Carbanions and Carbocations

Carbocation and carbanion are two of the most commonly used words in organic chemistry. These are the types of natural chemicals that charge electricity to the carbon atom. Carbocations and carbanions are often found, among other reactions. The main difference between carbocation and carbanion is that carbocation contains a positively charged carbon atom, whereas carbanion contains a negatively charged carbon atom.

Carbocation

• A carbocation is an ion with a well-charged carbon atom.
•  Among the simplest examples are methanium CH3+ and ethanium C2H7+. 
• Some carbocation may have two or more direct charges at the same carbon atom or at different atoms, such as an ethylene ion C2H42+.

• Until the early 1970s, all carbocation was called carbonium ion.
• In modern chemistry, carbocation is any positive carbon atom, which is divided into two main categories according to the charged carbon valence:

• +3 in carbenium ions (protonated carbenes),
• +5 or +6 in carbonium ions (protonated allies, coined similar to ammonium).
• Levels deal with carbocation only as if they were carbenium ions or discuss carbocation with a passing reference to the old term carbonium ion or carbenium and carbonium ions. 

Structure

The carbon atom charged in a carbocation is a “sextet,” i.e. it has only six electrons in its outer valence shell instead of the eight valence electrons that ensure maximum stability (octet law). Thus, carbocations tend to be active, demanding to replenish the octet of valence electrons and also to pay a neutral charge. One can reasonably think that carbocation has sp3 hybridisation with sp3 orbital empty, which provides good charging. However, carbocation regeneration is very similar to sp2 hybridisation and trigonal planar molecular geometry.

Carbanion

• Carbanion has a negative, trivalent carbon atom with eight electrons in its valence shell. 
• Carbanion has no electrons.
• Carbanions are Lewis’ bases (donors of electron pairs) with electronic components similar to amines.
• A carbanion is activated by electron donation groups linked to an anionic centre because the facility already has an octet of electrons. Therefore,
• The stable order of carbanion is the opposite of that of carbocations and radicals. Because we have observed that alkyl groups release electrons in relation to hydrogen, we can also claim that electron-releasing groups stabilise carbocation and disrupt carbanion.

Structure

The negatively charged carbon atom of carbanion sp3 hybridised. Like the other sp3-hybridised specimens we have discussed, four orbitals are oriented toward the corners of the tetrahedron. One of the sp3 hybrid orbitals contains a pair of unallocated electrons. As a result, carbanions have pyramidal geometry.

Now we’ll learn more in detail about carbanion and its types. 

Types of carbanion 

Various carbohydrates are essential; second and once

Tertiary goes after receiving the carbon atom

• If one carbon atom is attacked directly in anionic carbon, then it is called primary carbonation.
• If two atoms of carbon are attached to anionic carbon called secondary carbanion.
• If three carbons atoms are spreadly put on the anionic carbon. Then they are called tertiary carbanions.
• If no carbon atom attached to anionic carbon exists

It’s just called methyl carbanion.

Carbanion stability

Carbanion will increase its stability. Some important features are given below:

1. With an inductive effect
2. By resonance 
3. By aromatisation 
4. By % s-character

• Inductive effect

• If the + I group effect is connected to carbon anionic, then it lowers its stability by increasing the electron density in an anionic carbon.

• If – I group effect connected to carbon anionic, then increases its stability because it reduces the electron density of Anionic carbon.

• By aromatisation

• cyclic conjugated carbanion compliant with huckel’s rule.
• The Aromatic character due to the negative charge in cyclic structures

• Resonance effect

• unsaturated conjugated carbanion is strengthened by resonance.

• Such carbanions are more stable than saturated carbons.

• % s- actor

• Carbanion stability increased by % s- character

Let’s discuss some examples:

There are some organic reactions that involve carbanion:

For example :

1. Aldol condensation 
2. Michael’s addition 
3. Benzoin condensation 
4. Reactions involving Grignard reagent

Let’s take aldol condensation.

Aldol (aldehyde + alcohol) reaction is the Reaction of aldehyde (or ketone) enolate with another molecule of the aldehyde (or ketone) in the presence of NaOH or KOH to form β-hydroxy aldehyde (or ketone).

Conclusion

Now we know what carbocations and carbanions are and their significance. In this article, its properties are explained in detail, so we were able to understand it more easily. A carbocation is an ion with a well-charged carbon atom. Carbanion has a negative, trivalent carbon atom with eight electrons in its valence shell.