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ALKYNES
ALKYNES-Characterized by C C triple bond(s)
-Classified as unsaturated hydrocarbons
-empirical formula = CnH2n-2
(applies when the molecule only has one triple bond)
CnH2n-2, n=5
= C5H8
ALKYNESProperties:-Are hydrophobic like all hydrocarbons
-Have higher boiling points than alkanes and alkenes due to their ability to stack
ALKYNESSome IUPAC names of alkynes:
All alkynes have the suffix “yne”
ethyne propyne but-1-yne
ALKyNESIUPAC naming system:
prefix suffix
Number of carbons in the longest chain
family
but yneEx:
-#-
Location number
-1-
ALKYNESIUPAC naming system:
Name the following alkynes:
hex-1-yne hex-3-yne
ALKYNESIUPAC naming system:
Name the following alkynes:
4-methylhex-2-yne 5-ethyl-4,6,7-trimethylnon-2-yne
1 2 3 4
5 61
23
456
7
89
The triple bond has a higher numbering priority than the alkyl and halide substituents
ALKYNESIUPAC naming system:
Name the following alkynes:
hex-4-en-1-yne 3-ethylhept-1-en-4-yne
Alkenes are ordered first in the name, and the “e” ending is dropped.
Generally, double bonds and triple bonds have equal numbering priority* (aim to get the lowest numbers).
1
23
4
5
6
1 2
3 4 5 6
7
ALKYNESIUPAC naming system:
Name the following alkynes:
hex-1-en-5-yne
1
2
3
4
5
6
hex-5-en-1-yneor
65
43
2
1
*Double bonds have higher priority than triple bonds whenever there is ambiguity in their numbers. This uses the rule where alpha-order is final tie-breaker like before.
ALKYNESIUPAC naming system:
Name the following alkynes:
cyclononyne cyclooct-1-en-4-yne
1
2
3
4 5
6
7
8
ALKYNESIUPAC naming system:
Name the following alkyne:
3,4,5-trichloro-8,9-diethyl-5,7,7-trifluorocyclononyne
12
3
4
5
67
8
9
FF
F
Cl
Cl
Cl
ALKYNESDrawing alkynes:
Draw the following alkynes using line diagrams
non-2-yne
6
5
4
3
2
1
7
8
9
The triple bond cannot bend, so the bonds adjacent to a triple bond must be straight.
non-1-yne
6
5
4
3
2
1
7
8
9
ALKYNESDrawing alkynes:
Draw the following alkynes using structural diagrams
4,5-dibromohex-2-yne
C
H
Br
C
H
H
HC C
H
Br
C
H
H
CH
1,2-dimethylcyclooct-1-en-4-yne
C
C C
C C
C
C HH
H
C
H
H
H
H
H
H
HC
C
HH
HH
ALKENESRECALL:
Name the following alkenes:
4-methylpenta-1,3-diene hepta-1,3,6-triene
When there is more than one double bond, add the letter “a” to the end of the prefix (i.e. buta)
ALKYNESMultiple Double Bonds AND/OR Triple Bonds:
octa-2,4-dien-6-yne
When there is more than one triple bond, AND a double bond, add the letter “e” to the end of the double bond sufix -ene
dec-1-ene-4,9-diyne
When there is more than one double bond AND a triple bond, add the letter “a” to the end of the prefix (i.e. buta)
nona-5-7-diene-1,3-diyne
ALKYNES
undeca-1,6,-diene-3,9-diyne