Alcohols Flashcards
(32 cards)
Q: How are monohydric alcohols classified based on the carbon bearing the –OH?
Primary (1°): –OH on a C attached to 1 other C (e.g., ethanol)
Secondary (2°): –OH on a C attached to 2 other Cs (e.g., propan-2-ol)
Tertiary (3°): –OH on a C attached to 3 other Cs (e.g., tert-butanol)
Q: Classify ethanol, 2-propanol, and 2-methyl-2-propanol as primary, secondary, or tertiary.
Ethanol (CH₃CH₂OH): Primary (OH attached to 1° C).
2-Propanol (CH₃CHOHCH₃): Secondary (OH attached to 2° C).
2-Methyl-2-propanol (C(CH₃)₃OH): Tertiary (OH attached to 3° C).
Q: Give one common name and the IUPAC name for each class above.
1°: Common: Ethyl alcohol IUPAC: Ethanol
2°: Common: Isopropyl alcohol IUPAC: Propan-2-ol
3°: Common: tert-Butyl alcohol IUPAC: 2-Methylpropan-2-ol
Q: How do you hydrate an alkene to its alcohol? Conditions?
A: Electrophilic addition of steam:
Reagent: H₂O(g) + H⁺ catalyst
Conditions: 300 °C, 60 atm,
H₃PO₄
(Markovnikov addition)
Q: ii) What happens when alkenes react with KMnO₄ (acidic)?
A: Cold, dilute KMnO₄ (acidic) → diols (vicinal diol). Not alkanes!
Q: How does a haloalkane turn into an alcohol? Conditions?
A: Nucleophilic substitution:
RX + NaOH(aq) →(∆) ROH + NaX
Conditions: Reflux, aqueous
∆ = Heat Given.
Reflux => heating in a special method
Q: Reduce a carbonyl to an alcohol — what reagent & conditions?
Reagents: NaBH₄ (mild) or LiAlH₄ (strong)
Conditions: NaBH₄: aqueous, 0–25 °C; LiAlH₄: dry ether, room temp
Q: How to get an alcohol from a carboxylic acid?
A: Strong reduction:
Reagent: LiAlH₄ in dry ether, reflux
Q: vi) Hydrolyze ethyl acetate to ethanol. Conditions?
A: Acid (H₂SO₄) or base (NaOH) + heat.
CH₃COOCH₂CH₃ → CH₃COOH + CH₃CH₂OH (acid) or CH₃COO⁻Na⁺ + CH₃CH₂OH (base).
Q: Which hydrolysis gives you an alcohol from an ester? Conditions?
A: Ester + H₂O ⇌ Alcohol + Acid
Conditions: Dilute H₂SO₄, reflux (acidic hydrolysis) or NaOH and heat (saponification)
Q: Rank these by acidity: phenol, ethanol, water. Why?
A: Phenol > Water > Ethanol
Phenol stabilized by resonance; ethanol least acidic due to alkyl donation
Q: Why is phenol more acidic than ethanol?
A: Phenol’s conjugate base (phenoxide) is stabilized by resonance; ethanol’s (ethoxide) is not.
Q: Complete combustion of ethanol gives…?
CH3-CH₂-OH + O₂
A: CO₂ + H₂O+ + heat 🔥
Q: Ethanol + SOCl₂ → ? Conditions?
A: Ethyl chloride (C₂H₅Cl) + SO₂ + HCl
Conditions: Pyridine, 0 – 5 °C
Q: 2) Convert ethanol to chloroethane using SOCl₂.
A: CH₃CH₂OH + SOCl₂ → CH₃CH₂Cl + SO₂↑ + HCl↑.
Q: Ethanol + PBr₃ → ?
A: Bromoethane (C₂H₅Br) + H₃PO₃
Conditions: Anhydrous, 0 – 25 °C
Q: Lucas test: how do 1°, 2°, 3° alcohols behave?
3° → “Formation of oily layer (turbidity)” in < 1 min
2° → “Formation of oily layer (turbidity)” in ~5-10 min
1° → “No formation of oily layer (no turbidity) at room temperature”
Q: KBr + H₂SO₄ + ROH → ?
A: RBr + KHSO₄ + H₂O
Conditions: Warm (40-60°C)
Q: 6) Esterify ethanol with acetic acid. Catalyst?
A: Conc. H₂SO₄ (protonates –OH, drives equilibrium).
Q: 7) Oxidize ethanol vs 2-propanol. Products?
Ethanol (1°): KMnO₄/H+ → CH₃COOH (carboxylic acid).
2-Propanol (2°): K₂Cr₂O₇/H+ → (CH₃)₂CO (ketone).
Q: Dehydrate ethanol to ethene — reagent & conditions?
A: Conc. H₂SO₄, 170 °C → CH₂=CH₂ + H₂O
Q: Form an ester from ethanol + acetic acid — how?
A: Fischer esterification:
Reagents: CH₃COOH + C₂H₅OH
Conditions: Conc. H₂SO₄, reflux
Q: Oxidation products of each alcohol?
1° → Aldehyde → Carboxylic acid
2° → Ketone
3° → No reaction under mild oxidants
Q: Which alcohols give the iodoform test? Conditions?
BACK:
✔ Works for:
Ethanol
2° alcohols with –CH₃ on –OH carbon
Reagents: I₂ + NaOH, warm
Observation: Yellow CHI₃↓
Example:
Isopropanol → CHI₃ + CH₃COO⁻
❌ Fails: Methanol, most 1° & 3° alcohols
