Alcohols are easily protonated than phenols. Justify.

Alcohols are easily protonated than phenols. Justify.
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Ans. In phenols lone pair of electrons on the oxygen atom are delocalised over the benzene ring due to resonance and hence are not easily available for protonation. In contrast in alcohols, the lone pairs of electrons on the oxygen atom are localized due to absence of resonance and hence are easily available for protonation. 
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Phenol has smaller dipole moment than methanol. (OR) Why are dipole moments of phenols smaller than dipole moments of alcohols ?

Description : Phenol has smaller dipole moment than methanol. (OR) Why are dipole moments of phenols smaller than dipole moments of alcohols ?

Last Answer : Due to electron-withdrawing effect of the benzene ring, the C — O bond in phenol is less polar but in case of methanol due to electron-donating effect of — CH3 group, C — O bond is more polar.

Phenols do not undergo substitution of the — OH group like alcohols. Explain.

Description : Phenols do not undergo substitution of the — OH group like alcohols. Explain.

Last Answer : The C — O bond in phenols has some double bond character due to resonance and hence cannot be easily cleaved by a nucleophile. In contrast, the C — O bond in alcohols is a pure single bond and hence can be easily cleaved by a nucleo phile.

While separating a mixture of ortho and para-nitro phenols by steam distillation, name the isomer which will be steam volatile. Give reasons.

Description : While separating a mixture of ortho and para-nitro phenols by steam distillation, name the isomer which will be steam volatile. Give reasons.

Last Answer : In o-nitrophenol, there is intramolecular hydrogen bonding as follows : In p-nitrophenol, there is intramolecular hydrogen bonding as follows :   Due to intermolecular H ... -nitrophenol. Hence o-nitraphenol due to its lower b. p. is steam volatile while pnitrophenol is not.

Why is it that secondary alcohols can only undergo a single oxidation step in contrast to primary alcohols?

Description : Why is it that secondary alcohols can only undergo a single oxidation step in contrast to primary alcohols?

Last Answer : 1. Once the oxidation has reached the ketone stage, (primary alcohols on oxidation yield aldehyde where as secondary alcohols on oxidation yield a ketone), it is impossible to put more oxygen atoms on the relevant carbon atom without rupturing the backbone of the molecule.

Alcohols acts as weak bases. Explain.

Description : Alcohols acts as weak bases. Explain.

Last Answer : The oxygen atom of the hydroxyl group has two lone pairs of electrons. Therefore alcohols accept a proton from strong mineral acid to form oxonium ions. Hence act as weak bases.

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Description : Ortho and paranitrophenols are more acidic than phanel. Draw the resonance structures of the corresponding phonoxide ion.

Last Answer : Ans:- Electronwithdrawal by nitro group makes the plenoxide ion more resonance stabilized and so the strength of phenel increases.

Why phenol is acidic ?

Description : Why phenol is acidic ?

Last Answer :  Ans: In phenol dissociation takes place as follows.   The conjugate base of phenol ie. Phenoxide ion is resonance stabilized. This is why the negative charge on oxygen atom is ... ion has less tendency to form undissociated phenol molecule and equilibrium lies towards right direction.  

Ethers are cleaved by acids not by based. Why ?

Description : Ethers are cleaved by acids not by based. Why ? 

Last Answer : The C - O - C bond in ethers like the C - OH bond in alcohols is quite strong. In order to weaken it, the oxygen atom must be protonated. A subsequent nucleophile attack by a strong ... protonation of O atom of ether and therefore only acids can bring about the cleavage of ethers and not bases.

How an — OH group attached to carbon in the benzene ring activates benzene towards electrophilic substitution ?

Description : How an — OH group attached to carbon in the benzene ring activates benzene towards electrophilic substitution ?

Last Answer : The lone pair of electrons present on oxygen atom enter into resonance with the benzene ring. As a result, the electron density becomes higher at o- and p- position and due to higher electron density, the ring gets activated towards electrophilic substitution.

Di-tert butyl ether cannot be made by Williamson’s synthesis. Explain why ?

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Why are Grignard reagents soluble in ether but not in benzene ?

Description : Why are Grignard reagents soluble in ether but not in benzene ? 

