Free NCERT Class 12 Chemistry Chapter 11 Notes Alcohols, Phenols and Ethers - Download PDF

Alcohols, Phenols, and Ethers are three important classes of compounds that feature oxygen-containing organic compounds. When the OH group replaces the hydrogen atom in aliphatic hydrocarbons Alcohols are formed same goes for phenols when the OH group replaces the hydrogen of aromatic hydrocarbons then Phenols are formed while Ethers are formed when alkoxy (R-O) or aryloxy (Ar-O) group substitutes hydrogen atom in hydrocarbons. Oxygen-containing organic compounds like alcohol such as ethanol are used in soft drinks, beverages, and sanitizers while Phenols are used in antiseptics and disinfectants and Ether is used in the manufacturing of perfumes. Class 12 Chapter 7 Chemistry explains various concepts that we observe in our daily lives.

This Story also Contains

1. NCERT Class 12 Chemistry Alcohols, Phenols, and Ethers Notes
2. Classification of Alcohols and Phenols
3. Structure of Alcohols and Phenols
4. Preparation of Alcohols
5. Preparation of Phenols
6. Physical Properties of Alcohols and Phenols
7. Chemical Reactions of Alcohols and Phenols
8. Reactions of phenol
9. Some Commercially Important Alcohols
10. Preparation of Ether
11. Physical Properties of Ethers
12. Chemical Properties of Ethers
13. NCERT Class 12 Notes Chapter-Wise
14. Subject Wise NCERT Exemplar Solutions
15. Subject Wise NCERT Solutions
16. NCERT Books and Syllabus

NCERT Chapter 7 Class 12 Chemistry notes provide a structured approach to understanding the classification, properties, preparation, and reactions. NCERT notes of class 12 chemistry, Alcohols, Phenols, and Ether, are one of the essential sources of preparation for organic chemistry, whether students are preparing for class 12 CBSE boards or other competitive exams like NEET, JEE, BITSAT, etc. Notes are prepared by our subject experts in a comprehensive way that helps students understand the concepts in a very simple and easy way.

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NCERT Class 12 Chemistry Alcohols, Phenols, and Ethers Notes

Classification of Alcohols and Phenols

• Alcohols and phenols are classed as monohydric, dihydric, trihydric, or polyhydric depending on how many hydroxyl groups they have in their molecules: one, two, three, or many, respectively

• Alcohols with the OH group connected to a primary, secondary, or tertiary carbon atom are known as primary (1°), secondary (2°), and tertiary (3°) alcohols.

• Allylic alcohol is made up of an -OH group attached to an sp³ hybridized carbon next to a carbon carbon double bond, whereas benzylic alcohol is made up of an -OH group attached to an sp³ hybridized carbon close to an aromatic ring. Alcohols having -OH group bonded to carbon-carbon double bond is called vinylic alcohol

Structure of Alcohols and Phenols

Alcohols have sp³ hybridized oxygen atoms and hybrid atomic orbitals in a tetrahedral configuration. The R group determines the value of the ROH bond angle. Due to lone pair repulsion, this angle for methyl alcohol is (C – O – H) 108.9°.The -OH group in phenols is connected to sp² hybridized carbon, giving the C – O bond a partial double bond nature.

Preparation of Alcohols

a)From alkenes

This reaction is in accordance with Markonikov's rule, through acid catalyzed hydration.

CH₃CH=CH₂ + H₂O → CH₃-CH(OH) - CH₃

b)By hydroboration-oxidation

c)By reduction of aldehydes and ketones

RCHO + H₂ → R CH₂OH

$\mathrm{RCOR}\stackrel{\mathrm{NaBH}4}{\to }\mathrm{R}-\mathrm{CH}(\mathrm{OH})-\mathrm{R}$

d)By reduction of carboxylic acids

$\mathrm{RCOOH}\stackrel{{\text{ LiAl }}_4,{\mathrm{H}}_2\mathrm{O}}{\to }\mathrm{ROH}$

e)From Grignard reagents

$\mathrm{HCHO}+\mathrm{RMgX}\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to }{\mathrm{RCH}}_2\mathrm{OH}+\mathrm{Mg}(\mathrm{OH})\mathrm{X}$

$\mathrm{RCHO}+\mathrm{RMgX}\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to }\mathrm{R}-\mathrm{CH}(\mathrm{R})\mathrm{OH}+\mathrm{Mg}(\mathrm{OH})\mathrm{X}$

$\mathrm{RCOR}+\mathrm{RMgX}\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to }\mathrm{R}-\mathrm{C}(\mathrm{R})(\mathrm{R})\mathrm{OH}+\mathrm{Mg}(\mathrm{OH})\mathrm{X}$

Preparation of Phenols

a)From haloarenes

b)From benzenesulfonicacid

c)From diazonium salts

d)From cumenes

Physical Properties of Alcohols and Phenols

Lower alcohols are colourless liquids, C₅–C₁₁ alcohols are oily liquids, and C₁₂ and higher alcohols are waxy solids. Alcohols are miscible with water because their hydroxyl groups can form H-bonds with water. With increasing molecular mass, solubility decreases. Because polar molecules have intermolecular hydrogen bonding, the boiling points of alkanes are greater than expected.

