Section 1 — Alcohols: Classification and Preparation

Alcohols are classified as 1° ($RCH_{2}OH$), 2° ($R_{2}CHOH$), or 3° ($R_{3}COH$) depending on the number of carbon substituents on the carbinol carbon. Key examples: ethanol (1°, SMILES:CCO), propan-2-ol (2°, SMILES:CC(O)C), 2-methylpropan-2-ol (3°, SMILES:CC(C)(C)O).

Preparation routes include:

• Acid-catalyzed hydration of alkenes (Markovnikov product — -OH to more substituted C)
• Grignard reaction: RMgX + HCHO → 1° alcohol; RMgX + RCHO → 2° alcohol; RMgX + $R_{2}CO$ → 3° alcohol
• Reduction: $NaBH_{4}$ for aldehydes/ketones; $LiAlH_{4}$ for carboxylic acids ($NaBH_{4}$ too weak for acids)

Section 2 — Alcohol Reactions: Dehydration and Oxidation

Dehydration: conc. $H_{2}SO_{4}$, 443 K; Saytzeff's rule → more substituted alkene; ease: 3° > 2° > 1°.

Oxidation ladder:

• 1° alcohol --[PCC]--> aldehyde (stops; anhydrous conditions, no gem-diol formation)
• 1° alcohol --[$KMnO_{4}$ or $K_{2}Cr_{2}O_{7}$]--> carboxylic acid (aqueous, complete oxidation)
• 2° alcohol --[any oxidant]--> ketone (no further oxidation under normal conditions)
• 3° alcohol → resistant to oxidation (no H on carbinol C)

Lucas test: $ZnCl_{2}$/conc. HCl — 3°: immediate turbidity (SN1, stable carbocation); 2°: 5-20 min; 1°: no reaction at RT.

Section 3 — Phenol: Acidity and Substituent Effects

Phenol (SMILES:Oc1ccccc1) pKa ~10 vs alcohol pKa ~16-18. Phenoxide ion is resonance-stabilized (5 structures), making phenol much more acidic than aliphatic alcohols.

Substituent effects on acidity:

• -$NO_{2}$ (para): more acidic (EWG, -M effect stabilizes phenoxide further)
• -Cl (para): slightly more acidic (-I effect)
• -$CH_{3}$ (para): less acidic (EDG, +I destabilizes phenoxide)
• -O$CH_{3}$ (para): less acidic (+M destabilizes phenoxide)

Section 4 — Phenol: Named Reactions and Electrophilic Substitution

The -OH group strongly activates the ring for electrophilic aromatic substitution (EAS) and directs to ortho/para positions.

• Bromination: $C_{6}H_{5}OH$ + $3Br_{2}$/$H_{2}O$ → 2,4,6-tribromophenol (white ppt) + 3HBr; no Lewis acid catalyst needed
• Kolbe reaction: PhO^{-}$$Na^{+} + $CO_{2}$ → (125°C, 4-7 atm) → sodium salicylate → [$H_{3}O^{+}$] → salicylic acid (SMILES:OC(=O)c1ccccc1O); -COOH at ortho
• Reimer-Tiemann reaction: PhOH + $CHCl_{3}$/NaOH → salicylaldehyde (SMILES:O=Cc1ccccc1O); intermediate is dichlorocarbene (:$CCl_{2}$); -CHO at ortho
• Esterification: PhOH + $CH_{3}$COCl → phenyl acetate (SMILES:CC(=O)Oc1ccccc1)

Section 5 — Ethers: Williamson Synthesis and Cleavage

Williamson synthesis (SN2):

$\text{R-O}^-\text{Na}^+ + \text{R'-X (1° only)} \rightarrow \text{R-O-R'} + \text{NaX}$

Mandatory use of 1° alkyl halide; 2° or 3° halides give E2 elimination with the alkoxide base.

HI cleavage (excess HI): R-O-R' + HI → RI + R'OH → [+HI] → RI + R'I

Both fragments become alkyl iodides. For unsymmetrical ethers, smaller alkyl group attacks first (SN2 preferred).