Amines

Question 1

Hoffmann’s Ammonolysis preparatory method

Answer 1

(Haloalkane) RX + NH3 —–> 1° amine + HX —-RX—-> 2° amine + HX —-RX—-> 3° amine + HX —RX—-> quaternary salt

Question 2

A convenient method to prepare aromatic primary amines

Answer 2

By reduction of nitro compounds

R-NO2 + 6H —–Sn/HCl—-> 1° amine + 2H2O

Question 3

Reduction of nitro compounds in the presence of LiAlH4 gives

Answer 3

Primary amines

Question 4

Mendius reaction is ?

Answer 4

reduction of a nitrile with Na/C2H5OH

Question 5

Reduction of cyanides gives ?

Answer 5

1° amine

RCN + 4H ——LiAlH4 or Na/alc.———> 1° amine

Question 6

An example of Hoffmann’s bromamide reaction

Answer 6

Ethnamide + Br2 + 4KOH ——-> Methanamine + K2CO3 + 2KBr + 2H2O

Question 7

Treating a primary amide with bromine and caustic potash gives ?

Answer 7

a 1° amine containing one carbon atom less than the amide is obtained

Question 8

What is Gabriel phthalimide reaction?

Answer 8

• Phthalimide is treated with alcoholic KOH to get potassium phthalimide.
• Potassium phthalimide is treated with alkyl halide to get N-alkylphthalimide.
• N-alkylphthalimide undergoes hydrolysis with dil. HCl under pressure to get a 1° amine

Question 9

significance of gabriel phthalimide reaction

Answer 9

provides a convenient route for conversion of alkyl halide to primary amine without the formation of other products

Question 10

What is alkylation

Answer 10

aliphatic amine is heated with an alkyl halide and the H atoms attached get replaced one-by-one by the alkyl groups

Question 11

Ethylamine + ethyl bromide ——> ? + ethyl bromide ——-> ?

Answer 11

Diethylamine, Triethylamine

Question 12

Which amines undergo acylation with acid chlorides and acid anhydrides respectively?

Answer 12

1° amine and 2° amine

Question 13

1° amine + acid chloride ——> ?

Answer 13

N-alkylalkanamide + HCl

Question 14

Acid Anhydride + 2° amine ——–> ?

Answer 14

N,N - dialkylalkanamide + RCOOH

Question 15

Ethanoyl chloride + Methanamine ———> ?

Answer 15

N-methylethanamide + HCl

Question 16

Ethanoic anhydride + Ethanamine ——->

Answer 16

N-ethylethanamide + ethanoic acid

Question 17

Aniline + Ethanoyl chloride ——–?——–> ? + HCl

Answer 17

pyridine, N-phenylethanamide

Question 18

How is nitrous acid prepared?

Answer 18

NaNO2 + HCl ——> NaCl + HNO2

Question 19

1° amine + HONO + HCl ——> ? ——H2O—> ? + N2 + HCl

Answer 19

Diazonium salt, Alcohol

Question 20

CH3CH2NH2 + HNO2 + HCl ——> ? —-H2O—> ? + N2 + HCl

Answer 20

CH3CH2-N≡NCl , CH3CH2OH

Question 21

2° amine + HONO —–> ? + H2O

Answer 21

N-nitrosamine

Question 22

Libermann’s nitroso reaction

Answer 22

N-nitrosamine —C6H5OH + H2SO4—-> Green sol. —NaOH—> Deep Blue sol. —Dilution—-> Red sol.

Question 23

3° amine + HNO2 —> ? —Heat—> ? + ROH

Answer 23

Trialkylammonium nitrile , N-nitrosamine

Question 24

Carbylamine reaction

Answer 24

1° amine + chloroform + 3KOH (alc.) –heat—> isocyanide(carbylamine) + 3KCl + 3H2O

Question 25

Aniline + ? + 3KOH (alc.) —heat—> ? + 3H2O + ?

Answer 25

CHCl3, C6H5-N≡C + 3KCl

Question 26

Hinsberg’s test is used to distinguish amines. Product for each of amine

Answer 26

1° amine - clear solution —acidification—> precipitate
2° amine - insoluble substance —acidification—> no change
3° amine - no reaction —-acidification—> clear solution

Question 27

How does Hinsberg’s test work?

Answer 27

unknown amine is shaken with C6H5SO2Cl (Hinsberg’s reagent) in the presence of excess of aqueous KOH solution

Question 28

reaction of each type of amine with nitrous acid

Answer 28

1° amine - alcohol with the evolution of N2
2° amine - nitrosamine which separates as a yellow oily liquid
3° amine - soluble trialkylammonium nitrile salt which on heating decomposes to nitrosamine and alcohol