Important Questions for CSIR NET Chemical Science - REAGENTS

Most Important Questions on Reagents - Download PDF

1. The correct sequence of reagents to be used in the following conversion is

1. (I) NaH, 1-Fluoronaphthalene; (II) NaBH4; (III) i. (CH2O)n,Me2NH.HCl;ii.5N NaOH
2. (I) NaBH4; (II) NaH, 1-Fluoronaphthalene; (III) i.(CH2O)n,Me2NH.HCl; ii.5N NaOH
   
3. (I) i.(CH2O)n, Me2NH.HCl; ii.5N NaOH; (II) NaBH4; (III) NaH, 1- Fluoronaphthalene;
   
4. (I) i. (CH2O)n, Me2NH.HCl;ii.5N NaOH(II) NaH, 1- Fluoronaphthalene; (III) NaBH4
   

2. The major product of the following reaction is

3. Major product of the following reaction is

4. In the given transformation, the intermediate [A] and the major product B are -

5. The major products A and B formed in the following reactions are

6. The major product of the following reaction is

7. The major products A and B in the following reactions are

8. The major product informed in the following reaction is

9. The major product formed in the following reaction is

10. The major product formed in the following oxidation reaction is

Solutions

Solution 01:

The Mannich reaction is an organic reaction in which formaldehyde and a primary or secondary amine or ammonia amino alkylate an acidic proton positioned adjacent to a carbonyl functional group. A -amino-carbonyl molecule, commonly known as a Mannich base, is the result.

Reduction takes place with NaBH4.NaH abstracts the acidic proton. The negative charge thus formed behaves as a nucleophile and results in the final product.

Solution 02:

Solution 03:

First step is the formation of enolate ion and then cycloaddition reaction is taking place.

Solution 04: 

Solution 05:

The presence of lewis base favours the Michael1,4-addition reactions in enones.

InBr₃ activates the acid chloride and generate the acylium ion as electrophile.

Solution 06:

LDA will abstract the α- hydrogen which result into the formation of enolate followed by the attack at trimethylchlorosilane result in the formation of silyl enol ether.

At second step, ozonolysis followed by reduction takes place. After that, compound will undergo esterification to yield a desired product.

Solution 07:

LDA is used as a base for the formation of enolate anion. The presence of bulky isopropyl groups of LDA makes it very selective to remove proton from less hindered -carbon of the ketone.

Solution 08:

Solution 09:

In this reaction, deoxygenation of tosylhydrazones to hydrocarbons takes place. As compared to NaBH4, NaBH3CN is less reactive and more selective and is used to carry out conversion of conjugated tosyl hydrazone to hydrocarbon with the isomerization of double bond.

Solution 10:

In the presence of urea-H2O2, formation of epoxide will take place followed by hydrolysis result in the formation of trans diol. In the next step, reagent Br2/CCl4 will react with the other alkene and formation of bromonium ion will take place after that intramolecular nucleophilic attack (SN2) will take place and result in the formation of product.

Answers keys

1.  C
2.  B
3.  C
4.  A
5.  A
6.  D
7.  C
8.  D
9.   C
10.   B

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• Study Notes for CSIR NET Life Science - (Download PDF)
• Study Notes for CSIR NET Chemical Science - Download PDF Here!

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