Subjective Type

Account for the following: (i) pKb of aniline is more than that of methylamine. (ii) Ethylamine is soluble in water whereas aniline is not. (iii) Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.

Solution

(i) $$pK_b$$ of aniline is more than that of methylamine.
In aniline, the lone pair of electrons on $$N$$ atom is in resonance with benzene ring. Hence, it cannot be easily donated to an acid. This decreases its basicity. In methyl amine, the $$+I$$ effect of methyl group increases the electron density on $$N$$ atom so that the lone pair of electrons on $$N$$ atom can be easily donated to an acid. Hence, methylamine is more basic than aniline. Higher is the basicity, lower is the $$pKb$$ and vice versa.

(ii) Ethylamine is soluble in water whereas aniline is not. With increase in the molecular weight, the solubility decreases. Aniline has higher molecular weight than ethylamine.

(iii) Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide. Due to the $$+I$$ effect of $$-CH_3$$ group, methylamine is more basic than water. Therefore, in water, methylamine produces $$OH^-$$ ions by accepting $$H^+$$ ions from water. $$OH^-$$ ions react with ferric chloride to precipitate hydrated ferric oxide.

SIMILAR QUESTIONS

Organic Compounds Containing Nitrogen

The correct order of reactivity towards the electrophilic substitution of the compounds aniline $$(I)$$, benzene $$(II)$$ and nitrobenzene $$(III)$$ is:

Organic Compounds Containing Nitrogen

When semicarbazide reacts with a ketone(or aldehyde) to form semicarbazone. Only one nitrogen atom of semicarbazide acts as a nucleophile and attack the carbonyl carbon of the ketone. The product of the reaction consequently is $${ R }_{ 2 }C=N-NH-CO{ NH }_{ 2\\ }$$ rather than $${ R }_{ 2 }C=NCONH-{ NH }_{ 2 }$$. What factor account for the fact that two nitrogen atoms of semicarbazide are relatively non nucleophilic?

Organic Compounds Containing Nitrogen

The correct order of reactivity towards the electrophilic substitution of the compounds aniline (I) benzene (II) and nitrobenzene (III) is

Organic Compounds Containing Nitrogen

The carbylamine reaction is:

Organic Compounds Containing Nitrogen

Give one chemical test to distinguish between the following pairs of compounds. (i) Methylamine and dimethylamine (ii) Secondary and tertiary amines (iii) Ethylamine and aniline (iv) Aniline and benzylamine (v) Aniline and N-methylaniline.

Organic Compounds Containing Nitrogen

Primary and secondary amines react with acid chloride or acid anhydride to form:

Organic Compounds Containing Nitrogen

Following reaction gives two products. $$\displaystyle { CH }_{ 3 }{ CH }_{ 2 }{ NH }_{ 2 }\xrightarrow { ({ CH }_{ 3 }CO{ ) }_{ 2 }O,\ heat }A+B$$ Write the structures of the products formed.

Organic Compounds Containing Nitrogen

Give the structures of $$A,B$$ and $$C$$ in the following reaction: $${ CH }_{ 3 }COOH\xrightarrow [ \Delta ]{ { NH }_{ 3 } } A\xrightarrow [ ]{ { Br }_{ 2 }+KOH } B\xrightarrow [ ]{ CH{ Cl }_{ 3 }+NaOH } C$$

Organic Compounds Containing Nitrogen

Ethylamine reacts with acetyl chloride to form:

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