Unsaturated Hydrocarbons


Unsaturated hydrocarbons are made up of multiple covalent bonds between one or more than one C-C bonds in a single compound. The field of organic chemistry is usually common to have multiple covalent bonds reside between carbon atoms. In IUPAC nomenclature, the numbering is counted from the side where double bond comes first in counting among the total number of carbon atoms in the chain or ring structure.

Preparation of Unsaturated Hydrocarbons

There proper methods which are able to aid in the production of unsaturated hydrocarbon. The process of preparation is always in need of specific chemical reactions. In these particular processes, carbon monoxide is used to deliver a reaction with the atoms of hydrogen. The reaction is able to occur only in the presence of metals which are able to show the properties of oxides. These metals are very stable in nature for production of the perfect unsaturated hydrocarbons.

A single condition is mandatory for verification of the right way of the reaction from the first step. The condition is like, the metals are used in the reaction must belong to Group II to Group VII in the normal periodic. The metals are taking part in the reaction in its oxide state. There are two important factors, which look after the process of this reaction. The first is the atmospheric pressure, which should be in its rough state. The second factor which influences the preparation of unsaturated hydrocarbons is temperature. In such cases, the temperature must not go beyond 520°C.

Types of Unsaturated Hydrocarbons

  • Alkene - This is the first type of unsaturated hydrocarbon carries double bond between two C atoms in the organic molecular structure. This type of hydrocarbons makes a single or multiple set of double bonds. The general formula of alkenes is $\mathrm{C_nH_{2n}}$ signifies a double bond and does not belong to any functional group.

  • Alkyne - This is the second type of unsaturated hydrocarbon, where, a single set or multiple set of triple bonds are seen to lie between two adjacent carbon atoms. These unsaturated hydrocarbons are not a part of any functional group. Hence, the formula is used to denote this type of unsaturated hydrocarbon is $\mathrm{C_nH_{2-n}}$.

Figure 1: Difference between saturated and unsaturated hydrocarbon

  • Aromatic hydrocarbon - The final type is considered an unsaturated hydrocarbon in spite of being slightly stable. This is the reason behind this type of hydrocarbon has shapes of rings that remain closer to the pi electrons.

Physical Properties of Unsaturated Hydrocarbon

Unsaturated hydrocarbons have two major physical properties like, melting point and boiling point. The other properties include the solubility of unsaturated hydrocarbons and the total number of constituents present in the unsaturated hydrocarbon structure.

Hydrocarbon has a proportion of hydrogen in larger number than carbon. The melting point varies from one another as per unsaturation present in the hydrocarbons like in, alkenes and alkynes. Some of the melting and boiling points are lower than 0°C and some of hydrocarbons exist with above 100°C.

Figure 2: Unsaturated hydrocarbon: Benzene

The second physical property defines the solubility of the element in this context. The unsaturated hydrocarbons are mostly non-polar in nature hence; it is not able to soluble in protic or polar aprotic solvents. However, few of the unsaturated hydrocarbons are able to soluble but in very small in concentrations into polar solvents depend upon its degree of unsaturation. Hence, it is very convenient to mix these unsaturated hydrocarbons into non-polar solvents.

Uses of Unsaturated Hydrocarbons

  • Many fruits are turned into ripe food items by injecting a small dosage of alkenes.

  • This type of compound is used in the battlefields because it is used in the production of very poisonous mustard gas.

  • These are found in the plastic manufacturing units or sectors.

  • Products like cups, plates, and cartons to store eggs are made up from unsaturated hydrocarbons. The pharmaceutical industries use alkenes to manufacture anaesthetics for surgeries and medical uses.

  • These are used in the production of alcohol for commercial uses except for human consumption.

Effects of Unsaturated Hydrocarbons on the Human Body

The unsaturated hydrocarbons have severe effects on the human body. These are capable to make a person seriously ill which may cause as far as ending the life of the individual. The hydrocarbons found in the unsaturated state are very poisonous as these compounds produce mustard gas used on battlefields.

These are used in every household. The person who has been exposed to this toxic compound has more chances of getting several heart problems. The organic compound is able to create problems in the kidney and liver when these are used in quite often.


The tutorial explains the three types of unsaturated hydrocarbons with different physical properties. The products are derived using various synthesising processes are toxic to human health. These are produced from metal oxides belong to Group II to Group VII. The synthesis of those elements gives some convenient products used in the daily basis. The images give a brief synopsis of the tutorial to help the learners grasp the context.


Q1. What are the preliminary arrangements for the isomers found in an unsaturated hydrocarbon compound?

Ans. The preliminary arrangements for the isomers found in an unsaturated hydrocarbon compound are to develop shapes that are optical, geometrical and isomeric.

Q2. What is a chemical property that helps in the production of hydrocarbons in their unsaturated condition?

Ans. The chemical compounds of unsaturated hydrocarbons are very rich in carbon dioxide and water. This compound starts to get rid of this excess element by going through a process of combustion.

Q3. What is the total number of bonds that is present inside a hydrocarbon compound?

Ans. The total number of bonds that is present inside a hydrocarbon compound starts from one end to the other. In this case, the number of bonds may increase to form a ring of circles around the atom of carbon.

Updated on: 17-Apr-2023


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