Write the IUPAC name of the nitro compound, C 4 H 9 NO 2 which does not react with nitrous acid.

Primary and secondary nitro compounds react with nitrous acid to form nitroso-nitroalkane and pseudonitriles respectively because of the presence of α -hydrogen whereas, tertiary nitroalkanes do not react with nitrous acid as they do not have α - hydrogen. Hence, the given nitro compound is a tertiary nitro compound with four carbon atoms. Therefore, IUPAC name of the nitro compound, C 4 H 9 NO 2 is 2-methyl-2-nitropropane.

A saturated monoamine liberates nitrogen gas on reaction with nitrous acid in cold conditions. On heating with methyl iodide, it forms quaternary ammonium iodide (mol. mass = 215). Deduce the formula of the amine. (Given at. mass of iodine = 127).

Only primary amine gives nitrogen gas when reacts with nitrous acid. Whereas secondary amine gives nitrosamine and tertiary amine gives ammonium salt. Secondary amines react with nitrous acid to give yellow solution of nitroso amine without liberating nitrogen. Hence, it won't liberate nitrogen gas. So reactant is primary amine. Primary amines react with excess methyl iodide to form quaternary ammonium salts. In the presence of excess alkyl halides, one amine molecule can repeatedly react with a number of alkyl halide molecules and result in the formation of a quaternary ammonium salt. RNH 2 + 3 CH 3 I → RN CH 3 3 + ( quaternary ammonium salt ) ( Molecular mass R + 186 = 215 ; R = 29 ) Here R is C 2 H 5 molecular mass 29 so quaternary ammonium salt is C 2 H 5 N CH 3 3 + which molecular mass is 215.

Explain the following : Amines are less acidic than alcohols of comparable molecular masses.

Amines are less acidic than alcohols of comparable molecular masses because N - H bond is less polar than O - H bond. Hence, amines release H + ion more difficultly as compared to alcohol. Basicity can also see through the electronegativity of nitrogen and oxygen, oxygen has more electronegativity than a nitrogen atom means nitrogen can donate easily its lone pair. That's why amines are more basic than alcohols.

Explain the following : Diazonium salts of aromatic amines are more stable than those of aliphatic amines.

Resonance structures are a set of two or more Lewis Structures that collectively describe the electronic bonding a single polyatomic species including fractional bonds and fractional charges. The stability of benzene diazonium salt is due to the dispersal of the positive charge over the benzene ring. The structures of benzene are given below: Aliphatic amines do not form diazonium salt because the diazonium salts obtained by the aliphatic amines are quite unstable and give nitrogen and carbonium ion.

An amine is synthesized by Gabriel phthalimide synthesis. Compare its basicity with aniline.

Gabriel phthalimide synthesis is used for the preparation of primary amines. In this synthesis, phthalimide is treated with ethanolic potassium hydroxide to potassium salt of phthalimide which on heating with methyl halide followed by alkaline hydrolysis produces the methylamine. As we know higher the tendency to accept proton, higher will be the basicity of the compound. Due to the presence of methyl group, electron density on nitrogen in methylene is greater than aniline and nitrogen can donate its electron pair to proton while in aniline, the nitrogen atom is attached to the benzene ring and the lone pair present on nitrogen atom is delocalised over the entire benzene ring due to this it cannot accept a proton. Therefore, the methylene is more basic than aniline.

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12th Manipur Board

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Coupling reaction of benzene diazonium chloride with phenol is carried out in basic condition, but the same basic condition cannot be used for the coupling reaction wth aniline. Explain.

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