Transcript Intro to Organic Chemistry

Yeah, it is the last unit!
Organic Chemistry
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Organic Chemistry involves the study of Carbon based
compounds
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Almost all compounds utilized by living organisms involve
carbon hence the name “Organic” chemistry
What are some examples of Organic Based compounds?
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Petrochemicals
Dyes
Pharmaceuticals
- Biochemicals
- Polymers
- Life
Carbon is special!
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Carbon atoms can bond with other carbon
atoms in chains, rings, and networks.
These Bonds are covalent.
Carbon has 4 unpaired electrons & can
form 4 covalent bonds.
•
•C•
•
H can only form 1 bond
Halogens only form 1 bond
O, S can only form 2
N, P can only form 3
Carbons ability to form 4 covalent bonds, one or more
Of which can even be to another carbon atom leads to
carbons ability to form millions of different compounds.
There are 3 ways to draw organic
molecules:
1.
2.
3.
Structural formulas
Condensed structural formulas
Molecular formulas
Structural Formulas
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“–” A single line represents one pair of
electrons (a single bond).
“=“ A double line represents two pairs of
electrons (a double bond).
“” A triple line represents three pairs of
electrons (a triple bond).
Show
kind & number of atoms.
Draw
example on board
Condensed Structural Formulas
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These formulas show kind & number of
atoms as well as some information regarding
what atoms are bonded to what atoms.
They do not depict bonds
Examples: CH3CH2CH2CH3
Molecular Formulas
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These formulas show kind & number of
atoms but not necessarily any other
information
Examples: C4H10
Vocabulary
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Hydrocarbons: organic compounds
containing only carbon and hydrogen.
Straight chain: All C bonded to only 2 other
C’s
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Ex:
c-c-c-c-c-c-c
Branched: One or more C bonded to 3 or 4
other C’s c-c-c-c-c-c-c-c c
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Ex:
|
c
|
c
|
c-c-c
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c
Primary Categories of Hydrocarbons
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There are Five Hydrocarbon Categories
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Straight Chain or Branched
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Alkanes (Single Bonds) [hydrogen = 2n +2]
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Alkenes (Double Bond) [H = 2n]
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CH3CH2CH2CH3
CH3CH2CH=CH2
Alkynes (Triple Bond) [H = 2n – 2]
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CH3CH2C
CH
Primary Categories of Hydrocarbons
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Cyclic
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Aromatics (Benzene related compounds)
C6H6
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Non-aromatic
The simplest aromatic
Hydrocarbon (alternating
Double bonds)
Cyclopropane is the
Simples cyclic
hydrocarbon
Cyclopropane Cyclobutane Cyclopentane Cyclohexane
C 3H 6
C 4H 8
C5H10
C6H12
Naming straight-chain Alkanes
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All alkane names have the suffix –ane.
(Single Bonds) [hydrogen = 2n +2]
The prefix depends on the number of C’s.
Ex:
Methane
Ethane
1 Carbon
2 Carbon
What’s the chemical formula of each?
Alkanes
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A Homologous series of
saturated hydrocarbons.
Compounds with a
related structure differing
by the same repeating
unit (-CH2-)
Formula
Name
CH4
Methane
C2H6
Ethane
C3H8
Propane
C4H10
Butane
C5H12
Pentane
C6H14
Hexane
C7H16
Heptane
Prefix
Meth
Eth
Prop
But
Pent
Hex
Hept
Oct
Non
Dec
# of C atoms
1
2
3
4
5
6
7
8
9
10
Alkanes: base unit
CH4
CH3CH3
or C2H6
CH3CH2CH3
or C3H8
CH3CH2CH2CH3
or C4H10
CH3CH2CH2CH2CH3 or C5H12
-
Difference between each is one -CH2-
General formula is CnH2n+2
(n= no. of carbon atoms
Problem: What’s the formula for the alkane with 22 carbon
Problem: What is the structural formula for pentane?
