benzoic acid, C6H5CO2H, and some of its derivatives.

The compound below can be prepared by heating together a mixture of benzoic acid,
concentrated nitric acid and concentrated sulphuric acid.

diagram of benzoic acid with a NO2 group on carbon 3

Question
This nitration process is a slow one, despite the use of such vigorous conditions.
Suggest why benzoic acid is less reactive than benzene towards reagents of this
type.

Can someone please explain to me what the answer is for this question

Reply 1

lamalas600

1

The conc. nitric acid and conc. sulphuric acid produce an electrophile No2+ which is attracted to the benzene ring (delocalised electrons) and undergoes electrophilic substitution.
Benzoic acid reacts with NO2+ as attraction to the O-(because of difference of electronegativity with C) in the acid, which is a small difference and therefore slower than reacting NO2+ with benzene ring.

Reply 2

aqua05

OP

9

Original post by lamalas600

The conc. nitric acid and conc. sulphuric acid produce an electrophile No2+ which is attracted to the benzene ring (delocalised electrons) and undergoes electrophilic substitution.
Benzoic acid reacts with NO2+ as attraction to the O-(because of difference of electronegativity with C) in the acid, which is a small difference and therefore slower than reacting NO2+ with benzene ring.

is it coz the electron density in the benzene ring is less..as O will pull the electrons towards itself thus less electrophiles attract

Reply 3

lamalas600

1

Original post by aqua05

is it coz the electron density in the benzene ring is less..as O will pull the electrons towards itself thus less electrophiles attract

I think the electrophile will be attracted to the benzene ring because the electron density is high.

Reply 4

username913907

10

Different substituents have different effects upon the electron density in the aromatic ring. Groups with lone pairs, such as -OH, increase the electron density and therefore increase the rate of electrophillic addition.
Electron withdrawing groups such as the -NO2 or COOH group withdraw electron density making the ring less nucleophillic

Reply 5

aqua05

OP

9

Original post by JMaydom

Different substituents have different effects upon the electron density in the aromatic ring. Groups with lone pairs, such as -OH, increase the electron density and therefore increase the rate of electrophillic addition.
Electron withdrawing groups such as the -NO2 or COOH group withdraw electron density making the ring less nucleophillic