1. Introduction
Alcohols are compounds that have a hydroxyl group \[\left( {{\text{ - OH}}} \right)\] attached to a saturated carbon atom. Enols are compounds that have a hydroxyl group attached to an unsaturated carbon atom of a double bond. The saturated carbon can be alkyl, alkenyl, alkynyl, cycloalkyl, or benzyl. If, on the other hand, a hydroxyl group is attached to a benzene ring. Phenols are the name given to these compounds.
The alcohols are further classified as monohydric (containing one \[{\text{ - OH}}\] group), dihydric (containing two \[{\text{ - OH}}\] groups), and trihydric (containing three \[{\text{ - OH}}\] groups) (containing three \[{\text{ - OH}}\] groups).
Alcohol is used in both industry and everyday life. Chiefly ethanol, for example, is a common spirit used to polish wooden furniture. Sugar, cotton, and paper are all composed of compounds that contain groups. Phenols are found in a variety of important polymers, including Bakelite, as well as pharmaceuticals such as Aspirin. Ethers are commonly used as anaesthetics and solvents.
In alcohols, the oxygen of thegroup is attached to carbon by a sigma (bond formed by the overlap of a sp hybridised forbital of carbon with a sp hybridised orbital of oxygen. The following figure depicts structural aspects of methanol, phenol and methoxymethane.
2. Classification
Classification of alcohols and symmetrical and unsymmetrical ether
3. Structure of Functional Groups
In the structure of alcohols, the oxygen of hydroxyl group is connected to carbon through a sigma bond which is formed by the overlapping of \[\text{s}{{\text{p}}^{3}}\] hybridised orbital of C with a \[\text{s}{{\text{p}}^{3}}\] hybridised orbital of oxygen. The structural aspects of phenol, methanol and methoxymethane are depicted by the following figure.
Structure of methanol
Due to lone pair-lone pair repulsion, bond angle is slightly less.
Structure of Phenol
Since a pair of oxygen is delocalised on the ring, the length of the \[{\text{C - O}}\] bond is reduced.
Structure of Methoxymethane
Due to the general repulsive interaction between the two bulky (R) groups, the bond angle in methoxymethane is greater than the tetrahedral angle. The length of the \[{\text{C - O}}\] bond is the same as in alcohols.
4. Physical Properties
4.1 Boiling Point
The boiling points of alcohols and phenols rise as the number of carbon atoms increases (increase in van der Waals forces). The boiling point of alcohol decreases as branching increases (decrease in Van der Waals forces due to decrease in surface area). In alcohols and phenols, the -OH group contains a hydrogen atom that is bonded to an electronegative oxygen atom. As a result, it is capable of forming intermolecular hydrogen bonds with greater strength than amine.
Formation of intermolecular hydrogen bonds in alcohols and phenols
Alcohols and phenols have higher boiling points than other classes of compounds, such as hydrocarbons, ethers, and haloalkanes/haloarenes, amines with comparable molecular masses, due to the presence of strong intermolecular hydrogen bonding.
Their boiling points are lower than those of carboxylic acid, which has a stronger hydrogen bond. Boiling points for isomeric alcohols decrease as branching increases due to a decrease in van der Waals forces as size decreases. The boiling point sequence is primary alcohol > secondary alcohol > tertiary alcohol.
Due tolower dipole moment and the absence of H-bonding, the boiling point of ethers is very low and comparable to that of alkanes of comparable molecular mass.
4.2 Solubility
Alcohols and phenols are soluble in water due to their ability to form hydrogen bonds with water molecules. Solubility decreases as the size of the hydrophobic group increases (R). Higher concentrations of alcohol are insoluble. Because of the decrease in surface area of the nonpolar hydrocarbon part, branching increases solubility.
n-butyl alcohol < isobutyl alcohol < sec-butyl alcohol < tert-butyl alcohol
Formation of hydrogen bonds Between alcohol and water
Lower ethers are water soluble, but their solubility is lower than that of alcohol due to less H-bonding with water and being less polar.
5. Preparation of Alcohols
Flow chart showing preparation of alcohols
5.1 Alkane
Controlled oxidation
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5.2 Alkenes
5.2.1 Acid Catalyzed Hydration
Markovnikov addition with carbocation rearrangements.
