Transcript An Example

Organic
Chemistry
Chem 2014
Organic Chemistry
Organic Chemistry:
- the chemistry of carbon
and carbon-based compounds
- (C – C or C – H or C – R)
- (can be a few to hundreds of carbons
covalently bonded to one another)
Characteristics of Organic Compounds:
*Usually have strong odors and low boiling points
* Most do not conduct electricity
* Most will ignite and burn
* Slower rates of reactions
Organic Chemistry in everyday life:
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
• Animals, plants, and other forms of life consist
of organic compounds.
– Nucleic acids, proteins, fats, carbohydrates,
enzymes, vitamins, and hormones are all organic
compounds
• Besides carbon, the most common elements
in organic compounds are hydrogen, oxygen,
nitrogen, sulfur, and the halogens.
– All of the preceding elements are non-metals, therefore
organic compounds have covalent bonding.
Numbers and Types of Bonds for
Common Elements in Organic Compounds
Application of the octet rule indicates that these elements should
bond as shown below:
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Section 14.1
Review: Octet Rule
• Rule of Eight – elements want either 8 or 0
electrons in its outermost level (except for H
and He which want 2 or 0)
Each energy level can only hold
a certain number of electrons.
1st level
2nd level
3rd level
4th level
2 electrons
8 electrons
8 electrons
18 electrons
Periodic Table and Valence electrons
Group Number
Number of Valence
Electrons
1
1
2
2
13
3
14
4
15
5
16
6
17
7
18
*Helium only has 2 valence electrons
8
Bohr Diagrams
The Rutherford–Bohr model: where the negatively charged electron confined to
an atomic shell encircles a small, positively charged atomic nucleus and where an
electron jump between orbits is accompanied by an emitted or absorbed amount
of electromagnetic energy
• Carbon
• Argon
Let’s Practice Bohr Diagrams
Energy Levels Diagram HW wkst
• http://phet.colorado.edu/sims/html/build-an-atom/latest/build-an-atom_en.html
Lewis Structure
Placing valence electrons around element symbol
to decipher bonding patterns
Lets practice Lewis dot structures
Practice Lewis Dot Structures
1. Oxygen (e = _________) 2. Potassium (e = _______) 3. Bromine (e = ________)
4. Germanium (e= ______)
5. Aluminum (e = ______)
6. Phosphorus (e = ______)
Big Idea in Organic Chemistry
Structure controls Function
Each functional group has predictable reactivity
= atom or group of atoms that gives characteristic
chemical properties to a class of organic compounds
Drawing Organic Structures
Shortcuts make structures easier & faster to draw
Butane: C4H10
Lewis Structure
Carbon Atoms
Structural formula
H
H
H
H
H
C
C
C
C
H
H
H
H
Condensed Structures
molecular formula
CH3 CH2 CH2 CH3
CH3CH2CH2CH3
CH3(CH2)2CH3
H
Line Structure Carbon Skeleton
• 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
Types of Organic Compounds
Classified according to functional group
Hydrocarbons (H & C only)
Alkane
Alcohol
Carboxylic acid
O
OH
OH
Alkene
Ether
Amine
NH2
O
Alkyne
C
Ketone
Amide
O
O
C
NH2
Halocarbon
Aldehyde
Amino
Esteracid
O
O
Cl
Br
H
H2N
OH
Characteristics and Examples
Hydrocarbons
Alkane
Contain
Formula
n is # of
carbons
Naming
Alkene
Alkyne
C–C
C=C
C≡C
single bond
double bond
triple bond
CnH2n+2
CnH2n
CnH2n-2
Prefix (# of C’s)-ane # (count from smallest
direction of =) – Prefix
(# C’s) - ene
# (count from smallest
direction of ≡) –
(# C’s)
Examples
Linear/
skeletal
structure
See following
\/
\
Slides for
- yne
examples
Prefix
Organic Prefixes
•
•
•
•
•
•
MethEthPropButPentHex-
1 carbon
2 carbon
