info@urfaculty.com

www.urfaculty.com

Govt. Job/ Sarkari Naukri, NEET, CAT, Bank Exam & Study materials

Monday, 27 February 2017

Amines - IV


Ring substitution in aromatic amine:

Aniline is more reactive than benzeneand undergoes electrophilic substitution reaction preferably at ortho and para position.

(i) Bromination: Aniline reacts with bromine water at room temperature to give a white precipitate of 2, 4, 6-tribromoaniline

In order to stop reaction at monosubstitution activating effect of –NH2 group is reduced by acetylation. This prevents di and tri substituted products. Acetyl group is removed by hydrolysis.

(ii) Nitration:
(a)Under strongly acidic medium aniline gets protonated to form anilinium ion, which is deactivating group and is meta directing. Hence minitroaniline is also formed in 47 % along with ortho and para products.

Aromatic amines cannot be nitrated directly because HNO3 being a strong oxidising agent oxidises it forming black mass.

(b) Nitration by protecting the –NH2 group by acetylation reaction with acetic anhydride:

(iii) Sulphonation: Aniline reacts with conc. H2SO4 to form anilinium hydrogensulphate which on heating with sulphuric acid at 453 - 473K produces p-aminobenzene sulphonic acid, commonly known as sulphanilic acid, as the major product.

Click here to view complete Chemistry Free Study Materials and Notes for NEET Preparation

Click here to view complete Physics Free Study Materials and Notes for NEET Preparation

Click here to view complete Biology Free Study Materials and Notes for NEET Preparation

Click here to take NEET online practice tests by UrFaculty.com

No comments:
Write comments

Hey, we've just updated our test package. Check'it out here - https://goo.gl/r7FuPT
Join Youth Apps