Resonance/Mesomeric
Effect:
The
resonance or mesomeric effect refers to the polarity produced in a molecule as a result of
interaction two π-bonds or between a π-bond and a lone pair of
electrons. This effect operates through π-electron delocalization and is
transmitted along a chain of conjugated bonds.
Or
This is the movement
of electrons in a molecule where the electrons can shift between atoms or
bonds. This shift of electrons creates resonance structures, leading to
stabilization.
Resonance
Concept:
The
process in which different
Lewis structures can be written for a compound which involve identical positions of atoms
is called resonance. The actual
structure of a compound is considered to be a weighted average of all the contributing
structures. The representation of real structures as a weighted average
of two or more contributing structures is called resonance. These structures are also called resonance contributing structures or canonical forms. The actual
structure is a resonance
hybrid of all these structures. The resonance hybrid resembles each of
the contributing structures but is identical to none of them.
Representation
A double-headed arrow (↔) is placed between each pair of contributing structures. For example, there are various contributing structures of benzene:
Electromeric Effect
*Introduction
to Electromeric Effect*
- The *Electromeric Effect* is a temporary effect
that occurs in organic compounds when an attacking reagent interacts with the
molecule. It leads to the *complete
transfer of a pair of π electrons* from one atom to another in the
molecule.
- This effect is significant in the presence of multiple bonds (such as C=C or C=O), and is reversed once the attacking reagent is removed.
Negative Inductive
Effect (-I Effect):
- When an *electron-withdrawing group (EWG)* is attached to a carbon
chain, it pulls electron density away from the chain. This leads to a decrease in electron density along the chain.
- Example: ( C - C
δ+++ -- C
δ++ -- C
δ+--
A δ-)
- Here, A is an electron-withdrawing
group, causing a partial positive charge buildup on the adjacent carbons as
electron density is pulled towards A.
*-I
Effect Order:*
*Halogens:*
- F > Cl > Br > I
General Concepts of Organic
Chemistry
Organic Chemistry:
“Branch of
chemistry which deals with carbon compounds and its derivatives.”
Carbon (abundant ) → Tetravalent (4 bonds)
Organic
Reactions:
Chemical reactions that are undergone by organic
compounds .
Factors that
determine the reactivity of organic reactions:
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Synthesis of Tris(ethylenediamine)cobalt(III) Chloride Objective: To synthesize tris(ethylenediamine)cobalt(III) chloride [Co(en) 3 ]Cl 3 ...
