Give reasons for the following:(i) Aniline does not undergo Friedal- Crafts reaction.(ii) \\((CH_3)_2NH\\) is more basic than \\((CH_3)_3N\\) in an aqueous solution.(iii) Primary amines have higher boiling point than tertiary amines.

(i) Aniline does not undergo Friedel craft's reactions because the reagent \\(AlCl_3\\) (the Lewis acid which is used as a catalyst in friedel crafts reaction), being electron deficient acts as a Lewis base. and attacks on the lone pair of nitrogen present in aniline to form an insoluble complex which precipitates out and the reaction does not proceed.(ii) With increase in alkyl group, the +I effect will increase which will increase the ease of donation of lone pair electron. But in water one other factor is controlling the strength of basicity. Amine will accept a proton and form cation. This cation will be stabilised in water by salvation. Better the salvation by hydrogen bonding, higher will be the basic strength.(refer image)Thus with increase in methyl group, hydrogen bonding and stabilisation by salvation decreases. The net effect is when we move from secondary to tertiary amine basic strength (iii) In a tertiary amine there aren't any hydrogen atoms attached directly to the nitrogen. That means that hydrogen bonding between tertiary amine molecules is impossible. That's why the boiling point is much lower. The small amines of all types are very soluble in water.

In the following sequence of reactions, \\(CH_3Br\overset{KCN}{\rightarrow}A\overset{H_3O^+}{\rightarrow}B\overset{LiAlH_4}{\rightarrow}C\\)The end product C is:

The end product C is ethyl alcohol.\\(\displaystyle CH_3Br \overset{KCN}{\rightarrow}\underset {A}{CH_3-CN}\overset{H_3O^+}{\rightarrow}\underset {B}{CH_3-COOH}\overset{LiAlH_4}{\rightarrow}\underset {C}{CH_3-CH_2-OH}\\)Methyl bromide reacts with KCN to form acetonitrile. Br atom is replaced with CN group. Hydrolysis of cyano group gives carboxylic group. Reduction of carboxylic group gives hydroxyl group.

Write the following reaction: Reimer-Tiemann reaction.

When phenol reacts with chloroform in the presence of bases \\((NaOH/KOH)\\), an aldehyde \\((-CHO)\\) group gets introduced in the ring at a position ortho to the phenolic group and salicylaldehyde is formed. This reaction is called the Reimer-Tiemann reaction.

Predict the major product of acid catalysed dehydration:(i) 1-methyl cyclohexanol(ii) Butan-1-ol

Due to Saytzeff rule, in \\((i)\\) the product where double bond is formed at the more substituted carbon is the major product. But as Saytzeff rule is only valid for 2° and 3° alcohols, a primary alcohol like \\((ii)\\) will form a terminal alkene as the major product.

Write the equation involved in the following reactions:(i) Reimer-Tiemann reaction (ii) Kolbe's reaction

(i) Reimer-Tiemann reaction \\(\rightarrow\\) When phenol is treated with chloroform in the presence of sodium hydroxide, a \\(-CHO\\) group is introduced at the ortho position of the benzene ring. This reaction is known as the Reimer-Tiemann reaction. The intermediate is hydrolyzed in presence of alkalis to produce salicylaldehyde.(ii) Kolbe's reaction \\(\rightarrow\\) When phenol is treated with sodium hydroxide, sodium phenoxide is produced. This sodium phenoxide when treated with carbon dioxide, followed by acidification, undergoes electrophilic substitution to give ortho-hydroxybenzoic acid as the main product. This reaction is known as Kolbe's reaction.

Name the reagents used in the following reactions:(i) Oxidation of a primary alcohol to carboxylic acid.(ii) Oxidation of a primary alcohol to aldehyde.(iii) Bromination of phenol to 2,4,6-tribromophenol.(iv) Benzyl alcohol to benzoic acid.(v) Dehydration of propan-2-ol to propene.(vi) Butan-2-one to butan-2-ol.

(i) Oxidation of primary alcohol to carboxylic acid.Acidified \\( \displaystyle K_2Cr_2O_7\\) or acidified \\( \displaystyle KMnO_4\\)(ii) Oxidation of primary alcohol to aldehyde.Pyridinium chlorochromate (PCC) in \\( \displaystyle CH_2Cl_2\\) or Pyridinimium dichromate (PDC) in \\( \displaystyle CH_2Cl_2\\)(iii) Bromination of phenol to 2,4,6-tribromophenol.Aqueous bromine ( or bromine water)(iv) Benzyl alcohol to benzoic acid.Acidified or alkaline \\( \displaystyle KMnO_4\\) followed by hydrolysis with dil \\( \displaystyle H_2SO_4\\)(v) Dehydration of propan-2-ol to propene.85% phosphoric acid(vi) Butan-2-one to butan-2-ol.\\( \displaystyle NaBH_4\\) or \\( \displaystyle Ni / H_2\\)

Explain why is ortho nitrophenol more acidic than ortho methoxyphenol?

