Covers laboratory and industrial methods for preparing alcohols, including reactions of alkenes, haloalkanes, carbonyl compounds, and Grignard reagents. Discusses reaction conditions and mechanisms.
CH₂OH-CHOH-CH₂OH is a trihydric alcohol with three -OH groups on a 3-carbon chain, commonly known as glycerol.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard
The compound has a 2-carbon chain with -OH groups on both carbons. The base name is ethane, and with two -OH groups, it is ethane-1,2-diol.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard
Ethanol (CH₃CH₂OH) oxidizes to acetaldehyde, which has a CH₃CO- group and gives a yellow iodoform precipitate with I₂ and NaOH.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard
A trihydric alcohol has three -OH groups. Glycerol (CH₂OH-CHOH-CH₂OH) is a trihydric alcohol, also known as propane-1,2,3-triol.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard
Phenol reacts with conc. H₂SO₄ at 100°C to form phenol-4-sulfonic acid (4-hydroxybenzenesulfonic acid) via electrophilic substitution at the para position.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard
Pent-1-ene (CH₂=CHCH₂CH₂CH₃) reacts with H₂SO₄ and H₂O via acid-catalyzed hydration, adding -OH to the second carbon (Markovnikov’s rule) to form pentan-2-ol.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard
2-Methylpropan-2-ol ((CH₃)3COH), a tertiary alcohol, resists oxidation with KMnO₄ because it lacks an alpha hydrogen.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard
CH₂=CH-CH₂OH is a 3-carbon compound with a double bond and an -OH group, commonly known as allyl alcohol.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard
Hydroboration-oxidation of propene (CH₃-CH=CH₂) follows anti-Markovnikov addition, yielding propan-1-ol (CH₃-CH₂-CH₂OH).
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard
CH₃-CH(OH)-CH₂-OH (propane-1,2-diol) is a 3-carbon diol, commonly known as propylene glycol.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard
Ethane-1,2-diol (CH₂OH-CH₂OH) has two -OH groups, leading to more extensive hydrogen bonding than ethanol (CH₃CH₂OH), which has one -OH group, increasing its boiling point.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard
Lucas reagent (ZnCl₂ in conc. HCl) reacts fastest with tertiary alcohols like (CH₃)3COH due to the stability of the tertiary carbocation, causing immediate turbidity.
Ref: NCERT Class 12 Chemistry > Chapter 7: Alcohols, Phenols and Ethers > Topic: Preparation of Alcohols - from Alkenes Haloalkanes Carbonyls Grignard
