CHM 112
WORKSHEET FOR ALKENES, ALKYNES AND HALOCARBONS
Spring 2002
1.
Explain, based on the appropriate IMFs, why the melting points and boiling points of
alkenes and alkynes are so low.
Since the bonding in these molecules is non-polar covalent, the forces between molecules
are weak dispersion forces and the crystals they form are molecular crystals with weak
interactions between lattice points. Weaker forces require less energy to overcome.
Therefore, the melting points and boiling points are lower.
2.
Explain why double and triple carbon-carbon bonds are planar while a single C-C bond is
not.
For single bonds, carbon forms sp3 hybrid orbitals that arrange themselves 109.5o away in
three-dimensional space. Carbon in a double bond forms sp2 hybrid orbital and these are
arranged at 120o on a plane while carbon in a triple bond undergoes sp hybridization and
the resulting orbitals are180o apart, in a line.
3.
Write the IUPAC name for each of the following compounds.
CH 3
H
C
CH 3
H3C
H
C
C
H3C
CH
CH 3
CH
C
H
Br
CH 3
CH
H3C
CH 2
Br
CH 3
2-methyl-2-butene
3, 4-dibromo-1-cyclohexene
4, 5, 6-trimethyl-2-octene
H3C
H2
C
H3C
CH
CH
Cl
CH 2
CH 3
CH
CH 2
C
Br
Cl
H2C
H
C
C
Cl
Cl
C
H
CH 3
C
H2
CH 2
H3C
4-bromo-3-methyl-1-hexyne
5, 5-dichloro-3-nonene
1, 1-dichloro-2-ethyl
cyclopentane
4.
Write the full or condensed structural formulas for each of the following compounds.
1, 4-diiodo-1-cyclohexene
4-isopropyl-1-octene
H3C
I
CH 3
CH
H
C
H2C
I
2, 2-dichloro-5, 5, 6-trimethyl-3-decyne
H2
C
CH
C
H2
C
H2
CH 3
C
H2
2-bromo-1-iodo-3-methyl cyclopentane
I
Cl
CH 3
CH 3
C
H3C
C
H2
C
CH
C
C
Cl
C
H2
CH 3
Br
C
H2
CH 3
CH 3
H
H
cis-2-pentene
C
H3C
C
CH 2
H3C
5.
Look at the structures for 6-dodecene below. Which one has a trans double bond
configuration and which one has a cis configuration? How do the configurations affect
the overall shape of the molecule?
trans-6-dodecne
cis-6-dodecene
The hydrogens are on opposite sides of the molecule in the first image so it must be trans
while the hydrogens are on the same side in the second image so this must be the cis
configuration. When the same groups (i.e. hydrogens or carbon chains) are on the same
side of the double bond, the chain bends or appears to have a kink in it.
6.
Complete the following reactions:
H
C
H3C
+ H2O
C
OH
H2
C
H+
CH3
CH3
H3C
C
CH3
CH3
Br2/CCl4
CH3
CH3
Br
Br
Cl
H
C
CH 3
HCl
CH
C
H2
H2C
Cl
H3C
H2
C
C
C
H2
Cl
C
H2
CH 3
C
H2