Diazonium Salts & Synthetic Utility — Practice Questions

Free NEET Chemistry multiple-choice questions on Diazonium Salts & Synthetic Utility. Attempt each question and reveal the answer with a full explanation.

When Benzene diazonium chloride is treated with boiling water, the product obtained is: Phenol Benzene Chlorobenzene Nitrobenzene Benzene diazonium chloride is more stable than methyl diazonium chloride because: The positive charge is dispersed over the benzene ring via resonance The C-N bond in aryl diazonium is a double bond Methyl group is an electron withdrawing group Nitrogen gas is not a good leaving group in aryl salts In the reaction: RNH 2 HNO 2 ROH + H 2O + N 2 , if the amine is methylamine, the main product besides N 2 is: Dimethyl ether Methanol Methyl nitrite Nitromethane The reaction of benzene diazonium chloride with benzene in the presence of NaOH to give biphenyl is known as: Gomberg-Bachmann reaction Gattermann reaction Ullmann reaction Etard reaction The Mulliken-Barker test is used for the detection of which functional group? -NO 2 -NH 2 -CN -CHO In the Curtius rearrangement, the intermediate species that undergoes rearrangement is: Acyl azide Acyl nitrene Isocyanate Alkyl azide In the Hofmann mustard oil reaction, the role of HgCl 2 is to: Decompose the intermediate dithiocarbamic acid salt Act as an oxidizing agent for the amine Catalyze the addition of CS 2 Reduce the isothiocyanate The coupling of benzene diazonium chloride with m -phenylenediamine yields a dye known as: Chrysoidine Methyl orange Aniline yellow Butter yellow Which of the following compounds will produce a 'pseudonitrol' (which gives a blue color in alkaline solution) when treated with nitrous acid? 2-Nitropropane Nitroethane 2-Methyl-2-nitropropane Nitromethane The reaction of nitrobenzene with sodium arsenite ( Na 3AsO 3 ) in aqueous NaOH solution yields: Azoxybenzene Azobenzene Hydrazobenzene Aniline Which of the following is produced when N -ethyl- N -methylaniline reacts with HNO 2 ? p -Nitroso- N -ethyl- N -methylaniline N -Nitroso- N -ethylaniline p -Nitro- N -ethylaniline Benzenediazonium chloride Reduction of nitrobenzene with Zn and NaOH in methanol yields: Azobenzene Hydrazobenzene Aniline Nitrosobenzene The Mendius reaction involves the reduction of alkyl cyanides to primary amines using: Na / C 2H 5OH LiAlH 4 / Ether Sn / HCl H 2 / Pd The rate-determining step in the diazotization of aniline is the formation of: N 2 O 3 or H 2 NO 2 + Benzenediazonium ion Aniline hydrochloride N -nitrosoaniline The reaction of an alkyl isocyanide with O 3 (Ozone) followed by treatment with water yields: Alkyl isocyanate Alkyl amine Alkyl cyanide Carboxylic acid Which of the following amines will react with nitrous acid to form a carbocation that undergoes rearrangement to yield 2-methyl-2-butanol as the major product? Neopentylamine n-Butylamine Isopropylamine Isobutylamine During the Curtius rearrangement, which of the following is the intermediate that undergoes rearrangement to form an isocyanate? Acyl nitrene Acyl carbene Carbanion Acylium ion Which of the following reagents is used in the Lossen rearrangement to convert a hydroxamic acid derivative to a primary amine? Base (like NaOH ) LiAlH 4 Br 2/KOH Sn/HCl Which of the following is an example of a 'bis-azo' dye? Congo Red Methyl Orange Aniline Yellow Butter Yellow Which of the following sequences is most appropriate to convert Nitrobenzene to m -Bromophenol? Fe/HCl ; Br 2/Fe ; NaNO 2/HCl ; H 2O/ Br 2/Fe ; Fe/HCl ; NaNO 2/HCl ; H 2O/ Sn/HCl ; NaNO 2/HCl ; Br 2 ; H 2O/ HNO 3/H 2SO 4 ; Br 2/Fe ; H 3PO 2 In the Herz reaction, aniline reacts with which reagent to form a benzothiazathiolium chloride? Disulphur dichloride ( S 2Cl 2 ) Sulphuryl chloride ( SO 2Cl 2 ) Thionyl chloride ( SOCl 2 ) Phosphorus pentachloride ( PCl 5 ) In the Gabriel phthalimide synthesis, why is the use of secondary alkyl halides generally avoided? They tend to undergo elimination to form