Chemistry Assessment Questions for IIT JEE Exam on “Diazonium Salts in Synthesis of Aromatic Compounds”.
1. Diazonium salts are specifically used as intermediates in the production of which of the following compounds?
a) m-Bromotoluene
b) o-Bromotoluene
c) p-Bromophenol
d) o-Bromophenol
Answer: a
Clarification: m-Bromotoluene cannot be prepared from the direct bromination of toluene or by Friedel-Crafts alkylation of bromobenzene, because of the ortho, para directing nature of alkyl groups.
2. What is the minimum number of reactions required for the conversion of aniline to 1,3,5-tribromobenzene?
a) 2
b) 3
c) 4
d) 5
View Answer
Answer: b
Clarification: The three reactions are as follows:
(Rightarrow) Reaction 1: Aniline on treatment with bromine water gives 2,4,6-tribromoaniline.
(Rightarrow) Reaction 2: This on diazotisation with HNO2 gives 2,4,6-tribromobenzenediazonium chloride.
(Rightarrow) Reaction 3: This on reaction with H3PO2, reduces the diazo group to hydrogen, to give 1,3,5-tribromobenzene.
3. p-Iodonitrobenzene can be synthesized from p-nitroaniline.
a) True
b) False
Answer: a
Clarification: p-Nitroaniline on diazotisation gives p-nitrobenzenediazonium chloride with on treatment with potassium iodide replaces the N2+Cl– group to give p-iodonitrobenzene.
4. Diazonium salts are used in which of the following industries?
a) Pharmaceutical
b) Dye
c) Photography
d) Food
Answer: b
Clarification: Coupling reactions of diazonium salts produce azo compounds which are coloured in nature. This is used as an application in the manufacturing of dyes.
5. Diazonium salts are primarily used for the preparation of _______ substituted aromatic compounds.
a) alkyl
b) halogen
c) amino
d) COOH
Answer: b
Clarification: Diazonium salts are important intermediates for the introduction of -F, -Cl, -Br, -I, etc. groups into an aromatic ring. Certain compounds like aryl fluorides and aryl iodides cannot be prepared by direct halogenation and are prepared from diazonium salts.
Chemistry Assessment Questions for IIT JEE Exam,