[Dolphinsiu]

Arrange the reactivities of following nucleophiles in decreasing order with explanations:

1. (Me)2 C = CH(Me)
2. MeHC = CHMe
3. Me - C ? C - Me
4. (Me)2 C = CH(CN)
5. (Me)2 C = C (Me)2
6. H2C = CH(Ph)
7. H2C = CH(OCH3)

But I don't know how to explain. Would anyone help?

[alphahydroxy]

Consider how electron-rich the olefins are...

[Dolphinsiu]

Electron rich....

CC triple bond is sp-hybridized
CC double bond is sp2
CC single bond is sp3

the more s character, the more electron rich is the CC bond.

Also more substituted double bond, more electron-donating group, more electron rich is the bond..

And also nucleophilicity: CN > OCH3, as CN is more basic than OCH3
Ph is electron-withdrawing as it cause -I(inductive) effect

Am I correct?

Nucleophilicity(Reactivity of nucleophiles):
3>5>4>1>2>7>6

[PRIYA1022]

No..think again, Reactivity here is with respect to how electron rich your alkene is. Electron withdrawing groups on a multiple bond decrease the electron density of your compound and hence nucleophilicity decreases.
 Yes CN is a good nuceophile, but also a strong electron withdrawing group.

[Dolphinsiu]

3>5>1>4>2>7>6

Is it correct?

CN is electron-withdawing group, decreasing the nucleophilicity of alkene, less electron-rich.

OMe is electron-donar due to lone pair electron of O atom

Ph pi systems are delocalized and less nuclephilic

Alkyne is more nucleophilic than alkene due to two more pi systems, more electron-rich.