Download 6.5 Organic Lecture

4/18/2016
HYDROCARBONS
S
http://www.youtube.com/watch?v=mAjrnZ-znkY
HYDROCARBON BONDING
HYDROCARBONS
S
– A hydrocarbon is a compound consisting of only
hydrogen and carbon.
– The carbon to carbon can be single, double, or triple
bonds.
– The bonds are always nonpolar.
– Alkanes are hydrocarbons with only single bonds.
• Each successive compound differs from the
one before it only by a CH2
– As the number of Carbons increase so
does the MP/BP
– As the number of Carbons increase so does
structural isomers
HYDROCARBON BONDING
S
S
(A) straight
(B) branched
(C) in a closed ring
single (A)
double (B)
triple (C)
Each carbon atom has four
dashes, which represent
four bonding pairs of
electrons, satisfying the
octet rule.
1
S
First Ten Hydrocarbons
Name
2
ALKANES
CnH2n+2
3
4
5
6
Methane
Number of
Molecular
Carbon Atoms Formula
CH4
1
CH4
S
Condensed Structural
Formula
LEARN IT,
LOVE IT!
Ethane
2
C2H6
CH3CH3
Propane
3
C3H8
CH3CH2CH3
Butane
4
C4H10
CH3CH2CH2CH3
Pentane
5
C5H12
CH3CH2CH2CH2CH3
Hexane
6
C6H14
CH3CH2CH2CH2CH2CH3
Heptane
7
C7H16
CH3CH2CH2CH2CH2CH2CH3
Octane
8
C8H18
CH3CH2CH2CH2CH2CH2CH2CH3
Nonane
9
C9H20
CH3CH2CH2CH2CH2CH2CH2CH2CH3
Decane
10
C10H22
CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3
1
4/18/2016
H
S
#1 METHANE
S
S
#2 ETHANE
S
H H H H
H C H
H
H
C C C C H
H H H H
Methane
CH4
Butane
C4H10
Methane is Tetrahedral
H
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 634
#2 ETHANE
H
H
C
C
H
H
H
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 635
S
#3 PROPANE
S
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 635
2
4/18/2016
#3 PROPANE
H
H
H
H
C
C
C
H
H
H
S
Structure of Propane
S
H
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 635
#4 BUTANE
S
Structure of Butane
S
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 635
#5 PENTANE
S
S
Hydrocarbons
(alkanes)
SINGLE BOND
3
4/18/2016
ALKANE PROPERTIES
Name
Number of
Molecular Melting Boiling
Carbon Atoms Formula Point, oC Point, oC
S
# of
Isomers
Methane
1
CH4
-182.5
-161.5
0
Ethane
2
C2H6
-183.2
-88.6
0
n-Propane
3
C3H8
-187.7
-42.1
0
n-Butane
4
C4H10
-138.3
-0.5
2
n-Pentane
5
C5H12
-129.7
36.1
3
n-Hexane
6
C6H14
-95.3
68.7
5
n-Heptane
7
C7H16
-90.6
98.4
9
n-Octane
8
C8H18
-56.8
125.7
18
n-Nonane
9
C9H20
-53.6
150.8
35
n-Decane
10
C10H22
-29.7
174.0
75
butane
H H H H
H
NAMING ALKANES
S
1. Find the longest continuous chain of carbon
atoms in the molecule
2. Start numbering the chain at the carbon
nearest the first branching point
constituents have the lowest #s possible)
3. Name and number the constituents
Hydrocarbon groups that are attached to the
longest continuous chain and named using
the parent name, changing the –ane suffix
to –yl.
4. Write out the name of the molecule
S
Isomers of Pentane
S
C C C C H
H H H H
Isomers of
Butane
C4H10
H HH
H C H
H
C C C
H
H H H
methyl propane or isobutane
Timberlake, Chemistry 7th Edition, page 383
STRUCTURAL ISOMERS
Timberlake, Chemistry 7th Edition, page 385
S
• Carbon can make 4 covalent bonds
– There are more carbon-based compounds present on
earth than the total of all compounds lacking carbon
– Compounds that have the same molecular formula,
but different structures (arrangements of the atoms)
are called isomers.
• Example: Isomers of C4H10
– Butane:
CH3 CH2 CH2 CH3
– Isobutane:
CH3 CH
Structural Isomers
All have formula C5H12
NAMING ALKANES
S
• Identify the longest continuous chain.
