What Are the Effects of Carboxyl Groups on Electron Distribution?

In summary, electron withdrawing groups, or EWGs, are groups that have a high electronegativity and tend to pull electrons away from the rest of the molecule. They are often referred to as "thirsty suckers" because of their nature. It is important to understand the difference between EWGs and electron donating groups, or EDGs, and their effects on unsaturated bonds. When it comes to aromatic molecules, the effect of EWGs and EDGs can be context dependent, as seen with -OH acting as an EDG in some cases and an EWG in others. In the case of phenol, its acidity is due to resonance stabilization of the negative charge formed when the -OH group is deprotonated.
  • #1
pink_ele
17
0
what are electron withdrawing groups?
please give any important advice to solve questions based on it concept.
 
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  • #2
I like to think electron withdrawing groups as "thirsty suckers". They suck the electrons out of the ring... due to their electronegativity nature.

Take a look at many examples of ewd and electron donating group. You will see the difference. :) Just a pointer to help you: check the bond mulitiplicity in each case. You will find that unsaturated bond exist mostly in one of them.
 
  • #3
thank you
 
  • #4
can you tell me whether -OH (hydroxyl group) is electron withdrawing or electron releasing group ?
 
  • #5
electron withdrawing
 
  • #6
is phenol acidic due to the presence of an electron withdrawing group .ie -OH group?
 
  • #7
Phenol is acidic because the negative charge formed from deprotonating the -OH is stabilized by resonance with the aromatic ring.

Whether something is electron withdrawing or electron donating is somewhat context dependent. While -OH acts as an electron withdrawing group when it is attached to an alkyl chain, -OH acts as an electron donating group when attached to an aromatic system (such as in the case of phenol). In the case of aromatic molecules, the lone pair gets donated into the aromatic system, which outweighs the electron withdrawing effect from oxygen's electronegativity.
 
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  • #8
If OH on a benzene ring is actually an EDG (activating), why is it a strong acid in the meta position, and a weak acid in the para position. I understand activiting groups are O/P directing- I just don't see why OH would enhance the acidity of a benzene ring at all, if it is in fact an EDG.
 
  • #9
When we are discussing about meta/ortho/para positioning, we need a reference point.

What is the functional group on benzene that OH is taken with respect to?
 
  • #10
Sorry about that, its a Carboxyl group. CO2H
 

Related to What Are the Effects of Carboxyl Groups on Electron Distribution?

1. What are electron withdrawing groups?

Electron withdrawing groups (EWGs) are atoms or functional groups that have a high electronegativity, which causes them to attract electrons towards themselves in a chemical bond. This results in a partial positive charge on the atom they are attached to.

2. How do electron withdrawing groups affect the reactivity of a molecule?

Electron withdrawing groups decrease the electron density around the atom they are attached to, making it more difficult for that atom to participate in reactions. This can make the molecule less reactive overall, as the atom is less likely to form bonds with other atoms.

3. What are some examples of commonly used electron withdrawing groups?

Some common electron withdrawing groups include halogens (such as fluorine, chlorine, and bromine), carbonyl groups (such as ketones and aldehydes), nitro groups, and cyano groups. These groups are often used in organic synthesis to control the reactivity and properties of molecules.

4. How do electron withdrawing groups affect the acidity of a molecule?

Electron withdrawing groups can increase the acidity of a molecule by stabilizing the conjugate base. This is because the withdrawal of electrons towards the EWG makes it easier for the conjugate base to accept a proton. This effect is commonly seen in carboxylic acids, where the presence of electron withdrawing groups on the adjacent carbon atoms can greatly increase the acidity of the carboxylic acid group.

5. Can electron withdrawing groups affect the physical properties of a molecule?

Yes, electron withdrawing groups can affect the physical properties of a molecule. For example, the presence of EWGs can increase the melting and boiling points of a compound, as well as its polarity and solubility in polar solvents. This is because the EWGs have a stronger attraction for other molecules, making it more difficult for them to separate and for the compound to change states.

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