[ { "type": "scq", "q": "The major product formed in the following reaction is:\n$$\text{Substrate containing an ether and a secondary alcohol group} \xrightarrow[\text{Heat}]{\text{HI}} \text{Products} $$", "opts": { "A": "(1)", "B": "(2)", "C": "(3)", "D": "(4)" }, "ans": "B", "exp": "Reaction of the given ether/alcohol compound with concentrated HI under heat results in cleavage of the ether bond at the less sterically hindered or more stable carbon-oxygen bond position and substitution/elimination processes typical of HI cleavage." }, { "type": "scq", "q": "Which is the most suitable reagent for the following transformation?\n$\text{CH}_3-\text{CH}=\text{CH}-\text{CH}_2-\text{CH(OH)}-\text{CH}_3 \longrightarrow \text{CH}_3-\text{CH}=\text{CH}-\text{CH}_2\text{CO}_2\text{H}$", "opts": { "A": "$I_{2}/\text{NaOH}$", "B": "Alkaline $\text{KMnO}_{4}$", "C": "Tollen's reagent", "D": "$\text{CrO}_{2}\text{Cl}_{2}/\text{CS}_{2}$" }, "ans": "A", "exp": "The transformation involves the haloform reaction. The secondary alcohol group $-\text{CH(OH)CH}_3$ is oxidized to a methyl ketone $-\text{COCH}_3$, which then undergoes oxidative cleavage by $I_2/\text{NaOH}$ (iodoform reaction) to yield a carboxylic acid while keeping the carbon-carbon double bond intact." }, { "type": "scq", "q": "The major product of the following reaction is:\n$$ \text{4-chlorocyclohexanone} \xrightarrow{\text{(i) HBr, (ii) alc. KOH}} \text{Product} $$", "opts": { "A": "(1)", "B": "(2)", "C": "(3)", "D": "(4)" }, "ans": "A", "exp": "Treatment of the chloro-ketone with HBr followed by alcoholic KOH drives elimination and rearrangement to form the thermodynamically stable conjugated major product or phenol derivative depending on specific structural elimination pathways." }, { "type": "scq", "q": "The organic compound that gives following qualitative analysis is\n\begin{tabular}{|l|l|}\n\hline\n\textbf{Test} & \textbf{Inference} \\\\\n\hline\n(1) Dil. HCl & Insoluble \\\\\n(2) NaOH solution & Soluble \\\\\n(3) $Br_{2}/\text{water}$ & Decolourization \\\\\n\hline\n\end{tabular}", "opts": { "A": "(1) Cyclohexanol", "B": "(2) Phenol", "C": "(3) Cyclohexylamine", "D": "(4) Aniline" }, "ans": "B", "exp": "Phenol is acidic enough to dissolve in aqueous $\text{NaOH}$ but insoluble in weak acids like $\text{HCl}$. It easily undergoes electrophilic aromatic substitution with bromine water, resulting in the decolourization of bromine water and formation of a white precipitate." }, { "type": "scq", "q": "The major product of the following reaction is :\n$$ \text{Ethyl 2-hydroxy-3-(hydroxymethyl)benzoate} \xrightarrow[\text{CHCl}_3]{\text{H}_2\text{SO}_4\text{(cat.)}} \text{Product} $$", "opts": { "A": "(1)", "B": "(2)", "C": "(3)", "D": "(4)" }, "ans": "B", "exp": "Under acidic conditions, an intramolecular cyclization via lactonization or esterification occurs between the adjacent hydroxyl/carboxylic derivative groups to give a stable cyclic ester (lactone) as the major product." }, { "type": "scq", "q": "The major product [B] in the following reactions is\n$$ \text{CH}_3-\text{CH}_2-\text{CH(CH}_3)-\text{CH}_2-\text{OCH}_2-\text{CH}_3 \xrightarrow[\text{Heat}]{\text{HI}} [A]\text{ alcohol} \xrightarrow{\text{H}_2\text{SO}_4, \Delta} [B] $$", "opts": { "A": "$\text{CH}_3-\text{CH}_2-\text{CH}=\text{CH}-\text{CH}_3$", "B": "$\text{CH}_3-\text{CH}_2-\text{C(CH}_3)=\text{CH}_2$", "C": "$\text{CH}_3-\text{CH}=\text{C(CH}_3)-\text{CH}_3$", "D": "$\text{CH}_2=\text{CH}_2$" }, "ans": "C", "exp": "Cleavage of the ether with HI yields 2-methylbutan-1-ol. Dehydration of this alcohol with $\text{H}_2\text{SO}_4$ under heat involves a carbocation intermediate with a hydride/alkyl shift to form the more stable tertiary carbocation, giving 2-methylbut-2-ene as the highly substituted, major Saytzeff alkenes product." }, { "type": "scq", "q": "In the following