3 carbon
4 carbon
5 carbon
6 carbon
•
•
•
•
HeptOctNonDec-
7 carbon
8 carbon
9 carbon
10 carbon
Examples
Name
Molecular
Formula
propane
ethane
Lewis/ Structural
Formula
Condensed Structural
Formula
Linear
C3H8
CH3CH2CH3
\/
C2H6
CH3CH3
\
2-pentene
C5H10
CH3CHCHCH2CH3
2-butene
C4H8
CH3CHCHCH3
Name
Molecular
Formula
3-heptyne
C7H12
CH3CH2CCCH2CH2CH3
1-propyne
C3H5
CHCCH3
Structural Formula
Condensed Structural Formula
Alkanes – Energy Related Products
• Methane = primary component of natural gas
• Propane & Butane = primary component of
bottled gas
• Gasoline = pentane to decane
• Kerosene = alkanes with n = 10 to 16
• Alkanes with n > 16  diesel fuel, fuel oil,
petroleum jelly, paraffin wax, lubricating oil, and
asphalt
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Section 14.3
Organic Compound Nomenclature
• Due to the large number, variety, and
complexity of organic compounds, a
consistent method of nomenclature has
been developed.
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Section 14.3
IUPAC System of Nomenclature
For Alkanes
• Compound is named as a derivative of the longest
continuous chain of C atoms.
• Positions & names of the substituents added
– If necessary, substituents named alphabetically
– More than one of same type substituent – di, tri, tetra
• The C atoms on the main chain are numbered by
counting from the end of the chain nearest the
substituents.
– Each substituent must have a number.
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Section 14.3
Hydrocarbons wkst
Names of Linear Alkanes and Alkyl Substituents
# of
C atoms
Alkane
Alkyl substituents
Methane
1
CH4
2
CH3CH3
Ethane
-CH2CH3
Ethyl
3
CH3CH2CH3
Propane
-CH2CH2CH3
Propyl
4
CH3CH2CH2CH3
Butane
5
Pentane
6
Hexane
7
Heptane
8
Octane
9
Nonane
10
Decane
-CH3
Methyl
etc.
Root: number of C atoms
Suffix: functional group
(-ane for alkanes)
(-yl for alkyl groups)
An Example to Consider
• The longest continuous chain of C atoms is five
• Therefore this compound is a pentane derivative
with an attached methyl group
– Start numbering from end nearest the substituent
– The methyl group is in the #2 position
• The compound’s name is 2-methylpentane.
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Section 14.3
Drawing a Structure from a Name
An Example
• Draw the structural formula for
2,3-dimethylhexane.
• Note that the end name is hexane .
• Draw a continuous chain of six carbon (C)
atoms, with four bonds around each.
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Section 14.3
Drawing a Structure from a Name
An Example (cont.)
• Number the C atoms from right to left.
• Attach a methyl group (CH3--) to carbon
number 2 and number 3.
– Add necessary H atoms.
• 2,3-dimethylhexane
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Section 14.3
Drawing a Structure from a Name
Confidence Exercise
• Draw the structural formula for
2,2,4-trimethylpentane.
• Note that the end name is pentane .
• Draw a continuous chain of five carbon (C)
atoms, with four bonds around each.
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Section 14.3
Drawing a Structure from a Name
Confidence Exercise (cont.)
• Number the C atoms from right to left.
• Attach two methyl groups (CH3--) to carbon
number 2 and one to number 4.
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Section 14.3
Drawing a Structure from a Name
Confidence Exercise (cont.)
• Add necessary H atoms.
• 2,2,4-trimethylpentane
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Section 14.3
H
H
C
H
H
H
H
H
H H
C
C
C
C
H
H
H
H
Methane
CH4
Butane
C4H10
H
R?
C
H
Methyl
-CH3
H
H
R?
