Cyclohexane

Cyclohexane is a closed-ring cyclic organic compound with six carbon atoms. The molecular formula of cyclohexane is C₆H₁₂. It is a saturated organic compound in which all six carbons are attached in a closed-ring format with single bonds. Cyclohexane by nature is colorless and has a very mild odor.

This article deals with cyclohexane in detail discussing its formula, structure, properties, synthesis, application, and also comparison with benzene.

What is Cyclohexane?

Cyclohexane also known as cycloalkane is a cyclic hydrocarbon consisting of a ring of six carbon atoms bonded to each other with alternating single bonds. Each carbon atom in the ring is also bonded to two hydrogen atoms.

Learn, Alkanes

Cyclohexane Formula

Chemical formula for cyclohexane is C₆H₁₂

Cyclohexane Properties

properties of Cyclohexane can be stuided under two headings that includes,

• Physical Properties of Cyclohexane
• Chemical Properties of Cyclohexane

Physical Properties of Cyclohexane

Physical properties of cyclohexane are discussed below:

• Boiling Point of Cyclohexane: The boiling point of cyclohexane is 80.7°C. This property makes it useful as a solvent because it evaporates readily at relatively low temperatures.
• Density of Cyclohexane: Cyclohexane has a density of 0.779 g/cm³ at room temperature. This density allows it to be easily stored and transported.
• Molecular Weight of Cyclohexane: The molecular weight of cyclohexane is 84.16 g/mol. This information is crucial for calculating the amount of cyclohexane needed in chemical reactions.
• Melting Point of Cyclohexane: The melting point of cyclohexane is 6.55°C. This property is important for its storage and handling, especially in colder environments.

Chemical Properties of Cyclohexane

Chemical properties of cyclohexane are discussed below:

• Solubility: Cyclohexane is non-polar and therefore not soluble in water. However, it is highly soluble in non-polar solvents such as ether, chloroform, and benzene.
• Flammability: Cyclohexane is highly flammable. It forms explosive mixtures with air and should be handled with caution in the presence of ignition sources.
• Reactivity: Cyclohexane is relatively inert under normal conditions. However, it can undergo reactions such as oxidation, combustion, and substitution under appropriate conditions.
• Hydrogenation: Cyclohexane can undergo hydrogenation reactions, where hydrogen gas is added in the presence of a catalyst to convert double or triple bonds into single bonds. This reaction is important in the production of cyclohexane from benzene.
• Halogenation: Cyclohexane can undergo halogenation reactions, where halogen atoms such as chlorine or bromine can substitute hydrogen atoms on the cyclohexane ring.
• Dehydration: Cyclohexane can be dehydrated to form cyclohexene in the presence of a suitable catalyst and high temperatures.

Cyclohexanol to Cyclohexane

The conversion of cyclohexanol to cyclohexane involves a dehydration reaction, where water is removed from the cyclohexanol molecule to produce cyclohexene, followed by a hydrogenation reaction to convert cyclohexene to cyclohexane. Here are the reaction steps:

1. Dehydration of Cyclohexanol to Cyclohexene: C₆H₁₁OH → C₆H₁₀ + H₂O
2. Hydrogenation of Cyclohexene to Cyclohexane: C₆H₁₀ + H₂ → C₆H₁₂

Cyclohexane Structure

Cyclohexane has a closed ring structure. In cyclohexane, all carbons are attached to each other with single bond forming a ring and each carbon atom is also attached with two hydrogen.

Cyclohexane Electron Dot Structure

Electron dot structure of cyclohexane depicts the arrangement of its atoms and bonding electrons.

• It illustrates the sharing of electrons between carbon and hydrogen atoms in the cyclohexane molecule.
• In the electron dot structure, each carbon atom is depicted with four valence electrons, and each hydrogen atom is depicted with one valence electron.

Cyclohexane Electron Dot structure

Cyclohexane Conformation

Conformations are different shape of the same compound for enhanced stability. Cyclohexane exists in different types of conformation such as chair, boat, twisted boat.

• Chair conformation is the most stable and energetically favorable form of cyclohexane.
• In the chair conformation, the carbon atoms alternate in position, resulting in a chair-like shape.
• This conformation minimizes steric hindrance between hydrogen atoms and provides stability to the molecule.

Cyclohexane Chair Form

• Chair form refers to the stable, chair-like conformation of cyclohexane.
• It is characterized by alternating up and down positions of carbon atoms in the ring, resembling the shape of a chair.

Boat Form of Cyclohexane

• Boat form is another conformation of cyclohexane, where the ring adopts a boat-like shape.
• This conformation is less stable than the chair conformation due to increased steric strain between atoms.

Twist boat form of cyclohexane

• Twist boat form is an intermediate conformation between the chair and boat forms.
• It occurs when cyclohexane undergoes a slight distortion, resulting in a twisted boat-like shape.

Apart from the above three conformations of cyclohexane, following are two more possible structures of cyclohexane.