These are colourless liquids or crystalline solids that turn coloured over time due to gradual oxidation in the presence of air. Carboxylic acid is another name for phenol. Phenols establish intermolecular H-bonds with other phenol molecules and with water due to the presence of a polar -OH bond.

Chemical Reactions of Alcohols and Phenols

1)Acidity of alcohols and phenols

a)Reaction with metals

$2\mathrm{R}-\mathrm{OH}+2\mathrm{Na}\stackrel{\text{ yields }}{\to }2\mathrm{R}-\mathrm{O}-\mathrm{Na}+{\mathrm{H}}_2$

Acidity of alcohols

• The polar nature of the OH bond causes the acidity of alcohols.

• Order of acidity

Primary > Secondary Tertiary

• Alcohols are weaker acids than water

Acidity of phenols

Because the phenoxide ion is stabilized through resonance, phenol is more acidic than alcohols. The presence of an electron withdrawing group raises phenol's acidity by stabilizing the phenoxide ion, whereas the presence of an electron releasing group lowers phenol's acidity by destabilizing the phenoxide ion.

• Esterification

$\mathrm{Ar}/\mathrm{R}-\mathrm{OH}+\mathrm{R}-\mathrm{COOH}\stackrel{{\mathrm{H}}^{+}}{\to }\mathrm{Ar}/\mathrm{ROCOR}+{\mathrm{H}}_2\mathrm{O}$

Ar/R-OH + (RCO,)₂O + H⁺↔ Ar/ROCOR, + RCOOH

R/ArOH + R,COCl Pyridine→ R/ArOCOR, + HCl

• Reaction with hydrogen halides

ROH + HX yields→ RX + H₂O

• Dehydration

Alcohols H+, Heat→ Alkene + H₂O

Order of reaction

Tertiary > Secondary > Primary

• Oxidation

Alcohol Acidified KMnO₄→ Carboxylic acid

RCH₂OH Oxidation→ RCHO yields→ RCOOH

Reactions of phenol

• Halogenation

• Nitration

• Reimer-Tiemann reaction

• Kolbe’s reaction

• Reaction with zinc dust

• Oxidation

Some Commercially Important Alcohols

Methanol (CH₃OH)

• Wood-spirit is another name for it. It is a clear liquid with no discernible colour. It reaches a temperature of 337 degrees Fahrenheit when it boils. It is extremely poisonous. Even little doses can cause blindness, and excessive doses can even result in death

Preparation

CO + 2H₂ ZnO-Cr₂O₃,200-300 atm,573-673 K→ CH₃OH

Uses:

• Paints, varnishes, and other products use it as a solvent.It can be used to make formaldehyde.

Ethanol (C₂H₅OH)

• It is known as denatured spirit when combined with CuSO₄ and pyridine.It is a colourless liquid having boiling point 351 K

Preparation

${\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11}+{\mathrm{H}}_2\mathrm{O}\stackrel{\text{ Invertase }}{\to }\underset{\text{ Glucose }}{{\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6}+\underset{\text{ Fructose }}{{\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6}$

${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\stackrel{\text{ Zymase }}{\to }2{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}+2{\mathrm{CO}}_2$

Uses: It is a good solvent, Sterilization of surgical tools in laboratories and hospitals.

Preparation of Ether

a)By dehydration of alcohols

CH₃CH₂OH$\underset{443\mathrm{K}}{\overset{{\mathrm{H}}_2{\mathrm{SO}}_4}{\to }}{\mathrm{CH}}_2={\mathrm{CH}}_2$

CH₃CH₂OH $\underset{413\mathrm{K}}{\overset{{\mathrm{H}}_2{\mathrm{SO}}_4}{\to }}{\mathrm{C}}_2{\mathrm{H}}_5{\mathrm{OC}}_2{\mathrm{H}}_5$

b)Williamson synthesis

R-X + R-O-Na → R-O-R + NaX

Physical Properties of Ethers

Since ethers' C-O bonds are polar, they have a net dipole moment. Their boiling points are equivalent to alkanes with similar molecular weights, although they are lower than alcohols. It's because ethers don't have H-bonding. Ether miscibility with water is similar to that of alcohols of same molar mass. It's because ethers, like alcohols, can make H-bonds with water.

Chemical Properties of Ethers

a)Cleavage of C-O bonds

R-O-R + HX → RX + R-OH

R-OH + HX → R-X + H₂O

R-O-R + HX → R-X + R-OH

b)Electrophilic substitution reactions

• Halogenation

• Friedel craft’s reaction

• Nitration

Significance of NCERT Class 12 Chemistry Chapter 7 Notes

Alcohols, Phenols and Ethers class 12 notes provide significant insights for board exams and competitive exams like JEE and NEET. Class 12 chemistry chapter 7 notes can help you grasp the fundamental principles. This chapter is also useful for entrance exams and competitive exams like VITEEE, BITSAT, JEE Main Core, NEET, etc. As a result, knowledge of that chapter becomes much more important.

NCERT Class 12 Notes Chapter-Wise

Subject Wise NCERT Exemplar Solutions

Subject Wise NCERT Solutions

NCERT Books and Syllabus