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Right choice is (c) basic

Easy explanation: AMINES behave as nucleophiles due to the PRESENCE of unshared pair of ELECTRONS on N atom. This also makes them proton acceptor, and REACT with acids to form salts.

Correct answer is (d) Heating PHTHALIC ACID with NaOH

To elaborate: The chemical compounds involved in the Gabriel phthalimide synthesis are phthalimide, potassium phthalimide and N-alkyl phthalimide. These are formed in order when REACTED with DIFFERENT reagents like KOH and HALOALKANES.

The correct answer is (d) N,N-dimethylacetamide

Easiest explanation: Ethyldimethylamine is a TERTIARY amine with two methyl SUBSTITUENTS DIRECTLY attached to N atom. It can be obtained only from the reduction of a corresponding tertiary amide that has two methyl substituents attached to N atom.

Correct ANSWER is (b) Benzenamine

Easy explanation: The -CONH2 group of amides is REDUCED to a -CH2NH2 group and results in a COMPOUND having the same number of carbon atoms. The simplest AROMATIC amide is benzamide, which is reduced to give benzylamine. Hence, aniline cannot be formed as there is no corresponding amide that can be reduced to it with LiAlH4. However, it can be achieved by HOFFMANN bromamide degradation.

The correct option is (b) False

Easy explanation: Aniline is an aromatic ARYL AMINE, whereas benzylamine is am arylalkyl amine. Aniline is both accepted as the common and IUPAC names. The IUPAC NAMING of aryl AMINES is done by replacing the suffix ‘E’ of the arene by amine. Therefore, aniline is named as benzenamine.

The CORRECT option is (c) Ethanamine

The best I can explain: Ethylamine and AMINOETHANE are the names of CH3CH2NH2 according to the common system and second system respectively. In the IUPAC system, the naming is done by REPLACING the ‘e’ of the alkane by AMINE.

Correct option is (a) secondary

The explanation: In the GIVEN amine, all the THREE HYDROGENS of NH3 are replaced by one each of propyl, ETHYL and methyl GROUPS, and is a tertiary or 3° amine. Since all the three groups are alkyl and different, it is an aliphatic mixed amine.

Correct choice is (B) 1

The explanation: The nitrogen of NH3 forms sp^3 hybridised orbitals and also a valency of THREE (as it is attached to three HYDROGEN atoms). This results is one the orbitals having a lone pair of electrons, RESULTING in one unshared ELECTRON pair on nitrogen.

Correct option is (c) BASE

To EXPLAIN: Some amount of strong acid is produced at each step of alkylation. This acid can protonate the amine, MAKING the electron lone pair of N unavailable for NUCLEOPHILIC attack and THEREFORE halt the reaction. For this reason, the acid needs to be neutralised and hence, a base is needed during the reaction.

Right answer is (d) REMAINS unchanged

The EXPLANATION: BENZENEDIAZONIUM bromide is a salt, made of a positive diazonium group and a negative bromide ion. THUS, it remains neutral to litmus paper.

Correct choice is (a) COLD

Explanation: BENZENEDIAZONIUM salts are STABLE in cold environment, but readily react with water when the temperature increases EVEN SLIGHTLY.

Right option is (a) True

For EXPLANATION I would say: Solubility in water REQUIRES the presence of free HYDROGEN in the structure of a compound to form hydrogen BONDS. Tertiary amines do not have any hydrogen attached to the N atom and are not SOLUBLE in water.

The correct choice is (a) 3.38

Easy explanation: Aliphatic amines are stronger bases than AMMONIA and hence have a much lower pKb than ammonia. This is because of the electron donating NATURE of alkyl groups which increase the negative charge on nitrogen atom, MAKING it less PRONE to electron ACCEPTANCE.

Correct CHOICE is (b) False

The best I can explain: Primary, SECONDARY or tertiary amines can be formed depending on whether the amide used is primary, secondary or tertiary. This is because irrespective of the NUMBER of alkyl groups, the CO GROUP of amides is directly reduced to CH2.