Half Chair Conformation of Cyclohexane

• Half chair conformation occurs when cyclohexane temporarily distorts from its stable chair conformation.
• It is less stable and higher in energy compared to the chair conformation.

Cyclohexane Half Chair Conformation

Newman Projections of Cyclohexane

• Newman projections are used to visualize the conformational changes of cyclohexane.
• They provide a clear representation of the relative positions of carbon atoms and hydrogen atoms in the molecule.

Cyclohexane Newman Projection

Cyclohexane Chair Flip Energy Diagram

Cyclohexane Chair Flip Energy Diagram illustrates the energy changes that occur during the interconversion of the two chair conformations of cyclohexane: the “chair-up” and “chair-down” conformations. This diagram is essential in understanding the dynamics and stability of cyclohexane molecules.

Here’s a brief explanation of the Cyclohexane Chair Flip Energy Diagram:

• X-axis: The x-axis represents the progress of the chair flip, usually measured in terms of the degree of rotation or the angle between the two chair conformations.
• Y-axis: The y-axis represents the energy of the system. It shows the energy changes that occur during the chair flip process.
• Energy Profile: The energy profile typically exhibits a curve with two minima and a transition state in between. The two minima correspond to the two chair conformations, while the transition state represents the highest energy point during the chair flip process.
• Energy Barrier: The energy barrier between the two minima represents the activation energy required for the chair flip to occur. This energy barrier reflects the stability of the chair conformations and influences the rate of interconversion between them.
• Stability: The chair conformation with the lower energy is considered more stable. In most cases, the “chair-down” conformation is more stable than the “chair-up” conformation due to the distribution of steric interactions.
• Activation Energy: The activation energy required to overcome the energy barrier is influenced by factors such as temperature, pressure, and the presence of catalysts.
• Equilibrium: At equilibrium, the energy of the system is distributed between the two chair conformations according to their respective stabilities.

Check, Difference Between Axial and Equatorial Position

Synthesis of Cyclohexane

Cyclohexane can be synthesized through several methods, two of the most common being the hydrogenation of benzene and the dehydrogenation of cyclohexanol.

Hydrogenation of Benzene

Unsaturated benzene ring undergoes addition reactions with hydrogen gas (H₂) to form saturated cyclohexane.

C₆H₆ + 6H₂ → C₆H₁₂

Cyclohexanol to Cyclohexane: Dehydrogenation of Cyclohexanol

Cyclohexanol loses water (H₂O) under dehydrogenation conditions, forming cyclohexene, which is then further hydrogenated to yield cyclohexane.

Reaction: C₆H₁₁OH → C₆H₁₀ + H₂O

Followed by: C₆H₁₀ + H₂ → C₆H₁₂

Cyclohexane Substituted Compounds

Cyclohexane serves as a precursor for various substituted compounds, each possessing unique properties and applications in diverse fields. Some common examples of cyclohexane substituted compounds include:

Bromo Cyclohexane

Bromocyclohexane is obtained by the substitution of one or more hydrogen atoms in cyclohexane with bromine atoms. It finds application as an intermediate in organic synthesis and as a solvent in chemical reactions.

Methyl Cyclohexane

Methylcyclohexane is produced by replacing one of the hydrogen atoms in cyclohexane with a methyl group (-CH3). It is commonly used as a solvent in industrial processes and as a fuel additive.

1-Chloro-4-Ethyl Cyclohexane

This compound is formed by substituting one hydrogen atom with a chlorine atom and another with an ethyl group (-C2H5) in cyclohexane. It serves as a starting material in the synthesis of pharmaceuticals and agrochemicals.

Ethyl Cyclohexane

Ethylcyclohexane is generated by substituting one hydrogen atom in cyclohexane with an ethyl group (-C2H5). It is utilized as a solvent and as a precursor in the synthesis of other organic compounds.

2-Methyl Cyclohexane

2-Methylcyclohexane is obtained by introducing a methyl group (-CH3) at the 2-position of the cyclohexane ring. It is commonly used as a solvent and as an intermediate in organic synthesis.

Cyclohexane Carbaldehyde

This compound is formed by replacing one hydrogen atom in cyclohexane with a formyl group (-CHO). Cyclohexanecarbaldehyde is employed in the synthesis of fragrances, pharmaceuticals, and other organic compounds.