Reaction showing Acid Catalyzed Hydration of alkene
5.2.2 Oxymercuration-Demercuration
Markovnikov addition without carbocation rearrangements.
Example - 1
Reaction showing Oxymercuration-Demercuration
5.2.3 Hydroboration-Oxidation Anti-Markovnikov Addition.
Example-2
Reaction showing Hydroboration-Oxidation Anti-Markovnikov addition
5.2.4 SYN Hydroxylation
Reagents: Cold dil. \[{\text{KMn}}{{\text{O}}_{\text{4}}}/{\text{NaOH or Os}}{{\text{O}}_{\text{4}}}/{{\text{H}}_{\text{2}}}{{\text{O}}_{\text{2}}}\]
Example-3
Reaction showing Syn Hydroxylation
5.2.5 ANTI Hydroxylation
Reagents: Peroxy acids followed by acidic hydrolysis
Example-4
Reaction showing Anti Hydroxylation
5.3 Alkyl Halide
5.3.1 Second Order Substitution
Primary and some Secondary Halides
${{\left( \text{C}{{\text{H}}_{3}} \right)}_{2}}\text{CHC}{{\text{H}}_{2}}\text{C}{{\text{H}}_{2}}-\text{Br}\xrightarrow[{{\text{H}}_{2}}\text{O}]{\text{KOH}}{{\left( \text{C}{{\text{H}}_{3}} \right)}_{2}}\text{CHC}{{\text{H}}_{2}}\text{C}{{\text{H}}_{2}}-\text{OH}$
Example -6
Reaction between tertiary butyl chloride and acetone
5.3.2 Grignard Reagent/ Organolithium Reagent
Nucleophilic addition to the carbonyl group
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Addition to Formaldehyde-primary alcohol
Example-7
Reaction showing addition of Grignard Reagent to Formaldehyde forming primary alcohol
Addition to aldehyde-secondary alcohol
(Video) Alcohols Phenols Ethers Handwritten notes pdf | class 12th chemistry Chapter-11| pdf Notes By Saalik
Example-8
Reaction showing addition of Grignard Reagent to aldehyde forming a secondary alcohol
Addition to a ketone-tertiary alcohol
Example-9
Reaction showing addition of Grignard Reagent to a ketone forming a tertiary alcohol
Addition to an acid-halide or an Ester-tertiary alcohol
Example-10
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Addition to Ethylene oxide-primary alcohol (with two carbon atoms added)
Example-11
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5.4 Carbonyl Compounds
5.4.1 Catalytic Hydrogenation
Reaction showing Catalytic Hydrogenation
This method is usually not known as effective or selective as the use of hydride reagents.
5.4.2 Reduction with Metal Hydrides
Primary alcohol is produced on reduction of an aldehyde.
Example:
Reaction showing Catalytic Hydrogenation
Secondary alcohol is produced on reduction of a ketone.
Example:
Reaction showing reduction of a ketone to form a Secondary alcohol.
Tertiary alcohol is produced on reduction of an acid or ester.
Example:
Reaction showing reduction of an acid or ester to form a Tertiary alcohol .
Reduction of $LiAlH_4$ and $NaBH_4$
Reaction showing reduction of various functional groups in the presence of
6. Reaction of Alcohols
Flow chart showing reactions of alcohols
6.1 Dehydration
Dehydration Reaction of alcohol
6.2 Substitution
Substitution Reaction of alcohol
6.3 Esterification
It is catalyzed by an acid or a base.
Esterification Reaction of alcohol
6.4 Tosylation
It is used to convert poor leaving group OH to good leaving group OTs.
Example:
Tosylation Reaction of alcohol
6.5 Oxidation
Primary Alcohols
Oxidation Reaction of primary alcohol
Secondary alcohols
Oxidation Reaction of Secondary alcohol
In the presence of any oxidizing agent, secondary alcohol is oxidized to alcohol.
Tertiary alcohols
Oxidation Reaction of tertiary alcohol
$\mathrm{MNO}{_2}$ is an oxidizing agent which is used to oxidise only benzylic, allylic and propargylic alcohols.
Showing benzylic, allylic and propargylic alcohols.
Common Phenols and Aromatic Ethers
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7. Preparation of Phenols
Flow chart showing various methods of preparation of phenol
7.1 Dow’s Process
It is an industrial method which is used for the preparation of phenol. It takes place through a benzene mechanism.
