Do all basic groups show +I effect?

Or do they simply exhibit an electron donating tendency which has nothing to do with Inductive effects?

I can't decide if the electronegativity and basicity are completely decoupled phenomena. Does one have an effect on the other?

Or do I always have to consider them separately.

(note: I'm talking about lewis bases not just ones with -OH groups)

  • $\begingroup$ The basicity is determined by the amount of -OH ions present in solution, pka values are associated with electronegativit y and net charge. $\endgroup$ – Technetium Oct 8 '15 at 5:14
  • $\begingroup$ Can you give an example of these "basic" groups that you are talking about? Functional groups or substituents aren't usually classified as Lewis basic. $\endgroup$ – orthocresol Oct 8 '15 at 9:05
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    $\begingroup$ @orthocresol really? I heard amines being classified as Lewis bases often enough … or thioethers … $\endgroup$ – Jan Oct 8 '15 at 9:19
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    $\begingroup$ @OP: $\ce{NH2}$ is a basic group but shows a $-\mathrm{I}$ effect. These two have nothing to do with each other. Electronegativity and basicity are also two only distantly related concepts. $\endgroup$ – Jan Oct 8 '15 at 9:20
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    $\begingroup$ Don't worry, it's my bad. My brain hasn't really been working recently... Anyway, electronegativity determines the +I/-I effects. As Jan said, basicity often has very little to do with it. Inductive effects are about how strongly the group donates/withdraws electrons from adjacent atoms (usually carbons) in the same molecule, whereas (Lewis) basicity is a measure of how strongly the group donates electrons to an external Lewis acid, such as $\ce{H+}$. Superficially they may seem similar, but the electrons that play a role in these two phenomena are different. $\endgroup$ – orthocresol Oct 8 '15 at 18:17

In Inductive effect due to the EN difference between the adjacent atom or group, polarisation of sigma bond occurs, which causes a partial + and - charge on them. It is a permanent effect, which is effective upto 4-6$C$ only.

+I: polarisation occurs away from the atom or group, i.e., the adjacent group attached will act as electron pusher or donor or will have EN less than the carbon. Example

$\ce{CH3-(C=O)OH }$, $\ce{-CH3}$ will acquire a partial + charge and $\ce{-(C=O)OH }$ will acquire partial - charge.

-I: polarisation occurs towards from the atom or group, i.e., the adjacent group attached will act as electron puller or acceptor or will have EN more than the carbon.

Example $\ce{CH3-CH2-NO2}$, $\ce{-CH2-CH3}$ will have partial + charge and $\ce{-NO2}$ will have partial - charge.

As far as Lewis base is concerned its generally an electron pair donor, which makes it electron pucher most of the time , so, such lewis base would show +I effect.


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