NVS PERSPECTIVE ACADEMIC PLANNING (PAP) 2024-25

Swamy's Handbook-2024-Eng

FR & SR-PART III CCS LEAVE RULE

Important question of amines and diazonium salt

 SUBJECT – CHEMISTRY THEORY (043) 2022-23

CHAPTER- AMINES

MM: 70                                                                            TIME : 3 HOURS

General instructions: 

Read the following instructions carefully.

a) There are 35 questions in this question paper with internal choice.

b) Section A consist of 18 multiple-choice questions carrying 1 mark each.

c) Section B consists of 7 very short answer questions carrying 2 marks each.

d) Section C consists of 5 short answer questions carrying 3 marks each.

e) Section D consists of 2 case based questions carrying 4 marks each.

f) Section E consist of 3 long answer questions carrying 5 marks each.

g) All questions are compulsory.

h) Use of log tables and calculators is not allowed.

Section- A

The following questions are multiple choice questions with one correct answer each question carries one mark there is no internal choice in this section.

 

1. When a haloalkane is heated with KCN in aqueous ethanoic solution, the product formed is-

a) Alkyl nitrite                                                 

b) nitro alkane 

     c)  alkane nitrile                                                    

      d) carbylamine      

2. Amine that cannot be prepared by Gabriel phthalimide synthesis is-

a) Aniline                                                           

b)  benzyl amine 

     c) tertiary-butylamine 

     d) isobutylamine

3. Which of the following amine has highest boiling point?

a) Pentaamine  

b) 2-methylbutanamine

c) 2,2-dimethylpropamine

d) 3-methylbutamine              

4. The amine that reacts with NaNO2 and HCl to give yellow oily liquid is-

a) Ethylamine.    

b) Diethylamine

c) Isopropyl amine

d) Secondary butylamine    

5. Sandmeyer reaction of diazonium salt is a replacement of N2by-

a) Halogen Cl or Br

b) Hydroxyl group

c) Coupling

d) Hydrogen        

6. One of the following amines will not undergo Hoffmannbromamide reaction-

a) CH3CONHCH3

b) CH3CH2CONH2

c) CH3CONH2

d) C6H5CONH2   

7. The correct order of the basic strength of methyl substituted amines in aqueous solution is

a) CH3NH2 > (CH3)2NH > (CH3)3N

b) (CH3)2NH > CH3NH2 >  (CH3)3N

c) (CH3)3N >CH3NH2 > (CH3)2NH

d) (CH3)3N > (CH3)2NH > CH3NH2

8. The correct statement regarding the basicity of arylamine is

a) arylamines are generally more basic than alkylamines because of aryl group

b) arylamines are generally more basic than alkylamines because the nitrogen atom in aryalamines is sp- hybridised

c) arylamines are generally less basic than alkylamines because the nitrogen lone- pair electrons are delocalised by intraction with the aromatic ring π- electron system

d) arylamines are generally more basic than alkylamines because the nitrogen loan-pair electrons are not delocalisedby interaction with the aromatic ring π-electron system.            

9. What reagent is used in Hinsberg test of amines?

a) (CH3CO)2O and pyridine

b) C6H5SO2Cl followed by aq. NaOH

c) NaNO2 in aq. H2SO4

d) CH3I(excess) followed by AgOH  

10. Aniline reacts with sodium nitrite and hydrochloric acid at 273 -278 K to give:

a) Benzene

b) Benzene diazonium chloride

c) Chlorobenzene

d) o-chloroaniline    

11. Propane amide on reaction with bromine in aqueous NaOH gives:

a) Propanamine

b) ethanamine

c) N-Methyl ethanamine

d) Propanenitrile               

12. The gas evolved when methylamine reacts with nitrous acid is:

a) NH3

b) N2

c) H2

d) C2H6     

13. Which of the following is not correct regarding aniline?

a) It is less basic than ethyl amine

b) It can be steam distillated

c) It reacts with sodium to give hydrogen

d) It is soluble in water        

 

14. Acetamide and ethylamine can be distinguished by reacting with:

a) Aq. HCl and heat

b) Aq. NaOH and heat

c) Acidified KMnO4

d) Bromine water          

15. Given below are two statements labelled assertion (A) and reason(R).

Assertion(A)- Hinsberg's reagent can be used to distinguish primary amines from secondary amines.

