Question 1

The major product of which of the following reaction is not obtained by rearrangement reaction?

Accepted Answer

In option (A), the Friedel-Crafts alkylation of benzene with 1-chloropropane involves the formation of a primary carbocation, CH_3CH_2CH_2^+. This undergoes a 1,2-hydride shift to form a more stable secondary carbocation, CH_3CH^+CH_3, which then attacks the benzene ring to yield cumene. Thus, rearrangement occurs. In option (B), the acid-catalyzed dehydration of tert-butyl alcohol proceeds via the formation of a tert-butyl carbocation, (CH_3)_3C^+. Since it is already a highly stable tertiary c

Question 2

Consider the following reaction. Statement I : In the above reaction, product formed will be a mixture of benzyl alcohol and iodobenzene. Statement II : In the above reaction, the - O - CH _2- bond is

Accepted Answer

The given reactant is phenyl benzyl ether (C_6H_5-O-CH_2-C_6H_5). When it reacts with HI, the ether oxygen is first protonated to form an oxonium ion. The cleavage of the ether linkage then takes place. The C_6H_5-O bond has partial double bond character due to the resonance of the oxygen's lone pair with the benzene ring, making it strong and difficult to break. On the other hand, the O-CH_2 bond is a weaker single bond. Moreover, cleavage of the O-CH_2 bond can proceed via a highly stable benz

Question 3

Consider the following sequence of reactions The major product P is:

Accepted Answer

Step 1: The first reagent is Cu at 573 K . When a tertiary alcohol like tert-butyl alcohol is passed over heated copper at 573 K , it undergoes dehydration rather than dehydrogenation to form an alkene. (CH_3)_3C-OH Cu / 573 K CH_2=C(CH_3)_2 + H_2O The intermediate product is isobutylene (2-methylpropene). Step 2: The second set of reagents is H^+ and PhCOOH (benzoic acid). This is an acid-catalyzed addition of a carboxylic acid to an alkene, which is a standard method for synthesizing tert-buty

Question 4

Arrange the following compounds according to increasing order of boiling points. n - C _4 H _9 OH (A), n - C _4 H _9 NH _2 (B), n - C _4 H _ 10 (C) and C _2 H _5 NHC _2 H _5 (D).

Accepted Answer

Boiling point depends on the strength of intermolecular forces. n -C _4 H _ 10 (C) is a nonpolar alkane with only weak van der Waals forces, resulting in the lowest boiling point. n -C _4 H _9 OH (A) is an alcohol that forms strong intermolecular hydrogen bonds due to the high electronegativity of oxygen, giving it the highest boiling point. Both n -C _4 H _9 NH _2 (B) and C _2 H _5 NHC _2 H _5 (D) are amines and form hydrogen bonds, which are weaker than those in alcohols because nitrogen is le

Question 5

4.7 g of phenol is heated with Zn to give product X. If this reaction goes to 60\% completion then the number of moles of compound X formed will be _______ 10^ -2 . (Nearest Integer) (Given molar mass

Accepted Answer

The chemical reaction of phenol with zinc dust is given by: C_6H_5OH + Zn C_6H_6 + ZnO Product X is benzene (C_6H_6). Molar mass of phenol (C_6H_5OH) = 6 12 + 6 1 + 16 = 94 g mol^ -1 Number of moles of phenol taken = 4.7 94 = 0.05 mol From the stoichiometry of the reaction, 1 mole of phenol produces 1 mole of benzene. Theoretical moles of X formed = 0.05 mol Since the reaction goes to 60\% completion, the actual moles of X formed is: 0.05 60 100 = 0.03 mol This can be written as 3 10^ -2 mol. An

Question 6

Consider compounds A, B and C with following structural formulae A = CH_3 - CH_2 - CH_2 - CH_2 - CH_2 - OH B = CH_2 = CH - CH_2 - CH_2 - CH_3 C = HO - CH_2 - CH_2 - CH(OH) - CH_3 For the conversion of

Accepted Answer

Compound A is pentan-1-ol (CH_3-CH_2-CH_2-CH_2-CH_2-OH) and Compound B is pent-1-ene (CH_2=CH-CH_2-CH_2-CH_3). The conversion of an alcohol to an alkene is a dehydration reaction, which requires an acidic dehydrating agent such as concentrated H_2SO_4 or H_3PO_4. Thus, reagent D is concentrated H_2SO_4 or H_3PO_4. Compound C is butane-1,3-diol (HO-CH_2-CH_2-CH(OH)-CH_3). When C is treated with excess dehydrating agent (reagent D), both hydroxyl groups undergo elimination (dehydration). The elimi

Question 7

One mole of phenol is treated with dilute HNO_3 at 298 K to give a mixture of products. The mixture is separated by steam distillation. The steam volatile compound (X) is separated. The increase in pe