• The locations or other groups of atoms attached
to the longest chain are identified and
numbered by counting from the end of the
molecule which keeps the numbering system as
low as possible.
CH3
CH3
4
4/18/2016
METHYL GROUPS (R)
S
H
H C H
H
H
H
C C C C H
H H H H
Methane
CH4
H C
?
Butane
C4H10
H
H
?
R
H H H H
C H
R
H
C C C C H
H H H H
Methyl
-CH3
C C C
1
6
52
43
Butyl
-C4H9
S
H H CH3
H
S
H H H H
S
CH3
CH3
H H C H
3
4
C C C C C C
H C H
25
2,4,5 trimethyl 3ethyl octane
CH3
H C H
16
H
3, 3 dimethyl hexane
or
Lowest sum of numbers
is correct
4, 4 dimethyl hexane
2, 5 dimethyl 3,3diethyl nonane
ALKENES AND AKYNES
S
Hydrocarbons
Number of
Alkanes
Carbon Atoms CnH2n + 2
Alkenes
CnH2n
Alkynes
CnH2n-2
S
1
CH4
Methane
2
C2H6
Ethane
C2H4
Ethene
C2H2
Ethyne
3
C3H8
Propane
C3H6
Propene
C3H4
Propyne
Butane
C4H8
Butene
C4H6
Butyne
Pentene
C5H8
Pentyne
4
C4H10
5
C5H12
Pentane
C5H10
6
C6H14
Hexane
C6H12
Hexene
C6H10
Hexyne
Heptane
C7H14
Heptene
C7H12
Heptyne
Octene
C8H14
Octyne
7
C7H16
8
C8H18
Octane
C8H18
9
C9H20
Nonane
C9H18
Nonene
C9H16
Nonyne
C10H20
Decene
C10H18
Decyne
10
C10H22 Decane
5
4/18/2016
ALKENES AND ALKYNES
S
• Alkenes and Alkynes
– Alkenes are hydrocarbons with at least one double
carbon to carbon bond.
• To show the presence of the double bond, the –ane suffix
from the alkane name is changed to –ene.
– The alkenes are unsaturated with respect to hydrogen
• This means it does not have the maximum number of
hydrogen atoms as it would if it were an alkane (a
saturated hydrocarbon).
ALKYNES
ALKENES
S
CnH2n
S
S
S
S
(CnH2n-2)
6
4/18/2016
S
S
S
S
S
H H H H
H
C C C C H
C C C C H
1
Butane
C4H10
H
2
3
H
H H H H
• Ethylene is the gas that ripens fruit, and a ripe fruit
emits the gas, which will act on unripe fruit.
• A ripe tomato placed in a sealed bag with green
tomatoes will help ripen them.
S
H H H
H
4
H H
but(1)ene
1-butene
n-butene
H
H H H
C
C C C H
H
H H
Butene
Butane
C4H8
1
2
3
4
2-butene
7
4/18/2016
DNA damage
S
DO YOU CARE
S
NAMING ALKENES/ ALKYNESS
Guanine
+ HO
OH
8-Hydroxyguanine
S
– Naming is similar to naming alkanes except:
• The longest continuous chain must contain the
double bond.
• The base name now ends in –ene.
• The carbons are numbered so as to keep the
number for the double bond as low as possible.
• The base name is given a number which
identifies the location of the double bond.
– An alkyne is a hydrocarbon with at least one
carbon to carbon triple bond.
– Naming an alkyne is similar to the alkenes, except
the base name ends in –yne.
The most highly mutagenic lesions identified
FUNCTIONAL GROUPS S
ALCOHOLS
S
– Alkenes can also add to each other in an addition
reaction to form long chains of carbon compounds.
•
this is called polymerization
– The atom or group of atoms that are added to the
hydrocarbon are called functional groups.
• Functional groups usually have multiple
bonds or lone pairs of electrons that make
them very reactive. FREE RADICALS?????
8
4/18/2016
Alcohols
S
– An alcohol has a hydrogen replaced by a hydroxyl
(-OH) group.
– The name of the hydrocarbon that was substituted
determines the name of the alcohol.
– The alcohol is named using the hydrocarbon
name and adding the suffix –ol.
• If methane is substituted with an OH group it
becomes methanol
• If a pentane group is substituted with an OH
group it is pentanol.
• For alcohols with more than two carbon atoms
we need the number the chain so as to keep the
alcohol group as low as possible.
S
Naming Functional Groups
S
S
9