Problem: What is the name of the following
Hydrocarbon?
CH3-CH2-CH2-CH3
SIMPLE HYDROCARBONS
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Draw the structural formula and
condensed structural formula (chemical
formula) of the following:
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octane
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hexane
Drawing simple alkanes
Recall that the members of the group of alkanes
Forms a homologous series and each member of
This series differs from the last by 1 –CH2- unit
When we draw the structural formulas of the 1st
Three members of this group there is only one
Way each can be drawn.
CH4
CH3-CH3
CH3-CH2-CH3
Branched-chain alkanes
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Beginning with butane, C4H10, there is
more than 1 way to arrange the atoms
besides one carbon after another.
CH3-CH2-CH2-CH3
&
CH3
|
CH3-CH-CH3
Branched-chain alkanes
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In both butane structures we have the same numbers
and kind of atoms namely, C4H10
The general formula for each is also CnH2n+2 so each
represents the alkane “Butane”
Yet there is a difference. The difference lies in what
atoms are joined to what atoms
CH3-CH2-CH2-CH3
*
&
CH3
|
CH3-CH-CH3
*
Are there any other ways to draw 4 carbon butane? No
Naming branched-chain alkanes
Step 1: Find the longest continuous chain or
backbone of C atoms.
c-c-c-c-c-c-c-c-c-c
c
c
c
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What’s the longest chain?
The base name is derived from the number of
C’s in the longest chain.
10 carbons would be decane
Naming branched-chain alkanes
2.Branches are added as a
prefix and are named by
counting the number of C
atoms.
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The “branch” alkane
name ends in “yl.”
c-c-c-c-c-c-c-c-c-c
c
c
c
Methyl
CH3—
Ethyl
CH3CH2 –
Propyl
CH3CH2CH2
–
Butyl
CH3CH2CH2C
H2 –
Naming branched-chain alkanes
3.The location of the branch (or substituent group) is shown
by assigning numbers to the C’s in the backbone.
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Number from the end that gives the lowest number for the
first branch.
 Substituent groups (branches) are listed alphabetically
1 2 3 4 5 6 7 8 9 10
c-c-c-c-c-c-c-c-c-c
c
c
7-ethyl-3-methyldecane
c
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may be more than 1 of the same type of branch.
Use di, tri, tetra etc. for 2, 3, and 4
Number the locations and separate the # by a comma &
separate the last # from the name by a dash
Example:
H
H–C–H
H H
H–C–C–C–H
H H
H-C-H
|
H
Longest continuous chain has 3
carbon atoms – propane.
2 Branches each have 1 carbon –
dimethyl.
Branches have to be at C-2. WHY??
(Only give the number if necessary.)
Dimethylpropane or
C5H12 or
CH3C(CH3)2CH3
Name this compound
CH3
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H3C-C-CH2-CH3
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CH3
Longest continuous chain has 4
carbon atoms – butane.
2 Branches each have 1 carbon –
dimethyl.
Branches are at C-2. WHY??
2,2-Dimethylbutane or
C6H14 or
CH3C(CH3)2CH2CH3
Name this compound:
H
H–C–H
H H H
H– C–C–C–C–H
H
H
H–C–H H–C–H
H
H
Longest continuous chain has
6 carbon atoms: hexane
Branch is 1 carbon long: methyl
Branch is located at C-3
3-methylhexane or
C7H16 or
CH3CH2CH2CH(CH3)CH2CH3 or
CH3(CH2)2CH(CH3)CH2CH3
More Naming Problems
H3C
CH2
CH
CH3
CH3
CH3
CH3
CH
H3C
CH
CH3
CH
CH2
CH2
CH2
CH3
Problems:
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Draw the following:
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2 – methylpropane
3 – ethyl – 4 methylnonane
2,2 – dimethylpropane
2,3,4 – trimethyldecane
What name does this compound have?
Book: Try it for HW!
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Pg 336 #5
Pg 338 #8