Organic Reaction by Mechanism

The most prevalent types of organic chemistry reactions are addition reactions, elimination reactions, substitution reactions, pericyclic events, rearrangement processes, photochemical reactions, and redox reactions. In organic synthesis, organic processes are used to create new organic molecules. Organic methods are used to synthesize many man-made substances, including medications, polymers, food additives, and textiles. Two of the oldest organic reactions are the combustion of organic fuels and the saponification of lipids to produce soap. The Wohler synthesis, first performed in 1828, marks the birth of modern organic chemistry. The Grignard reaction, invented in 1912, the Diels-Alder reaction, invented in 1950, the Wittig reaction, invented in 1979, and the olefin metathesis, invented in 2005, have all received the Nobel Prize in Chemistry. The same variables that drive chemical reactions also influence organic reactions. Conjugation, hyperconjugation, and aromaticity are all factors that influence reactant and product stability, as well as the presence and stability of reactive intermediates such as free radicals, carbocations, and carbanions. In an organic molecule, there can be many isomers. Selectivity in terms of regioselectivity, diastereoselective, and enantioselectivity is thus an important criterion for many organic processes. The stereochemistry of pericyclic reactions is governed by the Woodward–Hoffmann principles, but the stereochemistry of many elimination processes is governed by Zaitsev’s rule. In the pharmaceutical sector, organic reactions are critical.

Organic Reaction by Mechanism:

The number of organic reactions and processes that can occur is unlimited. There are, however, some universal patterns that can be used to characterize a wide range of frequent or useful reactions. A stepwise reaction mechanism defines how each reaction works, albeit this detailed description of stages isn’t always clear from a list of reactants. Organic reactions can be categorized into a few different groups. Some reactions generally fall into more than one category. An addition-elimination pathway, for example, is followed by some substitution processes. 

There are five different kinds of organic reactions that can occur. The following are the details:

• Substitution reactions

• Elimination reactions

• Addition reactions

• Radical reactions

• Oxidation-Reduction Reactions

1) Substitution Reaction

In a substitution reaction, one atom or group of atoms replaces another atom or group of atoms, resulting in the production of a completely new material. Take the C–Cl bond, for example, where the carbon atom has a partial positive charge due to the presence of strongly electronegative chlorine atoms.

The nucleophile in a nucleophilic substitution reaction must have a pair of electrons and a high affinity for the electropositive species compared to the substituent that was originally present in the element. Certain parameters must be met in order for the substitution process to take place, such as keeping low temperatures close to room temperature.

A strong base, such as NaOH, must also be dilute because if the base is too concentrated, dehydrohalogenation may occur in the reaction. For the reaction to occur, the solution must be in an aqueous condition, such as water. Nucleophilic and electrophilic substitution reactions are two different types of substitution reactions.

2) Oxidation-Reduction Reaction

An oxidation-reduction (redox) reaction is a chemical reaction in which two species exchange electrons. Any chemical reaction in which a molecule, atom, or ion’s oxidation number changes by gaining or losing an electron is known as an oxidation-reduction reaction. Photosynthesis, respiration, combustion, and corrosion or rusting, to name a few basic life activities, all require redox reactions.

3) Addition Reaction

The elimination reaction as we know is the polar opposite of the known addition reaction. The components or molecules of A and B are added to the carbon-carbon multiple bonds in an addition reaction, which is called an addition reaction. When HCl is added to ethylene in the reaction below, it produces ethylene chloride.

Br2+ CH2 = CH2 → CH2 BrCH2 Br

4) Radical Reactions

Radicals and their mobility are involved in the majority of organic reactions. When a halogen is added to a usually saturated hydrocarbon, a free radical process is activated. In a radical reaction, there are typically three stages: initiation, propagation, and termination. When a weak link is broken, the reaction begins with the creation of free radicals. When the halogen is introduced to the hydrocarbon, a radical is formed, which leads to the formation of alkyl halide.

5) Elimination Reaction

Certain reactions necessitate the elimination and removal of neighboring atoms. In the view of the result of the formation of numerous bonds at the same time, very small molecules are generated as products. The conversion of ethyl chloride to ethylene is an example of a common elimination reaction.

CH3 CH2 Cl → CH2 = CH2  + HCl

The molecule that is eliminated in the aforementioned reaction is HCl, which can be formed by combining H+ from the carbon atom on the left side with Cl– from the carbon atom on the right side.

Conclusion

One species having a nonbonded (or bonded) pair of electrons “donates” an electron pair to an electron-deficient species in an organic reaction by creating a covalent bond between the two species. An organic reaction mechanism is a detailed, step-by-step description of how organic molecules react.