Alkynes are hydrocarbons with a triple bond between two carbon atoms. Common alkynes include acetylene (C2H2), propyne, butyne, pentyne, etc. Their molecular formulas follow the pattern of CnH2n-2. Alkynes are named based on the number of carbons and whether the chain is straight or branched. They are generally reactive due to the triple bond. Alkynes undergo addition, polymerization, substitution, and combustion reactions. They can also form isomers based on chain structure or carbon position.

1. Alkynes

2. Group Members
Novella I.C (20)
Nurul Izzatil A. (21)
R. Dandy Y. (22)
Raka S.W.S (23)
Reyan P.B. (24)
Rizqi Cahyo .Y (25)
Rosita Devi (26)
Sabrina Amelia J. (27)
Zaynita A . A (28)

3. Alkynes
Alkynes are aliphatic hydrocarbons (strai
ght chain), unsaturated hydrocarbon with a
triple bond between two carbon atoms.
Alkynes are traditionally known as
acetylenes, although the name acetylene also
refers specifically to C2H2, known formally
as ethyne using IUPAC nomenclature.
Like other hydrocarbons, alkynes are
generally hydrophobic but tend to be more
reactive. It is widely thought to be the greatest
of all the functional groups.

4. Common Formula of
Alkynes
n 2n-2
n : Number of C

5. Function of Common
Formula of Alkynes
• Determine the molecular
formula alkynes compounds.
• The molecular structure of these
compounds can be described by the molecular
formula.
Example :
Number of Carbons: 3
Index Numbers of Hydrogen : 2(3)-2
= 6-2 = 4
Molecular Formula: C3H4

6. Number of Carbons: 5
Index Numbers of Hydrogens: 2(5)-2 = 10-2 = 8
Molecular Formula: C5H8
Number of Carbons: 7
Index Numbers of Hydrogen: 2(7)-2 = 14-2 = 12
Molecular Formula: C7H12
Number of Carbons: 9
Index Numbers of Hydrogen: 2(9)-2 = 18-2 = 16
Molecular Formula: C9H16
http://chemistry.about.com/od/lecturenoteslabs/tp/Simple-Alkyne-Chains.htm

7. Nomenclatur
e of Alkynes

8. Straight Chain
1. Check the type of bond, if it has a triplicate
bond, meaning the compound is an alkyne compound.
2. Count the number of its C atom.
3. Write the prefix based on the number
of its C atom and ending with the suffix-una.
4. If the number of C atoms alkyne compounds of more
than 3, give the number of each atom in such a way
that the smallest number is located on
the C atom attached to a triple
bond. Then, naming compounds is initiated by the
first C atom numbers are bound to triplicate
bonds, followed by a dash (-) and the name of the
main chain.
http://smartchemistry.wordpress.com/2012/02/14/tata-nama-senyawa-alkuna/

9. Example
Butyne
2 - Pentyne

10. Branched Chain
1. Check the type of bond, if it has a triplicate
bond, meaning the compound is an alkyne compound.
2. Determine the main chain and branch chain. The main
chain is determined from the longest chain
of C atoms containing a triplicate bond.
3. Give the number of each atom in such a way that
the smallest number is located on the C
atom attached to a triplicate bond.
4. The main chain are named by the
rules straight chain alkyne compound naming.
5. Branched chain named after the number
of C atoms and the structure of the alkyl group.
6. Order in a compound name with a sequence of
writing the name of the compound alkanes and
alkenes.
http://smartchemistry.wordpress.com/2012/02/14/tata-nama-senyawa-alkuna/

11. Example
3-methyle-1-butyne (true) 2-methyle-3-butyne (false)
2,2-dimethyle-3-heptyne

12. Although the determination is wrong because
the one of the main chain has the
longest chain, but doesn't through the
triplicate.