alkenes. They are not reactive enough for nucleophilic substitution. They form unstable phthalimide derivatives. They react too violently with potassium phthalimide. Acetamide can be converted into methyl cyanide ( CH 3CN ) by heating with: P 2O 5 LiAlH 4 NaOH Br 2/KOH Which reagent is used in the Schiemann reaction to prepare fluorobenzene from benzene diazonium chloride? HBF 4 HF/Cu NaF F 2/FeCl 3 Which of the following is an example of an explosive compound derived from nitrogen? TNG (Trinitroglycerin) Aniline Nitrobenzene Benzonitirile The catalyst used in the Mendius reaction to reduce nitriles to amines is: Na/C 2H 5OH Sn/HCl Zn/NaOH LiAlH 4 Hofmann bromamide degradation reaction involves the conversion of: Amide to primary amine with one less carbon Amide to primary amine with same number of carbons Amine to amide Amide to secondary amine The conversion of Benzenediazonium chloride to Benzene using H 3PO 2 is a/an: Reduction Oxidation Substitution Elimination During the coupling of benzene diazonium chloride with phenol, the pH is maintained at: 9-10 4-5 1-2 7 Aniline is treated with NaNO 2/HCl at 0 C and the resulting solution is added to a cold alkaline solution of -naphthol. The color of the precipitate formed is: Orange-red Yellow Blue Deep Green Which of the following is the most suitable reagent for the conversion: R-CH 2-NO 2 R-CH 2-NH 2 ? Sn/HCl LiAlH 4 Both Sn/HCl and LiAlH 4 None of the above In the reaction C 6H 5N 2 +Cl - + H 2O X , what is 'X'? Phenol Benzene Chlorobenzene Aniline Which of the following species is the most stable? C 6H 5N 2 +Cl - at 273 K (CH 3) 3CN 2 +Cl - CH 3CH 2N 2 +Cl - CH 2=CH-N 2 +Cl - In the reaction: R-CN + 4[H] Na/C 2H 5OH R-CH 2NH 2 , the reagent is known as: Mendius reagent Sabatier-Senderens catalyst Lindlar's catalyst Birch reduction Which reagent can be used to convert nitrobenzene to phenylhydroxyl amine? Zn/NH 4Cl Zn/HCl Zn/NaOH Sn/HCl The product formed when Benzenediazonium chloride reacts with hypophosphorous acid ( H 3PO 2 ) in the presence of water is: Benzene Phenol Chlorobenzene Aniline The reaction: ArN 2 +Cl - + CuCN ArCN + N 2 + CuCl is an example of: Sandmeyer reaction Gattermann reaction Wurtz reaction Coupling reaction Reaction of aniline with NaNO 2 and HCl followed by treatment with KI yields: Iodobenzene Chlorobenzene Aniline hydrochloride Benzene In the reaction ArN 2 +Cl - Cu/HCl ArCl + N 2 + CuCl , the reaction is known as: Gattermann reaction Sandmeyer reaction Etard reaction Stephen's reaction Which species is the actual nitrating agent in the nitration of aniline in the presence of concentrated sulphuric acid? NO 2 + NO + HNO 3 HSO 4 - Nitroalkanes can exist in two tautomeric forms. The form containing the group -NO 2 is called the nitro-form, while the other form is known as: Aci-form Enol-form Keto-form Meso-form Benzene diazonium chloride on reaction with KCN in the presence of CuCN gives Benzonitrile. This reaction is: Sandmeyer reaction Gattermann reaction Balz-Schiemann reaction Stephen's reaction In the coupling reaction between benzene diazonium chloride and phenol, the electrophile attacks the phenol at: Para position Ortho position Meta position Oxygen atom The coupling of benzene diazonium chloride with aniline in a slightly acidic medium produces p -aminoazobenzene. The color of this dye is: Yellow Orange Red Blue The reaction: C 6H 5N 2Cl + HBF 4 C 6H 5F + BF 3 + N 2 is: Balz-Schiemann reaction Finkelstein reaction Swarts reaction Wurtz-Fittig reaction The coupling reaction of benzene diazonium chloride with aniline in a slightly acidic medium ( pH 4-5 ) produces: p-Aminoazobenzene p-Hydroxyazobenzene Aniline black Chlorobenzene Identify the electrophile in the diazotization of aniline. NO + NO 2 + NO 2 - HNO 2 Which of the following compounds reacts with NaNO 2 and HCl at 0-5 C to give an alcohol with evolution of N 2 gas? CH 3CH 2NH 2 (CH 3) 2NH C 6H 5NH 2 (CH 3) 3N What is the color of the dye obtained when benzene diazonium