The Clear Concept of Reaction in Organic Chemistry for Class 12


The field of science that deals with studying structures, physical and chemical properties of a particular material substance are termed chemistry. Though chemistry is an interesting field of study, some denotations need to be understood to make the learning of the subject easier and interesting.

It is required for us to know that all gases, liquids, and solids are not the same and vary in terms of their composition, which is why the classification of the matter is highly required.

Let us learn the class 12 organic chemistry reactions.

Classification of chemistry

Chemistry is further classified into five branches as follows:

  1. Organic chemistry deals with the study of properties and reactions of compounds of carbon.
  2.  Inorganic chemistry includes the study of all substances which are not organic.
  3. Physical chemistry is the study of principles in chemistry, including studies of properties of matter atoms, molecules, and various other fundamentals in chemistry.
  4. Biochemistry involves the study of the chemistry of living organisms structurally and functionally, examining their chemical components.
  5. Analytical chemistry deals with the study of separating, identifying, qualitative and quantitative analysis of compositions of various types of substances.

In this article, we are going to concentrate on what organic chemistry is and its concerning features.

Organic chemistry

Organic chemistry is the branch of science that focuses on the detailed study of the structure, property, and reaction of organic compounds with covalent bonding containing carbon. The structural formula can be determined by organic chemistry.

To better understand the behaviour, the properties such as chemical, physical, and evaluating chemical reactivity can be found. Chemical synthesis of natural products, polymers, and various drugs is included in the study of organic reactions. Carbon-based compounds and compounds like hydrocarbons (containing only carbon and hydrogen) are studied in organic chemistry.

The fundamentals of Organic chemistry

Many factors govern the organic reactions, and they are mostly the same as in any other chemical reaction. The specific factors are those factors that help in determining the stability of reactants and products like conjugation, hyperconjugation, and aromaticity and the presence and stability of reactive intermediates such as free radicals, carbocations, and carbanions.

Many isomers may also form an organic compound. It is crucial for many organic reactions that the selection has to be very specific, considering the regioselectivity, diastereoselectivity, and enantioselectivity. Zaitsev’s rule governs the elimination reactions, and the Woodward-Hoffman rules govern the stereochemistry of pericyclic reactions.

The field of pharmacy has a wide range of applications for organic reactions where they play a major role in the production and formulation processes.

By the mechanism of the organic reactions

There are no limits found when it comes to the number of organic reactions and mechanisms. However, some regular patterns have been found which can be used to reveal various common and useful reactions. Every reaction has a stepwise mechanism that explains how it happens, though these steps are not always clear from the list of reactants solely.

Organic reactions can be classified into various basic types, some reactions fitting into more categories than one, taking the example of some substitution reactions which follow an addition-elimination pathway.

By functional groups

The organic reactions may be classified depending upon the functional group involved in the reaction as a reactant and the functional group formed due to this reaction. For example, the reactant is an ester in the Fries rearrangement, and the reaction product is an alcohol.

What are organic reactions?

The organic compounds undergoing chemical reactions are termed organic reactions.

The five types of organic reactions which are commonly known are:

  1. Substitution reaction
  2. Elimination reaction
  3. Addition reaction
  4. Radical reaction
  5. Oxidation-reduction reaction.

Now explaining the above organic reactions in brief:

  1. Substitution reaction: In forming a new substance, an atom or its group is substituted by another atom or a group of atoms is the process of substitution reaction. The C-Cl bond is a perfect example of the substitution reaction. The carbon atom has a partial positive charge due to the presence of a highly electronegative chlorine atom.

Now coming to a nucleophilic reaction, the nucleophile must have a pair of electrons and a high affinity for the electropositive species compared to the substituent, which was already present initially.

  1. Elimination reaction: The type of atoms or groups of atoms that leave the molecule are typically known as elimination processes. Dehydrohalogenation, for example, is the removal of a hydrogen atom and a halogen atom; dehalogenation is the removal of both halogen atoms.

Two atoms or groups from a molecule are removed without being replaced by other atoms or groups in these reactions. The carbon atoms to which the previously attached atoms or groups were previously attached form a new C-C double bond. Change in hybridization is constantly present.

  1. Addition reaction: The exact opposite of the elimination reaction is the addition reaction. The components X and Y are added to the carbon-carbon multiple bonds called the addition reaction. An example is when adding HCl to ethylene results in the formation of methylene chloride.

HCl  + CH2 =  CH2 → CH3CH2Cl

  1. Radical reaction: There are many organic reactions involving radicals. The free radical mechanism is observed while adding a  halogen to a saturated hydrocarbon. The basic three stages of the radical reaction involve initiation, propagation, and termination. The reaction occurs when the weak bond breaks during the initiation process, resulting in the formation of free radicals. After adding halogen to the hydrocarbon, a radical is produced and finally results in the formation of alkyl halide.

The type of bond may also classify the organic reactions to carbon with respect to the element involved. Organosilicon chemistry, organosulfur chemistry, organophosphorus chemistry, and organofluorine chemistry have also been found to have many organic reactions.


The field of organometallic chemistry has advanced a lot with the changing times, offering new visions in the field of invention, medicine, and industrialisation. Organic chemistry has helped scientists, engineers, and people related to the field of research and analysis to come up with something new to serve humankind and make people’s lives easier globally.

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