Short Answer TypeArrange the following in the increasing order of their pKb values:
C6H5NH2, C2H5NH2, C6H5NHCH3
pKb tells the strength of a base. Lower is pKb value, stronger is the base. Now C6H5NH2 is a weak base because the lone pair is involved in resonance with the benzene and is thus not available for a donation while in C2H5NH2, C2H5 is an electron donating group, which increases the e- density on N thus felicitating the release of lone pair. Hence, C2H5NH2 is a strong base.
Thus, the correct order is:
C2H5NH2< C6H5NHCH3< C6H5NH2
Multiple Choice QuestionsIn the Hofmann bromamide degradation reaction, the number of moles of NaOH and Br2 used per mole of amine produced are:
Four moles of NaOH and two moles of Br2
Two moles of NaOH and two moles of Br2
Four moles of NaOH and one mole of Br2
Four moles of NaOH and one mole of Br2
On heating an aliphatic primary amine with chloroform and ethanolic potassium hydroxide, the organic compound formed is
an alkanol
an alkaneodiol
an alkyl cyanide
an alkyl cyanide
Considering the basic strength of amines in aqueous solution, which one has the smallest pKb value?
(CH3)2NH
CH3NH2
(CH3)3N
(CH3)3N
A compound with molecular mass 180 is acylated with CH3COCl to get a compound with molecular mass 390. The number of amino groups presents per molecule of the former compound is
2
5
4
4
An organic compound A upon reacting with NH3 gives B. On heating B gives C. C in presence of KOH reacts with Br2 to give CH3CH2NH2. A is
CH3COOH
CH3CH2CH2COOH
Ortho–Nitrophenol is less soluble in water than p– and m– Nitrophenols because
o–Nitrophenol is more volatile in steam than those of m – and p–isomers
o–Nitrophenol shows Intramolecular H–bonding
o–Nitrophenol shows Intermolecular H–bonding
o–Nitrophenol shows Intermolecular H–bonding
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