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Which of the substituents on the benzene rings donates electron density by resonance?

Which of the substituents on the benzene rings donates electron density by resonance?

Methyl and other alkyl groups are activating for EAS because of this inductive donation of electron density. Resonance effects are only observed with substituents containing lone pairs or π bonds.

What is the effect of substituents on benzene ring?

Each substituent either increases or decreases the electron density in the benzene ring, and this affects the course of electrophilic aromatic substitution. Donation of electron density to the ring makes benzene more electron rich and more likely to react with an electrophile.

How do electron donating groups affect reactivity of benzene?

In the following diagram we see that electron donating substituents (blue dipoles) activate the benzene ring toward electrophilic attack, and electron withdrawing substituents (red dipoles) deactivate the ring (make it less reactive to electrophilic attack). The first is the inductive effect of the substituent.

What substituents are bonded to the aromatic ring?

Most elements other than metals and carbon have a significantly greater electronegativity than hydrogen. Consequently, substituents in which nitrogen, oxygen and halogen atoms form sigma-bonds to the aromatic ring exert an inductive electron withdrawal, which deactivates the ring (left-hand diagram below).

Is och3 EWG or EDG?

Yes, OCH3 which belongs to the is the electron-withdrawing group (methoxy group). Here, the oxygen (in OCH3) is more electronegative than carbon due to which it will show -I effect which is electron-withdrawing.

Why is benzene electron withdrawing?

Since the halogens are very electronegative they cause inductive withdrawal (withdrawal of electrons from the carbon atom of benzene). Since the halogens have non-bonding electrons they can donate electron density through pi bonding (resonance donation).

What is deactivated benzene ring?

In organic chemistry, a deactivating group is a functional group attached to a benzene molecule that removes electron density from the benzene ring, making electrophilic aromatic substitution reactions slower and more complex relative to benzene.

Is benzene electron donating or withdrawing?

What are the substituents of the benzene ring?

Substituents in the benzene ring, such as amino groups (-NH2) and hydroxy groups (-OH), are known to be electron donating groups. When there is a nitrogen or oxygen atom in the alkyl chain, electrons are pulled due to the electronegativity, resulting in a lower electron density. In other words, the NMR chemical shift is low-field shifted.

Why are electron donating groups on a benzene ring activating?

Electron donating groups on a benzene ring are said to be activating, because they increase the rate of the second substitution so that it is higher than that of standard benzene. Electron donating groups are said to be ortho/para directing and they are activators.

How are electron donating substituents direct the phenyl ring?

To clarify what is meant by electron-donating and electron-withdrawing substituents: Any substituent whose first atom (the one that’s attached to the benzene ring) has a lone pair will be a pi electron donor to the phenyl ring, as shown in the resonance structure in the next figure. Pi electron donors to the phenyl ring.

How does a nitro substituent affect reactivity of benzene?

In contrast, a nitro substituent decreases the ring’s reactivity by roughly a million. This activation or deactivation of the benzene ring toward electrophilic substitution may be correlated with the electron donating or electron withdrawing influence of the substituents, as measured by molecular dipole moments.