Amines and Anilines

Introduction

Amine is a class of organic compound containing at least one N atom. In other words, amine can be regarded as substituted product of ammonia gas in which one or multiple hydrogen atoms are replaced by hydrocarbons. Based on the types of hydroxyl groups attached to N atoms, amine can be divided into fatty amines and aromatic amines. Lower fatty amines possess large solubility which can be attributed to the formation of hydrogen bond between amine molecule and water. Similar to ammonia, amine show alkalinity due to the unshared pairs of electrons of N atom.

As one of the most important amines, anilines have attracted numerous attention and found various application in practical utilization. Anilines also show weak alkalinity due to conjugation of N with aromatic ring, which makes it capable of precipitating trivalent or quadrivalent metal ion and separating them out. In addition, anilines can occur a variety of reactions involved substitution reaction, acetylation and halogenation. It is worthy noting that aniline is very toxic to blood and nerves and could cause poisoning through skin absorrtion and respiratory suction.

There are two main approach to produce aniline:

  1. Nitrobenzene undergoes hydrogenation catalyzed by active copper, which has the advantage of environmental friendliness and the potential utilization for large-scale production.
  2. Chlorobenzene reacts with ammonia to yield anilines in the presence of copper oxide catalyst at high temperature.

Applications

Agriculture:

Anilines are a class of important raw materials for the production of pesticides. Anilines derivatives including N-alkyl aniline, adjacent nitro aniline and phenylhydrazine play a significant role in sterilization. And many of the anilines derivatives are important reaction intermidiates when preparing common bactericide, insecticide and herbicide.

Microcrystalline analysis:

Some anions such as thiocyanate complex anions can be detected by anilines because anilines can react with them and precipitate would be formed. In addition, nitrite and carboxylic acid can also be examined by anilines.

Fluorescent Material:

As one of the most important intermediates in the dye industry, anilines an be used to produce a variety of dye including indigo, acid media BS and direct pink. Anilines derivatives with different substitute effect can be found in the preparation of many coomon dye.

Amine and anilines (Chem. Commun. ,2006(21), 2245)
(OrgLett. ,2008, 11(1), 97)

Organic synthesis:

Owing the presence of active –NH2 group, the hydrogen atom can be replaced by alkyl or acyl groups to secondary or tertiary anilines and acylanilines. Aromatic ring structure of anilines also makes them a useful candidate for the construction of organic compounds.

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