OC Ch 03 — 5-Minute Cram

Walking into the hall. Reagent → product table. Markovnikov rule. Ozonolysis recipe. EAS recipes. Don't dwell on "why".

1. Alkene reactions — reagent → product

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Reagent	Product
H₂ / Pt	Alkane (syn)
Br₂ / CCl₄	vic-Dibromide (Br₂ test — decolourises)
HX (no peroxide)	Markovnikov alkyl halide
HBr + ROOR	Anti-Markovnikov 1° alkyl bromide
H₂O / H₂SO₄	Markovnikov alcohol
Cold dilute KMnO₄	cis-1,2-diol (Baeyer test)
Hot conc. KMnO₄ / H⁺	Cleavage: ketone + acid (terminal CH₂ → CO₂)
O₃ then Zn / H₃O⁺	Two carbonyls (aldehyde + ketone)

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EmpiricalH to the C with more H's; X to the more substituted C.

WhyMost stable carbocation intermediate: 3° > 2° > 1° > methyl.

ExceptionHBr + peroxide → anti-Markovnikov (radical chain). Only HBr does this.

Propene + HCl2-chloropropane

Propene + HBr/ROOR1-bromopropane

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RuleEach sp² C becomes C=O. C had H → aldehyde. C had 2 C-subs → ketone.

Terminal =CH₂→ HCHO (formaldehyde)

2-methyl-2-butene→ acetone + acetaldehyde

Cyclohexene→ hexanedial (ring opens to single chain)

1-butene→ propanal + HCHO

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Reaction	Reagent	Electrophile	Product
Halogenation	Br₂ / FeBr₃	Br⁺	PhBr
Nitration	HNO₃ / H₂SO₄	NO₂⁺	PhNO₂
Sulfonation	SO₃ / H₂SO₄	SO₃H⁺	PhSO₃H
F-C alkyl.	RCl / AlCl₃	R⁺ (rearranges!)	PhR
F-C acyl.	RCOCl / AlCl₃	RCO⁺	PhCOR

o/p directors–OH, –OR, –NH₂, –R, halogens (activating except halogens which deactivate)

m directors–NO₂, –CN, –CHO, –COR, –COOH, –SO₃H (all deactivators)

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≡C–H pKₐ~25 (weakly acidic). Internal alkynes have no acidic H.

NaNH₂→ R–C≡C–Na (sodium acetylide)

[Ag(NH₃)₂]NO₃→ white Ag–C≡C–R ppt

[Cu(NH₃)₂]Cl→ red Cu–C≡C–R ppt

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F"C=C is two identical π bonds." → 1σ + 1π.

F"Benzene is unsaturated so addition > substitution." → opposite. EAS wins because aromaticity is preserved.

T"Cyclopropane vs propene by Br₂/CCl₄." — propene decolourises.

F"Markovnikov puts X on the less-substituted C." → X goes to the MORE substituted C.

McMurry & Ballantine 8e Ch 14 · TMU Slide pp.1–106 · Past Papers 2019–2022