chloride reacts with -naphthol in NaOH ? Orange-red Yellow Blue Green Aniline reacts with concentrated H 2SO 4 at 453-473 K to form: Sulphanilic acid Aniline hydrogen sulphate m-Amino benzene sulphonic acid Benzene sulphonic acid Which of the following reagents is used to convert nitrobenzene into hydrazobenzene? Zn / NaOH / CH 3OH Zn / HCl Zn / NH 4Cl LiAlH 4 / Ether What is the product formed when N -ethyl- N -methylaniline reacts with HNO 2 at 0-5 C ? p -nitroso- N -ethyl- N -methylaniline N -nitroso- N -ethyl- N -methylaniline m -nitroso- N -ethyl- N -methylaniline Benzenediazonium chloride The reagent used in the Mendius reaction is: Na / C 2H 5OH Sn / HCl LiAlH 4 H 2 / Pd The alkyl isocyanides on complete hydrolysis with dilute HCl give: Primary amine and formic acid Primary amine and salt of carboxylic acid Secondary amine Amide In the reaction of aniline with CHCl 3 and KOH , the intermediate is: Dichlorocarbene ( :CCl 2 ) Trichloromethyl radical Dichloromethyl cation Nitrene Which of the following can be used to distinguish between nitroethane and ethyl nitrite? Reaction with LiAlH 4 Boiling point measurement Hydrolysis with KOH All of these What happens when Benzenediazonium chloride is treated with Cu 2O and H 2O ? Phenol is formed Benzene is formed Chlorobenzene is formed Aniline is formed The reaction of aniline with a mixture of NaNO 2 and HCl at high temperature ( > 100 C ) yields: Phenol Chlorobenzene Nitrobenzene Benzenediazonium chloride Selective reduction of m -dinitrobenzene to m -nitroaniline can be achieved using which reagent? (NH 4) 2S Sn/HCl Fe/HCl LiAlH 4 Nitromethane reacts with chlorine in the presence of NaOH to produce which powerful insecticide and tear gas component? Chloropicrin Chloroform Carbon tetrachloride Phosgene The synthesis of Methyl Orange involves the coupling of diazotized sulphanilic acid with: N,N -Dimethylaniline Aniline Phenol -Naphthol Hydrolysis of alkyl isocyanides ( R-NC ) with dilute HCl gives: Primary amine and Formic acid Primary amine and Methanol Secondary amine and Water Ammonia and Carboxylic acid Nitroethane exhibits tautomerism. The tautomeric form which dissolves in NaOH is called: Aci-form Nitro-form Enol-form Meso-form Which of the following is used as an explosive? TNG (Trinitroglycerin) Nitrobenzene Ethylamine Aniline The dye 'Para-red' is obtained by the coupling of benzene diazonium chloride with: -Naphthol Phenol Aniline Salicylic acid The reduction of nitrobenzene with Zn/NaOH (alkaline medium) primarily yields which compound as the final product of bimolecular reduction? Hydrazobenzene Aniline Phenylhydroxylamine Nitrosobenzene Which of the following representations correctly shows the electronic structure of the Isocyanide group ( -NC )? -N + C - -N = C -N C -N - - C + The reaction of a carboxylic acid with hydrazoic acid ( HN 3 ) in the presence of concentrated H 2SO 4 to give a primary amine is called: Schmidt reaction Curtius rearrangement Hofmann reaction Beckmann rearrangement During Libermann's nitroso test, secondary amines react with HNO 2 to form a yellow oily nitrosamine. On warming this with phenol and H 2SO 4 , a green solution is formed which turns on addition of water. Red Blue Violet Yellow In the diazotization of aniline with NaNO 2 and HCl , an excess of HCl is used primarily to: Prevent the coupling of diazonium salt with unreacted aniline Increase the rate of reaction Stabilize the NaNO 2 Suppress the ionization of HNO 2 Acidic hydrolysis of methyl isocyanide ( CH 3NC ) yields: Methylamine and formic acid Methylamine and methanol Ethylamine and water Dimethylamine and CO 2 The intermediate species formed during the Stephen reduction of a nitrile to an aldehyde is: Aldimine hydrochloride Ketimine Amide Nitroso compound Methyl orange, a common indicator, is prepared by the coupling reaction of diazotized sulphanilic acid with: N,N -dimethylaniline Aniline Phenol β -naphthol In the reduction of benzene diazonium chloride