During World War II, the cities of Hiroshima and Nagasaki were destroyed by American forces with the help of two atomic bombs. Do you know that each of those bombs was equivalent to about 20,000 tonnes of T.N.T?
T.N.T. (Tri-nitrotoluene) is a widely known explosive material. It is prepared by the tri-nitration of toluene.
Toluene undergoes an electrophilic aromatic substitution reaction to form trinitrotoluene.
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Toluene is also known as toluol in some cases. It is an aromatic hydrocarbon. It's a benzene derivative with a monosubstituted methyl group. In the IUPAC system, toluene is referred to as methylbenzene. Toluene is primarily employed as a feedstock and a solvent in industry. Toluene-based inhalants are also used recreationally. Unfortunately, toluene has the ability to harm our bodies' neurological systems.
There are various methods for the preparation of toluene which are as follows.
Benzene reacts with methyl chloride in the presence of Lewis Acid(anhydrous AlCl3) results in the formation of Toluene as a major product.
Toluene is also formed when benzene reacts with dimethyl sulfate.
When acetylene is passed through propyne in a red hot copper tube, toluene is formed as a result of cyclic polymerization.
When a mixture of chlorobenzene and methyl chloride reacts with sodium metal in the presence of dry ether solution yields Toluene as a major product.
It follows a free radical mechanism.
When a sodium salt of (o, m, p)-toluic acid is heated in the presence of soda lime, toluene is formed.
When ortho, meta, or para cresol is distilled with zinc dust, toluene is obtained.
When p-toluidine is treated with nitrous acid and then with ethanol, toluene is obtained.
When phenyl magnesium bromide is treated with methyl bromide, toluene is formed.
The Toluene molecule contains both aromatic and aliphatic parts. So it shows the properties of both parts.
Toluene gives Electrophilic Aromatic Substitution reaction more readily than benzene because it contains a -CH3 group that is electron releasing in nature, it activates the benzene nucleus and gives EAS reaction.
The attached -CH3 group is an ortho and para directing group. On substitution, it gives a mixture of ortho and para derivatives.
In the presence of Lewis Acid(FeCl3 or AlCl3), toluene reacts with chlorine or bromine to give a mixture of o- and p-derivatives.
A mixture of ortho and para nitrotoluene is formed when toluene is treated with conc. HNO3 and conc. H2SO4
A mixture of ortho and para toluene sulphonic acid is formed when toluene is treated with conc. H2SO4
For the bromination of benzylic hydrogen, a selective brominating agent is used i.e., N-Bromosuccinimide(NBS).
It proceeds through a Free Radical mechanism and forms Benzyl Chloride.
It is also a free radical substitution reaction.
Methylcyclohexane is formed when vapours of toluene and hydrogen are heated at 200C in the presence of Nickel catalyst.
Q1. How to distinguish between Benzene and Toluene?
Solution: By Oxidation reaction.
Toluene is oxidized to benzaldehyde by using chromyl chloride and benzoic acid using hot concentrated Potassium permanganate
Benzene is stable, it does not undergo oxidation reactions easily.
Q2. Write the reaction for the conversion of toluene to benzene.
Solution: Toluene is first oxidized to Benzoic acid and then Decarboxylation of benzoic acid gives Benzene.
Q3. Calculate the number of sigma bonds and pi bonds in toluene.
Solution: There are 15 sigma bonds and 3 pi bonds in toluene
Q4. Write the reaction for the conversion of benzamide to toluene.
Benzamide undergoes Hoffmann bromamide degradation reaction i.e., is treated with Bromine in the presence of NaOH to give Aniline.
Aniline formed is treated with nitrous acid at low temperature forms Benzene diazonium chloride which on treated with H3PO4 forms Benzene.
The Formed benzene undergoes Friedel Crafts Alkylation reaction gives Toluene.
Q 1. What happens when the combustion of toluene takes place?
Answer: Toluene in the presence of oxygen burns with a smoky flame.
Q 2. How is trinitrotoluene(TNT) prepared from toluene?
Answer: TNT is prepared from toluene by nitration. On mononitration, nitrotoluene is formed and on further nitration dinitrotoluene and trinitrotoluene are formed.
Q 3. How is Toluene commercially prepared?
Answer: Toluene is commercially prepared from light oil fraction of coal-tar and in large quantities, it is obtained from catalytic dehydrogenation of petroleum products.
Q 4. What is the color of Toluene?
Answer: Toluene is clear, colorless liquid with a benzene-like smell.
Electrophilic Aromatic Substitution reactions of benzene
Chemical Reactions of Alkynes