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220 Chemistry: Matter and Change
Solving Problems: A Chemistry Handbook
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 21
The name of the compound is 2-ethyl-4,5-dimethyl-1,4-hexadiene.
Alkynes An unsaturated hydrocarbon that contains one or more
triple bonds between carbon atoms is called an alkyne. Alkynes with
one triple bond have the general formula C n H 2nϪ2 . The simplest
alkyne is ethyne (C 2 H 2 ), which is commonly called acetylene. The
next simplest alkyne is propyne (C 3 H 4 ). Their condensed structural
formulas are shown below.
Alkynes are named in the same way as alkenes, with the exception
that the name of the parent chain ends in -yne instead of -ene.
Practice Problems
5. Name the compounds represented by these condensed structural
formulas.
a.
b.
6. Draw condensed structural formulas for these compounds.
a. 3,3,4,4-tetramethyl-1-hexyne
b. 4-propyl-4-octene
c. 3-ethyl-2,6-dimethyl-2,5-heptadiene
Alkene and alkyne properties Both alkenes and alkynes are
nonpolar compounds with relatively low melting and boiling points
and low solubilities in water. These properties are similar to those of
alkanes. However, alkenes are more reactive than alkanes because
double bonds are good sites for chemical reactivity. The triple bonds
of alkynes cause them to be generally more reactive than alkenes.
▲
CH 2 CH 3
CH 3 CH 2
CH 3
CH 3 C CHCCH 2 CH 3
CH 3 CH 2
CH 3
CH 3
CH 3 C
CH CH
CH
Ethyne
Propyne
▲
CH 3 C CCH 2 C CH 2
CH 3
CH 3 CH 2 CH 3
6 5
4 3 2
1