Alkynes Flashcards
1
Q
Oxymercuration forms
A
Ketones
2
Q
Why are asymmetrical internal alkynes not useful for synthesis?
A
Form mixture with similar polarity and molecular weight so are hard to separate
3
Q
pKa of terminal alkenes
A
25
4
Q
How to form alkynyl anion
A
NaNH2, organolithium or Grignard
5
Q
Alkyne with H2 Pd/C forms
A
Alkanes
6
Q
Alkyne with H2 and lindlar catalyst forms
A
Cis alkenes
7
Q
Alkyne with Na and liquid NH3 forms
A
Trans alkenes
8
Q
Why is lindlar cis selective
A
2 H atoms bound to catalyst so delivered simultaneously to alkyne and poisoned so stops at alkene
9
Q
Why is Na and liquid NH3 trans selective
A
Steric
10
Q
Reduction of alkynes when there’s a hydroxyl or ether group
A
Use RedAl or LiAlH4
11
Q
When does an alkyne become electrophilic
A
When there’s a C=O next to it
