Reactions

Hydration of Alkenes

uses H2O requires an acid catalyst (H+)

rearrangements possible (carbocation intermediate)

markovinkovs rule

product is an alcohol

Pi bond is Nucleophile

H-Br

rearrangements possible

follows Markovnikov’s rule

Halogenation of Alkene form vicinal dihalide

adds Br2 or Cl2

anti-addition

solvent is CH2Cl2

no rearrangements (cyclic intermediate)

vicinal dihalide

Halogenation of alkene form halohydrin

Adds Br2 or Cl2

solvent is H2O

anti-addition

functional groups added: alcohol and alkyl halide

Oxymercuration / Demercuration Reaction of Alkenes

Markovnikov’s addition

no rearrangements

Step 1: Hg(OAc)2, H2O

Step 2: NaBH4

alcohol is product

Epoxidation of Alkene

adds either peracetic acid or mCPBA

no rearrangements

3 membered ring with oxygen formed

epoxide product

Hydroboration / Oxidation Reaction of Alkene

step 1: BH3, THF

step 2: H2O2, H2O, HO-

adds in anti-markovikovs rule

final product is alcohol

Hydrogenation of Alkene

adds H2 with metal catalysts Pt, Pd, or Ni

syn-addition

product is alkane

Hydrohalogenation of Alkynes

adds HCl, HBr, or HI

follows markovinkovs rule

intermediate is vinylic carbocation

using 2 moles creates geminal dihalide

Halogenation of Alkynes

Adding Br2 or Cl2

anti-addition: double bonds don’t rotate

2 mols to keep reaction going

Hydration of Alkynes

adding H2O and H+

markovinkovs rule

product is ketone

vinyl carbocation

enol forms to ketone called tautomerization

Hydroboration / Oxidation of Alkynes

step 1: BH3

step 2: H2O2, H2O, HO-

anti-markovinkov

aldehyde is product

enol forms to aldehyde called tautomerization

Hydrogenation of Alkynes

Add H2 and Pd, Pt, or Ni to form alkane (impossible to stop at double bond)

can use Lindlar’s catalyst to form cis-alkene

can use Na0, Li0, or NH3 to form trans-alkene

Terminal Alkyne Reactions

Terminal alkyne is slightly acidic, requires a strong base: NaNH2

product is an acetylide anion and can react with a carbon electrophile