NEET Questions Solved

Acetamide and ethyl amine can be distinguished by reacting with

(a) aq. HCl and heat

(b) aq. NaOH and heat

(d) bromine water

#Amines - Introduction,preparation and properties

(b) When acetamide is heated with aq. NaOH it forms NH₃ gas but ethylamine cannot form NH₃.

CH₃CONH₂ + H₂O $\overset{NaOH}{\to}$ CH₃COONa + NH₃

CH₃CH₂NH₂ + H₂O $\overset{NaOH}{\to}$ No reaction

Difficulty Level:

(a)
13%
(b)
41%
(c)
22%
(d)
26%

Predict the product,

#Amines - Introduction,preparation and properties

(a) Both aliphatic and aromatic secondary amines react with NaNO₂ + HCl(HNO2) to form N-nitrosoamines which are insoluble in dilute mineral acids and separate out as neutral yellow oily compounds.

Difficulty Level:

(a)
43%
(b)
21%
(c)
28%
(d)
10%

Intermediates formed during the reaction of RCONH₂ with Br₂ and KOH are

(a) RCONHBr and RNCO

(b) RNHCOBr and RNCO

(d) RCONBr₂

#Amines - Introduction,preparation and properties

(a) The reaction, RCONH₂ + Br₂ + KOH $\to$ RNH₂

is known as Hofmann bromamide reaction. The mechanism of this is given as:

Difficulty Level:

(a)
51%
(b)
24%
(c)
20%
(d)
7%

The final product C, obtained in this reaction

$\overset{{Ac}_{2} O}{\to}$ A $\to_{{CH}_{2} COOH}^{{Br}_{2}}$ B $\to_{H^{+}}^{H_{2} O}$ C

would be

(a) (b)

#Amines - Introduction,preparation and properties

(a) $\overset{{Ac}_{2} O}{\to}$ $\to_{{CH}_{2} COOH}^{{Br}_{2}}$ $\to_{H^{+}}^{H_{2} O}$

Difficulty Level:

(a)
48%
(b)
31%
(c)
14%
(d)
9%

Aniline is reacted with bromine water and the resulting product is treated with an aqueous solution of sodium nitrite in presence of dilute hydrochloric acid. The compound so formed is converted into a tetrafluoroborate which is subsequently heated. the final product is

(a) 1,3,5-tribromobenzene

(b) p-bromofluorobenzene

(d) 2,4,6-tribromofluorobenzene

#Amines - Introduction,preparation and properties

(d) -NH₂ group is greatly activating group. Hence, a reaction takes place rapidly.

Difficulty Level:

(a)
13%
(b)
13%
(c)
7%
(d)
68%

Aniline in a set of the following reactions yielded a coloured product Y.

#Amines - Introduction,preparation and properties

(a) Key Idea NaNO₂/HCl causes diazotisation of -NH₂ group and the diazonium chloride gives a coupling product with active aryl nucleus.

Difficulty Level:

(a)
87%
(b)
5%
(c)
7%
(d)
3%

How many primary amines are posible for the formula C₄H₁₁N ?

(a) 1

(b) 2

(d) 4

#Amines - Introduction,preparation and properties

Difficulty Level:

(a)
12%
(b)
22%
(c)
25%
(d)
43%

The product D in the following sequence of reactoins is,

${CH}_{3} COOH \overset{{NH}_{3}}{\to} A \overset{Heat}{\to} B \overset{P_{2} O_{5}}{\to} C \overset{Na + C_{2} H_{5} OH}{\to} D$ :

(a) ester

(b) amine

(d) alcohol

#Amines - Introduction,preparation and properties

(b) ${CH}_{3} COOH \overset{{NH}_{3}}{\to} {CH}_{3} {COONH}_{4} \overset{∆}{\to} {CH}_{3} {CONH}_{2} \overset{P_{2} O_{5}}{\to} {CH}_{3} CN \overset{Na + C_{2} H_{5} OH}{\to} {CH}_{3} {CH}_{2} {NH}_{2}$

Difficulty Level:

(a)
15%
(b)
59%
(c)
11%
(d)
17%

The IUPAC name of the compound having formula,

(a) 3-aminohydroxy propionic acid

(b) 2-amino-propan-3-oic acid

(d) 2-amino-3-hydroxy propionic acid

#Amines - Introduction,preparation and properties

(d) Follow IUPAC rules.

Difficulty Level:

(a)
4%
(b)
13%
(c)
8%
(d)
77%

Which of the following is the strongest base ?

#Amines - Introduction,preparation and properties

(a) Aliphatic amines are a stronger base than aromatic amines.

The basicity of amines is due to the nitrogen of the amine donating its lone pair of electrons. In aromatic amines, this lone pair is in conjugation(delocalized) with the aromatic ring. While in aliphatic mine this doesn't happen and thus the lone pair is ready to be donated.

Difficulty Level:

(a)
54%
(b)
19%
(c)
16%
(d)
13%