H
H
H H
C
C
C
C
H
H
H
H
Butyl
-C4H9
Where R = any other C atom or arrangement of C atoms
H
Example of R group
Expanded Structure
H
H
H H
H
C
C
C
H
H
H
C
Line Structure
H
H
C
H
H
2 - methylbutane
First Ten Hydrocarbons: Properties
Number of
Carbon Atoms
Molecular
Formula
Melting
Point, oC
Boiling
Point, oC
# of
Isomers
Methane
1
CH4
-182.5
-161.5
1
Ethane
2
C2H6
-183.2
-88.6
1
Propane
3
C3H8
-187.7
-42.1
1
Butane
4
C4H10
-138.3
-0.5
2
Pentane
5
C5H12
-129.7
36.1
3
Hexane
6
C6H14
-95.3
68.7
5
Heptane
7
C7H16
-90.6
98.4
9
Octane
8
C8H18
-56.8
125.7
18
Nonane
9
C9H20
-53.6
150.8
35
Decane
10
C10H22
-29.7
174.0
75
Name
Properties of Alkanes
Nonpolar → only London Dispersion Forces IMF
Larger molecular weight → Stronger London dispersion forces
Compound
Methane
Formula
CH4
MW
16
Boiling point (°C)
-164
Ethane
Propane
Butane
C2H6
C3H8
C4H10
30
44
58
-88.6
-42.1
-0.5
Pentane
C5H12
72
+36.0
Linear Alkanes:
1 - 4 C atoms: gas at room temp
5 - 15 C atoms: liquid at room temp
>15 C atoms: solid at room temp
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)
• 2 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
Alkenes are very Reactive and are
termed “unsaturated hydrocarbons”
• Alkenes will characteristically react with hydrogen to form the
corresponding alkane.
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Section 14.3
Alkynes are Unsaturated Hydrocarbons
• Due to the triple carbon bond, each alkyne molecule can react
with two molecules of hydrogen.
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Section 14.3
Chapter 26
Hydrocarbon Derivatives
Hydrocarbon Derivatives
Derivatives = molecules that contain C and H, as
as hydrocarbons, but also contain other
elements
• derivatives depend on their functional groups
which are atoms or group of atoms that give
the derivative its characteristic chemical
behavior
Derivatives
Alkane
Alcohol
Carboxylic acid
O
OH
OH
Alkene
Ether
Amine
NH2
O
Alkyne
Ketone
Amide
O
O
C
C
NH2
Halocarbon
Aldehyde
Esters
Amino
acid
O
O
Cl
Br
H
H2N
OH
Halocarbon
Definition
One or more of hydrogen atoms replaced with a member of
halogen family
General Formula
R–X
R symbolizes the hydrocarbon portion
X symbolizes the halogen atom
X can be F, Cl, Br, or I
Naming
(IUPAC)
1. Name hydrocarbon portion
2. Add prefix to indicate halogen, add -o
3. # of halogen placement
Properties
Primarily non polar
Low boiling points
Insoluble in water
Soluble in hydrocarbon solvent
Structure
Examples
CFC’s –chlorofluorocarbons
(aerosol cans, refrigerate gases)
Dry cleaning chemicals
Methanol
Pesticides
Alcohols
Definition
One or more of hydrogen atoms replaced with a member of
hydroxyl group (-OH)
General Formula
R – OH
R symbolizes the hydrocarbon portion
OH – hydroxyl group
Naming
(IUPAC)
Suffix –ol added to hydrocarbon root
Properties
*Similar to water (OH)
*Up to 4 C are soluble in water
*Higher boiling points
*Can be –diol (2 –OH) or –triol (3 -OH)
Structure
Examples
Butanol
Methanol
Ethanol – grain alcohol
Oxygen atom that is bonded to two carbon atoms
General Formula
R – O – R’
R and R’ → hydrocarbon chains
-O- → functional group
Ethers
Definition
Naming
(IUPAC)
1. Suffix –oxy added to smaller chain bonded to central oxygen
atom, remainder is named as before
2. Or use similar name: add suffix –yl to each hydrocarbon and
add ether
Properties
Oxygen creates slightly polar region
Some smaller molecules are soluble in water
