Transcript Organic Chemistry1

Organic Chemistry
There are more than a
million organic
compounds
HYDROCARBONS
• The simplest organic compounds
containing only carbon and hydrogens
– Carbon has 4 valence electrons and therefore
always forms 4 covalent bonds
HYDROCARBON PREFIXES
Prefix
Meth-
# of Carbons
1
EthPropBut-
2
3
4
PentHexHept-
5
6
7
OctNonDec-
8
9
10
Methods of Illustrating Hydrocarbons
Formula
C4H10
Description
Molecular Formula
Complete Structural Formula (Lewis Structure)
CH3-CH2-CH2-CH3
Condensed Structural Formula: C-H bonds
understood
CH3CH2CH2CH3
Condensed Structural Formula: C-C and C-H
bonds understood
CH3(CH2)2CH3
Condensed Structural Formula: All bonds
understood, parentheses indicate CH2 are linked
in a continuous chain
C-C-C-C
Carbon skeleton: all hydrogens and C-H bonds
understood
Line-angle formula: All carbons and hydrogens
understood; carbon atoms are located at each
intersection and at the ends of lines.
ALKANES
• A hydrocarbon in which there are only
single covalent bonds
– In an alkane, all the carbon-carbon bonds are
single covalent bonds
• All other bonds are carbon-hydrogen bonds
– The carbon atoms in an alkane can be
arranged in a straight chain or in a chain that
branches
• Alkanes are called saturated compounds
because they contain only single bonds
Straight Chain Alkanes
• Carbon atoms are one after another in a
chain
– Homologous Series: There is a constant
increment of change from one compound in
the series to the next
• In an alkane a CH2 is the increment of change
Naming Alkanes
•
•
For all alkanes the name ends in –ane
Count the carbon atoms and add the
appropriate prefix
Example: C6H14
To draw the structural formula:
1) Write the symbol for carbon as many times as
necessary
2) Complete each carbon’s 4 bonds with hydrogen atoms
Example: Octane
Branched Chain Alkanes
• An alkane with one or more alkyl groups
– Substituent: An atom or group of atoms that
takes the place of a hydrogen atom on a
parent alkane
– Parent Alkane: The longest continuous chain
of a hydrocarbon
– Alkyl Group: A hydrocarbon substituent
Naming the alkyl groups
• Name end in –yl
• Add the appropriate prefix based on # of
carbons in the alkyl group
Practice Problems
Drawing Structural Formulas for Alkanes
1)
2,2,4-trimethylpentane
2)
2,3-dimethylhexane
3)
4-ethyl-2,3,4-trimethyloctane
4)
3,3-dimethyl-4-ethyloctane
5)
hexane
6) 2-methylbutane
ISOMERS
• Compounds that have the same molecular
formula but different molecular structures
– Structural Isomers: compounds that have the
same molecular formula, but the atoms are
joined together in a different order
Differ in physical properties
like boiling and melting points
Also have different chemical
reactivities
The more highly branched the
hydrocarbon structure, the
lower the boiling point
Unsaturated Compounds
Compounds that contain double or triple carboncarbon bonds
Alkenes: hydrocarbons
containing one or more carboncarbon double covalent bonds
Plastics (more reactive than alkane)
Alkynes: hydrocarbons
containing one or more carboncarbon triple covalent bonds
Preparing organic solvents, starting
material for polymers, oxy-acetylene
flame for welding
NAMING ALKENES/ALKYNES
• The parent chain must contain the double/triple
bond. Number from the side closest to that bond.
• If it contains a double bond, it ends in –ene
• If it contains a triple bond, it ends in –yne
– # the double-triple bond
– Name substituents as with alkanes
Naming Examples
Structural Formula Examples
1) Propyne
2) Propane
3) Propene
HALOCARBONS
• Alkane + Halogen  Halocarbon + Hydrogen Halide
CH4 + Cl2  CH3Cl + HCl
• One of the branches is a halogen
– Named chloro, fluoro, bromo, iodo
• Building blocks for
things like Teflon & PVC
• Organic compounds can be classified
according to their functional group
– Functional Group: A specific arrangement
of atoms in an organic compound that is
capable of characteristic chemical reactions
Functional Groups (R = any carbon chain)
Compound
Type
Alcohol
Compound
Structure
—OH
Name ends
in
Functional
Group
-ol
Hydroxyl
Aldehyde
-al
Carbonyl
Carboxylic
Acid
-oic acid
Carboxyl
Ester
-oate
Ester
Ketone
-one
Ketone
Naming:
•drop the –e ending of the parent alkane name and add the ending to the proper
functional group ending
•Parent alkane is the longest continuous chain that includes the carbon attached
to the functional group
•If the functional group can occur at more than one position, its position is
designated with the lowest possible number.
•Alcohols containing 2, 3, or 4 –OH substituents are named diols, triols, and
tetrols
Compound
Type
Alcohol
Compound
Structure
—OH
Name ends
in
Functional
Group
-ol
Hydroxyl
Aldehyde
-al
Carbonyl
Carboxylic
Acid
-oic acid
Carboxyl
Ester
-oate
Ester
Ketone
-one
Ketone
CHALLENGE
NAME THIS!
Organic
Type
Properties
Uses
Alkane
Nonpolar
Gases/Liquids
Low boiling points
Insoluble in water
Gas/Oil/Fuels
Methane: Natural Gas
Propane: Homes/Grills
Butane: Lighters
Octane: Gasoline
Alcohol
Hydrogen Bonds
Liquids
Higher boiling points than the other groups
Soluble in water (up to 4 carbons)
Perfumes, Mouthwash, Hairspray, Antifreeze,
Rubbing Alcohol, Antiseptic, Alcoholic
Beverages
Aldehyde
(Ketones)
Weak Hydrogen bonds
Liquids or solids at room temperature
Boiling points lower than alcohols higher than alkanes
Soluble in water up to 5 carbons
Flavoring agents
Benzaldehyde: Almond oil
Cinnamaldehyde: Cinnamon oil
Vanilla flavoring
Carboxylic
Acid
Hydrogen bonds
Volatile liquids/Waxy solids
Higher boiling points than other compounds
Soluble in water up to 5 carbons
Acetic acid: Vinegar
Stearic acid: Wax candles
Fatty acids
Ester
Polar but no hydrogen bonds (H not attached to O)
Liquids
Lower boiling points than other compounds
Soluble in water up to 5 carbons
Pleasant, fruity odors (blueberries,
pineapples, pears, apples, bananas);
perfumes & fragrances
Boiling Points:
Carboxylic Acid > Alcohol > Aldehyde >
Alkane
Solubility in Water
Alkanes: Insoluble
Alcohol/Aldehyde/Ester/Carboxylic Acid:
Soluble up to 4-6 carbons
SYNTHESIS OF ESTERS
Esters may be prepared from a carboxylic acid and an alcohol
NAMING ESTERS