Chapter 8 - Molecule reactions

Question 1

What is t-BuOK (Potassium tert-butoxide)?

Answer 1

Strong base, bulky nucleophile.

Often used in elimination reactions (E2) to favor the formation of the less substituted (Hofmann) alkene. Removes a beta-hydrogen to form a double bond, often avoiding steric hindrance.

Question 2

What is MeONa (Sodium Methoxide)?

Answer 2

Strong base and strong nucleophile.

Can participate in both substitution (SN2) and elimination (E2) reactions, depending on conditions. In SN2, it replaces a leaving group with a methoxide group (-OCH3). In E2, it forms a double bond by removing a beta-hydrogen.

Question 3

What is OsO4 (Osmium Tetroxide)?

Answer 3

Oxidation.

Used in dihydroxylation reactions to add two hydroxyl (-OH) groups to a double bond (syn addition). Converts alkenes into 1,2-diols with both hydroxyl groups on the same face of the molecule.

Question 4

What is NaOH (Sodium Hydroxide)?

Answer 4

Strong base and nucleophile.

Acts in elimination (E2) reactions when paired with heat. In substitution (SN2) reactions, replaces a leaving group with a hydroxide group (-OH). Forms alkenes in elimination reactions and produces alcohols in substitution reactions.

Question 5

What is the function of HBr (Hydrogen Bromide) in reactions?

Answer 5

Addition.

Adds across a double bond in a Markovnikov fashion unless peroxides (ROOR) are present. Markovnikov adds Br to the more substituted carbon; Anti-Markovnikov (with ROOR) adds Br to the less substituted carbon.

Question 6

What reaction type is represented by Hg(OAc)2, H2O / NaBH4?

Answer 6

Oxymercuration-Demercuration.

Adds water across a double bond without carbocation rearrangements, producing alcohols with Markovnikov regiochemistry.

Question 7

What is the reaction type for BH3∙THF / H2O2, NaOH?

Answer 7

Hydroboration-Oxidation.

Adds water across a double bond in an anti-Markovnikov and syn addition fashion, producing alcohols with the hydroxyl group on the less substituted carbon.

Question 8

What is the function of Br2 (Bromine) in CCl4?

Answer 8

Halogenation.

Adds bromine across a double bond in an anti addition fashion, producing a vicinal dibromide with bromine atoms on opposite sides of the former double bond.

Question 9

What type of reaction does H2 / Pd, Pt, or Ni perform?

Answer 9

Catalytic Hydrogenation.

Reduces alkenes or alkynes to alkanes by adding hydrogen across the multiple bond (syn addition), removing double or triple bonds to saturate the molecule.

Question 10

What is KMnO4 (Cold, Dilute) used for?

Answer 10

Oxidation.

Adds hydroxyl groups (-OH) to both ends of a double bond in a syn fashion, producing a 1,2-diol.