Module No.
03(Q2)
Structure and nomenclature of Hydrocarbon compounds
Describe alkyne as hydrocarbon compound.
Specific Objectives
At the end of this module, learners are expected to:
1. describe and name simple alkynes;
2. use the general formula for alkyne to predict its molecular formula and
structural and condensed formula; and
3. draw the structures of alkyne.
Materials
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Pen
Bond paper or intermediate paper
Any Chemistry book or Laboratory Manual
Lesson
Another aliphatic hydrocarbon is alkyne which is under unsaturated
hydrocarbon. How are we going to distinguish alkane from alkene and alkyne?
Let’s start the discussion to compare at the later part.
1
The alkynes (also called acetylene) contain at least one carboncarbon triple bond. It has a general formula of CnH2n -2, where n = 2, 3, . . . .
The simplest alkyne is C2H2, ethylene, which is use for cutting and welding
metals.
Examples of Alkynes
Naming Alkynes
In naming alkynes, we follow the same guidelines used in alkanes except that
we first locate the presence of triple bond and assign the lowest possible
number in its location. The names of compounds containing triple bonds end
with -yne. As with the alkanes, the name of the parent compound is
determined by the number of carbon atoms in the longest chain. Numbering
the parent chain begins at the end nearer the triple bond so that the triple
2
bond receives a lower number. Compounds with more than one triple bond are
called diynes, triynes, and so forth.
Give the IUPAC names of the following compounds:
https://www.google.com/search?q=alkynes+examples&rlz=1C1SQJL_enPH774PH774&sxsrf=ALeKk025vY6LjIT9chG91AfJKB_Cc5wWw:1597895018619&tbm=isch&source=iu&ictx=1&fir=cql08v4UKETRCM%252C14c0C4njNqxdwM%252C_&vet=1&usg=AI4_kR8qUKguXvBDvV37o1CHhduhNaYNA&sa=X&ved=2ahUKEwi7kOTn7qjrAhUBfd4KHS57A1QQ_h0wA3oECAoQCg&biw=1366&bih=657#imgrc=57Y_B
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If you will name the two compounds, the first one is 2,2-dimethyl-3hexyne and the second one is 5-methyl-2-hexyne.
Directions: Do what is asked in the following given.
1. Draw the condensed formula for the following:
a. 3-methyl-1-butyne
b. 2,5,6-trimethyl-3,3-heptyne
c. 3-ethyl-4,5,5-trimethyl-1-hexyne
d. 2,5-dimethyl-3-heptyne
e. 4,4,5-trimethyl-2-hexyne
Agreement:
Give the IUPAC name of the following:
1.
2.
3
3.
4.
References
Chang, Raymond and Jayson Overby…General Chemistry The Essential
Concepts 6Th Edition. New York: The McGraw Hill Companies Inc, 2011
Key to Correction
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