Comparing Stability of Allylic Carbanions

In summary, when considering the C-H bond energy, cleavage of position (b) in the given diagram produces the least energy due to the formation of a carbanion stabilized by resonance. Additionally, when comparing the stability of allylic carbanions formed from positions (a) and (b), position (b) is more stable due to the presence of two allylic carbanions.
  • #1
gpavanb
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Homework Statement


Look at the diagram accompanying the question. Which has least C-H bond energy?


The Attempt at a Solution


On cleavage of a C-H bond, a carbanion is formed as carbon is more electronegative than hydrogen. So cleavage of (b) results in a carbanion stabilized by resonance
 

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  • #2
gpavanb said:

Homework Statement


Look at the diagram accompanying the question. Which has least C-H bond energy?


The Attempt at a Solution


On cleavage of a C-H bond, a carbanion is formed as carbon is more electronegative than hydrogen. So cleavage of (b) results in a carbanion stabilized by resonance

You can form 2 allylic (stabilized by resonance) carbanions (a and b). Which one is most stable?
 
  • #3
Cleavage of a results in a vinylic carbanion. b forms the more stable allylic carbanion
 
  • #4
Sorry, I read that wrong. It should have been position 'b' and 'd' produce the allylic carbanions. Which one is most stable?
 

1. What is a C-H bond?

A C-H bond is a type of chemical bond that forms between a carbon atom and a hydrogen atom. It is a covalent bond, meaning the atoms share electrons to form a stable molecule.

2. How does the energy of a C-H bond compare to other types of bonds?

C-H bonds have a relatively low bond energy compared to other types of bonds, such as C-C or C-O bonds. This is due to the smaller size and lower electronegativity of hydrogen compared to other elements.

3. What factors affect the energy of a C-H bond?

The energy of a C-H bond is affected by several factors, including the presence of nearby atoms or functional groups, the hybridization of the carbon atom, and the type of chemical reaction taking place.

4. How does the energy of a C-H bond vary in different molecules?

The energy of a C-H bond can vary significantly in different molecules, depending on the chemical environment and the types of atoms bonded to the carbon atom. For example, a C-H bond in a hydrocarbon molecule will have a different energy than a C-H bond in an alcohol molecule.

5. Why is understanding the energy of C-H bonds important in chemistry?

The energy of a C-H bond is important in many chemical reactions, as it can determine the stability and reactivity of molecules. It also plays a crucial role in the study of organic chemistry, as C-H bonds are present in most organic compounds.

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