Alkenes and alkynes

What is Markovnikov addition in hydrohalogenation?

The hydrogen atom adds to the less substituted carbon, forming the more stable carbocation.

What is Anti-Markovnikov addition in hydrohalogenation?

The hydrogen adds to the more substituted carbon, usually in the presence of peroxides (H2O2), and Br adds to the less substituted one.

Does hydrohalogenation involve rearrangements?

Yes, due to the carbocation intermediate.

What reagent causes anti-Markovnikov hydrohalogenation?

HBr with ROOR (peroxides).

What is the product of acid-catalyzed hydration of an alkene?

An alcohol via Markovnikov addition of H and OH.

What are the reagents for acid-catalyzed hydration?

H3O+, or H2O with catalytic H2SO4.

Does acid-catalyzed hydration involve rearrangements?

Yes, due to carbocation intermediates.

What is the main advantage of oxymercuration-demercuration over acid hydration?

No rearrangements due to absence of carbocation intermediate.

What are the reagents for oxymercuration-demercuration?

1) Hg(OAc)2, H2O, THF 2) NaBH4

What is the stereochemistry of hydroboration-oxidation?

Syn addition.

Is hydroboration-oxidation Markovnikov or anti-Markovnikov?

Anti-Markovnikov.

What are the reagents for hydroboration-oxidation?

1) BH3, THF 2) H2O2, NaOH

What is the stereochemistry of dihalogenation?

Anti addition.

What intermediate is formed in dihalogenation?

A halonium ion intermediate.

What solvent is typically used in dihalogenation?

CCl4 or another non-nucleophilic solvent.

What is the product of halohydrin formation?

A halogen and an OH group on adjacent carbons.

Where does the OH group add in halohydrin formation?

To the more substituted carbon.

What reagent forms epoxides from alkenes?

Peroxyacid like mCPBA.

What is the stereochemistry of anti dihydroxylation?

Anti addition.

What are the reagents for anti dihydroxylation?

1) mCPBA 2) H3O+ or NaOH

What reagents are used for syn dihydroxylation?

Cold KMnO4/NaOH or 1) OsO4 2) H2O2

What products are formed in ozonolysis of alkenes with reductive workup?

Aldehydes or ketones.

What are the reagents for reductive ozonolysis?

1) O3 2) DMS or Zn/HOAc

What products are formed in ozonolysis with oxidative workup?

Carboxylic acids or ketones.

What is the stereochemistry of catalytic hydrogenation?

Syn addition.

What reagents are used in catalytic hydrogenation?

H2 with Pt, Pd, or Pd/C.

What reagent gives cis alkene from alkyne?

H2 with Lindlar's catalyst.

What reagent gives trans alkene from alkyne?

Na or Li in liquid NH3.

What is the product of alkyne ozonolysis with H2O?

Carboxylic acids (and CO2 if terminal alkyne).

What is the result of acid-catalyzed hydration of alkynes?

Ketone via enol intermediate (Markovnikov).

What is the result of hydroboration-oxidation of terminal alkynes?

Aldehyde via enol intermediate (anti-Markovnikov).

What base is used to deprotonate terminal alkynes?

NaNH2 or NaH.

What is formed after deprotonating a terminal alkyne?

Acetylide ion (strong nucleophile).

What reaction extends the carbon chain of a terminal alkyne?

Alkylation via SN2 reaction with a methyl or primary alkyl halide.