My prof asked us the requisites for e delocalization.
Sigma e delocalization
-Must have c-h bond next to a sp2C
Pi e delocalization
-Must have sp3 lone pair attach to an sp2C. Prof said there are more requisites besides on what ive written. I think if it has high en? What is hyperconjugative releases btw? And how can i know if its hyperconjugative? Sorry if i ask a lot. I just really one to know more. Thank you in adv for answering all of my questions...
And also how would i know if the molecules or element in structure is either electrifilicity or nucleofilicity? For ex. Acetone. The carboxyl C is + and O is - but when you draw a canonical structure of it the H in ch3 became + and has double bond with carboxyl C. Why pls explain this to me...please
Pls answer
No problem at all! I'm here to answer all of your questions. Let's break it down step by step:
1. Sigma e delocalization:
To have sigma electron delocalization, there must be a C-H bond next to a sp2 carbon atom. This is because the adjacent sp2 carbon atom has a p orbital which can overlap with the sigma bond, allowing the electrons to be delocalized.
2. Pi e delocalization:
Pi electron delocalization requires a lone pair of electrons on an sp3 hybridized carbon atom attached to an sp2 carbon atom. This lone pair can overlap with the adjacent pi bonds, enabling electron delocalization.
Now, let's talk about hyperconjugation and how it relates to these concepts:
Hyperconjugation refers to the delocalization of electrons between a sigma bond and an adjacent empty (or low-lying) orbital. It occurs when a filled orbital, such as a C-H bond, interacts with an empty or low-lying antibonding orbital or a vacant p orbital.
The hyperconjugative effect helps stabilize molecules and transition states by lowering the energy of the system. It can impact various properties, including acidity, stability of radicals, and transition state stability in reactions.
To determine if a molecule or a specific bond can exhibit hyperconjugation, you need to consider a few factors:
1. Adjacent empty or low-lying orbital: Look for pi bonds or empty p orbitals adjacent to the bond in question.
2. Appropriate overlap: Ensure that there is proper alignment and orbital overlap between the filled orbital (e.g., C-H sigma bond or lone pair) and the empty or low-lying orbital.
3. Geometry: The bonding arrangement should allow for effective overlap between the orbitals involved in hyperconjugation.
By considering these factors, you can determine if hyperconjugation is possible in a given molecule or bond.
I hope this helps! Let me know if you have any further questions.