reaction sequence, structures of A and B, respectively will be\n$$ \text{2-(bromomethyl)phenol} \xrightarrow{\text{HBr}} \text{Intermediate} \xrightarrow{\text{Na, Ether}} A \text{ and } B \text{ (Intramolecular Product)} $$", "opts": { "A": "(1)", "B": "(2)", "C": "(3)", "D": "(4)" }, "ans": "D", "exp": "Reaction with HBr converts the phenolic/alcoholic sites appropriately, followed by a Wurtz-type intramolecular or intermolecular coupling in the presence of sodium and ether to yield cyclic or coupled structural products." }, { "type": "scq", "q": "The correct options for the products A and B of the following reactions are:\n$$ \text{Phenol} \xrightarrow[\text{H}_2\text{O}]{\text{Br}_2 \text{ (Excess)}} A$$\n$$\text{Phenol} \xrightarrow[\text{CS}_2, <5^\circ\text{C}]{\text{Br}_2} B$$", "opts": { "A": "(1) A = 2,4,6-tribromophenol; B = o-bromophenol", "B": "(2) A = 2,4,6-tribromophenol; B = p-bromophenol", "C": "(3) A = p-bromophenol; B = 2,4,6-tribromophenol", "D": "(4) A = o-bromophenol; B = p-bromophenol" }, "ans": "B", "exp": "In aqueous medium, phenol highly ionizes to phenoxide ion which strongly activates the ring, causing polybromination to yield 2,4,6-tribromophenol (A). In non-polar solvents like $\text{CS}_2$ at low temperatures, the reactivity is controlled, yielding mainly p-bromophenol (B) as the major product due to minimal steric hindrance." }, { "type": "scq", "q": "Given below are two statements:\nStatement I: Ethyl pent-4-yn-oate on reaction with $\text{CH}_3\text{MgBr}$ gives a $3^\circ$-alcohol.\nStatement II: In this reaction one mole of ethyl pent-4-yn-oate utilizes two moles of $\text{CH}_3\text{MgBr}$.\nIn the light of the above statements, choose the most appropriate answer from the options given below :", "opts": { "A": "(1) Both Statement I and Statement II are false.", "B": "(2) Statement I is false but Statement II is true.", "C": "(3) Statement I is true but Statement II is false.", "D": "(4) Both Statement I and Statement II are true." }, "ans": "C", "exp": "Statement I is true because the ester group reacts with Grignard reagent to produce a tertiary alcohol. However, Statement II is false because the terminal alkyne group ($-\text{C}\equiv\text{CH}$) contains an acidic proton which consumes an additional mole of Grignard reagent via an acid-base reaction, meaning more than two moles are utilized overall." }, { "type": "scq", "q": "The major product of the following reaction, if it occurs by $\text{SN}_2$ mechanism is:\n$$\text{Phenol} + \text{3-methylbut-2-enyl bromide} \xrightarrow{\text{K}_2\text{CO}_3, \text{ acetone}} \text{Product} $$", "opts": { "A": "(1)", "B": "(2)", "C": "(3)", "D": "(4)" }, "ans": "D", "exp": "The weak base $\text{K}_2\text{CO}_3$ deprotonates phenol to form a nucleophilic phenoxide ion. The phenoxide ion attacks the allylic bromide via an $\text{SN}_2$ pathway, yielding an allylic phenyl ether as the major product." }, { "type": "scq", "q": "Consider the following reaction:\n$$ \text{1-phenylpropan-2-ol} \xrightarrow[\Delta]{\text{Conc. H}*2\text{SO}*4} A + B$$\nChoose the correct statement:", "opts": { "A": "(1) The reaction is not possible in acidic medium", "B": "(2) Both compounds A and B are formed equally", "C": "(3) Compound A will be the major product", "D": "(4) Compound B will be the major product" }, "ans": "C", "exp": "Acid-catalyzed dehydration follows Zaitsev's rule. The elimination forms trans-1-phenylpropene (A) as the major product because it is highly stabilized by extended conjugation with the aromatic ring and exhibits less steric hindrance compared to the cis-isomer (B)." }, { "type": "scq", "q": "The given reaction can occur in the presence of:\n$$\text{Phenol} \longrightarrow \text{p-bromophenol (Major product)}$$\n(A) Bromine water \n(B) $\text{Br}_2$ in $\text{CS}_2, 273\text{ K}$ \n(C) $\text{Br}_2/\text{FeBr}_3$ \n(D) $\text{Br}_2$ in $\text{CHCl}_3, 273\text{ K}$\nChoose the correct answer from the options given below :", "opts": { "A": "(1) (B) and (D) only", "B": "(2) (A) and (C) only", "C": "(3) (B), (C) and (D) only", "D": "(4) (A), (B) and (D) only" }, "ans": "C", "exp": "Monobromination of phenol to selectively get p-bromophenol as the major product is achieved by running the reaction in non-polar or low-polarity solvents like $\text{CS}_2$ or $\text{CHCl}_3$ at low temperatures, or via standard Lewis acid catalysis $\text{Br}_2/\text{FeBr}_3$ where over-bromination is minimized compared to water." }, { "type": "scq", "q": "Main Products formed during a reaction of 1-methoxy naphthalene with hydroiodic acid are:", "opts": { "A": "(1) 1-naphthol and $\text{CH}_3\text{OH}$", "B": "(2) 1-naphthol and $\text{CH}_3\text{I}$", "C": "(3) 1-iodonaphthalene and $\text{CH}_3\text{OH}$", "D": "(4) 1-iodonaphthalene and $\text{CH}_3\text{I}$" }, "ans": "B", "exp": "The $\text{C}*{\text{aryl}}-\text{O}$ bond in 1-methoxy naphthalene has partial double bond character due to resonance and is much stronger than the $\text{C}*{\text{alkyl}}-\text{O}$ bond. Therefore, nucleophilic attack by $\text{I}^-$ occurs exclusively at the methyl group, producing 1-naphthol and methyl iodide ($\text{CH}_3\text{I}$)." }, { "type": "scq", "q": "Consider the following reaction and identify the Product P:\n$$\text{Alkenyl derivative} \xrightarrow{\text{(i) (BH}_3)_2, \text{ (ii) H}_2\text{O}_2/\text{OH}^-, \text{H}_2\text{O}} P \text{ (Major Product)} $$", "opts": { "A": "(1)", "B": "(2)", "C": "(3)", "D": "(4)" }, "ans": "D", "exp": "Hydroboration-oxidation is a regioselective reaction that results in the anti-Markovnikov addition of water across an alkene double bond, yielding the less substituted alcohol cleanly without skeletal rearrangement." }, { "type": "scq", "q": "Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).\nAssertion (A): Synthesis of ethyl phenyl ether may be achieved by Williamson synthesis.\nReason (R): Reaction of bromobenzene with sodium ethoxide yields ethyl phenyl ether.\nIn the light of the above statements, choose the most appropriate answer from the options given below:", "opts": { "A": "(1) Both (A) and (R) are correct and (R) is the correct explanation of (A)", "B": "(2) (A) is correct but (R) is not correct", "C": "(3) (A) is not correct but (R) is correct", "D": "(4) Both (A) and (R) are correct but (R) is NOT the correct explanation of (A)" }, "ans": "B", "exp": "Assertion A is true; ethyl phenyl ether can be synthesized via Williamson ether synthesis by reacting sodium phenoxide with ethyl bromide. However, Reason R is false because aryl halides like bromobenzene do not undergo nucleophilic substitution ($\text{SN}_2$) with sodium ethoxide under normal conditions due to partial double bond character of the $\text{C}-\text{Br}$ bond." }, { "type": "scq", "q": "The major product formed in the following reaction is :\n$$ \text{CH}_3-\text{C(CH}_3)_2-\text{CH(OH)}-\text{CH}_3 \xrightarrow{\text{conc. H}_2\text{SO}_4, \text{ a few drops}} \text{Major product} $$", "opts": { "A": "(1) $\text{CH}_3-\text{C(CH}_3)_2-\text{CH}=\text{CH}_2$", "B": "(2) $(\text{CH}_3)_2\text{C}=\text{C(CH}_3)_2$", "C": "(3) $\text{CH}_3-\text{CH(CH}_3)-\text{C(CH}_3)=\text{CH}_2$", "D": "(4) $\text{CH}_3-\text{C(CH}_3)=\text{CH}-\text{CH}_2\text{CH}_3$" }, "ans": "B", "exp": "Dehydration of 3,3-dimethylbutan-2-ol proceeds through a secondary carbocation. A 1,2-methyl shift occurs spontaneously to yield a more stable tertiary carbocation. Subsequent deprotonation gives the highly stable, most substituted alkene: 2,3-dimethylbut-2-ene." }, { "type": "scq", "q": "A compound 'X' is acidic and it is soluble in $\text{NaOH}$ solution, but insoluble in $\text{NaHCO}_3$ solution. Compound 'X' also gives violet colour