This set of Unit Processes Multiple Choice Questions & Answers (MCQs) focuses on “Sandmeyer reactions”.
1. What do we get by chlorinating hydroxy or methoxybiphenyl?
a) Hydroxy hypochlorite
b) Aniline
c) Alkali hypochlorite
d) None of the mentioned
View Answer
Explanation: On chlorinating Alkali hypochlorite we get hydroxy or methoxybiphenyl, the reaction is as follows : C6H5-C6H5-OH ————–> C6H5-C6H5-Cl-OH.
2. Which of the following is not a Chlorinating agent?
a) Thionyl Chloride
b) Sulfuryl Chloride
c) Phosphorus Chlorides
d) None of the mentioned
View Answer
Explanation: Thionyl Chloride (SOCL2), Sulfuryl Chloride (SO2CL2) and Phosphorus Chlorides(PCL3, PCL5) are all used as chlorinating agents.
3. Phosphorus pentachloride is employed as an esterification agent.
a) True
b) False
View Answer
Explanation: It is true that Phosphorus pentachloride is employed as an esterification agent in the treatment of alcohols, the halide becoming hydrolysed during the reaction.
4. What product do we get on chlorination of Fatty acids?
a) Alkyl chlorides
b) Acid chlorides
c) Chlorides
d) All of the mentioned
View Answer
Explanation: Acid chlorides can be made from the corresponding fatty acids by treatment with phosphorus halides such as : RCOOH + PCI5 ——-> RCOCl + POCl3 + HCI.
5. Which type of reaction do we use for the production of Fluorobenzene ?
a) Sandmeyer’s reaction
b) Addition reaction
c) Substitution reaction
d) Rearrangement reaction
View Answer
Explanation: The Sandmeyer reaction is a valuable procedure for the preparation of halogen derivatives, such as fluorobenzene that generally cannot be made by other more direct methods.
6. In Sandmeyer reaction, what is the intermediate compound formed before adding cuprous halide?
a) Alcohol halide
b) Diazonium halide
c) Aqueous halide
d) None of the mentioned
View Answer
Explanation: During the reaction, firstly we prepare the solution of diazonium halide and gradually add it to a solution of the corresponding cuprous halide. Afterwards the diazotization and replacement of the diazo group takes place in one operation.
7. What is the name of the following reaction: C6H5-NH2-HCL + HF —–> C6H5-NH2-HF + HCl?
a) Addition reaction
b) Substitution reaction
c) Sandmeyer’s reaction
d) None of the mentioned
View Answer
Explanation: The reaction is called Sandmeyer’s reaction because of the formation of diazonium solution, and sandmeyer’s reaction is used in formation of fluorination.
8. Why is the bromination of the paraffin hydrocarbons is slower than chlorination?
a) Because it’s milder
b) It reacts faster
c) Highly reactive
d) None of the mentioned
View Answer
Explanation: In general, methods similar to chlorination with chlorine and chlorides can be employed in the preparation of bromine derivatives. Because the reaction is milder, the bromination of the paraffin hydrocarbons does not proceed so rapidly or to a great degree; and with the lower permissible operating temperature, the formation of polybromine compounds occurs to a lesser extent.
9. The bromination of Benzaldehyde leads to the formation of _________
a) Brominebenzaldehyde
b) Bromobenzene
c) Bromobenzyl benzoate
d) None of the mentioned
View Answer
Explanation: The bromination of benzaldehyde leads to the formation of bromobenzyl benzoate according to the following reactions: C6H5-CHO + Br2 ———> C6H5-COBr + HBr.
10. Which of the following are anti-oxidants?
a) Diphenylamine
b) Thiophenol
c) Thiocresol
d) All of the mentioned
View Answer
Explanation: Normal additions occur in the absence of peroxides and in practice this condition can be brought about by working under carefully controlled conditions or by the addition of Antioxidants to the reaction mixture. Among the antioxidants found to be effective are diphenylamine, thiophenol, and thiocresol, the first being the least effective of the three.
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