Conjugation in Organic Chemistry

Conjugation is an important concept to understand in organic chemistry. It accounts for why we can see the world around us and is closely related to the idea of delocalization.

Conjugation in organic chemistry is a property of certain carbon containing compounds. Conjugation requires a molecule to have one or more carbon- carbon double bond.

Conjugated compounds have two or more alternating double bonds (pi bonds) in their structure. These molecules must have a double then single then double bond pattern. They can also occur in rings, like benzene (a commomly known conjugated hydrocarbon).

Due to delocalization conjugated bonds “move around” because the electron pairs are actually shared between several atoms in the molecule.

Normally pi bonds cannot rotate, but in many conjugated molecules they can. This is because the pi bonds are constantly moving back and forth so what we may draw as a pi bond may be a pi bond (double bond) part of the time and a sigma (single bond) the rest of the time, which allows the bond to rotate.

Conjugation is most common in carboniles and hydrocarbon compounds. The most often used examples of conjugated molecules are usually pigments and retinol (found in the human eye, the molecule that allows us to see light). The pigments that are conjugated appear colored to us because their conjugated bonds absorb certain wavelengths of light to move electrons around. We see only the colors of light not absobed by the bonds.

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