Amines Test

Result

Amines Test - 27

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Weekly Quiz Competition

Question 1
1 / -0

The correct order of increasing basicity of the given conjugate bases (R = $$CH_{3}$$) is:

A
$$RCO\bar{O} < HC \equiv \bar{C} < \bar{R} < \bar{N}H_{2}$$

B
$$\bar{R} < HC \equiv \bar{C} < RCO\bar{O} < \bar{N}H_{2}$$

C
$$RCO\bar{O} < NH_{2} < HC \equiv \bar{C} < \bar{R}$$

D
$$RCO\bar{O} < HC \equiv \bar{C} < \bar{N}H_{2} < \bar{R}$$

Solution

The order of acidity can be explained on the basis of the acids of the given conjugate base$$.$$ Stronger is the acid$$,$$ weaker is the conjugate base$$.$$ Since$$,$$ $$RCOO$$ is the stronger acid amongst all$$,$$ $$RCO{O}^{-}$$ is the weakest base$$.$$ Due to $$sp$$ hybridised carbon$$,$$ acetylene is also acidic and hence a weak base but stronger than $$RCO{O}^{-}.$$ As $${sp}^{3}$$ carbon is less electronegetive than $${sp}^{3}$$ nitrogen$$,$$ $${R}^{-}$$ is more basic than $$N{H}_{2}.$$
Question 2
1 / -0

The following sequence of reaction on $$"A"$$ gives.

A

B

C

D

Solution

(Refer to Image)
The correct answer is (A)
Question 3
1 / -0

The correct order of basic strength of the following compounds is :

A
2 > 1 > 3 > 4

B
1 > 3 > 2 > 4

C
3 > 1 > 2 > 4

D
1 > 2 > 3 > 4

Solution

Higher the electron density on electron donating group higher is the basic strength.

In compound $$3$$ the electron density is highest because of $$+\ I$$ effect of $$\text {methyl}$$ groups attached to nitrogen. Hence it has the highest basicity.

In compound $$1$$ there are two amine groups attached to the carbon in which one of the amine group is always available for donation. Hence it has the second highest basicity.

In compound $$2$$ again the ethyl group increases the basic strength of amine due to its $$+\ I$$ effect but lower than that of as in compound $$3$$.

The compound $$4$$ has the least basic strength because the carbonyl group attached to amine decreases the basicity by withdrawing the lone pair from Nitrogen through resonance effect.

The correct order of basic strength is-

$$3 > 1 > 2 > 4$$
Question 4
1 / -0

Among the following which statement (s) is/are correct?

A
Both N of pyrimidine are same basic strength.

B
In imidazole protonation take places on N-3.

C
In purine only one lone pair of N is delocalized.

D
Pyrimidine, imidazole and purine all are aromatic.

Solution

Pyrimidine has nitrogen atoms at 1 and 3 positions.
In purine only one lone pair of $$N$$ is delocalized. But lone pair electron does not take place in delocalization and imidazole also.
Question 5
1 / -0

Which of the following explode on heating?

A
Azides

B
Sulphates

C
Chlorides

D
Phosphides

Solution

some experiments describe on calcium and barium azid and tetrazene, which explode while they are solid.
The explosion of the molten azides is due to self heating of the liquid. Explosion is facilitated by the presence of an inert gas above the decomposing liquid self heating of the liquid azides is due to the retention of heat products of reaction near the surface.
Question 6
1 / -0

Gabriel phthalimide reaction is used for the preparation of __________ amines.

A
primary aromatic

B
secondary

C
primary aliphatic

D
tertiary

Solution

Gabriel phthalimide reaction is used for the preparation of primary amines.
Question 7
1 / -0

What is the correct order of basicity values of the following compounds?

A

B
$$NH_3\,>\,CH_3NH_2\,>\,CH_2\,=\,CH-NH_2\,>\,NH_2-CH_2-CH_2-N^+R_3$$

C

D
None

Solution

$$1.$$ $$NH_3\longrightarrow pk_a=34.5$$
$$2.$$ $$CH_3NH_4Br\longrightarrow pk_a=3.4$$
$$3.$$ $$CH_3NH_2\longrightarrow pk_a=10.6$$
$$4.$$ $$\begin{matrix} Me \\ Me \end{matrix}>\overset { + }{ S } - { CH }_{ 2 }-{ NH }_{ 2 } \rightarrow { pk }_{ a }=\sim 2$$
Order is $$4>2>3>1$$
Question 8
1 / -0

What would be the product for the following reaction ?

A
Ph-Cl

B
$$Ph-N_2$$

C

D

Solution

REF.Image.
$$ Na\, NO_{2} + HCl \rightarrow Nacl+ HNO_{2}$$
$$ HO -N = O + H^{+} \Rightarrow H_{2}O^{\oplus }-N =0$$
$$ H_{2}O^{\oplus}-N = 0 \rightarrow H_{2}O+N^{\oplus} =0 $$
Question 9
1 / -0

The correct order of basicity of the following compounds is?
$$\underset {(3)}{(CH_{3})_{4}NH}$$
$$\underset {(4)}{CH_{3}CONH_{2}}$$

A
$$2 > 1 > 3 > 4$$

B
$$1 > 3 > 2 > 4$$

C
$$3 > 1 > 2 > 4$$

D
$$1 > 2 > 3 > 4$$

Solution

$$ \begin{array}{l} \text { (4) lone pair is on resonance. } \\ \text { Hence, basisty order is } \\ \qquad 1>2>3>4 \end{array} $$
Question 10
1 / -0

Which of the following is not a primary amine?

A
tert - Butylamine

B
sec - Butylamine

C
Isobutylamine

D
Dimethylamine

Solution

Dimethylamine $$[(CH_3)_2 NH]$$ is a secondary amine as the central Nitrogen atom is substituted by two methyl groups and the nitrogen has one hydrogen. Tert-butyl amine, secondary butyl amine, isobutylamine are all the isomers of n-butyl amine, varying in the position of the $$N-$$group in the alkyl chain.