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Term-!, , ALCOHOLS,, , CHAPTER, , PHENOLS AND ETHERS, , , , > Alcohols: Nomenclature, methods of preparation, physical and chemical properties (of primary alcohols, only), identification of primary, secondary and tertiary alcohols, mechanism of dehydration., , > Phenols: Nomenclature, methods of preparation, physical and chemical properties, acidic nature of, phenol, electrophillic substitution reactions, uses of phenols., , > Ethers: Nomenclature, methods of preparation, physical and chemical properties, uses, , STAND ALONE MCQs [1 Mark each], , , , , , Q.1. How many alcohols with molecular formula, , C,H,,0 are chiral in nature? Explanation: In o-nitrophenol, nitro group is, {A)1 (B) 2 present at ortho position. Presence of electron, 3 (D)4 withdrawing group at ortho position increases, , the acidic strength. On the other hand, in, , Aas: Option (S)is corrects o-methylphenol and in o-methoxyphenol, , Explanation: electron releasing group (~CH, or -OCH,), at, CHg — CH; — fe CHg ortho or para positions of phenol decreases the, ba acidic strength of phenols. So, phenol is less, , acidic than o-nitrophenol., , lane 24's ltr inmiaftinerad if possesses elite Q.4. Which of the following species can act as the, , cena strongest base?, Q. 2. IUPAC name of m-cresol is § (A) °OH, , (A) 3-methylphenol (B) 3-chlorophenol (B) COR, , (C) 3:methoxyphenol —_(D) benzene-1,3-diol ce) oct, Ans. Option (A) is correct. ©) a8, , Explanation: (0) °o, , CH,, No,, Ans. Option (B) is correct., , OE, Explanation: Weakest acid has the strongest, , (i) -OH is functional group and -CH, is conjugate base. Since R-OH is the weakest acid,, substituent. therefore, °OR is the strongest base., (ii) TUPAC name : 3-methylphenol. Q.5. Which of the following compounds will react with, Q.3. Phenol is less acidic than . sodium hydroxide solution in water?, (A) ethanol (B) o-nitrophenol (A) C,H,OH (B) CjH;CH,OH, (C) o-methylphenel —_(D) o-methoxyphenol () (CH),COH (0) C,H,OH, Ans. Option (B) is correct. é ae

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Ans. Option (C) is correct., Explanation: Phenol being more acidic reacts, with sodium hydroxide solution in water to give, sodium phenoxide which is resonance stabilized., Alcohols are very weak acids., C,H,OH + NaOH > C,H,ONa+H,O, , 6. Which of the following compounds is aromatic, , alcohol?, , 1 oH a ‘u a", , @) @) Oo He, (A) A,B,C, D (B) A,D, (©) B,C (D) A, , Ans. Option (C) is correct., , Explanation: Compound (A) ie, phenol and, compound (D), that is, a derivative of phenol, cannot be considered as aromatic alcohol. As, phenol is also known as carbolic acid and cannot, be considered as aromatic alcohol. Compound (B), and (C) -OH group is bonded to Sp* hybridized, carbon which in turn is bonded to benzene ring., . Give IUPAC name of the compound given below., CH, - CH—-CH, - CH, - CH-CH,, & bn, (A) 2-Chloro-5-hydroxyhexane, (B) 2-Hydroxy-5-chlorohexane, (©) 5-Chlorohexan-2-ol, (D) 2-Chlorohexan-5-ol, Ans. Option (C) is correct., , , , , , Explanation:, én, -én- ¢n,-¢n, -CH-¢n,, | |, al OH, , S-chlorehexan-2-ol, , . Arrange the following compounds in increasing, order of boiling point. :, Propan-1-ol, butan-1-ol, butan-2-ol, pentan-1-ol, (A) Propan-1-ol, butan-2-ol, butan-l-ol, pentan-1ol, (B) Propan-1-ol, butan-I-ol, butan-2-ol, pentan-1ol, (C) Pentan-1-ol, butan-2-ol, butan-1-ol, propan-1ol, (D) Pentan-1-ol, butan-{-ol, butan-2-ol, propan-1ol, Ans. Option (A) is correct., , Explanation: Boiling point increases with increase, in molecular mass of the alcohols. Among, isomeric alcohols 1° alcohols have higher boiling, point than 2° alcohols. Thus, correct order is :, Propan-l-ol < Butan-2-ol < Bulan-l-ol <, pentan-1-ol, , Q.9. Which of the following species can act as the, strongest base?, , (A)-OH (B) -OR, , (C) -OCH; (D)-0, , ‘NO,, u, Ans. Option (B) is correct., Explanation: Weakest acid has the strongest, conjugate base. Since R-OH is the weakest acid,, therefore, -OR is the strongest base., Q. 10. The IUPAC name of anisole is, (A) 2-methyltoluene, (B) Methyl phenyl ether, (C) Methoxybenzene, (D) Fthoxybenzene uU, Ans. Option (C) is correct., Explanation: CH,OCH,, TUPAC name: Methoxybenzene, Q. 11. Williamson synthesis is used to obtain, (A) Primary alcohol (B) Ether, (C) Aldehyde (D) Ketone IR, Ans. Option (B) is correct., Explanation: Williamson synthcsit, obtain ether. For example,, R-X+Na-O-R—>R-O-R' + Nax, , Alkyl Sodium alkoxide Bther, halide, , is used to, , , , Q.12. Write the TUPAC name of the following compounds, CH,, —CH,, ir, CH,, (A) 2-Methoxy-isopropane, (B) 2-Methyl-2-methoxypropane, (C) 2-Methoxy-2-methylpropane, (D) 2-Methoxy-2,2 -dimethyl ethane, , Ans. Option (C) is correct,, , CH; —O—, , Explanation: 2-Methoxy-2-methylpropane., Longest carbon chain is taken as the parent, alkane in the IUPAC nomenclature., , Q.13. IUPAC name for the given compound is, , CH, - CH-O-CH, -CH,-CH,, , 3, (A) 2-ethoxy-2-methylethane., (B) 2-propoxypropane., (C) 2-methyl-2-ethoxypropane, (D) None of the above, , Ans. Option (B) is correct.

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| Explanation: IUPAC name of the compound is, 2-propoxypropane., Q. 14. Bond angle in ethers is slighUy less than, , (A) Square planar angle, , (B) Trigonal bipyramidal angle, , (C) ‘etrahedral angle, , (D) None of the above, Ans. Option (C) is correct., , Explanation: Bond angle in ether is slightly more, than the tetrahedral angle due to repulsion, between the two bulky alkyl groups., , @) ASSERTION AND REASON BASED MCQs, , , , Directions: In the following questions, A statement, of Assertion (A) is followed by a statement of, Reason (R). Mark the correct choice as., , (A) Both Aand Rare true and Ris the correct explanation, ofA, , (B) Both A and R are true but R is NOT the correct, explanation of A, , (©) Ais true but R is false, , (D) Ais false and Ris True, , Q.1. Assertion (A): Ortho and para-nitrophenol can be, separated by steam distillation., Reason (R): Ortho isomer associates through, intermolecular hydrogen bonding while para, isomer associates through intermolecular hydrogen, bonding, [UICBSE Delhi Set-It 2020], Ans. Option (C) is correct., , Explanation: Ortho isomer has intermolecular, H-bonding while para isomer has intermolecular, hydrogen bonding,, Q.2. Assertion (A): (CH,),C—O-CH, gives (CH,),C-I, and CI,OH on treatment with HI., Reason (R): The reaction occurs by S,,1 mechanism., [CBSE O.D. Set-I 2020], Ans. Option (A) is correct., Explanation: (CH,);C-O-CHy, gives (CH);C-I, and CH,OH on treatment with HI. The reaction, occurs by S,,1 mechanism., , Q. 3. Assertion (A): Carboxylic acids are more acidic than, phenols., Reason (R): Phenols are ortho and para directing., , (A&E] [CBSE SQP 2021], Ans. Option (B) is correct., , Explanation: Carboxylic acids are more acidic, than phenols as the carboxylate ion, the, conjugate base of carboxylic acid is stabilized, by two equivalent resonance structures. Thus,, the negative charge is delocalized effectively., However, in phenols, negative charge is less, effectively delocalized over oxygen atom and, carbon atoms in phenoxide ion., , Q.15. IUPAC name of the compound. CH, —CH—OCH,, |, CH., , oe _, 7, (A) I-methoxy-1-methylethane, , (B) 2-methoxy-2-methylethane, , (C) 2-methoxypropane, , (D) isopropylmethyl ether, , Ans. Option (C) is correct., , , , 7 et, fcc Oc,, , , , Explanation:, , , , , , [1 Mark each], oO o °, é — 4 = ¢Ko Kx‘ Ko, , Q.4. Assertion (A): Ethers behave as bases in the, presence of mineral acids., Reason (R) : In ethers, oxygen consists of lone pair, of electrons, U, Ans. Option (A) is correct., , Explanation: Ethers behave as bases in the, presence of mineral