In ortho nitro phenol, electron withdrawing nitro group is present in ortho position, the electron density of \\(O-H\\) bond is reduced.This makes removal of proton easy. After deprotonation, o-nitrophenoxide ion is resonance stabilized. Hence, ortho nitrophenol is a stronger acid.In ortho methoxyphenol, electron releasing methoxy group is present in ortho position, the electron density of \\(O-H\\) bond is increased.This makes removal of proton difficult. Hence, ortho methoxyphenol is less acidic.

The major product obtained on interaction of phenol with sodium hydroxide and carbon dioxide is?

Reaction of phenol with sodium hydroxide and carbon dioxide is Kolbe's Schmidt reaction that is a electrophilic substitution reaction resulting in the formation of salicylic acid as shown in the reaction.The major product obtained on interaction of phenol with sodium hydroxide and carbon dioxide is salicylic acid.

Which one of the following compounds has the most acidic nature?

Acidic nature is directly proportional to the stability of anion when acidic H is removed. Since in Phenol negative charge formed after the removal of acidic H will be delocalized in the whole ring. Hence it will be most stable. So phenol will be most acidic compound.

Which of the following is most acidic?

Option D is the correct answer. A methoxy group is mesomeric donating (+R) and inductive withdrawing (-I). We know that the +R effect is predominant over the -I effect. But +R effect is only valid when the substituent is at the ortho and para position.We also know that addition of Electron donating groups to the Benzene ring in phenol decreases its acidity while the addition of Electron withdrawing groups increase it.By that logic, m-Methoxyphenol is a stronger acid than phenol as the \\(-OCH_3\\) group at m-position imparts only -I effect to the ring.

Chemical Properties of Alcohols and Phenols - Reactions involving cleavage of O-H bond

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Acidic nature of alcohol or phenol with active metals

Alcohols react with metal hydrides to form metal alkoxides with the evolution of hydrogen gas.

C H_{3} O H + N a H \to C H_{3} O N a + H_{2}

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Acidic character of alcohols and water

1. Those Alcohols where the conjugate base is resonance stabilized will be more acidic.
2. The classic example is cyclohexanol and phenol.
3. Cyclohexanol has the pKa of a typical alcohol (about 16).
4. The pKa of phenol, however, is about 10.
5. In case of water it is amphoteric in nature.
6. They can behave as acid as well as base.

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Lower acidity of alcohols as compared to water

Alcohols behave as weak acids and ionize to a very small extent. It only give alkoxide ion and H+ ion on dissociation. The acidic nature of alcohols is due to the polarity of O-H bond. On account of this, the shared pair shifts towards O atom and the O-H bond becomes weak. This facilitates the release of a proton from the molecule.This is why alcohols behave as weak acids. Their acidic strength is even less than that of water.

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Effect of substituents on acidity of phenol

If stron electron withdrawing group is attached to phenol, the acidity of phenol increases, because electron-withdrawing group has the ability to de-localize negative charge, more than phenoxide ion itself.

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Acidic strength of nitrophenols

1. The acidic nature of the three nitrophenols increases in the order: meta < ortho < para.
2. Para nitorophenol is the most acidic among the three.
3. The nitro group attached to a conjugated system shows strong -M effect, and this decreases the electron density more at the ortho and para positions than at the meta position.
4. This factor helps greater stabilization of the conjugate base (nitro phenoxide ion) of the ortho and para isomers than that of the meta isomer.
5. So, meta nitrophenol is the weakest in terms of acidity.

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Acidic strength of cresols

The decreasing order of acidic strength: Phenol > m-Cresol > o-Cresol > p-Cresol.

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acidic strength of methoxy and amino nitrophenols

As amino and methoxy both are electron donating group and exert +R effect. Such group pumps electrons into the ring and thus intensify the negative charge of the phenoxide ion. This groups decreases the acidic strength of the phenol.

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Acidic strength of halophenols

As halogens are electron-withdrawing groups they withdraw electrons from the ring and results in dispersal of the negative charge of phenoxide ion and thus an increase in the stability of the ion. Consequently, acidic strength of the phenol increases.

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Acylation of alcohols and phenols

Alcohols and phenols react with acid chlorides and acid anhydrides in the presence of bases like pyridine as catalyst to form esters. This reaction is known as acylation.

