Chapter 8 Reactions + Info

HX (HCl, HBr, HI): Product and rules?

Alkyl halide. Markovnikov X, carbocation, rearrangements possible, no fixed syn/anti.

HBr + ROOR: Product and rules?

Alkyl bromide. Anti-Markovnikov Br, radical mechanism, no carbocation rearrangement.

Br₂ or Cl₂: Product and rules?

Vicinal dihalide (X on both alkene carbons). ANTI addition, no rearrangement.

Br₂ or Cl₂ + H₂O: Product and rules?

Halohydrin. OH on MORE substituted C, X on LESS substituted C. ANTI addition.

Br₂ or Cl₂ + ROH: Product and rules?

Haloether. OR on MORE substituted C, X on LESS substituted C. ANTI addition.

H₃O⁺ or H₂SO₄/H₂O: Product and rules?

Alcohol. Markovnikov OH, carbocation, rearrangements possible, no fixed syn/anti.

ROH + H⁺: Product and rules?

Ether. Markovnikov OR, carbocation, rearrangements possible, no fixed syn/anti.

1. BH₃/THF 2. H₂O₂/OH⁻: Product and rules?

Alcohol. ANTI-Markovnikov OH, SYN addition, no rearrangement.

1. Hg(OAc)₂/H₂O 2. NaBH₄: Product and rules?

Alcohol. Markovnikov OH, NO rearrangement, no fixed overall syn/anti.

1. Hg(OAc)₂/ROH 2. NaBH₄: Product and rules?

Ether. Markovnikov OR, NO rearrangement, no fixed overall syn/anti.

H₂ + Pd/C, Pt, or Ni: Product and rules?

Alkane. Adds two H atoms SYN across C=C.

mCPBA (RCO₃H): Product and rules?

Epoxide (3-membered oxygen ring). Stereospecific; alkene cis/trans relationships are retained.

1. X₂/H₂O 2. NaOH: Product?

Epoxide. First form a halohydrin, then intramolecular SN2 ring closure.

Epoxide + H₃O⁺/H₂O: Product and rules?

Anti vicinal diol. Acidic opening; water usually attacks the MORE substituted epoxide carbon.

Epoxide + ROH/H⁺: Product and rules?

Anti alkoxy alcohol. ROH usually attacks the MORE substituted epoxide carbon.

Epoxide + strong Nu⁻ under basic conditions: Rules?

Nu⁻ attacks the LESS substituted epoxide carbon by backside SN2, with inversion there.

OsO₄ followed by workup: Product and rules?

Vicinal diol. SYN addition of two OH groups; cis on a simple cycloalkene.

1. mCPBA 2. H₃O⁺: Product and rules?

Vicinal diol. ANTI addition of two OH groups; trans on a simple cycloalkene.

1. O₃ 2. DMS or Zn/H₂O: Product?

Reductive ozonolysis. Cleaves C=C and converts each alkene carbon into a carbonyl.

Ozonolysis: What do alkene carbons with 0, 1, or 2 H become?

0 H → ketone; 1 H → aldehyde; 2 H → formaldehyde.

Which alkene additions form carbocations that can rearrange?

Ordinary HX, H₃O⁺ hydration, and ROH/H⁺ ether formation.

How do carbocation rearrangements work?

Neighboring C–H or C–C bond migrates with its electrons toward C⁺. Positive charge moves to the donor carbon. Favor greater stability or ring-strain relief.

Which three reactions produce alcohols, and how do they differ?

H₃O⁺: Mark, rearranges. Oxymercuration: Mark, no rearrangement. Hydroboration: Anti-Mark, syn, no rearrangement.

Which two reactions form ethers, and how do they differ?

ROH/H⁺: Mark, rearrangements possible. Alkoxymercuration: Mark, no rearrangements.

What do syn, anti, wedge, and dash mean?

Syn = same-face addition; anti = opposite-face addition. Wedge = toward you; dash = away. Don't automatically equate syn with two wedges in every drawing.

HX mechanism: What arrows and intermediates?

π bond attacks H; H–X bond electrons go to X → carbocation. Rearrange if favorable. X⁻ attacks C⁺.

X₂ halogenation mechanism?

π bond reacts with X₂ → bridged halonium ion. X⁻ attacks from backside, opening ring → anti dihalide.

X₂/H₂O or X₂/ROH mechanism?

Form halonium ion → H₂O/ROH attacks more substituted C from backside → deprotonation → anti halohydrin/haloether.

Acid-catalyzed H₂O or ROH addition mechanism?

Protonate C=C → carbocation → rearrange if favorable → H₂O/ROH attacks → deprotonate O⁺.

Hydroboration mechanism: What must you draw?

Concerted 4-center syn addition of B–H across C=C. B bonds to LESS substituted C; H to MORE. Oxidation replaces C–B with C–OH (retention).

Oxymercuration mechanism: What must you draw?

Alkene forms bridged mercurinium ion → H₂O attacks MORE substituted C → deprotonation → NaBH₄ replaces HgOAc with H.

Alkoxymercuration mechanism: What must you draw?

Form bridged mercurinium ion → ROH attacks MORE substituted C → deprotonation → NaBH₄ replaces HgOAc with H.

Acid-catalyzed epoxide ring-opening mechanism?

Protonate epoxide O → H₂O/ROH attacks from backside (usually more substituted C) as C–O bond breaks → deprotonate.

OsO₄ mechanism: What intermediate forms?

Concerted addition across C=C forms a five-membered cyclic osmate ester with two C–O bonds on the same face.

Ozonolysis mechanism: What must you draw?

O₃ undergoes a concerted 1,3-dipolar cycloaddition across C=C → five-membered primary ozonide (molozonide).

Which detailed mechanisms are NOT required?

Organoborane oxidation by H₂O₂/OH⁻; NaBH₄ demercuration; osmate ester hydrolysis/NMO regeneration; molozonide rearrangement and ozonide workup.