Reaction Mechanisms (alkynes)

KOH/200C

removes halides & creates internal alkyne

H2 & Pd, Pt, Ni

adds 2 H's twice to turn back into alkane

Li & NH3(l)

adds two H & turns into a trans alkene

H2/Pd(BaSO4)/ quinoline

-LINDAR

-add two H's & urns into a cis alkene

HgSO4/H20 & H2SO4

-mark

-terminal alkyne turns into ketone

1) Sia2BH

2. H2O2, BH

-anti-mark

-terminal alkyne turns into aldehyde

KMnO4, H2O & neutral,cold

creates vicinal carbonyls (ketones or carboxylic acid)

1) KMnO4/H2O

2) OH/heat

(terminal alkyne)

terminal alkyne turns into carboxylic acid, H2O, & CO2

1) KMnO4/H2O

2) OH/heat

(internal alkyne)

2 carbonyl groups (carboxylic acid)

1) O3

2) H2O

-Terminal alkyne turns into 1 carboxylic acid, H2O, & CO2

-internal alkyne turns into 2 carboxylic acids

HBr

-mark & syn

-1 eq: TB turns in to DB, add H & Br

-2 eq: DB breaks, add H & Br again

HBr & ROOR

-anti-mark & syn

- add H to most substituted & Br to least substituted (same stereo)

Br2

add 2 Br (can be Cis or Trans)

NaNH2

removes an H & turns a terminal alkyne into an acetylide ion

CH3Br

backside attack on acetylide ion & CH3 gets added to parent chain

H3CCH(Br)CH3

backside attack on acetylide ion & terminal DB is created

1) acetylide ion

2) H3O+

acetylide ion gets added to carbonyl group & O turns into OH because of H2O

1) NaNH2/150C

2) H3O+

removes halides & creates terminal alkyne