Download Introduction to Organic Chemistry

Organic Chemistry
The chemistry of carbon
and carbon-based compounds
Why is carbon so special?
Carbon is unique among
the elements because:
-- it can have up to four bonds per C atom
 single, double, or triple bonds
–C–C–
C=C
–C=C–
-- it can form REALLY long chains of C atoms
-- its bonds are strong
Organic Chemistry
Organic Chemistry is everywhere!
Smells & tastes
fruits, chocolate, fish, mint
Medications
Aspirin, Tylenol, Decongestants, Sedatives
Addictive substances
Caffeine, Nicotine, Alcohol, Narcotics
Hormones/Neurotransmitters
Adrenaline, Epinephrine
Food/Nutrients
Carbohydrates, Protein, Fat, Vitamins
Genetics
DNA, RNA
Consumer products
Plastics, Nylon, Rayon, Polyester
Drawing Organic Structures
Shortcuts make structures easier & faster to draw
Butane: C4H10
Lewis Structure
H
H
H
H
H
C
C
C
C
H
H
H
H
Carbon Atoms
H
Condensed Structures
CH3 CH2 CH2 CH3
CH3CH2CH2CH3
CH3(CH2)2CH3
Line Structure
• Only shows bonds
• C atoms assumed at each end
and intersection of bonds
• H atoms not shown
• Assume 4 bonds to each C
• Fulfill C’s 4 bonds by adding H’s
Practice Drawing Structures
Formula
Lewis
Condensed
C2H6
CH3CH3
C3H8
CH3CH2CH3
C5H12
CH3CH2CH2CH2CH3
C6H14
CH3CH2CH2CH2CH2CH3
or CH3(CH2)3CH3
or CH3(CH2)4CH3
Line
Types of Organic Compounds
Classified according to functional groups
Alkane
Alcohol
Carboxylic acid
O
OH
OH
Alkene
Ether
Amine
NH2
O
Alkyne
C
Ketone
Amide
O
O
C
NH2
Haloalkane
Aldehyde
Amino acid
O
O
Cl
Br
H
H2N
OH
Big Idea in Organic Chemistry
Structure controls
Function
Each functional group has predictable reactivity
Naming Alkanes (or Paraffins)
• Made only of C and H
• All C atoms are tetrahedral
(only C-C single bonds)
• General formula = CnH2n+2
(CH4, C2H6, C3H8, C4H10,
etc.)
• Alkanes are named based
on the number of carbons
in the longest chain!
Naming Basic Alkanes
# of
C atoms
Alkane
1
CH4
2
CH3CH3
3
CH3CH2CH3
4
CH3CH2CH2CH3
Methane
Ethane
Propane
Butane
5
Pentane
6
Hexane
7
Heptane
8
Octane
9
Nonane
10
Decane
Alkyl substituents
-CH3
-CH2CH3
-CH2CH2CH3
Methyl
Ethyl
Propyl
etc.
Root: number of C atoms
Suffix: functional group
(-ane for alkanes)
(-yl for alkyl groups)
Linear vs. Branched Alkanes
• General formula = CnH2n+2 (CH4, C2H6, C3H8, C4H10)
• Can have linear or branched alkanes
CH3
C5H12
H3C
C
CH2 CH3
H
• Same molecular formula, different structure: structural isomers
• Branches, including other atoms bonded, are called
substituents. Common non-carbon ones are:
–NO2
nitro
–NH2
amino
–F
fluoro
–Br
bromo
–I
iodo
Naming Branched Alkanes (IUPAC)
Octane
4-ethyl
6
8
7
2
5
4
3
4-ethyl-3,5-dimethyloctane
1
3-methyl and 5-methyl = 3,5-dimethyl
1. Root name: name of longest continuous C chain (parent chain)
• Two equally long? Choose the one with more branches
2. Number C atoms in chain, starting at end with first branch
3. Identify substituents, give each a number (C it is connected to)
• Two or more identical substituents: use prefixes (di-, tri-, tetra-, etc.)
4. List substituents alphabetically before root name
• Do not alphabetize prefixes
5. Punctuation: commas separate numbers from each other
hyphens separate numbers from names
no space between last substituent & root name
Provide each counterpart.
1
2
5-ethyl-3-methyloctane
3
7
5
4
6
8
(C11H24)
4-ethyl-2-methylhexane
(C9H20)
Naming Alkanes Practice
a. 2,4-dimethylpentane
e. 2,3-dimethylpentane
b. 2,4-dimethylhexane
f. 2,2-dimethylhexane
c. 2,4,6-trimethylheptane
g. 2,5-dimethylhexane
d. 3-ethyl-2-methylpentane
h. 4-methylheptane
Isomers
The fat dog shook himself, and then rolled over on the
wet rug.
OR
The dog shook the fat rug, then rolled over and wet on
himself.
These two statements use the same words...
but have very different meanings!
Likewise, isomers may have the same formula, but
have very different structures…
Structural Isomer Practice
• On piece of your own paper, draw AND name
ALL of the isomers for the following alkanes:
# isomers
Formulas
C5H12
3
C6H14
5
C7H16
9
Some of your drawings may look different, but they are
only different structures (isomers) if they also have
different names
If you complete that, try to draw and name all of the
isomers for octane (C8H18) in your HW. There are 18
of them!
Structural Isomers: C5H12
pentane
2-methylbutane
2,2-dimethylpropane
Structural Isomers: C6H14
hexane
2,3-dimethylbutane
2-methylpentane
2,2-dimethylbutane
3-methylpentane
Structural Isomers: C7H16
heptane
2,2-dimethylpentane
2-methylhexane
2,3-dimethylpentane
3-methylhexane
Structural Isomers: C7H16
2,4-dimethylpentane
3-ethylpentane
3,3-dimethylpentane
2,2,3-trimethylbutane
Naming Practice
Two equal numbering options?
Number based on alpha order
Cl
6
1
2
5
3
4
4
2
5
3
1
6
F
F
Cl
5-chloro-2-fluorohexane
2-chloro-5-fluorohexane
Br
2-chloro-4-fluoro-2,3-dimethylpentane
I
Br
Cl
2-bromo-3-ethyl-4-iodopentane
2-bromo-4-chloro-3-isopropylpentane
Provide each counterpart.
Br
3-bromo-2-chlorohexane
Cl
2-ethyl-1,1-diiodoheptane
I
I
2-methyl-1-nitrobutane
NH2
NO2
NO2
2-amino-6-nitro-3-propyl heptane
Structural Isomers
What are the possible structural isomers of C3H7Br?
Br
Br
1-bromopropane
2-bromopropane
What are the possible structural isomers of C4H9Cl?
Cl
Cl
1-chlorobutane
2-chloro-2-methylpropane
Cl
2-chlorobutane
Cl
1-chloro-2-methylpropane
Cycloalkanes
• Alkanes with closed ring(s) of C atoms
• General formula: CnH2n (C3H6, C4H8, C5H10, etc.)
• Naming: use cyclo- prefix before alkane name
cyclopropane
n=3
C3H6
cyclobutane
n=4
C4H8
cyclopentane
n=5
C5H10
cyclohexane
n=6
C6H12
Naming substituted cycloalkanes:
• 1 substituent: no numbering necessary
• 2 or more substituents: lowest numbering scheme, then
by alpha
CH3
CH3
methylcyclopentane
1-chloro-5-methylcyclohexane
Cl
1-chloro-3-methylcyclohexane
Fun Common Names
windowpane
basketane
broken
windowpane
boxane
Teepane