Alkynes (Reactions)

alkylation reaction

alkane and halogen

dehydrohalogenation mechanism

start with alkene and a halogen (Br2, Cl2)

halogenation

alkyne and Br2 or Cl2

n/a symmetric, 1st and 2nd additions anti, 2nd addition removes stereocenters 

regioselectivity and stereoselectivity of halogenation 

addition of hydrogen halides

alkyne and HX (X is Br or Cl) 

markovnikov, n/a

regioselectivity and stereoselectivity of addition of hydrogen halides

geminal dihalide

product of hydrogen halide addition

hydroboration oxidation for terminal alkyne

hydroboration oxidation for internal alkyne

R2BH H2O2 NaOH

reagents for hydroboration oxidation

non markovnikov n/a

regioselectivity and stereoselectivity for hydroboration oxidation

acid catalyzed hydration

H2SO4 H2O 

reagents for acid catalyzed hydration

markovnikov n/a

regioselectivity and stereoselectivity for acid catalyzed hydration

hydrogenation lindlar catalyst

n/a syn cis product

regioselectivity and stereoselectivity for hydrogenation with lindlar

dissolving metal reduction

NaNH3

reagents for dissolving metal reduction

n/a anti trans product

regioselectivity and stereoselectivity for dissolving metal reduction 

hydrogenation

adds 2H per pi bond