No H bonds so lower boiling points than alcohol but higher than
hydrocarbons
Structure
Examples
Worksheet Review
Definition
-oxygen atom bonded to single carbon atom by a double bond
-called a carbonyl group (C=O)
Aldehydes
Aldeyde has carbonyl group attached to end of hydrocarbon
chain
General Formula
R – CHO
Naming
(IUPAC)
Add suffix –al to the root name
Properties
More polar than hydrocarbons
Higher melting and boiling points than hydrocarbons
Lower melting and boiling points than alcohol
Structure
Examples
-Methanol (HCOH) = formaldehyde – used to make polymers and
used to be used for biological preservation – found to be
carcinogenic
-Used as flavorings in food and candy and as fragrances in
inhalants and perfumes
-Vanilla flavor in ice cream and cinnamon in hot chocolate
Ketones
Definition
Ketone has a carbonyl group on the interior of a hydrocarbon
General Formula
R-COR’
Naming
(IUPAC)
Add suffix –one to the root name
Name must include which C it is attached to b/c always on
interior C when a Ketone
Properties
More polar than hydrocarbons
Higher melting and boiling points than hydrocarbons
Lower melting and boiling points than alcohol
Structure
Examples
-Propanone (CH3COCH3) = acetone - volatile liquid and vapor is
flammable
-Cortisone= hormonal response to fight or flight, treatment of
severe allergic reactions; too much bad b/c breaks down
connective tissue, increases production of stomach acid and
decreasing protective mucus membranes resulting in gastric
ulcer
Worksheet Review
Carboxylic Acids
Definition
Characterized by presence of a carboxyl group
General Formula
R – COOH
Naming
(IUPAC)
Prefix + -anoic acid
Properties
-carboxyl end is very polar making it soluble in water
-higher boiling points than hydrocarbons
Structure
Examples
(see also book pg 852)
-Fatty acids
-Formic acids (simplest form HCOOH) – from ants
-Acetic acid – (CH3COOH) – responsible for sour taste of vinegar
-lactic acid – responsible for sour cow’s milk
Definition
Similar to carboxylic acid, but has hydrocarbon group in place of H atom
of carboxy group
General
Formula
R-COOR’
Naming
(IUPAC)
-named for the alcohol and acid from which they are produced
-alcohol name (suffix changed to –yl) + acid name (suffix changed to –oate)
Ester
Example : ethanol + propanoic acid = ethyl propanoate
OR
-alcohol name (-yl) + acid (-ate) = propyl alcohol + formic acid = propyl
formate
Properties
Structure
Examples
(see also book
pg 856)
-polar but do not form H bonds with each other
-boiling points are lower than BP of similar alcohols or acids
-distinctive odors based on alcohol and acid reaction (typically fruity odors)
Worksheet
Review
Amines
Definition
Contains an amino group (-NH2) attached to hydrocarbon chain
General Formula
R-NH2
Naming
(IUPAC)
-add suffix –amine to root name of hydrocarbon
Properties
-amino group is polar
-higher boiling points than HC but lower than alcohols
-weak bases
2◦ = R-NHR’
3◦ = R-NR’R”
Structure
Examples
-amino groups found in DNA, vitamins, anesthetic drug
-basis of nicotine, cocaine, amphetamines
-unpleasant odors = cadaverine produced by bacteria on
decaying organisms – can cause food poisoning
-found in suntan lotion
Definition
Amino group attached to carbon of carboxyl group
General Formula
R-CONH2
Naming
(IUPAC)
-add suffix –amide to root of hydrocarbon
Amides
Properties
Structure
Examples
nylon and urea, which exist
in chains, and caffeine,
which exists in a ring
Worksheet Review