with ethanol, the ethanol is oxidized to: Acetaldehyde Acetic acid Ethyl nitrite Diethyl ether Which of the following diazonium salts is stable at 0-5 C ? C 6H 5N 2 +Cl - CH 3N 2 +Cl - C 2H 5N 2 +Cl - (CH 3) 2CHN 2 +Cl - Primary and secondary nitroalkanes containing α -hydrogen atoms show tautomerism. The tautomer is called: Aci-nitro form Nitroso form Enol form Keto form In the Hofmann bromamide degradation, the first intermediate formed by the action of Br 2 and KOH on the amide is: N -bromoamide Alkyl isocyanate Nitrene Carbene Which of the following amines will not form a diazonium salt at 0-5 C ? Diethylamine Aniline p -Toluidine Benzylamine Identify the dye produced when benzene diazonium chloride reacts with N,N -Dimethylaniline. Butter yellow Methyl orange Aniline yellow Phenolphthalein What is the hybridisation of the Nitrogen atom in the isocyanide group ( R-NC )? sp sp 2 sp 3 dsp 2 In the coupling reaction of benzene diazonium chloride and phenol, the reaction is carried out in a medium which is: Mildly alkaline ( pH 9-10) Strongly acidic ( pH 1-2) Mildly acidic ( pH 4-5) Strongly alkaline ( pH 13-14) Which of the following reacts with ArN 2 +Cl - to produce a yellow dye known as 'Butter Yellow'? N,N -Dimethylaniline Aniline Phenol Resorcinol Benzene diazonium chloride reacts with warm methanol ( CH 3OH ) to primarily produce: Anisole Benzene Phenol Chlorobenzene Which of the following compounds will NOT undergo Hofmann Bromamide Degradation? CH 3CONHCH 3 CH 3CONH 2 C 6H 5CONH 2 CH 3CH 2CONH 2 In the reaction: R-NO 2 + 6[H] Sn/HCl R-NH 2 + 2H 2O , how many electrons are involved in the reduction of one mole of nitro group to amino group? 6 4 2 3 When benzene diazonium chloride is treated with an aqueous solution of potassium iodide ( KI ), the product formed is: Iodobenzene Chlorobenzene Benzene Phenol Which of the following statements is true for the zwitterionic form of sulphanilic acid? It has a high melting point and is insoluble in organic solvents. It is highly soluble in water and organic solvents. It does not react with strong bases. It exists as a liquid at room temperature. The reaction of benzene diazonium chloride with HBF 4 followed by heating with NaNO 2 and Cu powder is used to prepare: Nitrobenzene Fluorobenzene Benzene Aniline When N,N -Dimethylaniline is treated with nitrous acid at 0-5 C , the substitution occurs at which position? Para Ortho Meta Nitrogen atom (N-nitrosation) The reaction of R-CONH 2 with Br 2 and KOH involves the formation of which intermediate that undergoes rearrangement? Acyl nitrene Carbene Carbonium ion Carbanion Aniline is treated with a mixture of NaNO 2 and HCl at 0-5 C to form 'A'. 'A' reacts with fluoroboric acid ( HBF 4 ) to form 'B'. 'B' on heating gives 'C'. Identify 'C'. Fluorobenzene Chlorobenzene Benzene Nitrobenzene During the synthesis of Methyl Orange, what is the sequence of reagents used starting from Sulphanilic acid? (1) NaNO 2/HCl ; (2) N,N -Dimethylaniline (1) HNO 3/H 2SO 4 ; (2) NaOH (1) NaNO 2/HCl ; (2) Phenol (1) Sn/HCl ; (2) NaNO 2/HCl When N,N -Dimethylaniline is treated with NaNO 2 and HCl at 273 K , the product obtained is: p -Nitroso- N,N -dimethylaniline Benzenediazonium chloride N -Nitroso- N -methylaniline o -Nitroso- N,N -dimethylaniline The melting point of p -nitroaniline is much higher than that of o -nitroaniline. This is primarily because: p -Nitroaniline forms intermolecular hydrogen bonds, while o -nitroaniline forms intramolecular hydrogen bonds. The molecular weight of p -nitroaniline is higher. The nitro group in p -position is more electron withdrawing. o -Nitroaniline is more symmetric. Which of the following statements is true for the 'Amine Inversion' process? It is faster in primary amines than in tertiary amines. It is impossible in quaternary ammonium salts. It requires an activation energy of about 100 kcal/mol . It changes the configuration of a chiral nitrogen center from R to S. The product obtained by the