Example:
Showing Dow’s Process
7.2 Cumene Process
Example:
Showing Cumene Process
7.3 Distillation of phenolic acids with soda lime
Example:
7.4 Benzene
Example:
Showing reaction of Benzene with Hydrogen peroxide to yield phenol
7.5 Grignard Reagent
Example:
Showing the formation of phenol using grignard reagent
8. Reaction of Phenols
8.1 Formation of Ethers
Williamson Synthesis
Showing the Reaction of phenols - Williamson synthesis
Nucleophilic Aromatic Substitution
Example:
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8.2 Formation of Esters
Example:
Showing the Reaction of phenols - Formation of Esters
8.3 Fries Rearrangement
Example:
Showing the Reaction of phenols - Fries Rearrangement
8.4 Reactions of Benzene Ring
8.4.1 Hydrogenation
Example:
Showing the Reaction of phenols - Hydrogenation
8.4.2 Oxidation to Quinones
Example:
Showing the Reaction of phenols - Oxidation to quinones
8.4.3 Electrophilic Substitution
Halogenation
Example:
Showing the Reaction of phenols - Electrophilic substitution (a) Halogenation
Nitration
Showing the Reaction of phenols - Electrophilic substitution (b) Nitration
Sulphonation
Showing the Reaction of phenols - Electrophilic substitution (c) Sulphonation
Diazonium Salt Coupling-Azophenols
\[{\text{Ar}}{{\text{N}}_{\text{2}}}^ \oplus + {{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{G}} \to {\text{p}} - {\text{G}} - {{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}} - {\text{N}} = {\text{N - Ar}}\]
Here, G is an electron releasing groups such as -OH, -OR.
Ring Alkylation
Example:
Showing the Reaction of phenols - Electrophilic substitution (e) Ring Alkylation
RX and $\text{AlC}{{\text{l}}_{3}}$ give poor yields as aluminum chloride coordinates with lone pairs of oxygen.
Kolbe’s Synthesis
Example:
Showing the Reaction of phenols - Electrophilic substitution (f) Kolbe’s Synthesis
Reimer-Tiemann Synthesis of phenolic Aldehydes
Example:
Showing the Reaction of phenols - Electrophilic substitution (g) Reimer-Tiemann Synthesis of phenolic Aldehydes
This reaction involves the formation of $\text{CC}{{\text{l}}_{2}}$.
Formation of Aspirin
Example:
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Formation of oil of wintergreen
Example:
Showing the Reaction of phenols - Electrophilic substitution (j) Formation of oil of wintergreen
9. Ethers
9.1 Williamson Ether Synthesis
\[{\text{R}} - {{\text{O}}^ - } + {\text{R}}' - {\text{X}} \to {\text{R}} - {\text{O}} - {\text{R}}' + {{\text{X}}^ - }\]
Note:
Substrate and leaving Group in Williamson synthesis
Leaving group, that, is, \[{\text{X}} = {\text{Cl, Br, I, OTs etc}}{\text{.}}\]
Substrate-Alkyl group R’ should be primary.
9.2 Alkoxymercuration-Demercuration
Showing the Alkoxymercuration-Demercuration
This type of reaction follows Markovnikov orientation.
9.3 Bimolecular Dehydration of Alcohols
This is an industrial method which is used for the synthesis of ethers.
\[2\text{R}\frac{{{\text{H}}^{\oplus }}}{{{1}^{{}^\circ }}}\text{OH}\overset{{}}{\mathop{\text{R}}}\,-\text{O}-\text{R}+{{\text{H}}_{2}}\text{O}\]
10. Reactions of Ethers
10.1 Cleavage by HBr and HI
Showing the Cleavage by HBr and HI
10.2 Autoxidation
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11. Preparation of Epoxide
11.1 Peroxy Acid Epoxidation
Showing the Preparation of epoxide-1 Peroxy Acid Epoxidation
11.2 Base-Promoted Cyclization of Halohydrins
Showing the Preparation of epoxide-2 Base-promoted cyclization of halohydrins
Example
Showing the reaction of 2-Chloro-1-Phenylethanol tp yield 2-Phenyloxirane
12. Reactions of Epoxides
12.1 Acid-Catalyzed Opening
In Water
Showing the Reactions of Epoxides - (a) In water
Anti-stereochemistry is followed here.