with neutral $\text{FeCl}_3$ solution. The compound 'X' is :", "opts": { "A": "(1) o-Nitrophenol", "B": "(2) Phenol", "C": "(3) Benzoic acid", "D": "(4) Benzyl alcohol" }, "ans": "B", "exp": "Phenol is weakly acidic, enabling it to react with strong bases like $\text{NaOH}$ to form water-soluble sodium phenoxide, but it cannot decompose weak bases like $\text{NaHCO}_3$. Its characteristic test is forming a violet complex with neutral $\text{FeCl}_3$ solution." }, { "type": "scq", "q": "When ethanol is heated with conc. $\text{H}_2\text{SO}_4$ a gas is produced. The compound formed, when this gas is treated with cold dilute aqueous solution of Baeyer's reagent, is:", "opts": { "A": "(1) Formaldehyde", "B": "(2) Formic acid", "C": "(3) Glycol", "D": "(4) Ethanoic acid" }, "ans": "C", "exp": "Heating ethanol with concentrated $\text{H}_2\text{SO}_4$ at $170^\circ\text{C}$ generates ethene gas ($\text{CH}_2=\text{CH}_2$). Treating ethene with cold, dilute, alkaline $\text{KMnO}_4$ (Baeyer's reagent) results in syn-hydroxylation to produce ethane-1,2-diol (ethylene glycol)." }, { "type": "scq", "q": "The major product in the given reaction is:\n$$ \text{Cyclic ether derivative} \xrightarrow{\text{(1) } \text{H}^+, \text{ heat}}{\text{(2) HBr}} \text{Product} $$", "opts": { "A": "(1)", "B": "(2)", "C": "(3)", "D": "(4)" }, "ans": "C", "exp": "Acid-catalyzed opening of the cyclic ether ring followed by nucleophilic substitution with hydrobromic acid replaces the hydroxyl positions or completes elimination/halohydrin transformations to form the brominated product." }, { "type": "scq", "q": "Identify the major product A and B for the below given reaction sequence.\n$$ \text{Benzene} \xrightarrow{\text{(1) Cumene synthesis steps, (2) } \text{O}_2, \text{ (3) } \text{H}^+/\text{H}_2\text{O}} A \xrightarrow{\text{Br}*2 \text{ in CS}*2} B$$", "opts": { "A": "(1) A = Phenol, B = o-bromophenol", "B": "(2) A = Phenol, B = p-bromophenol", "C": "(3) A = Acetone, B = p-bromophenol", "D": "(4) A = Phenol, B = 2,4,6-tribromophenol" }, "ans": "B", "exp": "The industrial preparation of phenol from cumene (isopropylbenzene) via autoxidation produces phenol (A) and acetone as a byproduct. Subsequent bromination of phenol in a non-polar solvent like $\text{CS}_2$ yields para-bromophenol (B) as the major product." }, { "type": "integer", "q": "In the following reaction:\n$\text{Cumene hydroperoxide} \xrightarrow{\text{H}^+/\text{H}*2\text{O}} A + B$\nIf compound A is phenol, determine the structural identifier number for the primary organic byproduct B among standard aliphatic ketones (e.g., Acetone). Enter its molecular count of carbon atoms.", "ans": "3", "exp": "Acid-catalyzed cleavage of cumene hydroperoxide generates phenol and acetone ($\text{CH}_3\text{COCH}_3$). The byproduct acetone contains exactly 3 carbon atoms." }, { "type": "integer", "q": "Evaluate the major product (P) configuration of the given reaction where Me is $-\text{CH}_3$ group interacting with localized tertiary alcohol centers under strong acid dehydration conditions. Determine the total number of methyl substituents directly attached to the sp2 carbons of the resulting alkene.", "ans": "3", "exp": "Dehydration of highly branched secondary/tertiary alcohols involves carbocation rearrangement (methyl shifts) to establish a highly substituted double bond conformation according to Saytzeff's rule, yielding 3 methyl groups on the double bond carbons." }, { "type": "integer", "q": "The correct order of nucleophilicity in polar protic solvents is evaluated among various conjugate bases. Among the following options: (1) $F^- > OH^-$, (2) $H_2O > OH^-$, (3) $ROH > RO^-$, (4) $NH_2^- > NH_3$, select the option index that correctly represents valid relative nucleophilicity.", "ans": "4", "exp": "Conjugate bases are always stronger nucleophiles than their corresponding conjugate acids. Thus, $NH_2^-$ is a significantly stronger nucleophile than $NH_3$, matching option (4)." }, { "type": "integer", "q": "Hex-4-ene-2-ol on treatment with PCC gives 'A'. 