Amines are usually formed from amides, imides, halides, nitro compounds, etc. They exhibit hydrogen bonding which influences their physical properties. In alkyl amines, a combination of electron releasing, steric and H-bonding factors influence the stability of the substituted ammonium cations in protic polar solvents and thus affect the basic nature of amines. Alkyl amines are found to be stronger bases than ammonia. Amines being basic in nature, react with acids to form salts. Aryldiazonium salts, undergo replacement of the diazonium group with a variety of nucleophiles to produce aryl halides, cyanides, phenols and arenes.
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(ii) Propanenitrile to 1-aminopropane
Amines are usually formed from amides, imides, halides, nitro compounds, etc. They exhibit hydrogen bonding which influences their physical properties. In alkyl amines, a combination of electron releasing, steric and H-bonding factors influence the stability of the substituted ammonium cations in protic polar solvents and thus affect the basic nature of amines. Alkyl amines are found to be stronger bases than ammonia. Amines being basic in nature, react with acids to form salts. Aryldiazonium salts, undergo replacement of the diazonium group with a variety of nucleophiles to produce aryl halides, cyanides, phenols and arenes.
(ii) Propanenitrile to 1-aminopropane
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Solution and Explanation
Propanenitrile is \( \mathrm{CH_3CH_2C{\equiv}N} \) and 1-aminopropane is \( \mathrm{CH_3CH_2CH_2NH_2} \). Both have three carbons, so no carbon is gained or lost. Only the cyano group \( \mathrm{-C{\equiv}N} \) must change into \( \mathrm{-CH_2-NH_2} \). This is a reduction.
Step 2: Key Formula or Approach:
Nitriles are reduced to primary amines by catalytic hydrogenation (\( \mathrm{H_2} \) with Ni, Pd or Pt) or by \( \mathrm{LiAlH_4} \). Each \( \mathrm{C{\equiv}N} \) takes up four hydrogen atoms.
Step 3: Detailed Explanation:
Treat propanenitrile with hydrogen gas in the presence of nickel catalyst. The carbon-nitrogen triple bond is saturated step by step and the primary amine is formed.
\[ \mathrm{CH_3CH_2C{\equiv}N + 2H_2 \xrightarrow{Ni} CH_3CH_2CH_2NH_2} \]
Propan-1-amine (1-aminopropane) is obtained in one step.
Final Answer:
Propanenitrile is converted to 1-aminopropane by reduction with \( \mathrm{H_2/Ni} \) (or \( \mathrm{LiAlH_4} \)). \[ \boxed{\mathrm{CH_3CH_2CN \xrightarrow{H_2/Ni} CH_3CH_2CH_2NH_2}} \]
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(ii) Ethylamine is soluble in water whereas aniline is not.
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(iv) Although amino group is o– and p– directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline.
(v) Aniline does not undergo Friedel-Crafts reaction.
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- Assertion (A) : Aromatic primary amines can easily be prepared by Gabriel phthalimide synthesis. Reason (R) : Gabriel phthalimide synthesis is used to prepare only aliphatic primary amines.
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