acids like HCl due to, presence of lone pair of electrons on oxygen, atom and form stable oxonium salts with, mineral acids., , oe + =, , GH,-G-C,H, + HCIL— C,H,-O-GH, Cl, , Diethyl ether, , Q.5. Assertion (A) : The C-O-C bond angle in ethers is, slightly less than tetrahedral angle., , Reason (R): Due to the repulsive interaction, between the two alkyl groups in ethers., , (| [CBSE Delhi Set-I 2020], , Diethyl exonium chloride, , Ans. Option (D) is correct., , Explanation: The C-O-C bond angle in ether is, slightly greater than tetrahedral angle. It is due, to the repulsive interaction between the two, alkyl groups in ethers., Q. 6. Assertion (A): Methoxy ethane reacts with HI to, give ethanol and iodomethane., Reason (R): Reaction of ether with II follows S,2, (A&E [CBSE SQP 2021], , mechanism., , Ans. Option (A) is correct., Explanation: Methoxy ethane reacts with HI to, give ethanol and iodomethane. Reaction of ether, with HI follows Sy2 mechanism.

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CASE-BASED MCQs, , , , I. Read the passage given below and answer the, following questions :, Alcoholsare versatile compounds. They act both as, nucleophiles and electrophiles. he bond between, O-H is broken when alcohols act as nucleophiles., , (i) Alcohols as nucleophiles, , H, we se Id, R—-G—H+C——+R—Q—C——>, , R-0—¢—+H!, , (ii) The bond between C-O is broken when they, act as, electrophiles. Protonated alcohols react, in this manner., , Protonated alcohols as electrophiles, R-CH,-OH+H-R-CH,+OH,, Based on the cleavage of O-H and C-O bonds, the, reaction of alcohols and phenols may be divided, into two groups :, (a) Reactions involving cleavage of O-H bond, (b) Reactions involving cleavage of C-O bond, Acidity of alcohols and phenols, (i) Reaction with metals Alcohols and phenols react, with active metals such as sodium, potassium, and aluminium to yield corresponding alkoxide/, phenoxides and hydrogen., , 2R-O-H + 2Na-— 2R-O-Na + H,, Sodium., Alkoxide, , Q.1. Write down the decreasing order of reactivity of, sodium metal towards primary, secondary and, tertiary alcohols., , (A) 1ale<2°ale<3%ale, (©) ale<1°ale<2°ale, , (B) Lalc>2°ale>3%ale, (D) 3%alc>Pale < 2°alc®, , , , Ans. Option (B) is correct., , Explanation: Na metal is basic and alcohols are, acidic in nature. Hence, reactivity of Na metal, towards alcohols decreases as the acidic strength, of alcohols decreases due to steric hinderance, of alkyl groups in tertiary alcohol and increase, in electron density on an oxygen atom in the, hydroxyl bond., , , , Q.2. Name the following reaction:, , OH ONa OH, CHCI,+aqNa0H CHO Ht cEO,, 30K, Phenol Sodium salt of Sallcylaldehyde, Salcylaldehyde, (A) Williamson’s synthesis, , (B) Kolbe’s reaction, (C) Reimer-Tiemann reaction, (D) Sandmeyer’s reaction, Ans. Option (C) is correct., , Q.3. Given the descending order of acid strength of, alcohols., (A) RCH,OH > RR’CHOH >> RR’R’COH, (B) RCH,OH > RR'R’COH > RR’'CHOH, (C) RCILOM ~< RR'CIOI << RRR’COIL, (D) RCH,OH < RR'R"COH < RR’'CHOH, Ans. Option (A) is correct., , Explanation: The more stable the alkoxide ion,, the more acidic is the alcohol. Electron releasing, effect (+1 effect ) of alkyl group in secondary, and tertiary alcohols makes the alkoxide ion less, stable., , Q. 4. Write the IUPAC name of the following compound:, 1CH, 3, , 3C—OH, or 3CH,, (A) 2-methyl, 2-phenyl ethanol, , (B) 2-phenyl butanol, (C) 2-Phenylopropan-2-ol, , [A&E, , (D) 1-methyl, 1-phenyl ethanol (Al, Ans. Option (C) is correct., Explanation:, 1CH,, , 2 — OH, Cr 3CH,, TUPAC name = 2-Phenylpropan-2-ol, Tl. Read the passage given below and answer the, following questions:, Oxidation of alcohols involves the formation of a, carbon-oxygen double bond with cleavage of an, O-H and C-H bonds., H,C-O;H —=C=0, Bond breaking, Such a cleavage and formation of bonds occur, in oxidation reactions. These are also known as, dehydrogenation reactions as these involve loss of, dihydrogen from an alcohol molecule. Depending, on the oxidising, agent used, a primary alcohol is

