Organic chemistry is a branch of chemistry that deals with compounds containing carbon.
Organic chemistry is of crucial importance for several reasons:
Living Organisms: Organic chemistry is fundamental to understanding the chemistry of living organisms, as the majority of the molecules that make up living systems, such as proteins, lipids, and carbohydrates, are organic compounds.
Pharmaceuticals and Medicines: Many of the drugs and medicines used to treat various diseases and conditions are organic compounds or are derived from organic sources. Understanding the structure and reactivity of organic compounds is essential for the development of new and improved pharmaceutical agents.
Energy and Fuels: Organic compounds, particularly hydrocarbons, are the primary components of fossil fuels, such as natural gas, petroleum, and coal, which are essential sources of energy for our modern society.
Materials and Polymers: Organic chemistry is the foundation for the synthesis and understanding of a wide range of materials, including plastics, rubber, fibers, and other polymeric materials, which have numerous applications in our daily lives.
Hydrocarbons are a class of organic compounds that consist solely of carbon and hydrogen atoms.
They are the simplest organic compounds and can be classified into two main categories:
saturated hydrocarbons
unsaturated hydrocarbons.
Saturated hydrocarbons:
Saturated hydrocarbons are characterized by the presence of only single bonds between the carbon atoms. The general chemical formula for saturated hydrocarbons is CnH2n+2, where n represents the number of carbon atoms in the molecule.
Examples of saturated hydrocarbons include methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10).
Unsaturated hydrocarbons:
Unsaturated hydrocarbons are characterized by the presence of at least one double or triple bond between the carbon atoms. The general chemical formula for unsaturated hydrocarbons with double bonds is CnH2n, and for those with triple bonds, it is CnH2n-2.
Examples of unsaturated hydrocarbons include ethylene (C2H4), acetylene (C2H2), and benzene (C6H6).
The distinction between saturated and unsaturated hydrocarbons is important because it affects their chemical reactivity and physical properties.
Saturated hydrocarbons are generally more stable and less reactive, while unsaturated hydrocarbons are more reactive and can undergo various chemical transformations, such as addition reactions and aromatic substitutions.
The understanding of the properties and reactions of saturated and unsaturated hydrocarbons is crucial in fields such as organic chemistry, biochemistry, materials science, and energy production, as these compounds play a fundamental role in a wide range of applications.
How the components of crude oil are separated from each other by fractional distillation.
Fraction
Temperature Range
Composition
Uses
Gases
Under 40°C
Methane, Ethane, Propane, Butane
Fuel for heating, cooking, and power generation
Petroleum Ether
40-60°C
Pentane, Hexane
Solvent, cleaning agent, and fuel additive
Gasoline/Petrol
60-200°C
Mixture of Hydrocarbons (C5-C12)
Fuel for internal combustion engines
Kerosene
175-325°C
Mixture of Hydrocarbons (C12-C16)
Fuel for jet engines and heating oil
Diesel Fuel
250-350°C
Mixture of Hydrocarbons (C12-C20)
Fuel for diesel engines and power generation
Lubricating Oils
300-400°C
Mixture of Hydrocarbons (C20-C50)
Lubricants for machinery, engines, and vehicles
Waxes
Above 400°C
Mixture of High-Molecular-Weight Hydrocarbons
Candles, polishes, and coatings
Bitumen
Above 400°C
Mixture of High-Molecular-Weight Hydrocarbons
Road surfacing, roofing, and waterproofing
Alkanes are a class of saturated hydrocarbons. They have the general chemical formula CnH2n+2, where n represents the number of carbon atoms in the molecule.
Formula:
The general formula for alkanes is CnH2n+2, where n is the number of carbon atoms in the molecule. For example, methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10) are all alkanes.
Natural Sources:
Alkanes are the main components of natural gas and petroleum (crude oil). These fossil fuels are formed from the decomposition of organic matter over millions of years under high temperature and pressure conditions. The lightest alkanes, such as methane and ethane, are found in natural gas, while the heavier alkanes, such as pentane, hexane, and heptane, are present in petroleum.
Physical Properties:
Alkanes have the following physical properties:
They are generally colorless, odorless, and flammable.
They have low melting and boiling points, with the lighter alkanes being gases at room temperature and the heavier ones being liquids or solids.
They are insoluble in water but soluble in nonpolar solvents, such as ether and carbon tetrachloride.
They have a high energy content and low reactivity, making them useful as fuels.
Chemical Properties:
Alkanes are generally unreactive due to the stability of the carbon-carbon and carbon-hydrogen bonds. However, they can undergo the following types of reactions:
Chemical Properties of Ethane:
Combustion:
2C2H6 + 7 O2 → 4 CO2 + 6 H2O
Substitution Reaction with Halogens:
C2H6 + Cl2 → C2H5Cl + HCl
C2H5Cl + Cl2 → C2H4Cl2 + HCl
C2H4Cl2 + Cl2 → C2H3Cl3 + HCl
(and so on, forming higher-substituted ethanes)
Cracking (Thermal Decomposition):
C2H6 → CH4 + CH2
(Ethane can be cracked to produce methane and methylene)
Halogenation:
C2H6 + Br2 → C2H5Br + HBr
(Ethane can undergo halogenation reactions to form alkyl halides)
Oxidation:
C2H6 + [O] → CH3CHO + H2O
(Ethane can be oxidized to form acetaldehyde)
Uses:
Alkanes have a wide range of uses, including:
Fuels: The lighter alkanes, such as methane, ethane, propane, and butane, are used as fuels for heating, cooking, and power generation.
Transportation Fuels: The heavier alkanes, such as those found in gasoline and diesel fuel, are used as fuels for internal combustion engines in vehicles.
Solvents: Some alkanes, such as hexane and heptane, are used as solvents in various industrial and laboratory applications.
Lubricants: The heavier alkanes, such as those found in lubricating oils, are used as lubricants for machinery, engines, and vehicles.
Petrochemical Feedstocks: Alkanes can be used as starting materials for the production of a wide range of other organic compounds, including alkenes, alcohols, and plastics.