Alkyne Reactions MT2

RC≡CR + H2 with Pt

RCH2CH2R,
Turns alkyne into the alkane

RC≡RC + H2 with Lindlar catalyst

Turns alkyne into the alkene, forms the cis alkene

RC≡RC
1. liquid Na, NH3
2. H+, H2O

Trans alkene

RC≡RC + HX
(repeat process twice)

RCH2CX2R
Geminial dihaloALKANE,
first time adding HX adds a halogen onto one of the adjacent carbons

RC≡RC
+ Br2, Br-

trans haloalkene (BRs on opposite side)

RC≡RC
Hg2+, H2O

alkane where one of the carbons has an caarbonyl group

RC≡CH
HBr, ROOR

RCH=CHBr
Br attaches to the less substituted carbon,

H attaches to the more substitued reaction
Remember radical bromination!

RC≡RC
1. CH3CH2CH2CH2Li
2. epoxide
3. H+, H2O

RC≡CCH2CH2OH
One of the R groups gets replaced by the Li, the carbon attached to the Li is now nucleophilic and attacks the epoxide (attacks more substituted side), then the water is attacked by the oxygen, adding an alcohol

RC≡CR
1. CH3CH2CH2Li
2. R’ (C=O) R’’
3. H+, H2O

adds another C which has R’ and R’’ and an OH group
(still alkyne)

what is tautomerizing and when does it happen?

tautomerization happens when an alkyne reacts with a acid, water, and Hg2+. When the alcohol group is formed, the H on the OH attaches to the other carbon and the O forms a double bond with the carbon its attached to!

RC≡CR

RC≡CR
NaNH2, liquid NH3
R’X (R’X = primary)

RC≡CR’