Download CHM 123Chapter 23.1

CHM 123
Chapter 23 – Organic Chemistry
23.1 – Organic chemistry and their structures
Organic chemistry is the study of carbon containing compounds and their properties. This includes
the great majority of chemical compounds on the planet, but some substances such as
carbonates and oxides of carbon are considered to be inorganic substances even though they
contain carbon.
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Organic compounds also may contains O, S, N and halogens
Organic Compounds
Use mostly covalent bonding
Are gases, liquids or solids with low
melting points
Mostly insoluble in water
Many are soluble in organic solvents
such as petroleum, benzene and
hexane
Solution in water generally do not
conduct electricity
Almost all burn
Slow to react with other chemicals
Inorganic Compounds
Mostly ionic bonding
Are generally solids with high melting
points
Many are water soluble
Most are not soluble in organic
solvents
When dissolved in water conducts
electrical current
Most not combustible
Often undergo fast chemical
reactions
 Two types
◦ Saturated hydrocarbons
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◦ Unsaturated hydrocarbons
Writing Formulas for organic molecules
• carbon has 4 valence electrons and hydrogen has 1.
carbon achieves an octet by forming four bonds with H or other carbons
Structure Presentation
E.g.
methane: CH4
All single carbon has four bonding position, completely saturated by the four hydrogen atoms.
There is only one possible arrangement of the atoms.
Condensed formula
2D formula
3D formula
CH4
E.g.
Ethane: C2H6
Only two carbon atoms are connected to each other and there are six possible bonding sites.
These are filled by the six hydrogen atoms
Condensed formula
2D formula
3D formula
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E.g. Propane: C3H8
Condensed formula
2D formula
3D formula
Because single bonds allow rotation, there are number of ways that alkanes can be drawn
using slightly different representation.
Constitutional isomers: Compounds that have the same molecular formula but different
structural formulas (a different connectivity of their atoms).
• For the molecular formulas CH4, C2H6, and C3H8, only one structural formula is
possible. There are no constitutional isomers for these molecular formulas.
E.g. How many alkane structures can you draw from C4H10? (*Hint: always start with a straight
chain carbon-carbon backbone)
E.g. How many isomers can you draw from C3H7Cl?
* Do cycloalkanes have isomers? YES
E.g. There are two possible ways to make ring using four carbon atoms of C4H8.
E.g
How many constitutional isomer can you draw from C5H10?
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23.2 – 23.3 – Functional groups and naming alkanes
IUPAC rules
Name
# Carbons
Condensed formula
Methane
1
CH4
Ethane
2
CH3CH3
Propane
3
CH3CH2CH3
Butane
4
CH3CH2CH2CH3
Pentane
5
CH3CH2CH2CH2CH3
Hexane
6
CH3CH2CH2CH2CH2CH3
Heptane
7
Octane
8
CH3CH2CH2CH2CH2CH2CH2CH3
Nonane
9
CH3 CH2 CH2CH2CH2CH2CH2CH2CH3
Decane
10
CH3CH2CH2CH2CH2CH2CH3
CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3
Alkyl groups: substituents that branch off the main chain.
(groups attached to parent)
CH3
meth (Me)
CH2CH3
ethyl (Et)
CH2CH2CH3 propyl (Pr)
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Example
Name these alkanes
Functional Groups
• a characteristic feature of organic molecules that behave in a predictable way.
• composed of an atom or group of atoms.
• groups that replace a hydrogen atom in the corresponding alkane.
• a way to classify families of organic compounds.
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Classify each of the following as: alcohol, ether, aldehyde, ketone, carboxylic acid, ester, amine, or
amide.
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