Download Alkynes Def: unsaturated hydrocarbon with The framework → triple

Alkynes
Def: unsaturated hydrocarbon with
The framework Æ triple bond consists of:
*Like alkenes, pi bonds
IUPAC naming: Similar to
• Longest continuous chain with
• Parent compound =
• Number to give
Ex:
4-sec-butyl-2-octyne
Br
CH3
Cl
Summer Notes
NO2
CHE 261
Chpt. 9 – pg. 1`
FG Priority
**When multiple
•
•
•
•
•
•
•
•
•
•
• FG given
• Highest priority =
• Highest priority also
• Multiple bonds
• Other FG named
Esters
Aldehydes
Ketones
Alcohols
Amines
Alkenes
Alkynes
Ethers
Ex:
OCH3
OH
Common Naming: as derivatives of
H
C
C
R
H
C
C
H
R
C
C
R'
Ex:
CH2CH3
C
Summer Notes
C
H
C
CHE 261
C
CH3
C
Chpt. 9 – pg. 2`
C
CH(CH2)3
*Properties of alkynes depend on :
R
C
C
R
H
C
C
R'
Physical Properties:
• Nonpolar Æ
• Low Mol. Wt. (≤ C4) Æ
• Boiling pts Æ
• Density Æ
• *Acidity Æ
Table 9-2 ( pg 388)
o High
o Electrons of conj. Base
Ex: Which base can deprotonate acetylene, alkoxides or amide ions?
*Remember in acid-base reactions,
H
C
C
H
H
C
C
H
OR
NH2
*Acetylide ions are
Summer Notes
CHE 261
Chpt. 9 – pg. 3`
Reactions of Alkynes
1.
H
2.
Nucleophilic substitution
C
C
R
X
Snythesis by
*Requires
R
3.
X
X
C
C
H
H
(
)
R
Addition reactions “Whatever alkenes can do
1 equivalent reactant Æ
2 equivalents reactant Æ
Ex: Hydrogenation
R
C
C
R'
*Correct reactant/catalyst can select
Lindlar’s catalyst Æ
Na/NH3 Æ
Other additions: X2, HX, HOH*
Summer Notes
CHE 261
Chpt. 9 – pg. 4`
Ex: Addition of HOH – Markovnikov orientation
*Catalyzed by
R
C
C
H
H2O
HgSO4
H2SO4
Keto-enol tautomerization – rapid equilibrium of
Ex: Addition of HOH – Anti-markovnikov orientation
*Called
R
C
C
H
(1) Sia2BH*THF
(2) H2O2 , NaOH
Suggested problems: 27(a, b, c, h ,k), 28a, 29(a, b, c, d), 30a, 33 (a, b, c,
d, e, f, l, m)
Summer Notes
CHE 261
Chpt. 9 – pg. 5`