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Mechanism of esterification

The esterification reaction of carboxylic acids with alcohols is a kind of nucleophilic acyl substitution. Protonation of the carbonyl oxygen activates the carbonyl group towards nucleophilic addition of the alcohol. Proton transfer in the tetrahedral intermediate converts the hydroxyl group into

^{+} O H_{2}

group, which, being a better leaving group, is eliminated as neutral water molecule. The protonated ester so formed finally loses a proton to give the ester.

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Acidic character of alcohol

The acidic character of alcohols is due to the electronegative oxygen atom which withdraws the electrons of the O-H bond towards itself. As a result, the O-H bond becomes weak and hence a proton can be easily abstracted by a strong base. Actually, alcohols are very weak acids even weaker than water.

Chemical Properties of Alcohols and Phenols - Reactions involving cleavage of O-H bond

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Acidic nature of alcohol or phenol with active metals

definition

Acidic character of alcohols and water

definition

Lower acidity of alcohols as compared to water

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Effect of substituents on acidity of phenol

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Acidic strength of nitrophenols

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Acidic strength of cresols

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acidic strength of methoxy and amino nitrophenols

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Acidic strength of halophenols

definition

Acylation of alcohols and phenols

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Mechanism of esterification

definition

Acidic character of alcohol

REVISE WITH CONCEPTS

Chemical Properties of Alcohols - Reactions Involving Cleavage of C - O Bond

Electrophilic Aromatic Substitution Reactions in Phenols

Other reactions of Phenols

Quick Summary With Stories

Acidity of Alcohols and Phenols

Phenols - Esterification

Give reasons for the following:
(i) Aniline does not undergo Friedal- Crafts reaction.
(ii) $(C H_{3})_{2} N H$ is more basic than $(C H_{3})_{3} N$ in an aqueous solution.
(iii) Primary amines have higher boiling point than tertiary amines.

In the following sequence of reactions,

$C H_{3} B r \to K C N A \to H_{3} O^{+} B \to L i A l H_{4} C$

The end product C is:

Write the following reaction: Reimer-Tiemann reaction.

Predict the major product of acid catalysed dehydration:
(i) 1-methyl cyclohexanol
(ii) Butan-1-ol

Write the equation involved in the following reactions:
(i) Reimer-Tiemann reaction (ii) Kolbe's reaction

Explain why is ortho nitrophenol more acidic than ortho methoxyphenol?

The major product obtained on interaction of phenol with sodium hydroxide and carbon dioxide is?

Which one of the following compounds has the most acidic nature?

Which of the following is most acidic?

definition

Acidic nature of alcohol or phenol with active metals

definition

Acidic character of alcohols and water

definition

Lower acidity of alcohols as compared to water

definition

Effect of substituents on acidity of phenol

definition

Acidic strength of nitrophenols

definition

Acidic strength of cresols

definition

acidic strength of methoxy and amino nitrophenols

definition

Acidic strength of halophenols

definition

Acylation of alcohols and phenols

definition

Mechanism of esterification

definition

Acidic character of alcohol

REVISE WITH CONCEPTS

Chemical Properties of Alcohols - Reactions Involving Cleavage of C - O Bond

Electrophilic Aromatic Substitution Reactions in Phenols

Other reactions of Phenols

Quick Summary With Stories

Acidity of Alcohols and Phenols

Phenols - Esterification

Give reasons for the following: (i) Aniline does not undergo Friedal- Crafts reaction. (ii) (CH3​)2​NH is more basic than (CH3​)3​N in an aqueous solution. (iii) Primary amines have higher boiling point than tertiary amines.

In the following sequence of reactions, CH3​Br→KCNA→H3​O+B→LiAlH4​C The end product C is:

Write the following reaction: Reimer-Tiemann reaction.

Predict the major product of acid catalysed dehydration: (i) 1-methyl cyclohexanol (ii) Butan-1-ol

Write the equation involved in the following reactions: (i) Reimer-Tiemann reaction (ii) Kolbe's reaction

Explain why is ortho nitrophenol more acidic than ortho methoxyphenol?

The major product obtained on interaction of phenol with sodium hydroxide and carbon dioxide is?

Which one of the following compounds has the most acidic nature?

Which of the following is most acidic?

Give reasons for the following:
(i) Aniline does not undergo Friedal- Crafts reaction.
(ii) $(C H_{3})_{2} N H$ is more basic than $(C H_{3})_{3} N$ in an aqueous solution.
(iii) Primary amines have higher boiling point than tertiary amines.

In the following sequence of reactions,

$C H_{3} B r \to K C N A \to H_{3} O^{+} B \to L i A l H_{4} C$

The end product C is:

Predict the major product of acid catalysed dehydration:
(i) 1-methyl cyclohexanol
(ii) Butan-1-ol

Write the equation involved in the following reactions:
(i) Reimer-Tiemann reaction (ii) Kolbe's reaction