Accepted Answer

When phenol is treated with dilute HNO _3 at 298 K , it undergoes electrophilic aromatic substitution to give a mixture of ortho-nitrophenol and para-nitrophenol. The mixture is separated by steam distillation. Ortho-nitrophenol is steam volatile due to intramolecular hydrogen bonding, whereas para-nitrophenol is not steam volatile due to intermolecular hydrogen bonding. Thus, the steam volatile compound (X) is ortho-nitrophenol. Molecular formula of phenol: C _6 H _6 O Molar mass of phenol = (6

Question 8

Match the LIST-I with LIST-II List-I (Compound) List-II (Test) A. Cyclohexanol I. Hinsberg's reagent test B. Cyclohexylamine II. Phthalein dye test C. Cyclohexanecarbaldehyde III. Lucas test D. Phenol

Accepted Answer

Cyclohexanol is a secondary alcohol, which gives a positive Lucas test. Cyclohexylamine is a primary aliphatic amine, which reacts with Hinsberg's reagent (benzenesulfonyl chloride) to form a product soluble in alkali. Cyclohexanecarbaldehyde is an aliphatic aldehyde, which gives a positive Tollen's test (silver mirror test). Phenol undergoes the phthalein dye test by reacting with phthalic anhydride in the presence of concentrated sulfuric acid to form phenolphthalein, which gives a pink colour

Question 9

Amongst the following, the total number of compounds soluble in aqueous NaOH at room temperature is:

Accepted Answer

To determine which compounds are soluble in aqueous NaOH, we need to identify the compounds that are sufficiently acidic to react with NaOH (a strong base) to form water-soluble sodium salts. Generally, carboxylic acids and phenols are acidic enough to dissolve in aqueous NaOH, whereas alcohols, aldehydes, amines, and hydrocarbons are not. Let us analyze each compound: (I) Benzaldehyde: It is an aldehyde. It does not have an acidic proton and is insoluble in aqueous NaOH. (II) 1-Naphthol: It is

Question 10

Identify the colour of compound 'X' in the sequence of the reaction.

Accepted Answer

The given reaction sequence represents the synthesis and acid-base behaviour of phenolphthalein. When phenol reacts with phthalic anhydride in the presence of concentrated H_2SO_4, phenolphthalein is formed. In acidic or neutral medium, phenolphthalein exists in a lactone form which is colourless. Upon addition of a moderate amount of alkali (NaOH), the lactone ring opens and a proton is removed, forming a dianion with an extended conjugated quinonoid structure. This extended conjugation is resp

Question 11

A molecule (X) with following structure under mild acidic condition is hydrolysed to produce (Y) and (Z). Identify the correct statements about (Y) and (Z). A. Both (Y) and (Z) have same molar mass. B

Accepted Answer

Molecule (X) is an ether with two enol ether functional groups attached to the central oxygen atom. On mild acidic hydrolysis, an enol ether cleaves to give a carbonyl compound and an alcohol. The 1-propenyl side (CH_3-CH=CH-O-) hydrolyses to propanal, CH_3CH_2CHO. The isopropenyl side (-O-C(CH_3)=CH_2) hydrolyses to the enol of acetone, which tautomerises to acetone, CH_3COCH_3. Therefore, (Y) and (Z) are propanal and acetone. Statement A: Both (Y) and (Z) have the same molar mass. Propanal and

Question 12

The reactions which produce alcohol as the product are: A. CH _ 4 + O _ 2 [ ] Mo _ 2 O _ 3 B. 2 CH _ 3 CH _ 3 +3 O _ 2 [ ] ( CH _ 3 COO )_ 2 Mn C. ( CH _ 3 )_ 3 CH KMnO _ 4 D. 2 CH _ 4 + O _ 2 Cu / 52

Accepted Answer

Analyzing each reaction for alcohol production: Reaction A: CH_4 + O_2 Mo_2O_3, produces formaldehyde, not alcohol. Reaction B: 2CH_3CH_3 + 3O_2 (CH_3COO)_2Mn, produces acetic acid, not alcohol. Reaction C: (CH_3)_3CH KMnO_4 tert-butyl compound undergoes oxidation to produce tert-butyl alcohol as the primary product. Reaction D: 2CH_4 + O_2 Cu/523K/100atm produces methanol (CH₃OH), a primary alcohol. Reaction E: The diene compound with KMnO_4/H^+ produces vicinal diol, which is technically an al

Question 13

From the following, how many compounds contain at least one secondary alcohol? Choose the correct answer from the options given below:

Accepted Answer

A secondary alcohol has the OH group on a carbon bonded to exactly two other carbon atoms. Analyzing each structure: I contains only primary alcohols and carboxylic acid. II has OH on a carbon bonded to two other carbons (secondary alcohol). III has tertiary and primary alcohols only. IV has secondary alcohols on the cyclopentanone ring. V has OH on a secondary carbon (between two CH groups). VI has the central carbon as tertiary with three OH groups. Compounds II, IV, and V contain at least one

Question 14

The unsaturated ether on acidic hydrolysis produces carbonyl compounds as shown below:- aligned CH _ 3 - CH = CH - & O - CH = CH _ 2 \ & H _ 3 O ^ (+) \ CH _ 3 - CH _ 2 - CH = & O and O = CH - CH _