Cyclohexane vs Benzene

Cyclohexane and Benzene are two common organic compounds whose structures resemble each other. Let’s take a detailed comparison between them in the table below:

Properties	Cyclohexane	Benzene
Formula	C6H12	C6H6
Saturation	Saturated	Unsaturated
Structure	Closed Ring	Closed Ring
Bond	Single Bond	Alterante Single and Double Bond
Aromaticity	Non Aromatic	Aromatic

Cyclohexane Uses

Cyclohexane finds diverse applications across various industries due to its unique properties as a colorless, flammable liquid with a relatively low boiling point and high solvency power. Some of the key uses of cyclohexane include:

• Solvent: Cyclohexane serves as a widely used non-polar solvent in industrial applications. It is particularly valuable in dissolving non-polar substances such as oils, fats, waxes, resins, and polymers. It is utilized in the production of adhesives, coatings, paints, varnishes, and other products where a non-polar solvent is required.
• Nylon Manufacturing: Cyclohexane is a crucial component in the production of adipic acid, a key precursor in the synthesis of nylon. Adipic acid is produced through the oxidation of cyclohexane, which is then used in the manufacture of nylon 6,6, a widely used synthetic polymer.
• Chemical Intermediate: Cyclohexane serves as a versatile chemical intermediate in the synthesis of various organic compounds. It undergoes numerous chemical reactions, including hydrogenation, halogenation, oxidation, and nitration, to produce a wide range of derivatives.
• Extraction Medium: Cyclohexane is utilized as an extraction medium in extracting non-polar compounds due to its non-polar nature such as in the extraction of oils, fats, and other organic compounds from natural sources.
• Analytical Chemistry: Cyclohexane is frequently used as a solvent in analytical chemistry techniques such as gas chromatography (GC) and liquid chromatography (LC). It serves as a mobile phase solvent for separating and analyzing organic compounds based on their chemical properties and interactions.
• Pesticide Formulation: Cyclohexane is employed in the formulation of pesticides and herbicides due to its ability to dissolve active ingredients and other formulation components effectively.

Cyclohexane Safety Precautions

When handling cyclohexane, it’s crucial to follow safety precautions to minimize risks associated with its flammability, toxicity, and potential health hazards.

• Ventilation: Always work with cyclohexane in a well-ventilated area to prevent the accumulation of vapors. Use fume hoods or work outdoors whenever possible to ensure adequate airflow and minimize exposure to vapors.
• Personal Protective Equipment (PPE): Wear appropriate personal protective equipment, including safety goggles, chemical-resistant gloves, and lab coats or protective clothing, to protect against skin contact and eye exposure.
• Fire Safety: Cyclohexane is highly flammable. Keep it away from open flames, sparks, and heat sources. Ensure that fire extinguishing equipment, such as fire extinguishers and fire blankets, is readily available in the work area.
• Storage: Store cyclohexane in tightly sealed, properly labeled containers in a cool, well-ventilated area away from direct sunlight, heat sources, and incompatible substances. Follow local regulations and guidelines for storage and handling of flammable liquids.
• Handling: Use caution when transferring or dispensing cyclohexane to minimize spills and splashes. Use equipment designed for handling flammable liquids and ensure that containers are properly grounded during transfers.
• Emergency Procedures: Familiarize yourself and your team with emergency procedures in case of spills, leaks, or accidents involving cyclohexane. Know the location of emergency eyewash stations, safety showers, and spill containment kits.
• Health Hazards: Cyclohexane exposure can cause irritation to the eyes, skin, and respiratory system. Avoid direct contact with skin and eyes. In case of skin contact, promptly remove contaminated clothing and wash the affected area with soap and water. Seek medical attention if irritation persists.
• First Aid: Ensure that first aid supplies, including eye wash solutions and emergency eyewash stations, are readily available in the work area. Train personnel in basic first aid procedures for chemical exposures.
• Safety Training: Provide comprehensive safety training to personnel handling cyclohexane, including hazard awareness, proper handling procedures, emergency response protocols, and the use of personal protective equipment.

Cyclohexane Frequently Asked Questions

What is Cyclohexane also known as?

Cyclohexane is also known as hexahydrobenzene.

What is the molecular formula of cyclohexane?

The molecular formula of cyclohexane is C₆H₁₂

Is cyclohexane soluble in water?

Cyclohexane is not soluble in water because it is a non-polar solvent, while water is a polar solvent. Polar and non-polar substances typically do not mix well.

Is Cyclohexane Flammable?

Yes, cyclohexane is flammable. It forms explosive mixtures with air and should be handled with caution in the presence of ignition sources.

Why does Cyclohexane have 12 hydrogens?

The molecular formula of cyclohexane (C6H12) suggests that it contains 12 hydrogen atoms. Each carbon atom in the cyclohexane ring is bonded to two hydrogen atoms, resulting in a total of 12 hydrogens in the molecule.

How many Sigma and Pi bonds are there in Cyclohexane?

Cyclohexane contains only sigma (σ) bonds and no pi (π) bonds. It consists of single bonds between carbon atoms, which are sigma bonds resulting from the overlap of atomic orbitals.

How is Cyclohexane different from Benzene?

Cyclohexane and benzene are both cyclic hydrocarbons, but they differ in their chemical structure and properties. Cyclohexane is an aliphatic hydrocarbon with a saturated ring structure, while benzene is an aromatic hydrocarbon with a delocalized pi electron system. Benzene has alternating double bonds, making it highly unsaturated, while cyclohexane consists of single bonds, making it saturated.