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Practice each question, then open the answer or worked solution.
The best reagent for converting-2-phenylpro-panamide into 1-phenylethanamine is.
Ans: (B)
Hoffmann bromamide reaction- it is also called degradation reaction as in this reaction primary amide group is treated with halogen first (Br) then the halogen-substituted amide product is converted to a primary amine with the release of carbon dioxide gas.
Hoffmann bromamide degradation reaction is shown by.
Ans: (B)
Hoffmann invented a method for producing primary amines by treating an amide with bromine in an aqueous or ethanolic sodium hydroxide solution. An alkyl or aryl group migrates from the amide's carbonyl carbon to the nitrogen atom during this degradation reaction.
$\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CONH}_{2} \stackrel{\mathrm{Br}_{2}+\mathrm{NaOH}}{\longrightarrow} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2}$
The correct increasing order of basic strength for the following compounds is
Ans: (D)
The greater the electron density towards the ring, the greater its basic strength.
The electron withdrawing group reduces basic strength, whereas the electron donating group increases basic strength.
Methylamine reacts with $\mathrm{HNO}_{3}$ to form
Ans: (C)
Methyl amine reacts with $\mathrm{HNO}_{3}$ form methanol with release of nitrogen gas and water as side products.
$\mathrm{CH}_{3} \mathrm{NH}_{2}+\mathrm{HNO}_{3} \stackrel{0^{\circ}-5^{\circ} \mathrm{C}}{\rightarrow} \mathrm{CH}_{3} \mathrm{OH}+\mathrm{N}_{2}+\mathrm{H}_{2} \mathrm{O}$
The gas evolved when methylamine reacts with nitrous acid is .
Ans: (B)
Primary aliphatic amines react with nitrous acid to form aliphatic diazonium salts, which are unstable and release nitrogen gas and alcohol quantitatively.
In the nitration of benzene using a mixture of conc. $\mathrm{H}_{2} \mathrm{SO}_{4}$ and conc. $\mathrm{HNO}_{3}$, the species which initiates the reaction is.
Ans: (C)
In the process of nitration of benzene, firstly $\mathrm{H}_{2} \mathrm{SO}_{4}$ dissociates into $\mathrm{H}^{+}$and $\mathrm{HSO}_{4}{ }^{-}$. The proton produced further reacts with $\mathrm{HNO}_{3}$ to give a positively charged complex that is unstable and dissociates into nitronium ions and water as products. The nitronium ion is an electron-deficient species i.e. electrophile that attacks the electron cloud of the benzene ring.
$\mathrm{H}_{2} \mathrm{SO}_{4} \text { (conc.) } \longrightarrow \mathrm{H}^{+}+\mathrm{HSO}_{4}^{-}$
$\mathrm{H}^{+}+\mathrm{HNO}_{3} \longrightarrow \mathrm{H}_{2} \mathrm{NO}_{3}^{+}$
$\mathrm{H}_{2} \mathrm{NO}_{3}^{+} \longrightarrow \mathrm{NO}_{2}^{+}+\mathrm{H}_{2} \mathrm{O}$
Reduction of aromatic nitro compounds using Fe and HCl gives.
Ans: (C)
Using active metals like iron in acidic conditions can be efficiently used for the reduction of nitro compounds.
Under the acidic conditions, the intermediate compounds that may form are readily reduced to primary amine and pure product of primary amine is obtained.
The most reactive amine towards dilute hydrochloric acid is
(A) $\mathrm{CH}_{3}-\mathrm{NH}_{2}$
(B)
(C)
(D)
Ans: (B)
Greater will be the basic character, greater will be its reactivity towards dilute hydrochloric acid. As, (B), secondary amine, it will be the most basic among all and hence the most reactive amine towards acid.
Acid anhydrides on reaction with primary amines give.
Ans: (A)
On Reaction of acid anhydrides with primary amines, amides are formed as the primary product along with carboxylic acid.
$(\mathrm{RCO})_{2} \mathrm{O}+\mathrm{RNH}_{2} \rightarrow \mathrm{RCONH}_{2}+\mathrm{RCOOH}$
The reaction as $\mathrm{Ar} \mathrm{N}_{2} \mathrm{Cl}^{-} \stackrel{\mathrm{Cu} / \mathrm{HCl}}{\longrightarrow} \mathrm{ArCl}+\mathrm{N}_{2}+\mathrm{CuCl}$ is names
Ans: (B)
Diazonium salts react with copper powder and halogen acid to form aryl halide.
Gattermann reaction is a Sandmeyer reaction variant in which Cu powder replaces CuCl.
This substitution produces aryl halide more easily and under milder conditions than the Sandmeyer reaction.
