1. UNIT 6
Theories of Covalent Bonding and
Intro to Organic Chemistry:
Nomenclature of Alkenes, Alkynes,
Alcohols
2. Structural Isomers Have the Same
Molecular Formula
Draw the line angle structure of:
(CH3)2CHCH2C(CH3)3
The molecular formula of this compound is
C8H18. Draw three more structural isomers of
octane.
3. .. .. ..
:O = S = O:
Valence Bond Descriptions
What orbitals overlap to form
each of the bonds in SO2?
• The S-O sigma bond in each double bond is
formed by the overlap of an O sp2 hybrid
orbital with a S sp2 hybrid orbital.
• Each S-O pi bond is formed by the overlap of
the S 3pz orbital with the O 2pz orbital.
• Two sp2 orbitals on each of the O’s and one
sp2 orbital on the S are not involved in any
bond.
4. Nomenclature of Alkenes
Number the C chain from the end that
brings you to the double bond sooner,
then use the alkane naming rules and -ene.
IUPAC (common)
H2C=CH2 ethene (ethylene)
H2C=CH-CH3 propene (propylene)
Planar geometry around the double bond
120° bond angles to the C atoms in the
double bond
5. Nomenclature of Alkenes
geometric isomers
All four are
structural isomers.
What are the bond
angles?
trans-but-2-ene
bp = 1°C
cis-but-2-ene
bp = 4°C
methylpropene
bp = - 7°C
but-1-ene
bp = -6°C
C
C
H3C
H3C
H
H
C C
CH3
H3C
H
H
C C
H3C
H
H
CH3
C
H
H
H
CH3CH2
C
7. Alkynes
Contain at least one C≡C bond. Alkynes are
unsaturated molecules.
The two π bonds make the geometry through the
triple bond linear.
The triple bond is highly reactive, so alkynes are
not found widely in nature, though they are used as
intermediates in industrial processes.
8. Nomenclature of Alkynes
Number the C chain from the end that
brings you to the triple bond sooner, then
use the alkane naming rules and -yne.
IUPAC (common)
HC≡CH ethyne (acetylene)
HC≡C-CH3 propyne
Linear geometry around the triple bond
180° bond angles to the C atoms in the
triple bond
9. Alkynes
Draw the condensed structural formula and line angle
structure for 4-methylpent-2-yne.
CH3 - C ≡ C - CH - CH3
|
CH3
CH3C≡CCH(CH3)2
*
What is the hybridization on the starred C? What is
the geometry? Give a VB description of one of the C-
C pi bonds.
10. Alcohols
Contain the -OH (hydroxyl) group.
Alcohols are NOT bases. In fact, some can be
acidic (phenol).
Can be soluble in polar solvents such as water
(hydrocarbons are not soluble in water).
Primary (1°) alcohols: R – CH2 - OH
Secondary (2°) alcohols: R - CH - R'
|
OH
Tertiary (3°) alcohols: R″
|
R - C - R'
|
OH
R,R',R″
designate the
rest of the
molecule.
R represents an
alkyl group.
11. Nomenclature of Alcohols
Number the C chain from the end that
brings us to the -OH group sooner, then
use the alkane naming rules and -ol.
1° alcohols IUPAC (common)
CH3CH2OH ethanol (ethyl alcohol)
CH3CH2CH2OH propan-1-ol (n-propyl alcohol)
or 1-propanol
*CH3OH *Methanol is not primary, it’s a
methyl alcohol.
12. Nomenclature of Alcohols
Number the C chain from the end that
brings us to the -OH group sooner, then
use the alkane naming rules and -ol.
2° alcohols IUPAC (common)
CH3CHCH3 propan-2-ol (isopropyl alcohol)
| or 2-propanol
OH
CH3CHCH2CH3 butan-2-ol or 2-butanol
|
OH
13. Nomenclature of Alcohols
Which are primary? Secondary? Tertiary?
isopropyl alcohol
IUPAC: propan-2-ol
or 2-propanol
t-butyl alcohol
IUPAC: methylpropan-2-ol
ethylene glycol
IUPAC: ethane-1,2-diol
14. Nomenclature of Alcohols
1°? 2°? 3°? Give the IUPAC name of each.
OH
OH
OH
OH
Br
OH
Give a VB description of one of the O-H bonds.
15. Nomenclature of Alcohols
phenol
IUPAC: phenol
propylene glycol
glycerine, glycerol
IUPAC: propane-1,2,3-triol
Draw the line angle structure for
2-methyl-3-butyn-2-ol
16. Nomenclature of Alcohols
IUPAC: 10,13-dimethyl-17-(6-methylheptan-2-yl)-
2,3,4,7,8,9,11,12,14,15,16,17-
dodecahydro-1H-cyclopenta[a]phenanthren-3-ol
What is the H-C-C bond angle for either of the “dashed” H’s?