Last Answer : Ans. Grignard reagents from co-ordination complexes with ether but not benzene since the former has lone pair of electrons but the later does not.

Name the products obtained when anisole is treated with HI.

Description : Name the products obtained when anisole is treated with HI.

Last Answer : Ans. Phenol and methyl iodide. 

What is usually added to ethyl alcohol to make it unfit for drinking purposes ?

Description : What is usually added to ethyl alcohol to make it unfit for drinking purposes ?

Last Answer : Ans. Methanol and Pyridine. 

What is the main product obtained when vapours of t-butyl alcohol are passed over copper at 300° ?

Description : What is the main product obtained when vapours of t-butyl alcohol are passed over copper at 300° ?

Last Answer : Ans. Isobutylene (2-Methyl propene) 

Phenols can be easily distinguished from alcohols because (a) phenols are soluble in NaOH, but alcohols are not (b) alcohols are soluble in NaOH, but phenols are not (c) phenols are soluble in NaHCO3, but alcohols are not (d) alcohols are soluble in NaHCO3, but phenols are not

Description : Phenols can be easily distinguished from alcohols because (a) phenols are soluble in NaOH, but alcohols are not (b) alcohols are soluble in NaOH, but phenols are not (c) phenols are soluble in NaHCO3, but alcohols are not (d) alcohols are soluble in NaHCO3, but phenols are not

Last Answer : phenols are soluble in NaOH, but alcohols are not

Which group forms the strongest H-bonds to water molecules? (a) Alcohols (b) Ethers (c) Phenols (d) All equally strong

Description : Which group forms the strongest H-bonds to water molecules? (a) Alcohols (b) Ethers (c) Phenols (d) All equally strong

Last Answer : Phenols

Assertion : Phenols are more acidic than aliphatic alcohols. Reason : Phenoxides are stabilized by resonance.

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Last Answer : Assertion : Phenols are more acidic than aliphatic alcohols. Reason : Phenoxides are stabilized by resonance. ... D. A is incorrect but R is correct

Which of the following statements describes the first step in the mechanism of the aldol condensation? (a) An alpha hydrogen is abstracted by the base to form an enolate anion. (b) A nucleophilic base attacks the carbonyl carbon atom. (c) The carbonyl oxygen is protonated by the base ion. (d) The alpha hydrogen is abstracted by an acid to the enolate anion.

Description : Which of the following statements describes the first step in the mechanism of the aldol condensation? (a) An alpha hydrogen is abstracted by the base to form an enolate anion. (b) A nucleophilic base attacks ... by the base ion. (d) The alpha hydrogen is abstracted by an acid to the enolate anion.

Last Answer : An alpha hydrogen is abstracted by the base to form an enolate anion

At physiological pH the ammonia is protonated to form

Description : At physiological pH the ammonia is protonated to form

Last Answer : At physiological pH the ammonia is protonated to form

Which nitrogen is protonated readily in the guanidine?

Description : Which nitrogen is protonated readily in the guanidine?

Last Answer : Which nitrogen is protonated readily in the guanidine? A. 1 B. 2 C. 3 D. none of the above

Which of the following statement is not correct with respect to alcohols as alternate fuel in IC engines a) anti-knock characteristics of alcohol is poor b) alcohol contains about half the heat energy of gasoline/litre c) alcohol does not vaporize as easily as gasoline d) alcohols are corrosive in nature

Description : Which of the following statement is not correct with respect to alcohols as alternate fuel in IC engines a) anti-knock characteristics of alcohol is poor b) alcohol contains about half the heat ... /litre c) alcohol does not vaporize as easily as gasoline d) alcohols are corrosive in nature

Last Answer : Answer: a Explanation: Anti-knock characteristics of alcohol is good.

Which one of the following compounds form zwitterions?(a) carbonyl compounds (b) amino acids (c) phenols (d) heterocyclic compounds

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Last Answer : amino acids

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Explain why nucleophilic substitution reactions are not very common in phenols.

Description : Explain why nucleophilic substitution reactions are not very common in phenols.

Last Answer : Explain why nucleophilic substitution reactions are not very common in phenols.