reduction of methyl isocyanide with sodium and ethanol is: Dimethylamine Ethylamine Methylamine Trimethylamine In the Gabriel Phthalimide synthesis, the reactivity of alkyl halides follows the order: RI > RBr > RCl RCl > RBr > RI RBr > RI > RCl RI > RCl > RBr In the diazotization of aniline, the reaction rate is highest when the pH is maintained at approximately: Lower than 2 7 9 to 10 12 to 14 The reaction of urea ( NH 2CONH 2 ) with nitrous acid ( HNO 2 ) yields: CO 2 , N 2 , and H 2O CO , N 2 , and H 2O NH 4NO 2 NH 2NO 2 The reaction of N,N -Dimethylaniline with nitrous acid at 273 K results in the formation of p -Nitroso- N,N -dimethylaniline. This reaction is an example of: Electrophilic aromatic substitution Nucleophilic aromatic substitution Free radical substitution Elimination reaction Benzene diazonium chloride on reduction with SnCl 2 and HCl yields which of the following compounds? Phenylhydrazine Aniline Chlorobenzene Benzene Which of the following compounds will NOT react with nitrous acid ( HNO 2 ) at 0-5 C to produce a reaction that results in a color change or gas evolution? 2-Nitro-2-methylpropane Nitroethane 2-Nitropropane Aniline Benzene diazonium chloride reacts with resorcinol ( 1,3 -dihydroxybenzene) in a basic medium to produce a dye. The structure of this dye is formed by coupling at which position of resorcinol? Position 4 Position 2 Position 5 Position 1 Benzene diazonium chloride reacts with sodium sulphide ( Na 2S ) to produce: Diphenyl sulphide Thiophenol Benzene Chlorobenzene Which of the following diazonium salts is the most stable towards spontaneous decomposition? p -Nitrobenzenediazonium chloride Benzenediazonium chloride p -Methoxybenzenediazonium chloride p -Methylbenzenediazonium chloride Which of the following has the highest acidity ( lowest pK a )? Nitromethane ( CH 3NO 2 ) Acetonitrile ( CH 3CN ) Acetone ( CH 3COCH 3 ) Ethane ( C 2H 6 ) What is the effect of increasing pH (making the solution more basic) on the rate of diazotization of aniline? The rate decreases. The rate increases. The rate remains unchanged. The reaction stops completely at pH > 7 . Sulphanilic acid exists as a dipolar ion (zwitterion) because it contains: Both acidic ( -SO 3H ) and basic ( -NH 2 ) groups in the same molecule Two acidic groups Two basic groups A phenolic group and an amine group What is the product of the reaction between N,N -dimethylaniline and nitrous acid ( HNO 2 ) at 0-5 C ? p -Nitroso- N,N -dimethylaniline N -Nitroso- N,N -dimethylaniline Benzenediazonium chloride m -Nitroso- N,N -dimethylaniline Identify the product 'C' in the following sequence: C 6H 5NH 2 NaNO 2/HCl, 273K A CuCN/KCN B H 2/Ni C Benzylamine Aniline Benzonitrile N-methylaniline Benzene diazonium chloride reacts with hypophosphorous acid ( H 3PO 2 ) to give: Benzene Phenol Chlorobenzene Nitrobenzene What is the product of the reaction between Benzenediazonium chloride and phenol in a weakly basic medium? p-Hydroxyazobenzene p-Aminoazobenzene Azobenzene Chlorobenzene The correct sequence of reagents for the conversion: Nitrobenzene Benzene is: Sn/HCl , then NaNO 2/HCl , then H 3PO 2 LiAlH 4 , then H 3PO 2 H 2/Pd , then Cl 2/AlCl 3 NaOH , then CH 3I Electrolytic reduction of nitrobenzene in strongly acidic medium produces: p-aminophenol Aniline Azobenzene Phenylhydroxylamine What is the product formed when N,N-Dimethylaniline reacts with nitrous acid at 273-278 K ? p-Nitroso-N,N-dimethylaniline N-Nitroso-N,N-dimethylaniline Benzene diazonium chloride N-Methylaniline Benzenediazonium chloride reacts with HBF 4 followed by heating with NaNO 2 in the presence of Copper to give: Nitrobenzene Fluorobenzene Benzene Phenol The product of the reaction: Benzene diazonium chloride + Ethanol is: Benzene Phenol Ethyl phenyl ether Acetaldehyde and Benzene In the Hofmann bromamide degradation reaction, the intermediate species formed are: Nitrene and Isocyanate Carbene and Nitrene Carbocation and Nitrene Isocyanide and Nitrene