In Alcohols
Showing the Reactions of Epoxides - (b) In alcohols
Here, the alkoxy group is bonded to the more highly substituted carbon.
Example:
Reaction of methyl Oxirane to yield 2-Methoxy-propan-1-ol
Hydrohalic Acids (X = Cl, Br, I)
Showing the Reactions of Epoxides - (c) Hydrohalic Acids (X = Cl, Br, I)
12.2 Base-Catalyzed Opening
With Alkoxides
Showing the Reactions of Epoxides - 2 Base-Catalyzed opening (a) With Alkoxides
The alkoxy group is bonded to less highly substituted carbon.
Example:
Reaction of Propylene oxide to yield 1-Methoxy-2-propanol
With Organometallics
Showing the Reactions of Epoxides - 2 Base-Catalyzed opening (b) With Organometallics
Example:
Reaction of Propylene oxide to yield 1-Cyclohexyl-2-Propanol
Note:
Opening of Epoxide Ring
In acid catalyzed opening, a nucleophile attacks the epoxide carbon, allowing a more stable carbocation to be formed.
Nucleophile attacks on the less hindered carbon in base catalyzed opening.
13. Acidic Strength
Despite the fact that oxygen is more electronegative than sulfur, alcohols are weaker acids than thiols. $\text{R}{{\text{O}}^{-}}$, the conjugate base of alcohol, is more basic than $\text{R}{{\text{S}}^{-}}$ because the negative charge in $\text{R}{{\text{O}}^{-}}$ is placed on smaller oxygen atoms, resulting in higher charge density. However, because the $\text{R}{{\text{S}}^{-}}$ negative charge is dispersed on larger sulphur, it is a poor base and its conjugate acid is more acidic.
Due to the +I effect of the alkyl group, all alcohols (except $\mathrm{CH}_{3} \mathrm{OH}$) are weaker than $\mathrm{H}_{2} \mathrm{O}$. $\mathrm{CH}_{3} \mathrm{OH}$ is slightly more powerful than $\mathrm{H}_{2} \mathrm{O}$. Because of the electron withdrawing benzene ring and the resonance stabilized phenolic ion, phenols are stronger than alcohol. Because alkoxide ions, the conjugate base of alcohol, lack resonance, they are less stable and more basic. Phenol is less stable than carboxylic acid, which has a strong electron-drawing carbonyl group and more stable, resonating structures.
14. Test for Alcohols, Phenols and Ethers
14.1 Analysis of Alcohols-Characterization
Cold concentrated sulfuric acid dissolves alcohols. This property is shared by alkenes, amines, almost all oxygen-containing compounds, and easily sulfonated compounds. (Alcohol, like other oxygen-containing compounds, produces oxonium salts that dissolve in the highly polar sulfuric acid.)
Cold dilute, neutral permanganate does not oxidize alcohols (although primary and secondary alcohols are oxidized by permanganate under more vigorous conditions). However, as we've seen, alcohols frequently contain impurities that oxidize under these conditions, so the permanganate test should be used with caution.
Alcohols have no effect on the color of bromine in carbon tetrachloride. This characteristic distinguishes them from alkenes and alkynes.
The evolution of hydrogen gas from alcohol reactions with sodium metal is useful in characterization.
The formation of an ester upon treatment with an acid chloride or anhydride often indicates the presence of a hydroxide group in a molecule. Some esters have a pleasant odor; others have high melting points and can be used to make identifications.
The Lucas test, which is based on the difference in reactivity of the three classes towards hydrogen halides, determines whether an alcohol is primary, secondary, or tertiary. Alcohols with fewer than six carbons are soluble in the Lucas reagent, which is a solution of concentrated hydrochloric acid and zinc chloride. The cloudiness that appears when the chloride separates from the solution indicates the formation of a chloride from an alcohol. As a result, the time required for cloudiness to appear is a measure of the alcohol's reactivity. The Lucas reagent reacts immediately with tertiary alcohol. Within five minutes, a secondary alcohol reacts. At room temperature, a primary alcohol does not react significantly. Benzyl alcohol and alllyl alcohol react with the Lucas reagent as quickly as tertiary alcohols. Allyl chlorides, on the other hand, is soluble in the reagent.