The CORRECT answer is (a) True

Explanation: When NH3 is taken in excess in the reaction mixture, the alkyl halide is more likely to react with an NH3 MOLECULE RATHER than with a molecule of amine which is present in smaller amount. THEREFORE, only primary amine is formed as the main product.

Right choice is (d) 373K, sealed tube

The best I can EXPLAIN: The cleavage of the carbon-halogen BOND (of the alkyl halide) by a nucleophile takes place under HIGH pressure and temperature. Thus, the ammonolysis is CARRIED out in a sealed tube at about 100°C.

Correct choice is (c) Fe/HCl

The BEST I can explain: Reduction of nitroalkanes with iron SCRAP and HCl is preferred because of the formation of FECL2 which gets hydrolysed to release HCl during the reaction. Thus, only a SMALL amount of HCl is required to INITIATE the reaction.

Correct answer is (a) Ethylmethylamine

To explain: In the common system, aliphatic amines are named by prefixing the alkyl group to amine, i.e., alkylamine. In case of two DIFFERENT alkyl groups, it is named by LISTING the alkyl groups in alphabetical order before the word amine, just LIKE in ethylmethylamine. Aniline is a common name but is also accepted by IUPAC.

The CORRECT ANSWER is (b) NH3

To elaborate: There are three hydrogen atoms in ammonia. When ONE or more of these is substitutes by an alkyl/aryl group, the resultant compound is an amine. Hence, they are derivatives of NH3.

Correct answer is (d) weakly acidic

The explanation: Aniline is a compound that is slightly basic in nature. To COUNTER the basic EFFECT of aniline during its coupling with DIAZONIUM salt, in is conducted in a slightly acidic medium of pH 4 to 5.

The correct ANSWER is (b) NaNO2/Cu powder

Easiest explanation: BENZENEDIAZONIUM fluoroborate on TREATMENT with an aqueous SOLUTION of sodium NITRITE in the presence of copper (from copper powder), gives nitrobenzene.

The correct choice is (b) NANO2 and HCl

Best explanation: ANILINE actually REACTS with HNO2 (NITROUS acid) at 273K to form Benzenediazonium chloride. But this nitrous acid in produced in situ, by a mixture of NaNO2 and HCl.

The correct choice is (B) R2NH > R3N > RNH2

The explanation is: There is a subtle interplay of inductive effect, solvation effect and stearic hinderance of alkyl GROUPS to determine the order of basicity of alkylamines in AQUEOUS solutions. For ethyl substituted amines, it is 2°>3°>1°

Correct choice is (c) ortho and para

Explanation: The ortho and para positions with respect to NH2 group in aniline are centres of HIGH electron DENSITY. This is DUE to the resonance STRUCTURES of aniline. Thus, NH2 is ortho and para DIRECTING and a powerful activating group.

Correct option is (B) LiAlH4-ether

Easiest explanation: Lithium aluminium hydride is a reducing agent but does not REACT with nitro compounds. Instead it REDUCES nitriles to give CORRESPONDING primary amines.

The correct option is (d) 390 K

Easy explanation: Alcohols have HIGHER boiling POINTS than AMINES of comparable molecular MASSES. This is because the electronegativity of N is lower than that of O, which results in the OH bond in alcohols being more polar and hence stronger (in hydrogen bonding) than the N-H bond in amines.

Right choice is (a) Propane

For explanation: All given compounds have similar molecular masses and can be compared. Ethanamine has a higher BOILING point than propane because it is a POLAR MOLECULE and forms intermolecular hydrogen bonds. However, it has a LOWER boiling point than ethanal, ETHANOL and methanoic acid as the O-H bonds in these compounds is more polar than the N-H bond in ethanamine. This makes the hydrogen bonds stronger.

Correct option is (a) Methyl group

To EXPLAIN: 2-Methylbenzenamine is an aromatic AMINE which is a derivative of benzenamine with the PRESENCE of a methyl group as SUBSTITUENT at the ORTHO position.

