Amines MCQs for NEET — Chemistry Questions with Answers

(b) Secondary amine is reacted with benzene sulphonyl chloride to form solid compound which is insoluble in alkali

key idea: the reagent which can convert -CONH2 group into -NH2 group is used for this reaction. among the given reagents only NaOH/Br convert -CONH₂ group into -NH₂ group. Thus, it is used for converting acetamide to methyl amine. This reaction is called Hofmann bromamide reaction.

${\mathrm{CH}}_3{\mathrm{CONH}}_2+\mathrm{NaOH}={\mathrm{Br}}_2^{}\to \underset{\mathrm{methyl} \mathrm{amine}}{{\mathrm{CH}}_3{\mathrm{NH}}_2}+\mathrm{NaBr}+{\mathrm{Na}}_2{\mathrm{CO}}_3+{\mathrm{H}}_2\mathrm{O}$

The reduction of methylisocyanide (CH3NC) with lithium aluminium hydride (LiAlH4) yields methylamine, which is a secondary amine. Nitroethane and acetamide yield primary amines, while methylcyanide forms a primary amine on reduction with LiAlH4.

According to the NCERT text, 'Nitrogen orbitals in amines are therefore, sp3 hybridised and the geometry of amines is pyramidal. Each of the three sp3 hybridised orbitals of nitrogen overlap with orbitals of hydrogen or carbon depending upon the composition of the amines. The fourth orbital of nitrogen in all amines contains an unshared pair of electrons.'

The NCERT text states, 'In common system, it is known as aniline. It is also an accepted IUPAC name. While naming arylamines according to IUPAC system, suffix ‘e’ of arene is replaced by ‘amine’. Thus in IUPAC system, $C_6H_5–NH_2$ is named as benzenamine.' Both Aniline and Benzenamine are accepted IUPAC names. However, Aniline is specifically stated as an accepted IUPAC name and is the more commonly recognized form.

The NCERT text states, 'Amines are classified as primary (1o), secondary (2o) and tertiary (3o) depending upon the number of hydrogen atoms replaced by alkyl or aryl groups in ammonia molecule. If one hydrogen atom of ammonia is replaced by R or Ar, we get $RNH_2$ or $ArNH_2$, a primary amine (1o).'

The NCERT text provides an example: '$CH_3NHCH_2CH_3$ is named as N-methylethanamine'. This directly matches the given structure for the question.

The NCERT text states, 'In IUPAC system, primary amines are named as alkanamines. The name is derived by replacement of ‘e’ of alkane by the word amine. For example, $CH_3NH_2$ is named as methanamine.'

Table 9.1 in the NCERT context lists '$CH_3–CH_2–CH_2–NH_2$' with the common name 'n-Propylamine' and IUPAC name 'Propan-1-amine'.

The NCERT text states, 'To name secondary and tertiary amines, we use locant N to designate substituent attached to a nitrogen atom. For example, $CH_3 NHCH_2CH_3$ is named as N-methylethanamine...'