13. Determining of the main chain is true
(Name: 3,5-dimethyle-3-prophyle-1-hexyne
http://www.chem-is-try.org/materi_kimia/kimia_organik_dasar/hidro-karbon/alkuna/

14. Triplicate bond More than
One
1. Check the type of bond, if it has a triple bond, meaning the
compound is an alkyne compound.
2. Count the number of its C atom.
3. Count the number of triplicate bond.
4. If the number of all triplicate bonds = 2, compound names
end with the suffix-diuna. If the number of all triplicate
bonds = 3, compound names end with the suffix-triuna.
5. Give the number of each atom in such a way that the
smallest number is located in two or three C atoms bound to
the first triplicate bond. Then, naming compounds C atom
numbers preceded by the first and second / third that
bound to the triplicate bond, followed by a dash (-) and the
name of the main chain.
6. If there is a branched-chain, branched chain names similar
to the naming of alkyne compounds.

15. 1,3-Pentadiyne

16. Physical and
Chemical
Properties of
Alkyne

17. Physical Properties of
Alkyne
• Alkyne is non-
polar, have intermolecular
forces are weak and have
a molecular masssimilar
to alkanes and alkenes.
• The higher interest alkyne, the
greater the boiling point.
• At room temperature, the
first three tribes are gaseous, the
next rates are liquid, while the
greater rates are in solid shape

18. Some physical properties of the alkyne
Nama alkuna Mr
Melting Boiling
Molecular Density On phase
point point
formula (g/Cm3 ) 250 C
(oC) (0 C)
Etyne C2H2 26 -81 -85 Gas
-
Propyne C3H4 40 -103 -23 - Gas
But-1-yne C4H6 54 -126 8 - Gas
Pen-1-yne C5H8 68 -90 40 0,690 Cair
Hex-1-yne C6H10 82 -132 71 0,716 Cair
Hept-1-yne C7H12 96 -81 100 0,733 Cair
Okt-1-yne C8H14 110 -79 126 0,740 Cair
Non-1-yne C9H16 124 -50 151 0,766 Cair
Dec-1-yne C10H18 138 -44 174 0,765 Cair

19. Chemical Properties of
Alkyne
• With the same amount of C, the alkyne is
more reactive than alkanes
• The existence of a triple bond which is
owned alkyne allow the addition reactions,
polymerization, substitution and combustio
n

20. A. Addition reaction of alkynes
In contrast to alkenes, alkynes have triple
bonds so the adition reaction can take place in
two stages
Example
Alkyne adition with the halogen

21. • Alkyne adition to the halide acid
Markovnikov law applicable,
H atoms of hydrogen halides into atoms C
double bind more H atoms.

22. B. Polymerization reaction of alkynes
In the etyne addition polymerization reaction
(C2H2), two molecules etyne combine to
form one molecule vinyl etyne (C4H4)

23. C. Substitution reaction of alkynes
Substitution on the alkyne reaction involves the
release of H atoms bound to the C C bond at the
end of the chain of alkyne
2CH CH + 2Na 2CH C-Na + H2 CH C-CH3 + NaI
Etyne natrium asetilide propyne

24. D. Combustion reaction of alkynes
Combustion alkyne with a limited amount
of O2, CO or C will result in
2C2H2(g) + 5O2(g) 4CO2(g) + 2H2O(g)

25. Alkyne Isom
ers

26. Alkyne Isomers
Type of the alkyne isomers i structure
isomers, namely framework/chain isomers
and position isomers. Isomers of alkyne is
started from alkyne butyne.

27. Examples of C5H8 isomers :
• Chain isomers
Pen-1-yne 3-methyl but-1-yne
• Position isomers
Pen-1-yne Pen-2-yne

28. • Alkyne also get isomers with cycloalkene that called
functional group isomers
• C4H6 Functional group isomers
CH C CH2 CH3
CH CH2 CH
CH CH2 CH CH CH3
Cyclobutene 3-methyl cyclopropene

29. Thank
You