Reason(R)- Benzenesulphonyl chloride is called Hinsberg'sreagent.

Select the most appropriate answer from the option given below :

a. Both A and R are true and R is the correct explanation of A.

b. Both A and R are true but R is not the correct explanation of A.

c. A is true but R is false.

d. A is false but R is true.             

16. Given below are two statements labelled assertion (A) and reason(R).

Assertion(A)- Solubility of amines in water decreases with increase in molar mass.

Reason(R)- Intermolecular H bonds formed by the higher amines are weaker.

Select the most appropriate answer from the option given below :

a. Both A and R are true and R is the correct explanation of A

b. Both A and R are true but R is not the correct explanation of A.

c. A is true but R is false.

d. A is false but R is true.             

17. Given below are two statements labelled assertion (A) and reason(R).

Assertion(A)- Amines behave as a Lewis base.

Reason(R)- Amines have an unshared pair of electrons on nitrogen atom.

Select the most appropriate answer from the option given below :

a. Both A and R are true and R is the correct explanation of A.

b. Both A and R are true but R is not the correct explanation of A.

c. A is true but R is false.

d. A is false but R is true.          

18. Given below are two statements labelled assertion (A) and reason(R).

Assertion(A)- Acylation of amines gives a mono substituted product whereas alkylation of amines gives poly substituted product.

Reason(R)- Acyl group sterically hinders the approach of further acyl groups.

Select the most appropriate answer from the option given below :

a. Both A and R are true and R is the correct explanation of A.

b. Both A and R are true but R is not the correct explanation of A.

c. A is true but R is false.

d. A is false but R is true.         

 

 

 

 

Section - B

This section contains 7 questions with internal choice in two questions. The following questions are very short answer type and carry 2 marks each.

 

19. How will you distinguish between the following pairs of compounds:

        i) Aniline and ethanamine.

       ii) Aniline and N-methylaniline

20. Give reasons:

        i) Aniline does not undergo friedal Craft reaction.

       ii) (CH3)2NH is more basic than (CH3)3N in an aqueous solution.

OR

       i) Although -NH2 group is o/p directing in electrophilic substitution reactions, yet aniline, on nitration gives good yield of m-nitroaniline.

      ii) pKb of methylamine is less than that of aniline.

21. Write chemical equations for the following conversion:

       i) nitrobenzene to benzenoic acid

       ii) aniline to benzyl alcohol

OR

        i) Write the reaction involved in the following: Diazotisation

       ii) Give reason:

            Aromatic diazonium salts are more stable than aliphatic diazonium salts.

22. Illustrate the following with an example of reaction in each case-

       i) Sandmeyer reaction

       ii) coupling reaction

23. Complete the following reactions:

       i) CH3CH2NH2 + CHCl3+alc.KOH------->

       ii) CH3NH2+ C6H5COCl---------->

24. Ammonolysis of alkyl halides is not a good method to prepare pure primary amines. Explain.

25. State and illustrate the following:

                    Gabriel phthalimide synthesis.

     

Section- C

Section contains 5 questions with internal choice in two questions the following questions are sort answer type and carry 3 marks each.

