Inductive Effect: Why Does Charge Decrease?

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Discussion Overview

The discussion centers around the inductive effect in organic chemistry, specifically addressing why the positive charges on carbon atoms decrease as the carbon chain length increases. Participants explore the implications of electronegativity and the influence of attached atoms, such as chlorine, on the distribution of charge within a carbon chain.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants express confusion about the initial question regarding the inductive effect and the behavior of positive charges on carbon atoms in a chain.
  • One participant explains that the positive charge on the first carbon (A) is influenced by the electronegativity of chlorine, which generates a partial positive charge that diminishes on subsequent carbons (B, C, etc.) due to the nature of electron sharing.
  • Another participant reiterates that the positive charge on carbon A is not a complete positive charge and is compensated by shared electron pairs with carbon B, leading to a weaker charge on B.
  • It is noted that the inductive effect generally becomes negligible after 3-4 carbon atoms in the chain.
  • One participant argues that the partial positive charge on carbon A has the capacity to attract shared electron pairs similarly to chlorine, as it is generated by chlorine's influence.
  • Another participant counters that while chlorine generates a strong partial positive charge, the charge on carbon A is weaker and less effective at polarizing carbon B due to the nature of carbon's electronegativity.
  • There is a discussion about the factors affecting carbon's charge, including its electronegativity and the presence of a positive charge, but it is noted that carbon's own electronegativity does not play a role in C-C bonds.

Areas of Agreement / Disagreement

Participants express differing views on the strength and implications of the partial positive charge on carbon atoms, particularly in relation to electronegativity and the influence of other atoms. The discussion remains unresolved with multiple competing perspectives on the inductive effect.

Contextual Notes

Some assumptions about the nature of charge distribution and the influence of electronegativity are not fully explored, and the discussion does not resolve the extent to which these factors interact in different molecular contexts.

Karan Punjabi
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Guys, I just understand that what is inductive effect but I'm not getting the reason that why as chain increases the positive charges on each carbon atom after 3 or 4 bonds decreases or becomes negligible?
 
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Not sure what the question is.
 
Dr. Courtney said:
Not sure what the question is.
Consider n-pentyl chloride on 1 carbon atom which is attached to chlorine atom there is a partial positive charge and on second carbon atom it is said that there is less positive charge and as we move further we get more less positive charge. So why?
 
Lets name the carbons to make it easier. The carbon attached to chlorine is A, the next one B... and so on.

Now the positive charge on A is generated by highly EN chlorine. It is not a complete positive charge mind you, because the electron pairs A shares with B compensate for this charge. Now the partial shifting of the electron pair A-B (electron pairs shared by A and B) towards generates a partial negative charge on B. This charge will be smaller than that on A because it is not generated due to a highly EN atom, but by another partial positive charge (which itself is weak). From B to C, the charge decreases further and we generally neglect inductive effect after 3-4 carbons.
 
CrazyNinja said:
Lets name the carbons to make it easier. The carbon attached to chlorine is A, the next one B... and so on.

Now the positive charge on A is generated by highly EN chlorine. It is not a complete positive charge mind you, because the electron pairs A shares with B compensate for this charge. Now the partial shifting of the electron pair A-B (electron pairs shared by A and B) towards generates a partial negative charge on B. This charge will be smaller than that on A because it is not generated due to a highly EN atom, but by another partial positive charge (which itself is weak). From B to C, the charge decreases further and we generally neglect inductive effect after 3-4 carbons.
I understood you but I was going for the fact that the partial positive charge on Carbon A is having the same capacity to attract shared pairs of electrons as chlorine atom because the partial positive charge is generated due to chlorine.
 
Sorry for the delay in answering.

Yes you are right that chlorine generates the partial positive charge. But this charge is not as strong as chlorine because its effect is suppressed by the movement of bond pair A-B. Chlorine can attract shared pairs as it is its fundamental property (being so EN). Carbon is attracting only because it has a partial charge. This charge is not sufficient enough to polarise carbon B as much as chlorine polarises carbon A.
 
That means there are two factors for carbon i.e its electronegativity and positive charge on it
 
Yes. But its own EN doesent olay a role when it is bonded to another carbon. C-C bonds don't have polarity.
 

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