Anilines

What is Anilines?

Anilines are the organic compounds in the class of group coming in organic chemistry which are also called as aminobenzene or phenylamine.

Have you ever wondered what is behind the blue colour of the jeans you wear? Yes, this colour is probably due to the chemical compound named aniline, which is used as a dyeing agent in the cloth industry.

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These compounds are said to be toxic in nature and also known to be one of the classes of aromatic amines. These are used in a wide variety of industrial and are known to possess all the characteristics of an aromatic compound. The aniline compounds are said to have the formula C6H5NH2 wherein the amino group is supposed to be attached to the Phenyl group.

Anilines

Anilines – Structure

Aniline, also known as aminobenzene or phenylamine, has 6 carbon (C) atoms, 7 hydrogen (H) atoms, and 1 nitrogen (N) atom in its chemical formula of C6H7N or C6H5NH2. Because aniline has an amino group in its structure, it is also an amine, hence it is classified as an aromatic amine.

Aniline is a musty, fishy-smelling yellowish to brownish, greasy liquid. -6°C melting point; 184°C boiling temperature; 158°F flash point Water-insoluble and somewhat denser than water. Vapors are more dense than air. Because aniline is an aromatic molecule that combines readily with other aromatic compounds, a low aniline point suggests a low diesel index. A high aniline point suggests a highly paraffinic gasoline with a high Diesel index and excellent ignition quality.

Aniline Structure

The above image shows the structure of an Aniline compound. These compounds have the formula C6H5NH2 with a phenyl group (C6H5) attached to the amino group (NH2) as shown.

Aniline is in the form of a yellowish and somewhat brownish oily liquid having a musty and a fishy odour. It smells like the odour of a rotten fish. It is a kind of chemical substance which is a flammable liquid and has an unpleasant odour. The compound is soluble in water. It can also be colourless to light brown. It has a chemical formula of C6H5NH2 or C6H7N and since it has 6 carbon atoms, 1 nitrogen atom and 7 hydrogen atoms in its chemical formula, it is classified under organic compounds.

Anilines – Physical Properties

The physical properties of Anilines are given below-

  • Aniline has a boiling of about 184 oC and melting of about -6 o
  • The compound is slightly soluble in water and sometimes freely soluble in the chemicals such as alcohol and ether.
  • This organic compound tends to darken when exposed to air and light.
  • It is said to be weak base and on its reaction with strong acids, it forms anilinium ion -C6H5-NH3+.
  • The compound is said to be toxic when it gets inhaled through the air or gets absorbed into the skin as it produces nitrogen oxides which are harmful to the environment.

Anilines – Reactions

  1. Oxidation Reaction- The oxidation reactions of anilines compounds leads to the formation of carbon-nitrogen bonds.
  2. Basicity- As it is known that anilines are weak bases. On reaction with strong acids, the compounds form ions of anilinium.
  3. Acylation- In acylation reaction, anilines reacts readily with carboxylic acids forming amides.

The other reactions include alkylation reaction, Diazotization, hydrogenation, Wohl-Aue reaction, etc.

Anilines – Uses

Anilines are employed in various fields of science and everyday life as given below-

  • Anilines are used in the rubber industry for the processing of rubber chemicals and products such as car tyres, balloons, gloves, etc.
  • It is used as a dyeing agent in the manufacture of clothes such as jeans, etc
  • It is employed in the production of drugs such as paracetamol, Tylenol, acetaminophen.
  • It is used as a pesticide and fungicides in the agricultural industry
  • It is utilized in the manufacture of polyurethane which is, in turn, used in the making of plastics.

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Frequently Asked Questions – FAQs

Which is more basic aniline or methylaniline?

Because the methyl group (an electron releasing group) increases the electron density on nitrogen in N-methylaniline, it is more basic than aniline.

Why is aniline toxic?

The skin, eyes, and respiratory tract are all irritated by aniline. All methods of exposure can cause effects. Aniline causes methemoglobinemia, which reduces oxygen transport to tissues. Aniline can also induce red blood cell destruction, resulting in immediate or delayed hemolytic anaemia.

Which is the most basic anime?

The most basic is piperidine (conjugate acid pKa = 11.2). There is no resonance because the lone pair is in a sp3 hybrid orbital.

Why is nitrogen more basic than oxygen?

Because oxygen is more electronegative than nitrogen, it clings to its lone pair more strongly. As a result, the nitrogen lone pair is more likely to break away and make a new connection with a proton — in other words, it is more basic.

Is an aniline an electrophile?

Acetylation refers to the nucleophilic replacement reaction with acetic anhydride that results in the creation of Acetanilide. The nucleophile in this reaction is aniline, and the nucleophile is an acetic anhydride group acyl (CH3CO-).

To learn more about aniline and other important chemical compounds, download BYJU’S – The Learning App.

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