel source in lighters and camping stoves.

Partial Combustion of Butane

When butane undergoes combustion in the presence of limited oxygen, then it forms carbon mono oxides rather than CO₂. The balance chemical equation for that is as follows:

2 C₄H₁₀ + 9 O₂  →  8CO + 10 H₂O

Halogenation of Butane

Butane can react with halogens, such as chlorine (Cl₂) or bromine (Br₂), to form halogenated derivatives. For example, the reaction with chlorine yields chlorobutane,

C₄H₁₀ + Cl₂  ⇢  C₄H₉Cl + HCl

The specific product formed depends on the conditions and the number of chlorine molecules reacting with butane.

Dehydrogenation of Butane

Butane can be dehydrogenated to form butenes, which are unsaturated hydrocarbons. This reaction typically requires a catalyst, such as platinum or chromium, and elevated temperatures:

C₄H₁₀  → C₄H₈ + H₂

The resulting butenes can be used as intermediates in the production of polymers or other chemicals.

Butane reacts with oxygen and burns to form carbon dioxide or carbon monoxide and water, when oxygen is present in a sufficient amount as -

2 C₄H₁₀ + 13 O₂  ⇢  8 CO₂ + 10 H₂O

Uses of Butane

Butane is very useful in day to day activities of humans in many ways. Some of these use cases are as follows:

• Fuel: Butane is widely used as fuel in portable gas stoves, and camping stoves as butane can be easily liquefied under moderate pressure, making it suitable for storage and transportation in portable containers.
• Lighter Fluid: Butane is commonly used as fuel in lighters. The pressurized butane gas is released when the button of the lighter is clicked and a spark ignites the gas to create fire and provide flame for lighting various things such as candles, gas stoves etc. 
• Aerosol Propellant: Butane is used in aerosol products such as hairspray, deodorants, air fresheners, and spray paints.
• Refrigerant: For small-scale refrigerators such as camping fridges, butane is used as a refrigerant as it has a low boiling point.

Read More

• Classification of Organic Compounds
• Functional Groups
• Nomenclature of Organic Compounds

Sample Questions on Butane

Question 1: What are the disadvantages of Butane?

Answer:

Butane has several applications as well as disadvantages, In small quantities there is no effect, If the person was highly exposed to Butane, it causes cardiac arrest, Central nervous system depression, Cancer, Drowsiness, Unconsciousness, Temporary memory loss, Blood pressure fluctuations and some times may lead to death

Question 2: What are the different types of Butane?

Answer:

Butane is under the group of Alkanes, It is a highly flammable easy liquifying gas. It can be found as two structural isomers that are n-butane and isobutane or sometimes a combination of both.

Question 3: Where is butane found?

Answer:

Generally, butane occurs in natural gas, In natural gas, butane presents an extent of 1 percent. the butane will stay in the air for about 40 minutes. And also butane occurs in petroleum, In petroleum, Butane is present in a very small amount. 

Question 4: Can Butane Evaporate?

Answer:

Butane evaporates at atmospheric pressure. Butane changes liquid immediately when compressed and then immediately turns to gas with reduced pressure, that is the reason for Butane using in Lighters.

Question 5: What are the isomers of Butane?

Answer:

The butane is under the group of alkanes and the molecular formula is C₄H₁₀. Butane consists of 2 isomers that are n-butane and isobutane.