Organic Chemistry
Ch. 18
Organic Chemistry
• Study of organic molecules:
– Hydrocarbons
– Alcohols
– Acids
– Vitamins
– Ethers
• Naming hydrocarbons
• Naming side groups
• Formation of polymers
Alkane
• Saturated Hydrocarbons
– Maximum # of H atoms; all
single bonded carbon atoms
• Can exist as Chains or Rings
• Longest chain of carbons is
called the Parent Chain
• Parent Chain tells you the
base name
• ALWAYS end in ANE
• Rings always include
“Cyclo”
Properties of Alkanes
• Alkanes vary in Parent
Chain length and
complexity
• Longer Parent Chains=
higher melting/boiling
points
• 1-4 carbons  gases
• 5-16 carbons liquids
• +16 carbons solids
• Rings burn more uniformly
while chains tend to
explode
• Produce Structural Isomers
– Same molecular formula but
different structure and
therefore different name
Writing Compounds
• Shorthand: Pentane
CH3-CH2-CH2-CH2-CH3
Shows number of Carbon/Hydrogen but no structure
• Condensed:
CH3CH2CH2CH2CH3
• Structural Diagram:
Naming Alkanes
• Simple Alkanes you follow base
name; Side groups make things pentane
more complicated
• Side group- any carbon chain,
alcohol, ether, etc…attached to
the parent chain
2-methylbutane
• Rules:
1) Parent chain is longest number
of carbons
2) Side groups must have the
LOWEST position numbers
possible
3) Alkane side groups end in “-yl”
4) Multiple side groups use Latin
numbers; di, tri, etc…
5) Multiple side groups are
alphabetical
2,2-dimethylpropane
4-ethyl-3-methylheptane
Practice Naming Alkanes
CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
nonane
3-ethylhexane
5-(1-methylpropyl)decane
cyclopropylcyclopentane
(2,2-dimethylpropyl)
cycloheptane
Alkenes
• Unsaturated Hydrocarbons;
missing H atoms due to
double bonds
• Can exist as Chains or Rings
• Longest chain of carbons is
called the Parent Chain
(contains double bond)
• Parent Chain tells you the
base name
• ALWAYS end in ENE
• Rings always include “Cyclo”
ethene
3-octene
cyclodecene
• Rules:
Naming Alkenes
1) Double bond must
have the lowest
position number
2-methyl-3-heptene
possible
2) Use di, tri, ect… plus
“ene” when there are
multiple double bonds
3) If double bond is a side
3,3-dimethyl-1-hexene
group add “-yl” to ene
4) Rules for side groups
still apply
Draw: 2,2,5-trimethyl-3-nonene
Properties of Alkenes
• Ethene gas is huge part of
plastic production
• Double bond produces
Geometric Isomers
– Double bond stops free
rotation of atoms
– Cis isomers Same side
– Trans isomers
Opposite side
• Trans Alkenes have higher
melting points than Cis
Alkenes
• Alkenes become Alkanes
through Hydrogenation
– Reacting with H2 gas
Cis
Trans
Practice Naming Alkenes
2-ethlyhexene
trans-2-pentene
cis-3-(1-methylethyl)-2hexene
cyclopentene
Aromatic Hydrocarbons
• 6 carbon Alkene ring
– Benzene
• Electrons shared equally
in the ring; resistant to
Hydrogenation
• Give of distinct aromas:
– Cinnamaldehyde
肉桂醛
• Cinnamon
– Phenylethanol
苯乙醇
• Roses
Alkynes
• Unsaturated
Hydrocarbons
• Contain triple bonded
carbon atoms
• Naming rules are the
same for Alkenes
• ALWAYS ends in YNE
• The longer the Alkyne
the higher the
boiling/melting
points
• Made into Alkenes
with Hydrogenation
propyne
5-ethyl-3-heptyne
5-cyclopropyl-1-hexyne
Practice Naming Alkynes
5-methly-2-hexyne
4-methyl-1,5-octadiyne
5-ethyl-2-methyl-3-heptyne
2-methyl-3-hexyne