CBSE 2025 · Region 7 · Set 1 · Q30 · 4 marks
Amines are usually formed from amides, imides, halides, nitro compounds, etc. They exhibit hydrogen bonding which influences their physical properties. In alkyl amines, a combination of electron releasing, steric and H-bonding factors influence the stability of the substituted ammonium cations in protic polar solvents and thus affect the basic nature of amines. Alkyl amines are found to be stronger bases than ammonia. Amines being basic in nature, react with acids to form salts. Aryldiazonium salts, undergo replacement of the diazonium group with a variety of nucleophiles to produce aryl halides, cyanides, phenols and arenes. Answer the following questions :(a)How can you convert the following ?(i)Ethanoic acid to methanamine(ii)Propanenitrile to $\displaystyle 1$-aminopropane(b)Why is $\displaystyle \mathrm{pK}_{\mathrm{b}}$ value of aniline more than that of methylamine ?(c)Arrange the following in increasing order of their basic strength in aqueous solution : $\displaystyle \mathrm{CH}_{3}-\mathrm{NH}_{2}, \quad\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NH}, \quad\left(\mathrm{CH}_{3}\right)_{3} \mathrm{~N}$(ii)Give the structures of A and B in the following reaction : $\displaystyle \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NO}_{2} \xrightarrow{\mathrm{Fe} / \mathrm{HCl}} \mathrm{A} \xrightarrow[273 \mathrm{~K}]{\mathrm{HNO}_{2}} \mathrm{~B}$
Amines are usually formed from amides, imides, halides, nitro compounds, etc. They exhibit hydrogen bonding which influences their physical properties. In alkyl amines, a combination of electron releasing, steric and H-bonding factors influence the stability of the substituted ammonium cations in protic polar solvents and thus affect the basic nature of amines. Alkyl amines are found to be stronger bases than ammonia. Amines being basic in nature, react with acids to form salts. Aryldiazonium salts, undergo replacement of the diazonium group with a variety of nucleophiles to produce aryl halides, cyanides, phenols and arenes. Answer the following questions :
(a)
How can you convert the following ?
(i)
Ethanoic acid to methanamine
(ii)
Propanenitrile to $\displaystyle 1$-aminopropane
(b)
Why is $\displaystyle \mathrm{pK}_{\mathrm{b}}$ value of aniline more than that of methylamine ?
(c)
Arrange the following in increasing order of their basic strength in aqueous solution : $\displaystyle \mathrm{CH}_{3}-\mathrm{NH}_{2}, \quad\left(\mathrm{CH}_{3}\right)_{2} \mathrm{NH}, \quad\left(\mathrm{CH}_{3}\right)_{3} \mathrm{~N}$
(ii)
Give the structures of A and B in the following reaction : $\displaystyle \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NO}_{2} \xrightarrow{\mathrm{Fe} / \mathrm{HCl}} \mathrm{A} \xrightarrow[273 \mathrm{~K}]{\mathrm{HNO}_{2}} \mathrm{~B}$
Marking-scheme solution
(i)
(ii)(b)
Aniline undergoes resonance and as a result the electrons on the N-atom are less
available for donation.
(i)
(CH3)3N < CH3NH2< (CH3)2NH
(c)
(ii)
A= C6H5NH2 ; B= =C6H5N2+Cl
AminesPreparation of AminesApplycase_studymedium
More from Amines
- Which of the following is least basic?2023 · asked 3×
- Which of the following molecules is chiral in nature?2025 · asked 3×
- Amines have a lone pair of electrons on nitrogen atom due to which they behave as Lewis base. Greater the…2025 · asked 3×
- The best reagent for converting propanamide into propanamine is.2025 · asked 3×
- Write equations involved in the following reactions: (i) Ethanamine reacts with acetyl chloride. (ii) Aniline…2022 · asked 3×
- Account for the following: (i) pk b of aniline is more than that of methylamine. (ii) Aniline does not…2022 · asked 3×
- Answer any five questions of the following: N,N-diethyl-benzenesulphonamide is insoluble in alkali. Give…2024 · asked 3×
- A compound 'X' with molecular formula C 3 H 9 N reacts with C 6 H 5 SO 2 C l to give a solid, insoluble in…2024 · asked 3×
CBSE Class 12 Chemistry past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.