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oxidised to an aldehyde which in turn is oxidised to, , a carboxylic acid., , Strong oxidising agents such as acidified potassium, , permanganate are used for getting carboxylic acids, , from alcohols directly. CrO, in anhydrous medium, is used as the oxidising agent for the isolation of, aldehydes., , In these questions a statement of assertion followed, , bya statement of reason is given. Choose the correct, , answer oul of the following choices., , (A) Assertion and reason both are correct, statements and reason is correct explanation, for assertion., , (B) Assertion, statements but reason is not correct explanation, for assertion., , (C) Assertion is correct statement but reason is, wrong statement., , (D) Assertion is wrong statement but reason is, correct statement, , Q. 1. Assertion (A): Dehydrogenation, alcohols is an oxidising reaction., Reason (R): It involves loss of dihydrogen from, alcohol., , . Option (A) is correct., , and reason both are correct, , reaction of, , An, , B, , ra Dehydrogenation means loss al, , dihydrogen from a molecule., , Q.2. Assertion (A): CH,CH,OH can be converted, into CH,CHO by treatment with pyridinium, , chlorochromate., Reason (R): PCC is a better reagent for oxidation of, primary alcohols to aldehydes. [Al, , An:, , B, , . Option (A) is correct,, Explanation: PCC (Pyridinium chlorochromate), , is a better reagent for converting ethyl alcohol, into acetaldehyde., Q.3. Assertion (A): Tertiary alcohols do not undergo, oxidation reactions., , Reason (R): They do not have the required C-H, bond. il, , Ans. Option (A) is correct., , Explanation: Tertiary alcohols do not undergo, oxidation reactions because the carbon atom that, carries the -OH group does not have a hydrogen, atom., , Q.4. Assertion (A): Vapours of primary and secondary, alcohols are passed through heated copper an, aldehyde and ketone are formed., , Reason (R): It’s a dehydration reaction IRI, , Ans. Option (C) is correct., , Explanation: Vapours of primary and secondary, alcohols are passed through heated copper, an aldehyde and ketone are formed. It's a, dehydrogenation reaction., , IIL Read the passage given below and answer the, following questions:, The reaction of phenol with aqueous sodium, hydroxide indicates that phenols are stronger, acids than alcohols and water. Due to the higher, electronegativity of sp* hybridised carbon of, phenol to which -OH is attached, electron density, decreases on oxygen. ‘This increases the polarity of, O-T bond and resulls in an increase in ionisation of, phenols than that of alcohols. Now let us examine, the stabilities of alkoxide and phenoxide ions., In alkoxide ion, the negative charge is localised, on oxygen while in phenoxide ion, the charge is, delocalised. The delocalisation of negative charge, makes phenoxide ion more stable and favours the, ionisation of phenol., , Q.1. Phenol is less acidic than___, (A) ethanol (B) o-nitrophenol, (C) o-methylphenol (D) o-methoxy phenol, ul, , Ans. Option (B) is correct., , Explanation: Phenol is less acidic than, o-nitrophenol as electron withdrawing (—NO,), group increases the acidity of phenols., , Q. 2. Which of the following is most acidic?, (A) Benzyl alcohol (B) Cyclohexanol, (©) Phenol (D) m-Chlorophenol, (A&E, Ans. Option (D) is correct., , Explanation: m-chlorophenol is most acidic as, electron withdrawing (—Cl )group increases the, acidity of phenols., Q.3. Mark the correct order of decreasing acid strength, of the following compounds., , OH OH OH, NO,, , (a) (b) ©, OH OH, NO,, OCH,, (4) (), , (Aje>d>b>a>c, (B)b>d>a>c>e, (Qd>e>c>b>a, (Dje>d>c>b>a, Ans. Option (B) is correct., , (A&E)