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Description : The smell of fat turned rancid is due to (A) Presence of vit E (B) Presence of quinones (C) Phenols (D) Volatile fatty acids

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Description : Protein is a polymer of (A) Sugars (B) Phenols (C) Amino acids (D) Carboxylic acids

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Description : Phenols are added in gasoline to (A) Improve the octane number (B) Act as an antioxidant (C) Reduce its viscosity (D) Increase its pour point

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Last Answer : (a) You will tell the male students that girls have no option except to depend on the school teacher for their academic assistance.

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Last Answer : Ans.--- Amines are less acidic than alcohols because of oxygen higher electronegative & smaller size. Therefore O-H breakes easily than N-H bond. 

Primary alcohols have boiling points that are _____________ the corresponding aldehydes. (a) Lower than (b) Higher than (c) About the same

Description : Primary alcohols have boiling points that are _____________ the corresponding aldehydes. (a) Lower than (b) Higher than (c) About the same

Last Answer : Higher than

Thiols are alcohol analogs in which the oxygen has been replaced by sulfur (e.g., CH3SH). Given the fact that the S–H bond is less polar than the O–H bond, which of the following statements comparing thiols and alcohols is correct? (a) Hydrogen bonding forces are weaker in thiols. (b) Hydrogen bonding forces are stronger in thiols. (c) Hydrogen bonding forces would be the same. (d) No comparison can be made without additional information

Description : Thiols are alcohol analogs in which the oxygen has been replaced by sulfur (e.g., CH3SH). Given the fact that the S-H bond is less polar than the O-H bond, which of the following ... (c) Hydrogen bonding forces would be the same. (d) No comparison can be made without additional information

Last Answer : Hydrogen bonding forces are weaker in thiols.

Why do alcohols have boiling points much higher than hydrocarbons of similar molecular weight? (a) Alcohols have greater van der Waals attraction forces. (b) Alcohol molecules have greater molecular symmetry. (c) Hydrogen bonds must be broken in the process of volatilization. (d) Alcohols must overcome greater ionic forces in the process of volatilization.

Description : Why do alcohols have boiling points much higher than hydrocarbons of similar molecular weight? (a) Alcohols have greater van der Waals attraction forces. (b) Alcohol molecules have greater ... of volatilization. (d) Alcohols must overcome greater ionic forces in the process of volatilization.

Last Answer : Hydrogen bonds must be broken in the process of volatilization

Upon hydrolysis, proteins give (a) Amino acids (b) Hydroxy acids (c) Fatty acids (d) Alcohols

Description : Upon hydrolysis, proteins give (a) Amino acids (b) Hydroxy acids (c) Fatty acids (d) Alcohols

Last Answer : Amino acids

Aliphatic primary amines react with cold nitrous acid to form (a) Alcohols (b) Diazonium salts (c) Nitriles (d) Nitroalkanes

Description : Aliphatic primary amines react with cold nitrous acid to form (a) Alcohols (b) Diazonium salts (c) Nitriles (d) Nitroalkanes

Last Answer : Alcohols

Esters can be formed by nucleophilic substitution reactions of : (a) carboxylic acids and alcohols ; acid-catalyzed (b) acid chlorides and alcohols (c) both of the above (d) neither of the above

Description : Esters can be formed by nucleophilic substitution reactions of : (a) carboxylic acids and alcohols ; acid-catalyzed (b) acid chlorides and alcohols (c) both of the above (d) neither of the above

Last Answer : both of the above

. Hunsdiecker reaction is used for the preparation of (a) Alkyl chlorides and bromides (b) Alkyl nitrates and nitrites (c) Ketenes (d) Alcohols

Description : . Hunsdiecker reaction is used for the preparation of (a) Alkyl chlorides and bromides (b) Alkyl nitrates and nitrites (c) Ketenes (d) Alcohols

Last Answer : Alkyl chlorides and bromides

The greater acidity of carboxylic acids compared to alcohols arises primarily from : (a) the electron-donating effect of the hydroxyl group (b) the electron-withdrawing effect of the carboxyl oxygen (c) the acidity of α-hydrogens of carboxylic acids (d) the resonance stability associated with the carboxylate ion

