Compared with toluene, aniline is prone to electrophilic substitution reactions, because amino nitrogen atoms in aniline molecules are sp3 hybrid, although there is no unhybrid p orbital, sp3 hybrid nitrogen atoms contain more p components, and there are lone electron pairs on nitrogen atoms to form similar pπ conjugations with benzene rings. The result of conjugations is that the electron cloud tends to average. A pair of electrons on the nitrogen atom will be transferred to the benzene ring, and the density of the electron cloud on the benzene ring will increase, which is easy to occur electrophilic substitution reaction, which is manifested in the reaction of aniline and bromine water immediately to produce white precipitation of 2, 4, 6-tribromoaniline. Methyl group in toluene is an electron donor group, which increases the density of the electron cloud on the benzene ring, but the increase degree is small and the activation capacity is smaller than that of amino group. In properties, toluene and bromine are heated to form o-bromotoluene and p-bromotoluene under the action of iron tribromide.
Aniline is prone to electrophilic reactions?
Aniline > Acetanilide > toluene In nitrobenzene
aniline and acetaniline, the N lone pair electron is conjugated with the benzene ring, so the benzene ring is activated. Aniline is more active than acetyl aniline due to the influence of electron absorption of acetyl group.
The activation ability of methyl group is weak, while nitro passivates the benzene ring due to the electron absorption induction effect and electron absorption conjugation effect (no lone pair of electrons on N, only N=O double bond is electron absorption).
So aniline > Acetanilide > toluene nitrobenzene