Pi bonds as Nucleophiles

Question 1

Unlike carbonyl groups, the C=C bond of most alkenes is

Answer 1

non-polar

Alkenes are electron-rich, making them good electron donors (nucleophiles(, with the most electron density above and below the plane of the C=C bond.

Question 2

What does alkene stability depend on?

Answer 2

• Substitution; the more substituted the more stable
• Steric effects; disubstituted alkene isomers have different stabilities

Question 3

Substitution in Alkenes

Answer 3

When we talk about how substituted an alkene is, we’re referring to how many carbon atoms (or alkyl groups) are directly attached to the carbons in the double bond.

Monosubstituted: one carbon bonded to the double bond (least stable)
Disubstituted: two carbons
Trisubstituted: three carbons
Tetrasubstituted: four carbons (most stable)

More alkyl groups = more hyperconjugation, which helps delocalize the electrons of the π bond and stabilize the pi bond