Right OPTION is (c) coupling

For explanation I would say: Benzenediazonium salts react with highly reactive ELECTRON rich aromatic compounds to form AZO compounds of the form Ar-N=N-Ar, where Ar REPRESENTS an aromatic group. This type of reaction is known as coupling reaction.

The correct option is (B) fluoroboric acid

The EXPLANATION is: When benzenediazonium chloride is treated with fluoroboric acid, diazonium fluoroborate is formed, which on heating gets decomposed to give fluorobenzene. This is known as Balz-Schiemann reaction.

Correct option is (a) True

Easy explanation: It is DIFFICULT to introduced IODIDE and fluoride ions into the BENZENE ring and are carried out by SEPARATE reactions involving potassium iodide and fluoroboric acid respectively.

Correct answer is (d) C6H5N2^+BF4^–

The BEST EXPLANATION: Certain DIAZONIUM SALTS such as fluoroborates are INSOLUBLE in water. This makes them stable enough to be dried and stored.

The correct choice is (a) potassium iodide

Explanation: Iodine is not EASILY introduced in the BENZENE ring directly. When an aqueous solution of benzene diazonium salt is warmed with excess potassium iodide, iodobenzene is FORMED.

Correct option is (B) Colourless crystals

Best explanation: BENZENEDIAZONIUM chloride is usually obtained in crystal form. It is unstable and formed for a short period when ANILINE REACTS with nitrous acid. It is a salt with chlorine as the negative group and diazo group as POSITIVE.

Right option is (a) 0°C

To EXPLAIN I would SAY: Benzene DIAZONIUM salts are prepared by the reaction of aniline with nitrous ACID at very low temperatures (273-278K). If the TEMPERATURE was to cross 278K, phenol will be formed instead.

The correct choice is (a) Propanenitrile

To EXPLAIN I would say: ETHYLAMINE on heating with CHLOROFORM and ethanolic KOH forms an isocyanide, ethyl isocyanide (CH3CH2NC) along with KCL and H2O. This is known as carbylamines reaction. Propanenitrile (CH3CH2CN) is not FORMED as it is the cyanide form of ethyl isocyanide.

Right option is (d) no REACTION

For explanation I would say: The amine that is treated with CH3COCl is a tertiary amine (N,N-dimethylmethanamine). It does not undergo reaction with acetyl CHLORIDE as it does not have a replaceable hydrogen atom. Therefore, for the acylation of an amine, a H atom on nitrogen is required along with the LONE PAIR of electrons.

Correct answer is (a) True

Best explanation: In arylalkyl amines, the lone pair od electrons on N is not conjugated with the BENZENE ring and is not delocalized. Hence, the lone pair of electrons on n atom INN arylalkyl amines is more readily AVAILABLE for PROTONATION than that on the N atom of BENZENAMINE.

Right answer is (c) p-Nitroaniline

The best explanation: All the compounds can be considered as aniline with an electron WITHDRAWING (deactivating) group substituted at the PARA position to NH2. Since nitro group is the most deactivating group compared to halogen and cyanide, p-nitroaniline is the LEAST basic COMPOUND.

The correct CHOICE is (d) r > p > q

Explanation: This peculiar order of BASIC strength is due to a combination of inductive, solvation and stearic effects of the ALKYL groups in the amines. In methyl substituted amines, the solvation effect superimposes the inductive effect to make CH3NH2 more basic than (CH3)3N. The 2° compound is the most basic because of its higher inductive effect than primary amine and higher solvation than TERTIARY amine.

Right answer is (d) CH3CH2NH3Br

Best EXPLANATION: Since amines are BASIC in nature, they react with acids to FORM salts of ammonium. Ethanamine (CH3CH2NH2) reacts with HBr in a REVERSIBLE reaction to form ethylammonium bromide through ADDITION.

The correct option is (d) B > A > C

Explanation: A, B and C are RESPECTIVELY the 2°, 1° and 3° isomers of the compound C3H9N. Primary and SECONDARY amines have two and one hydrogen atoms respectively for hydrogen bonding. Whereas, tertiary amines do not have intermolecular ASSOCIATION due to absence of H for hydrogen bonding.