Organic Compounds Containing Nitrogen
- The correct order of decreasing basic strength of the given amines is : Answer: 3. N-ethylethanamine > ethanamine > N-methylaniline > benzenamine Key idea: aliphatic amines are stronger bases than aromatic ones,... 1
- Given below are two statements :Statement I : Benzenediazonium salt is prepared by the reaction of aniline with nitrous acid at 273 - 278 K. It decomposes easily in the dry state.Statement II : Insertion of iodine into the benzene ring is difficult a… Answer: 1. Both Statement I and Statement II are correct Statement I is correct: diazotisation of aniline with NaNO₂/HCl is done at 273-278... 1
- Predict the major product 'P' in the following sequence of reactions -(i) HBr, benzoyl peroxide; (ii) KCN; (iii) Na(Hg)/C_2H_5OH -> P (Major), starting from 1-methylcyclopentene Answer: 1. methylcyclopentane with CH₂NH₂ (see figure) Key idea: HBr with peroxide adds anti-Markovnikov, KCN replaces Br by CN, and Na(Hg)/... 1
- Identify the major product C formed in the following reaction sequence :CH_3-CH_2-CH_2-I NaCN A [Partial hydrolysis]OH^- B [Br_2]NaOH C (major) Answer: 2. propylamine Key idea: follow each step. CH₃CH₂CH₂I+NaCN→ CH₃CH₂CH₂CN (A, butanenitrile). Partial hydrolysis with OH^- gives CH₃CH... 1
- Given below are two statements:Statement I : Aniline does not undergo Friedel-Crafts alkylation reaction.Statement II : Aniline cannot be prepared through Gabriel synthesis.In the light of the above statements, choose the correct answer from the opti… Answer: 2. Both Statement I and Statement II are true. Key idea: the -NH₂ group of aniline is basic and reacts with Lewis acids; Gabriel syn... 1
- Which of the following reactions will NOT give primary amine as the product? Answer: 4. mathrmCH₃NC xrightarrow[(ii)\ H₃O^(oplus)](i)\ LiAlH₄ Product Key idea: Find which reaction does not give R-NH₂ . 1: LiAlH₄ reduc... 1
- Some tranquilizers are listed below. Which one from the following belongs to barbiturates? Answer: 1. Veronal Key idea: Barbiturates are derivatives of barbituric acid. Veronal (barbital) is a barbiturate (others: luminal, seconal)... 1
- Identify the product in the following reaction :Benzenediazonium chloride (C_6H_5N_2^+Cl^-) with (i) Cu_2Br_2/HBr (ii) Mg/dry ether (iii) H_2O → Product Answer: 3. benzene (structure) Key idea: Follow each step: Sandmeyer reaction, then Grignard formation, then hydrolysis. C₆H₅N₂^+Cl^- with C... 1
- The product formed from the following reaction sequence is[benzonitrile] [(iii) H_2O](i) LiAlH_4, H_2O;\ (ii) NaNO_2 + HCl Answer: 1. [structure in figure] Key idea: follow each step. LiAlH₄ reduces the nitrile C₆H₅CN to the primary amine C₆H₅CH₂NH₂ (benzylamine)... 1
- Which of the following sequence of reactions is suitable to synthesize chlorobenzene ? Answer: 2. Benzene, Cl₂ , anhydrous FeCl₃ Key idea: chlorobenzene is made by electrophilic substitution of benzene with Cl₂ and a Lewis acid... 1
- Given below are two statements :Statement I :Primary aliphatic amines react with HNO_2 to give unstable diazonium salts.Statement II :Primary aromatic amines react with HNO_2 to form diazonium salts which are stable even above 300 K.In the light of t… Answer: 4. Statement I is correct but Statement II is incorrect. Key idea: diazonium salts of aliphatic amines are unstable; aromatic ones a... 1
- The reagent 'R' in the given sequence of chemical reaction is :2,4,6-tribromoaniline NaNO_2, HCl,\ 0-5^° C 2,4,6-tribromobenzenediazonium chloride R 1,3,5-tribromobenzene Answer: 2. CH₃CH₂OH Key idea: replacing the diazonium group by hydrogen (hydro-de-diazoniation) needs a mild reducing agent. Ethanol (or H₃P... 1
- Identify the compound that will react with Hinsberg's reagent to give a solid which dissolves in alkali. Answer: 3. CH₃CH₂-ddotNH₂ Key idea: Hinsberg's reagent (benzenesulphonyl chloride) reacts with primary and secondary amines; the sulphonamid... 1
- Which of the following is a cationic detergent ? Answer: 3. Cetyltrimethyl ammonium bromide Cationic detergents have a positively charged head group, usually a quaternary ammonium salt. Cet... 1
- Which of the following amine will give the carbylamine test ? Answer: 1. Aniline (C ₆ H ₅ NH ₂ ) The carbylamine test (heating with CHCl₃ and alcoholic KOH to give a foul-smelling isocyanide) is given o... 1
- The correct order of the basic strength of methyl substituted amines in aqueous solution is : Answer: 1. (CH₃)₂NH > CH₃NH₂ > (CH₃)₃N In aqueous solution basicity depends on both the inductive effect (more alkyl groups push electrons)... 1
- Which of the following reactions is appropriate for converting acetamide to methanamine ? Answer: 1. Hoffmann hypobromamide reaction Key idea: Hoffmann bromamide reaction removes one carbon from an amide to give a primary amine. C... 1
- The correct increasing order of basic strength for the following compounds is : [(I) aniline, (II) 4-nitroaniline, (III) 4-methylaniline] Answer: 3. II < I < III Key idea: basic strength depends on how available the lone pair on N is. -CH₃ is electron-donating (+I, hyperconjuga... 1
- A given nitrogen-containing aromatic compound A reacts with Sn/HCl, followed by HNO_2 to give an unstable compound B. B, on treatment with phenol, forms a beautiful coloured compound C with the molecular formula C_12H_10N_2O. The structure of compoun… Answer: 1. nitrobenzene ( C₆H₅NO₂ ) Key idea: nitro compound → amine → diazonium salt → azo dye. C₆H₅NO₂xrightarrowSn/HClC₆H₅NH₂ C₆H₅NH₂xrig... 1
- Which one of the following nitro-compounds does not react with nitrous acid? Answer: 2. [structure shown in figure] Key idea: a nitroalkane reacts with HNO₂ only if it has an alpha-hydrogen. Primary give nitrolic acid... 1
- The correct statement regarding the basicity of arylamines is : Answer: 1. Arylamines are generally less basic than alkylamines because the nitrogen lone-pair electrons are delocalized by interaction with... 1