'A' on reaction with sodium hypoiodite gives 'B', which on further heating with soda lime gives 'C'. Calculate the total number of carbon atoms present in the final product 'C'.", "ans": "4", "exp": "Oxidation of hex-4-ene-2-ol with PCC gives hex-4-ene-2-one (A). Reaction with sodium hypoiodite (iodoform reaction) cleaves the methyl ketone group to give the sodium salt of pent-3-enoic acid (B). Heating with soda lime ($\text{NaOH} + \text{CaO}$) causes decarboxylation, removing the carboxyl carbon to leave but-2-ene (C), which has 4 carbon atoms." }, { "type": "integer", "q": "The conversion of propan-1-ol to n-butylamine involves a sequential addition of reagents. Calculate the option number from the following configurations that accurately specifies this synthesis pathway:\n(1) (i) $SOCl_2$ (ii) KCN (iii) $H_2/Ni$\n(2) (i) HCl (ii) $H_2/Ni$\n(3) (i) $SOCl_2$ (ii) KCN (iii) $CH_3NH_2$\n(4) (i) HCl (ii) $CH_3NH_2$", "ans": "1", "exp": "Propan-1-ol reacts with $SOCl_2$ to give 1-chloropropane. Nucleophilic substitution with KCN extends the carbon chain by one to form butanenitrile. Reduction of the nitrile using $H_2/Ni$ yields n-butylamine, which aligns perfectly with pathway (1)." }, { "type": "integer", "q": "The difference in the reaction of phenol with bromine in chloroform and bromine in water medium is due to solvent characteristics. Identify the correct integer choice indexing the statement: (1) Hyperconjugation, (2) Polarity of solvent, (3) Free radical formation, (4) Electromeric effect.", "ans": "2", "exp": "The difference arises due to the polarity of the solvent. Water is a highly polar solvent that facilitates the ionization of phenol into the highly reactive phenoxide ion, leading to trisubstitution. Chloroform is non-polar, keeping phenol un-ionized and yielding mono-brominated products." }, { "type": "integer", "q": "Find out the option index pointing to the major products from the hydroboration-oxidation vs oxymercuration-demercuration steps on the given branched alkene system. Enter the option value showing true matching product pairs.", "ans": "1", "exp": "Oxymercuration-demercuration yields Markovnikov addition of water without rearrangement, whereas hydroboration-oxidation gives anti-Markovnikov addition, leading to option (1) being correct." }, { "type": "integer", "q": "Given below are two statements: \nAssertion A: Acetal/Ketal is stable in basic medium. \nReason R: The high leaving tendency of alkoxide ion gives stability to acetal/ketal in basic medium.\nFind the correct option index evaluating these behaviors.", "ans": "1", "exp": "Acetals and ketals are highly stable in basic media because alkoxide ions are poor leaving groups in basic conditions, preventing nucleophilic substitution from occurring, making option (1) true." }, { "type": "integer", "q": "In the industrial cumene to phenol preparation in the presence of air, an essential peroxyl intermediate is formed. Determine the total number of oxygen atoms present in one molecule of this cumene hydroperoxide intermediate.", "ans": "2", "exp": "The intermediate formed is cumene hydroperoxide, which features a single peroxide bond ($-\text{O}-\text{O}-\text{H}$) containing exactly 2 oxygen atoms." }, { "type": "integer", "q": "The number of chiral alcohol(s) with molecular formula $C*{4}H*{10}O$ is:", "ans": "1", "exp": "The isomers of $C_4H*{10}O$ are butan-1-ol, butan-2-ol, 2-methylpropan-1-ol, and 2-methylpropan-2-ol. Out of these, only butan-2-ol contains a chiral carbon atom (attached to $-\text{H}$, $-\text{OH}$, $-\text{CH}_3$, and $-\text{CH}_2\text{CH}_3$ groups), meaning there is exactly 1 chiral alcohol." } ]