Description : The greater acidity of carboxylic acids compared to alcohols arises primarily from : (a) the electron-donating effect of the hydroxyl group (b) the electron-withdrawing effect of the carboxyl ... of α-hydrogens of carboxylic acids (d) the resonance stability associated with the carboxylate ion

Last Answer : the resonance stability associated with the carboxylate ion

Aldehydes undergo oxidation with KMnO4/H+ to give (a) Alcohols (b) Acetals (c) Ketones (d) Acids

Description : Aldehydes undergo oxidation with KMnO4/H+ to give (a) Alcohols (b) Acetals (c) Ketones (d) Acids

Last Answer : Acids

Which of the following reagents can be used to oxidize 1° alcohols to aldehydes? (a) KMnO4 (b) MnO2 (c) K2Cr2O7 (d) PCC

Description : Which of the following reagents can be used to oxidize 1° alcohols to aldehydes? (a) KMnO4 (b) MnO2 (c) K2Cr2O7 (d) PCC

Last Answer : PCC

The acid-catalyzed dehydration mechanism for alcohols is best described as a(n) : (a) E1 . (b) E2 . (c) SN1 (d) SN2

Description : The acid-catalyzed dehydration mechanism for alcohols is best described as a(n) : (a) E1 . (b) E2 . (c) SN1 (d) SN2

Last Answer : E1 .

Which of the following alcohols will give a yellow precipitate of iodoform with iodine and dilute NaOH solution? (a) 1-Propanol (b) 2-Propanol (c) 1-Butanol (d) 2-Methyl-2-propanol

Description : Which of the following alcohols will give a yellow precipitate of iodoform with iodine and dilute NaOH solution? (a) 1-Propanol (b) 2-Propanol (c) 1-Butanol (d) 2-Methyl-2-propanol

Last Answer : 2-Propanol

Lucas test is used to determine the type of (a) alcohols (b) acids (c) amines (d) carbohydrates

Description : Lucas test is used to determine the type of (a) alcohols (b) acids (c) amines (d) carbohydrates

Last Answer : alcohols

The high boiling points of alcohols, as compared to the corresponding alkanes, are due to (a) Hydrogen bonding (b) Heavy oxygen atom (c) Water solubility(d) None of these

Description : The high boiling points of alcohols, as compared to the corresponding alkanes, are due to (a) Hydrogen bonding (b) Heavy oxygen atom (c) Water solubility (d) None of these

Last Answer : Hydrogen bonding

The number of structural isomers of alcohols with molecular formula C4H9OH is (a) 5 (b) 4 (c) 3 (d) 6

Description : The number of structural isomers of alcohols with molecular formula C4H9OH is (a) 5 (b) 4 (c) 3 (d) 6

Last Answer : 4

The number of structural isomers of alcohols with molecular formula C3H7OH is (a) 5 (b) 4 (c) 3 (d) 2

Description : The number of structural isomers of alcohols with molecular formula C3H7OH is (a) 5 (b) 4 (c) 3 (d) 2

Last Answer : 2

Which of the following alcohols can be prepared by the reaction of methyl formate with excess Grignard reagent? (a) 1-pentanol (b) 2-pentanol (c) 3-pentanol (d) 2-methyl-2-pentanol

Description : Which of the following alcohols can be prepared by the reaction of methyl formate with excess Grignard reagent? (a) 1-pentanol (b) 2-pentanol (c) 3-pentanol (d) 2-methyl-2-pentanol

Last Answer : 3-pentanol

Which of the following classes of compounds is unreactive toward sulfuric acid? (a) Alkanes (b) Alcohols (c) Alkenes (d) Alkynes

Description : Which of the following classes of compounds is unreactive toward sulfuric acid? (a) Alkanes (b) Alcohols (c) Alkenes (d) Alkynes

Last Answer : Alkanes

Which of the following show n→ ℿ * electronic transitions? a. Alcohols b. Ethers c.Alkanes d. Aldehydes

Description : Which of the following show n→ ℿ * electronic transitions? a. Alcohols b. Ethers c.Alkanes d. Aldehydes

Last Answer : d. Aldehydes