Aniline is a type of organic base which is used in the making of several dyes, explosives, plastics, drugs, and rubber, and photographic chemicals. Anilines are the organic compounds that lie in the class of groups coming in the organic chemistry that is referred to as aminobenzene or phenylamine. These compounds are known to be toxic and to be one of the classes of the aromatic amines. They are used in a variety of industrial applications and possess all the characteristics of that of an aromatic compound. The aniline compounds are known to have the formula C6H5NH2 in which the amino group is attached to the phenyl group.
Aniline occurs in the form of a yellowish and slightly brownish oily liquid which has a fishy and a musty odour. It smells like a rotten fish. It is a chemical substance that is a flammable liquid and has a very unpleasant odour. The compound of aniline is soluble in water which is colourless to light brown. Its chemical formula is C6H5NH2 or C6H7N. Since it consists of 6 carbon atoms, 7 hydrogen atoms, and 1 nitrogen atom in its chemical formula, it is an organic compound. Today, we will learn about what is anilines, the phenylamine structure, its physical properties and uses.
Given below is the aminobenzene structure.
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The structure of benzenamine has a pyramidal shaped molecule and has a nitrogen hybridization which lies in between sp3 and sp2. Due to this, the nitrogen lone pair lies in an spx hybrid orbital and has a high p character. The amino group in aniline is much flatter than that in an aliphatic amine, which is because of the conjugation of the lone pair of electrons along with the aryl substituent.
Let us discuss the physical properties of anilines which are given below.
The boiling of aniline is 184.13 °C and its melting point is −6.3 °C.
The compound of aniline is slightly soluble in water and many times freely soluble in the chemicals like alcohol and ether.
This organic compound turns darker when it is exposed to light and air.
It is known to be a weak base and when it reacts with strong acids, it tends to form an anilinium ion C6H5N3+.
It is said to be toxic when it is inhaled via the air or tends to get absorbed into the skin since it produces nitrogen oxides that are harmful to the human body as well as the environment.
Let us now take a look at some of the reactions of anilines and the aniline compounds.
Oxidation Reaction: Oxidation reactions of the anilines compounds tend to lead to the formation of the carbon-nitrogen bonds.
Basicity: Anilines are weaker bases and on reacting with stronger acids, the compounds form anilinium ions.
Acylation: In the acylation reaction, anilines tend to react readily with the carboxylic acids and form amides.
The other reactions of anilines consist of alkylation reaction, hydrogenation, Diazotization, Wohl-Aue reaction, etc.
Anilines are used in various fields of science and everyday life. Some of the uses of anilines are given below.
Anilines have their uses in the rubber industry to process the rubber chemicals and products like car tyres, gloves, balloons, etc.
It is also used as a dyeing agent for the manufacturing of clothes like jeans, etc.
It is used for the production of drugs, for example, paracetamol, acetaminophen, and Tylenol.
It is also used in the form of pesticides and fungicides when it comes to the agricultural industry.
It is also used for the manufacturing of polyurethane which is then used for making plastics.
1. Why is Aniline a Weaker Base?
Ans: Aniline is a weaker base since the lone pair over the nitrogen atom in the NH2 group is in conjugation with the π-electrons that are present in the benzene ring. Due to this, it is not readily available for the donation. A weaker base is the one that tends to donate its lone electron pair. Since the pi-electrons are not readily available for donation from the benzene ring, it makes for a weaker base.
Also, the weaker basicity of anilines is due to the inductive effect from the electronegative sp2 carbon atom and the resonance effects, as the electron lone pair of nitrogen is delocalized partially into the pi system of a benzene ring.
2. What is the IUPAC Name of Aniline?
Ans: Aniline is an organic compound and has the formula denoted by C6H5NH2. It consists of a phenyl group which is attached to an amino group, which makes aniline the prototypical aromatic amine. It is amongst the most volatile amines and has the odour similar to that of a rotten fish. It ignites readily and tends to burn with a smoky flame, which is a characteristic of an aromatic compound.
The IUPAC name of aniline is Benzenamine. However, it is also called benzamine or phenylamine.
Chemically, aniline is known to be an electron-rich derivative of benzene, and as a consequence, it tends to react rapidly in the electrophilic aromatic substitution reactions. Similarly, it is also prone to oxidation reactions. Aniline can also be diazotized for giving a diazonium salt, which then tends to undergo many nucleophilic substitution reactions.