Describe the methods of preparation and important reactions of toluene.
Answers
Answer:
1. Preparation of toluene
(i) Toluene is prepared by reacting benzene with methyl chloride in the presence of Lewis acid like zinc chloride.
C6H5H +CH3Cl → C6H5CH3 + HCl
(ii) Toluene is prepared by reacting benzene with methanol.
C6H5H + CH3OH → C6H5CH3 + H2O
2.Reactions of toluene
(i) Oxidation of Toluene: Oxidation of toluene in the presence of potassium permanganate or water gives benzaldehyde which is again oxidised to form benzoic acid.
(KMnO4/H2O)
C6H5CH3 → C6H5COOH
(ii) Bromination of toluene: toluene reacts with bromine to in presence of heat and light to form bromophenylmethane.
(sunlight)
C6H5CH3 + Br2 → C6H5CH2Br + HBr
Toulene reacts with bromine in the presence of iron(III)bromide to produce o-bromotoluene and p-bromotoluene.
(iii) Nitration of toluene: toluene reacts with nitric acid in the presence of sulphuric acid to give 63% of o-nitrotoluene 3% of m-nitrotoluene and 34% of p-nitrotoluene.
Answer:
Toluene is an aromatic hydrocarbon. It is a colourless liquid and is insoluble in water. Its odour is of paint. Its IUPAC name is methyl benzene. Its formula is C7H8.
It is used in paints, glues, nail polish remover, etc. It is used in printing and leather tanning.
Preparation of toluene:
Toluene can be extracted from natural sources and it is prepared from organic substances. It is prepared by alkylation of benzene using methanol. One of such method is Friedal Craft Alkylation. In this method, benzene react with alkyle halide in presence of Aluminium Chloride (AlCl3) which gives toluene as product.
It can also be prepared by cyclization of n-heptane and it is further followed by aromatization.
Important reactions of toluene are:
In electrophilic aromatic substitution reaction, toluene acts as an aromatic hydrocarbon because toluene is more reactive than benzene towards electrophiles.
Explanation: