UNIT 6
Theories of Covalent Bonding and
Intro to Organic Chemistry:
Nomenclature of Alkenes, Alkynes,
Alcohols
Structural Isomers Have the Same
Molecular Formula
Draw the line angle structure of:
(C H 3 ) 2 C H C H 2 C (C H 3 ) 3
The molecular formula of this compound is
C8H18. Draw three more structural isomers of
octane.
Valence Bond Descriptions
.. .. ..
:O = S = O:
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.
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
Nomenclature of Alkenes
H 3C
H
C
H 3C
H 3C
CH3
C
C
C
H
H
H
cis-but-2-ene
C H 3C H 2
C
bp = 4°C
H
methylpropene
bp = - 7°C
What are the bond
angles?
H
C
H
geometric isomers
but-1-ene
H 3C
H
C
H
bp = -6°C
C
CH3
trans-but-2-ene
bp = 1°C
All four are
structural isomers.
Nomenclature of Alkenes
Name this alkene.
Cl Cl
6,6-dichloro-5-ethyl-4-methylhept-1-ene
Give a VB description of the C-Cl bond.
Draw the line angle structure for
1-chloro-3-methyl-1,3-butadiene
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.
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
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 CC pi bonds.
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:
 Tertiary (3°) alcohols:
R,R',R″
R - CH - R' designate the
|
rest of the
OH
molecule.
R″
R represents an
|
alkyl group.
R - C - R'
|
OH
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.
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
CH3CHCH3
|
OH
IUPAC (common)
propan-2-ol (isopropyl alcohol)
or 2-propanol
CH3CHCH2CH3 butan-2-ol or 2-butanol
|
OH
Nomenclature of Alcohols
isopropyl alcohol
IUPAC: propan-2-ol
or 2-propanol
t-butyl alcohol
IUPAC: methylpropan-2-ol
ethylene glycol
IUPAC: ethane-1,2-diol
Which are primary? Secondary? Tertiary?
Nomenclature of Alcohols
OH
OH
OH
OH
OH
Br
1°? 2°? 3°? Give the IUPAC name of each.
Give a VB description of one of the O-H bonds.
Nomenclature of Alcohols
propylene glycol
glycerine, glycerol
IUPAC: propane-1,2,3-triol
phenol
IUPAC: phenol
Draw the line angle structure for
2-methyl-3-butyn-2-ol
Nomenclature of Alcohols
IUPAC:
10,13-dimethyl-17-(6-methylheptan-2-yl)2,3,4,7,8,9,11,12,14,15,16,17dodecahydro-1H-cyclopenta[a]phenanthren-3-ol
What is the H-C-C bond angle for either of the “dashed” H’s?
Draw Line Angle and 3-D Structures
Give Condensed Structural Formula
Cl Cl
O
H
C H 3 C C l 2 C H (C H 2 C H 3 )C H (C H 3 )C H 2 C H O
Functional Groups - Review
alcohol
ether
alkene
R = alkyl group
-X
halide
alkyne
amine (1°)
- C≡N
nitrile
Functional Groups - Review
aldehyde
ketone
carboxylic acid
ester
amide
aromatic
ring
Functional Groups
Circle and label each functional group.
fructose
threonine
γ-butyrolactone (GBL)
O
H
acetaminophen
O
O