Amines Test

Result

Amines Test - 61

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Weekly Quiz Competition

Question 1
1 / -0

Most basic species amongst the following is:

A

B

C

D

Solution

Cyclohexylamine is the most basic among all, as the nitrogen is outside the ring and exhibits $$sp^3$$ hybridization, and the cyclic ring is also non resonating, there by the lone pair of electrons on the nitrogen can be easily available.
Question 2
1 / -0

The most basic amine among the following is:

A

B

C

D

Solution

Only $$-CH_3$$ group is electron donating group hence it increases the electron density on nitrogen making it most basic.

So, option C is correct.
Question 3
1 / -0

Arrange the following compounds in increasing order of basicity.
$$CH_3NH_2, \, (CH_3)_2NH,\,NH_3, \, C_6H_5NH_2$$

A
$$C_6H_5NH_2 \, <\, NH_3 \, <\,(CH_3)_2NH \,<\, CH_3NH_2$$

B
$$CH_3NH_2 \, <\, (CH_3)_2NH\, <\, NH_3 \,<\,C_6H_5NH_2$$

C
$$C_6H_5NH_2 \, <\, NH_3 \,<\, CH_3NH_2\, <\, (CH_3)_2NH$$

D
$$(CH_3)_2NH \,<\, CH_3NH_2\,<\, NH_3 \,<\, C_6H_5NH_2$$

Solution

Aromatic amines are least basic as the lone pair of electrons on the nitrogen are not freely available due to the presence of the conjugated ring.

The secondary amines are most basic here as both the $$-R$$ groups are electron-donating to the nitrogen, thereby the electron density increases on the nitrogen.

Hence, the order is $$C_6H_5NH_2 < NH_3 < CH_3NH_2 < (CH_3)_2NH$$

Option C is correct.
Question 4
1 / -0

The correct order of increasing basic nature of the following bases is:

A
$$2 < 5 < 1 < 3 < 4$$

B
$$5 < 2 < 1 < 3 < 4$$

C
$$2 < 5 < 1 < 4 < 3$$

D
$$5 < 2 < 1 < 4 < 3$$

Solution

Presence of electron withdrawing ($$-I$$ or $$-M$$ group ) like $$-NO_2$$ at p-position will decrease the basicity, so (2) will be the least basic, whereas presence of electron donating ($$+I$$ or $$+M$$) group like $$-OCH_3$$ at p-position in (4) will increase the basicity so (4) will be the most basic.

Hence correct order of increasing basic character is 2 < 5 < 1 < 3 < 4.
Question 5
1 / -0

The strongest base among the following is:

A
$$C_6H_5NH_2$$

B
$$p - NH_2C_6H_4NH_2$$

C
$$m - NO_2C_6H_4NH_2$$

D
$$C_6H_5CH_2NH_2$$

Solution

Benzylamine ($$ C_6H_5CH_2NH_2$$) is the strongest base among all because the aliphatic amines are more basic than aromatic amines.
Question 6
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Identify $$Z$$ in the sequence.
$$C_6H_5NH_2 \xrightarrow [273K]{NaNO_2 + HCl} \, X\, \xrightarrow{CuCN} \, Y\, \xrightarrow [Boil]{H^+/H_2O} \, Z\,$$

A
$$C_6H_5CN$$

B
$$C_6H_5CONH_2$$

C
$$C_6H_5COOH$$

D
$$C_6H_5CH_2NH_2$$

Solution

$$C_6H_5NH_2 \xrightarrow [273K]{NaNO_2+HCl} \underset{(X)}{C_6H_5\overset{+}{N_2}C \overset {-}{l}} \xrightarrow {CuCN} \underset{(Y)}{C_6H_5CN} \xrightarrow [boil]{H^+/H_2O} \underset{benzoic \, acid (Z)}{C_6H_5COOH}$$
Question 7
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The correct order of decreasing basicity of the above compounds is :

A
I $$>$$ II $$>$$ III $$>$$ IV

B
II $$>$$ I $$>$$ III $$>$$ IV

C
III $$>$$ IV $$>$$ I $$>$$ II

D
II $$>$$ I $$>$$ IV $$>$$ III

Solution

The order of decreasing basicity of the given compounds is (C) III > IV > I > II.

As the $$-NH_2$$ group has a lone pair of electrons on nitrogen to donate to electron deficient species.

Hence, its power to donate electrons it increased when an electron donation group (+R, +I) is attached and its donating power is decreased when an electron withdrawing group is attached at its para position.

Since $$NO_2$$ is an electron withdrawing group hence it decreases the electron density over $$-NH_2$$ group hence it decreases the basicity.

On the other hand $$-OCH_3$$ (+M effect) group increase the electron density more than $$CH_3$$ group (+I effect).
Question 8
1 / -0

$$CH_3-\overset{\,\,\,\,\,NH}{\overset{||}{\underset{(1)}{C}}}-NH_2$$, $$CH_3-\underset{(2)}{CH_2}-NH_2$$

$$\underset{(3)}{(CH_3)_2}NH$$, $$CH_3-\overset{O}{\overset{||}{\underset{(4)}{C}}}-NH_2$$
The correct order of the basicities 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

The correct order is $$2<1<3<4$$.Since, more the number of $${ 2 }^{ o }-NH$$- group,more is the basic nature.

(i)Thus, 3 and 4 are more basic than 1 and 2

(ii)Between 3 and 4, 4 has one two $$-N{ H }_{ 2 }$$ group , while 3 has only one $$-N{ H }_{ 2 }$$

$$\therefore $$ 4 is more basic than 3.

(iii)Between 1 and 2,1 has one $$-N{ H }_{ 2 }$$ group with no resonance,thus is more basic than 2.
Question 9
1 / -0

Product of this reaction is?

A

B

C

D
Question 10
1 / -0

$$ \xrightarrow [ { H }^{ + } ]{ \Delta }$$ (Major product )

A
$$CH_3 - \underset{O}{\underset{||}{C}} - NH - Ph$$

B
$$PhCH_2 - \underset{O}{\underset{||}{C}} - NH_2$$

C
$$Ph - \underset{O}{\underset{||}{C}} - NHCH_3$$

D
$$PhCH_2CH_2NH_2$$

Solution

Here migration of group takes place. The group migrates with a negative charge to the electron deficient $$N$$. Out of $$-CH_{3}$$ and $$-pH$$ group, this is possible for $$-CH_{3}$$ group. This is because , negative charge on $$-pH$$ group is unstable.