241. Which of the following reactions will not give $$N, N$$ - dimethyl benzamide ?
A
B
C
D
Answer :
242. Secondary amines can be prepared by
A
reduction of nitro compounds
B
reduction of amides
C
reduction of isonitriles
D
reduction of nitriles
Answer :
reduction of isonitriles
243. Aniline is an activated system for electrophilic substitution. The compound formed on heating aniline with acetic anhydride is
A
B
C
D
Answer :
244. Compound $$'A'$$ ( molecular formula $${C_3}{H_8}O$$ ) is treated with acidified potassium dichromate to form a product $$'B'$$ ( molecular formula $${C_3}{H_6}O$$ ) .$$'B'$$ forms a shining silver mirror on warming with ammonical silver nitrate. $$'B'$$ when treated with an aqueous solution of $${H_2}NCONHN{H_2}$$ . $$HCl$$ and sodium acetate gives a product $$'C’.$$ Identify the structure of $$'C'$$.
A
B
C
D
Answer :
245. Ethylene can be prepared in good yield by
A
\[C{{H}_{3}}C{{H}_{2}}{{N}^{+}}{{\left( C{{H}_{3}} \right)}_{3}}{{I}^{-}}\xrightarrow{\text{heat}}\] \[C{{H}_{2}}=C{{H}_{2}}+{{\left( C{{H}_{3}} \right)}_{3}}N+HI\]
B
\[C{{H}_{3}}C{{H}_{2}}{{N}^{+}}{{\left( C{{H}_{3}} \right)}_{3}}O{{H}^{-}}\xrightarrow{\text{heat}}\] \[C{{H}_{2}}=C{{H}_{2}}+{{\left( C{{H}_{3}} \right)}_{3}}N+{{H}_{2}}O\]
C
\[\text{Both (A) and (B)}\]
D
\[C{{H}_{3}}C{{H}_{2}}N{{H}_{2}}\xrightarrow{\text{heat}}C{{H}_{2}}\] \[=C{{H}_{2}}+N{{H}_{3}}\]
Answer :
\[C{{H}_{3}}C{{H}_{2}}{{N}^{+}}{{\left( C{{H}_{3}} \right)}_{3}}O{{H}^{-}}\xrightarrow{\text{heat}}\] \[C{{H}_{2}}=C{{H}_{2}}+{{\left( C{{H}_{3}} \right)}_{3}}N+{{H}_{2}}O\]
246. Primary amines react with acid chloride or acid anhydride to form
A
tertiaryammonium salts
B
substituted amides
C
diazonium salts
D
nitro compounds
Answer :
substituted amides
247. Carbylamine forms from aliphatic or aromatic primary amine via which of the following intermediates ?
A
Carbanion
B
Carbene
C
Carbocation
D
Carbon radical
Answer :
Carbene
248. Which of the following compounds gives dye test ?
A
Aniline
B
Methylamine
C
Diphenylamine
D
Ethylamine
Answer :
Aniline
249. Which is formed when acetonitrile is hydrolysed partially with cold $$conc.$$ $$HCl?$$
A
Acetic acid
B
Acetamide
C
Methyl cyanide
D
Acetic anhydride
Answer :
Acetamide
250. Which of the following statements is incorrect?
A
Diazonium salts are very good intermediates for the introduction of $$- F, -Cl, - Br, -CN$$ groups into the aromatic ring.
B
Cyano group cannot be introduced by nucleophilic substitution of chlorine in chlorobenzene.
C
Aryl fluorides and iodides can be prepared by direct halogenation.
D
The replacement of diazo group by other groups is helpful in preparing those aromatic compounds which cannot be prepared by direct substitution.
Answer :
Aryl fluorides and iodides can be prepared by direct halogenation.