Cycloalkanes

Introduction

Various organic compounds, such as cycloalkanes, have distinct features based on their structure. Body fat exists in humans & some food, as well as hair products, contain these hydrocarbons. As a result, these organic compounds can be found in all aspects of daily life. Numerous organic compounds found naturally or synthesised in labs comprise rings of carbon (C) atoms with distinct chemical characteristics; these compounds are referred to as cycloalkanes. Cycloalkanes only have carbon-hydrogen (C-H) bonds but also carbon-carbon (C-C) single bonds, but the C-atoms are arranged in a ring. Cyclopropane is the tiniest cycloalkane.

What are Cycloalkanes?

A few organic complexes are cycloalkanes. They can vary based on their structure. Everything in the real world is made of hydrocarbons. Because of their saturated nature, their structure resembles a ring composed of these hydrocarbons. They are composed of hydrogen (H) & carbon (C) bonds that form a cyclic structure, & all kind of them are stable. The most stable cycloalkane is the smallest cycloalkane.

C_n H_2n is the general formula for deciding the type of cycloalkane. In this formula, 'n' represents the no. of atoms in the chemical molecule. They include cyclopentane (C₅ H₁₀), cyclobutane (C₄ H₈), cyclohexane (C₆ H₁₂), cycloheptane (C₇ H₁₄), cyclooctane (C₈ H₁₆), & many others. The no. of C-atoms in each of these cycloalkanes varies.

Classification of Hydrocarbons

Based on the carbon skeleton in their structure, hydrocarbons are divided into 2 broad categories.

Acyclic/open-chain hydrocarbons

Are composed of a straight chain of carbon compounds that may or may not be branched. There is no ring structure.

There are 2 kinds of open chain hydrocarbons −

• Hydrocarbons with a straight chain

  Straight chain hydrocarbons are further classified into 2 types −

  • Hydrocarbons that are saturated: Saturated hydrocarbons are compounds with single carbon-carbon (C-C) bonds. These are also referred to as alkanes.

  • Unsaturated hydrocarbons: Unsaturated hydrocarbons are carbon compounds with double or triple carbon-carbon bonds (alkanes) (alkynes).

• Hydrocarbons with branched chains

Hydrocarbons with a closed chain/cycle

Closed chain hydrocarbons are hydrocarbons with a ring-shaped carbon skeleton.

These hydrocarbons are further classified as follows −

• Aromatic Hydrocarbons

• Alicyclic Hydrocarbon

Organic Compounds and Cycloalkanes

It was previously thought that organic compounds were obtained from nature & living organisms & could not be prepared in labs. This description was rejected when Wohler created urea in the lab from the inorganic substance ammonium cyanate. Eventually, organic compounds were defined as those with carbon (C) elements in their structure. Organic compounds, which are carbon (C) compounds are researched using a branch of science known as organic chemistry.

Nomenclature of Cycloalkanes

There's only 1 ring in cyclohexane, which is named by adding the prefix 'cyclo' to the alkane's original name. It denotes the no. of carbon atoms in the cycloalkane.

Cyclopropane, for instance, is named after a carbon (C) ring with three C-atoms as well as six H-atoms.

No. of C-Atoms in the Ring	Prefix	Name	IUPAC Name
4	Cyclo	butane	cyclobutane
6	Cyclo	hexane	cyclohexane

In the complexes listed, only carbon & hydrogen are present.

When any substituent is attached in the carbon (C) ring by replacing any 1 hydrogen, suffix & prefix are added according to the functional group's priority series. The group's position is also not stated.

No. of C-Atoms in the Ring	Substituent Group	Prefix	Suffix	IUPAC Name
6	-OH	-	ol	cyclohexanol
6	-Cl	Chloro	-	Chlorocyclohexane

When there is more than one substituent present by replacing 2 H-atoms than the position of the substituent group, the group with the highest priority receives the lowest no. When there are multiple priority groups, alphabetical order is used. E.g., if there are 2 groups, 'ethyl' & 'methyl,' the 'ethyl' group has the lowest no.

Cycloalkanes Properties

• They have a higher melting as well as boiling point.

• They are more densely packed.

• They have many London or dispersion forces.

• C-atoms are close together in their ring structure.

• They are extremely reactive.

• Angle strain is evident in them.

• The first 4 classes are in a gaseous state at room temperature.

• They are not water-soluble.

• Their molecules are destroyed when they are burned.

Common Uses

• They are used as an organic solvent in the development of pharmaceuticals.

• These are used in the production of hair products as well as in the food industry.

• In the medical field, cycloalkane cyclopropane is used as an anaesthetic agent.

• Carboplatin, derived from cyclobutane, is used to treat cancer.

• They are also employed in the oil and gas industries.

• Their classes are used for pigmentation & as fragrances in the perfume industry.

• A few of these saturated hydrocarbons are found as steroids in the plant as well as animal tissues.

Conclusion

The structure of various organic compounds, such as cycloalkanes, is distinguished according to their structure. The smallest cycloalkane is the most stable cycloalkane that is cyclopropane. The general formula for determining the type of cycloalkane is C_n H_2n. They have a different no. of C-atoms. They are used in various fields such as in the oil and gas industries, pharmaceuticals, cosmetics, as well as the food industry. Some of the saturated hydrocarbons are also found as steroids in both plants as well as animal tissues. They tend to have a higher melting point as well as a higher boiling point. They are more compactly packed and are highly reactive. Hydrocarbons are classified into acyclic/open hydrocarbons chains as well as closed chain/cycle hydrocarbons based on the carbon (C) skeleton in their structure.

FAQs

1. What are the cyclohexane (cycloalkane) conformers?

They contain 12 H-atoms in addition to 6 C-atoms. Their conformers include chair form, boat form, & half chair form. Each of the shapes is distinct.

2. Which of the following cycloalkanes is the most stable?

The most stable cycloalkane is the smallest cycloalkane. Cyclopropane is the most stable of the cycloalkanes. It has a triangle structure as well as the structural formula is (CH₃ CH₂ CH₃).

3. What is the definition of cycloalkane ring strain?

Ring strain is an instability that occurs when the bonds in a molecule form an abnormal angle, with 109.5° being the ideal bond angle of sp³ hybridised carbon (C). It affects the structures of the smaller cycloalkanes, increasing their potential energy. Ring strain equals torsional strain plus steric strain plus angle strain.

4. Which Newman projection is the most stable?

At room temperature, the staggered and eclipsed conformations of a molecule generally interconvert, but each conformation, and thus its corresponding Newman projection, is not equally stable: The staggered conformations are more stable (have lower energy levels) than the eclipsed conformations.

5. What exactly is the distinction between axial as well as equatorial positions?

Each C-atom in a chair conformation has an axial as well as an equatorial position. The axial substituents are found above & below the ring along a perpendicular axis, whereas the equatorial substituents are found in the ring's plane around the equator. During a ring flip, the axial and equatorial positions are interconverted.