26.  a) Write the chemical reaction of methylamine with benzyl chloride and write the 

             IUPAC name of the product obtained.

       b) Arrange the following in the increasing order of their pkbvalues:

              C6H5NH2 , NH3 , C2H5NH2 ,(C2H5)2 NH

27. Write the structures of main products when aniline reacts with the following reagents:

          i) Br2 water.          

         ii) HCl

         iii) (CH3CO)2O/Pyridine

 

28. Write the structures of A, B and C in the following:

                                Br2/aq. KOH                      NaNO2+ConcHCl/0-5 0C                  KI/∆

      i) C6H5CONH2  ---------- ---------àA ------ ---------------à  B ------ ----à  C

                         KCN                         LiAlH4                             CHCl3+alcKOH

     II) CH3Cl ---- ----------à A ---- -----------à  B -------------------- ---à   C

 

29. Give reasons for any three of the following observations:

a. Aniline is acetylated before nitration reaction.

b. pKb of aniline is smaller than the m-nitro aniline.

c. Primary amine on treatment with benzene sulfonyl chloride forms a product which is soluble in NaOH, however secondary amine gives product which is insoluble in NaOH.

d. Aniline does not react with methyl chloride in the presence of anhydrous AlCl3 catalyst.

30. Write the structures of main products when benzenediazonium chloride reacts with 

      the following reagents.

a) CuCN

b) CH3CH2OH

c) KI

Section- D

The following questions are case based questions. Each question has an internal choice and carries 4(1+1+2) marks each. Read the passage carefully and answer the questions that follow.

 

31. Benzene ring in aniline is highly activated. This is due to the sharing of lone pair of nitrogen with the ring which results in increase in the electron density on the ring and hence facilitates the electrophilic attack. The substitution mainly takes place at Ortho and para positions because electron density is more at Ortho and para positions. On reaction with aqueous bromine all the ortho and para position get substituted resulting  in the formation of 2,4,6- tribromoaniline. To get a monobromocompound, the amino group is acetylated before bromination. After bromination, the bromoacetanilide is acid hydrolysed to give the desired halogenated amine.     

a) Why does -NH2 group facilitates electrophilic attack in aniline?

b) Explain why: in aniline, the substitution mainly takes place at Ortho and Para positions.

c) Show the conversion of benzene into aniline.

 

32. In amines the N atoms of the amino group are SP3hybridised. Amines readily lose its electron pair and act as a base. In aliphatic amines ,the alkyl group tends to increase the electron density on the nitrogen atom due to the +I effect. In aromatic amines, the basic strengths are influenced by the presence of an electron withdrawing group at the O-, m- and p- position in the ring.

a) Lower member of aliphatic amines are soluble in water .Why?

b) Out of (CH3)3N  and and (CH3)2NH which one is more basic in aqueous solution?

c) Which isomer of C3H9N which does not react with Hinsberg’s reagent.

 

 

Section- E

The following questions are long answer type and carry five marks each two questions have internal choice.

 

33. An organic compound A with molecular formula C7 H7NO reacts with Br2/aq. KOH to give compound 'B', which upon reaction with NaNO2 and HCl at 00 Celsius gives 'C'. Compound 'C' 

on heating with CH3CH2OH gives hydrocarbon 'D'.  compound 'B' on further reaction with Br2 water gives white precipitate of compound 'E'. Identify the compound A,B,C,D and 'E'.

Also justify your answer by giving relevant chemical equations.               

OR

An aromatic compound 'A' on treatment with aqueous ammonia and heating forms compound 'B' which on heating with Br2 and KOH forms a compound 'C' of molecular formula C6H7N. write the structure and IUPAC names of the compound A, B and C .Justify your answer by giving relevant chemical equations.          

34. i) Write the structure of main products when benzenediazonium chloride (C6H5N2+Cl-) reacts with the following reagents:

a) KI         b) C2H5OH

      ii) write the structures of A B and C in the following reactions:

                                                                     LiAlH4                                    HNO2 /Low temp

CH3Cl+ KCN (alc)----------------->A-- --------------------->B------------------------>C

                                                                           OR

     i) Write the reactions involved in the following:

a) Hoffmann’s Bromamide degradation reaction

b) Carbylamine reaction

35. i)    Convert the following:

a) Phenol to N-phenylethanamide

b) Chloroethane to methanamine

c) Propanenitrile to ethanal.

ii) What happens when-

a) N-ethylethaneamine reacts with benzenesulphonyl chloride.

b) Aniline reacts with chloroform in the presence of alcoholic potassium hydroxide.

 

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