Showing which alcohol gives positive or negative Iodoform test.
Oxidation, halogenation, and cleavage are all involved in the reaction.
Showing Oxidation, halogenation, and cleavage reactions.
14.2 Analysis of Glycols, Periodic Acid Oxidation
$\mathrm{HI}{O_4}$ compounds with two or more-OH or C=O groups attached to adjacent carbon atoms undergo oxidation with cleavage of carbon-carbon bonds when exposed to periodic acid.
Showing Analysis of Glycols, Periodic Acid Oxidation
14.3 Miscellaneous Tests
Ceric Ammonium Nitrate Test-
With this reagent, alcohols produce a red color.
\[{\text{Ce}}{\left( {{\text{N}}{{\text{H}}_{\text{4}}}} \right)_{\text{2}}}{\left( {{\text{N}}{{\text{O}}_{\text{3}}}} \right)_{\text{6}}}{\text{ + RC}}{{\text{H}}_{\text{2}}}{\text{OH}} \to {\text{Ce}}{\left( {{\text{N}}{{\text{H}}_{\text{4}}}} \right)_{\text{2}}}{\left( {{\text{N}}{{\text{O}}_{\text{3}}}} \right)_{\text{5}}} + {\text{RCOOH + HN}}{{\text{O}}_{\text{3}}}\]
Potassium Dichromate Test –
Alcohols change the color of orange dichromate to green. Tertiary alcohols fail this test.
Ester test:
Alcohol produces a fruity aroma of ester with carboxylic acid.
Methanol reacts with salicylic acid to produce winter green oil.
14.4 Victor Meyer's Test
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14.5 Differentiation Test
14.5.1 Alcohols and Phenols
Litmus Test: Phenol turns blue litmus red but not alcohol.
Ferric Chloride:
$\mathrm{FeCl}_{3}: \text { Phenol } \stackrel{\text { Neutral } \mathrm{FeCl}_{3}}{\longrightarrow} \text { Blue-Violet }$
Coupling Reaction:
$\text { Phenol + Diazonium Salt } \frac{\text { weakly basic }}{\text { medium }} \text { Yellow or }$
$\text { Diazonium Salt + Alcohol } \frac{\text { weakly basic }}{\text { medium }} \text { No Reaction }$
Bromine Water Test:
Showing Bromine Water test
14.4.2 Alcohols and Ethers
Alcohols react with Na to give${{\text{H}}_{2}}$, but not ethers.
Alcohol gives fumes ofHClwith ${{\text{PCl}}_{5}}$but not ethers.
14.5.3 Sodium Bicarbonate Test
Phenol, ROH and $\mathrm{H}_{2} \mathrm{O}$ do not displace $\mathrm{CO}_{2}$ from carbonate \& bicarbonates but $\mathrm{RCOOH} \& \mathrm{RSO}_{3} \mathrm{H}$ gives brisk effervescence of $\mathrm{CO}_{2}$ which proves that $\mathrm{RCOOH} \& \mathrm{RSO}_{3} \mathrm{H}$ are stronger acids $\mathrm{H}_{2} \mathrm{CO}_{3}$ but phenol is weaker acid than $\mathrm{H}_{2} \mathrm{CO}_{3}$. Nitrophenols also give effervescence of $\mathrm{CO}_{2}$ with $\mathrm{Na}_{2} \mathrm{CO}_{3}$. Trinitrophenol (Picric Acid) is highly acidic due to strong electron withdrawing effect of three groups its acidic strength is comparable to that of carboxylic acids. Its anion is highly resonance stabilised.
$\mathrm{RCOOH}+\mathrm{NaHCO}_{3} \longrightarrow \mathrm{RCOON}^{\ominus \oplus}+\mathrm{CO}_{2} \uparrow+\mathrm{H}_{2} \mathrm{O}$
$\mathrm{Ph}-\mathrm{OH}+\mathrm{NaHCO}_{3} \longrightarrow \text { No Reaction}$
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15.5.4 $\mathrm{FeCl}_{3}$ Test:
Phenol gives characteristic purple colour with $\mathrm{FeCl}_{3}$ but alcohols do not react with $\mathrm{FeCl}_{3}$. Carboxylic acids also form buff coloured precipitate with $\mathrm{FeCl}_{3} .$ Only acetic acid forms red coloured precipitate with $\mathrm{FeCl}_{3}$, so it can be used as a test for acetate salts.
