Explanation
Answer:
Primary amine has higher boiling point than secondary followed by tertiary amine, this is because higher boiling points of the primary amines is that they can form hydrogen bonds with each other as well as van der Waals dispersion forces and dipole-dipole interactions.
Tertiary amine has no hydrogen left for forming Hydrogen bonds among themselves so can not show intermolecular H-bonding. So intermolecular force will be weak and low boiling point of tertiary amines
I=Ethyldimethyl amine=30
II=n−butylamine=10
III=diethylamine=20
In primary amines only one hydrogen is substituted by an alkyl group, in secondary amines, two hydrogens are substituted by alkyl groups and in tertiary amines, all the three hydrogens are substituted by alkyl groups thereby resulting in the absence of intermolecular hydrogen bonding. Higher the hydrogen bonding difficult is to break the bonds thereby high boiling point.
Intermolecular hydrogen bonding is maximum in primary amines and absent in tertiary amines.
So order of boiling points will be II>III>I
Hinsberg reagent is Benzenesulphonyl chloride (C6H5SO2Cl). It reacts with primary and secondary amines to form sulphonamides.
It reacts with primary amine to form acidic compound which is soluble in alkali because hydrogen (H) attached to nitrogen(N) in sulphonamide is strongly acidic due to presence of stronf electron withdrawing sulphonyl group.
Now, out of the options given in the question, only isopropyl amine is a primary amine. Dimethyl amine and N-methyl ethaneamine are secondary amines and N,N-dimethylaniline is tertiary amine.
Hence,option (b) is correct.
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