Accepted Answer

Acidic hydrolysis of vinyl ethers involves the addition of water across the double bond followed by the elimination of alcohol/phenol to form carbonyl compounds. In the given reaction: CH_3-CH=CH-O-C(CH_3)=CH_2 H_3O^+ P + Q The hydrolysis occurs at both vinyl ether linkages. The left part CH_3-CH=CH-O- hydrolyzes to form propanal: CH_3-CH_2-CHO (P). The right part -O-C(CH_3)=CH_2 hydrolyzes to form acetone: CH_3-CO-CH_3 (Q). P is an aldehyde (propanal) and Q is a ketone (acetone). Fehling soluti

Question 15

A hydroxy compound ( X ) with molar mass 122 ~g ~mol ^ -1 is acetylated with acetic anhydride, using a large excess of the reagent ensuring complete acetylation of all hydroxyl groups. The product obt

Accepted Answer

In acetylation, each hydroxyl group reacts: R-OH + (CH₃CO)₂O → R-O-CO-CH₃ + CH₃COOH. Each -OH is converted to -OCOCH₃, resulting in a net mass increase of 42 g/mol per hydroxyl group (addition of acetyl group mass 43, removal of hydrogen mass 1). Given: Original molar mass = 122 g/mol, Product molar mass = 290 g/mol Total mass increase = 290 - 122 = 168 g/mol Number of hydroxyl groups = 168 ÷ 42 = 4

Question 16

Consider the following two reactions A and B. Numerical value of [molar mass of x+ molar mass of y] is \_\_\_\_.

Accepted Answer

Reaction A: Phenol reacts with metallic sodium to produce sodium phenoxide and hydrogen gas. C₆H₅OH + Na → C₆H₅ONa + ½H₂. The gas evolved is x = H₂ with molar mass 2 g/mol. Reaction B: Benzoic acid reacts with sodium bicarbonate to produce sodium benzoate, water, and carbon dioxide. C₆H₅COOH + NaHCO₃ → C₆H₅COONa + H₂O + CO₂. The gas evolved is y = CO₂ with molar mass 44 g/mol. Therefore, molar mass of x + molar mass of y = 2 + 44 = 46.

Question 17

A mixed ether ( P ), when heated with excess of hot concentrated hydrogen iodide produces two different alkyl iodides which when treated with aq. NaOH give compounds ( Q ) and ( R ). Both ( Q ) and (

Accepted Answer

The mixed ether (P) upon heating with conc. HI undergoes cleavage to form two different alkyl iodides. Treatment with aq. NaOH converts these iodides to alcohols (Q) and (R). Both (Q) and (R) giving yellow precipitate with NaOI indicates both are secondary or primary alcohols capable of iodoform reaction. For both cleavage products to yield iodoform-positive alcohols, the mixed ether must have both alkyl groups capable of forming such alcohols. Option (1) represents a symmetric mixed ether where

Question 18

The correct sequence of reagents for the above conversion of X to Y is :

Accepted Answer

The transformation of (X) benzene with Br and CH₃ substituents to (Y) benzene with CH₂COOH requires: First, NaOEt causes elimination of HBr to form an alkene intermediate. Second, B₂H₆/H₂O₂ performs hydroboration-oxidation, adding hydroxyl group in anti-Markovnikov fashion to yield a primary alcohol. Third, Jones reagent oxidizes the primary alcohol to carboxylic acid. The sequence NaOEt → B₂H₆/H₂O₂ → Jones reagent produces the desired carboxylic acid product.

Question 19

Match List - I with List - II. array l List - I & List - II \ Functional group (detection) & Change observed during detection \ A. Unsaturation (Baeyer's test) & I. Red colour appears \ B. Alcoholi

Accepted Answer

Unsaturation (Baeyer's test) involves decolorization of the reagent, represented by discharge of color (IV). Alcoholic groups (Ceric ammonium nitrate test) produce a red color (I). Aldehyde groups (Tollen's reagent) produce a characteristic silver mirror effect (II). Phenolic groups (FeCl₃ test) produce a violet or pink color (III). The correct matching is A-IV, B-I, C-II, D-III.

Question 20

Given below are two statements: Statement I : Phenol on treatment with CHCl _ 3 /aq. KOH under refluxing condition, followed by acidification produces p-hydroxy benzaldehyde as the major product and o

Accepted Answer

Statement I: The reaction of phenol with CHCl_3 and aqueous KOH is the Reimer-Tiemann reaction. In this reaction, the major product is o-hydroxybenzaldehyde (salicylaldehyde) due to the formation of a stable six-membered chelate ring via intramolecular hydrogen bonding. p-hydroxybenzaldehyde is formed as the minor product. Thus, Statement I is false. Statement II: o-hydroxybenzaldehyde (salicylaldehyde) has intramolecular hydrogen bonding, making it more volatile (steam volatile). p-hydroxybenza

Alcohols Phenols and Ethers — Previous Year Questions & Solutions