Showing Ferric Chloride Test in case of phenols
How to Name Alcohols?
One of the questions that students find trouble solving is to name the alcohols. Well, we are here to help you understand the nomenclature of alcohols. Given below are the steps that will help you name alcohols.
First, you need to look for the carbon atoms present in the longest carbon chain, which contains the OH group.
Now you have to use the prefix to find out the carbon atom's position, which is carrying the OH bond, and then add ”ol” at the end of it. Also, take the number from that end of the chain, which is closest to the alcohol group.
After that, use numbers and di-, tri-, etc, according to the formula.
In case a molecule has multiple bonds in addition to the alcohol group. Give that molecule carbon that has an OH group attached to the lowest possible serial number.
Chapter 11 Chemistry Class 12 Notes
In Class 12 Chemistry Chapter Alcohol Phenol and Ether notes, you will study how to classify different phenols and ethers and name them according to the number of hydroxyl groups attached.
(Image to be added soon)
(Alcohol-based hand sanitizer)
Monohydric phenol contains one -OH group. The dihydric phenols have two -OH groups. They can be ortho, meta, and even para-derivative. Finally, the third type of phenols is trihydric phenols, which have three -OH groups.
When it comes to the classification of ether, students will learn about two types of ether; the first one is symmetrical ether, which is also known as simple ether; in this form of ether, the alkyl or the aryl groups attached to either side of the oxygen atoms are the same.
On the other hand, in notes of chapter 11 chemistry class 12, you will be introduced to the asymmetrical ether, which is said to be a mixed ether that has different alkyl or aryl groups attached to either side of the oxygen atoms.
Class 12 Chemistry Chapter 11 Notes
In the notes of chemistry class 12 alcohols phenols and ethers, you will also get to learn about different properties of ether. Ether is used in anesthetics and diethyl ethers also have other medical uses. Ethers are mainly colourless, sweet-smelling liquids at room temperature.
Short Answer Type Questions
Draw the structure of 2, 6-Dimethylphenol.
Draw the structural formula of 2-methylpropan- 2-ol molecules.
The C-O bond is much shorter in phenol than in ethanol. Give a reason.
Long Answer Type Questions
Write the equations involved in the following reactions:
(i) Williamson ether synthesis
(ii) Kolbe’s reaction
How are the following conversions carried out?
(i) Propene to Propan-2-ol
(ii) Ethyl chloride to Ethanal
Answer:
(i) Propene to propan-2-ol
Write the mechanism of acid dehydration of ethanol to yield ethene.
Write the structures of the products when Butan-2-ol reacts with the following:
(a) CrO3
(b) SOCl2
Practice Questions
Preparation of ethers by acid dehydration of secondary or tertiary alcohols is not a suitable method. Give reasons.
Write the equation of the reaction of hydrogen iodide with:
(i) 1-propoxypropane (ii) methoxybenzene and (iii) benzyl ethyl ether
How are the following conversions carried out?
(i) Propene to propan-2-ol
(ii) Benzyl chloride to Benzyl alcohol
(iii) Anisole to p-Bromoanisole
Key Features of Revision Notes for CBSE Class 12 Chemistry Chapter 11
Revision Notes for CBSE Class 12 Chemistry Chapter 11 - Alcohols, Phenols and Ethers are curated by our subject experts as per the latest guidelines for CBSE Class 12.
These Revision Notes provide a detailed explanation of the topics covered in the chapter.
Students can refer to these notes by downloading them for their offline self-study.
These notes follow the latest curriculum of CBSE Class 12 Chemistry. So they can be used while revising the chapter.
All reactions are explained with labelled diagrams.
Balanced chemical equations, explanations are provided wherever required.
Conclusion
Revision Notes for CBSE Class 12 Chemistry Chapter 11 Alcohols, Phenols and Ethers are now available in PDF format on Vedantu. Students can rely on these revision notes as they are prepared by the top subject experts. Moreover, we have also provided students with extra questions on this page, which are useful from an examination point of view. Students can use these revision notes and important questions for the preparation and revision of these topics.