Aim: How can we describe Hydrocarbons?

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Transcript Aim: How can we describe Hydrocarbons?

What is meant by the term
Organic?
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Page 2
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Characteristics of organic compounds
• Formed as a result almost exclusively of covalent
bonding
• Generally nonpolar  Generally insoluble in water
– usually soluble in nonpolar solvents (other organic
compounds)
• Non-electrolytes except organic acids which are
weak electrolytes
• Have low melting points (due to weak
intermolecular forces that hold them together)
– The great number of carbons leads to a higher melting
point.
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Characteristics of organic compounds
, (continued)
• Have slower reaction rates than inorganic
compounds
– covalent bonds within organic molecules are strong
– activation energies are high
– catalysts are often used to increase reaction rates
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How can we describe Hydrocarbons?
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• Hydrocarbons
– Definition - compounds composed of only
hydrogen and carbon
– There are so many hydrocarbons found in nature;
nearly impossible to study all! They are grouped
in Homologous series.
– Homologous series - group of organic compounds
with similar properties and related structures
(differ from each other by CH3)
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3 Important Homologous Series of
Hydrocarbons:
1. Alkanes
2. Alkenes
3. Alkynes
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• Aliphatic - hydrocarbon chains
– Saturated
• Definition - has no bonds that can be broken to add
extra hydrogen
• called Alkanes
–
–
–
–
–
family of hydrocarbons with all single bonds
general formula CnH2n+2
named with suffix "ANE“
Table P – Organic Prefixes
As the number of carbons increases, the boiling point
increases.
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TAKE OUT PAPER AND DRAW PLEASE
• Name and draw the first ten Alkanes
– Go to table P and look at the prefix for the
number of carbons
• 1 carbon is Meth
– All alkanes end in ‘ane’
» ‘meth’ and ‘ane’
» Methane
• 2 carbons is Eth
– All alkanes end in ‘ane’
» ‘eth’ and ‘ane’
» Ethane
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The First Ten Straight-Chain Hydrocarbons
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The First Ten Straight-Chain Hydrocarbons
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Page 3
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What are the
Unsaturated Hydrocarbons?
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– Unsaturated - has double or triple bonds that can
be broken to add more hydrogen
• Alkenes
–
–
–
–
family of hydrocarbons with at least one double bond
general formula CnH2n
named with suffix "ENE“
Starts with Ethene.
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Alkenes
TAKE OUT PAPER AND DRAW PLEASE
• Draw the first nine Alkenes
– Go to table P and look at the prefix for the
number of carbons
• 2 carbons is Eth
– All alkenes end in ‘ene’
» ‘eth’ and ‘ene’
» Ethene
• 3 carbons is Prop
– All alkenes end in ‘ene’
» ‘prop’ and ‘ene’
» Propene
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Alkenes
TAKE OUT PAPER AND DRAW PLEASE
• Draw the first nine Alkenes
– Go to table P and look at the prefix for the
number of carbons
• 4 carbons is But
– All alkenes end in ‘ene’
» ‘but’ and ‘ene’
» Butene
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Alkenes
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Alkynes
• Alkynes
–
–
–
–
family of hydrocarbons with one triple bond
general formula CnH2n-2
named with suffix "YNE“
Starts with Ethyne.
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Alkynes
• Draw the first nine Alkynes
– Go to table P and look at the prefix for the
number of carbons
• 2 carbons is Eth
– All alkenes end in ‘yne’
» ‘eth’ and ‘yne’
» Ethyne
• 3 carbons is Prop
– All alkenes end in ‘yne’
» ‘prop’ and ‘yne’
» Propyne
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Packet Page 4
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With this ring I,
get confused?
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The Benzene Series
(Aromatic hydrocarbons)
The benzene series consists of molecules which are cyclic in nature.
The general formula is CnH2n-6.
Benzene
H
C
H
C
C
H
C6H6
H
C
C
H
C
H
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Although it appears that the structure has alternating double and single
bonds, the bonding involves six identical bonds. A resonance
structure is used to show structural formula of benzene.
H
H
C
C
H C
C H
H C
C H
H
C
C
H
H
C
H
C
C
H
C
H
An abbreviated structural formula can be used in place of the above:
OR
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Toluene or
Methylbenzene C7H8
H
C
H
C
C
CH3
H
C
C
H
C
H
An abbreviated structural formula can be used in place of the above:
CH3
CH3
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Alkylderivatives of Benzene
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Page 5 Practice
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Aim: How can we name organic
compounds?
We have rules!!!!
YAY!!!!!!!!!!!
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• Rule 1: Find the longest continuous chain
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• Rule 2: Assign numbers to each C atom in the longest
chain, starting at the end with the attached group.
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• Rule 3: If more than one of the same types of group is
attached to the main chain prefixes are used to identify
the attached groups.
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• Rule 4: When naming alkenes or alkynes the carbon
with the double/triple bond, the carbon number with
the double/triple bond must be identified in the name.
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Packet Pages
10-11
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Aim: How can we represent
organic compounds?
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What are we showing in the
following pictures?
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Different ways to represent one
compound
•
•
•
•
•
Molecular Formula
Structural Formula
Condensed Structural Formula
Ball-and-Stick Model
Space-Filling Model
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Molecular Formula
• Shows the kind and number of atoms in a
compound.
• Example: CH4 or C2H6
• Tells us that there are carbon and hydrogen
atoms. For methane, there are 4 hydrogens
for 1 carbon atom.
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Structural Formula
• In addition, shows the bonding patterns and
two-dimensional view.
• For example:
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Condensed Structural Formula
• Written structural formula
• For example: Methane: CH4
• Ethane:
CH3CH3
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Ball-and-Stick Model
• Shows a 3D structure of the compound
• Example:
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Space-Filling Model
• Shows the actual structure of the compound
• Example:
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Molecules Models of Organic
Hydrocarbons
Fig 8.4
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Isomers
• Isomers: When a molecular formula
can be represented by more than one
structural arrangement
• Isomers have the same molecular
formula, but different physical and
chemical properties.
• As the # of carbon atoms increases, so
does the # of possible isomers
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Isomers
• How would you draw the structural
formula for a 4 carbon hydrocarbon?
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Structural Isomers of Butane
Fig 8.5
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Isomer Practice
•Draw 3 Isomers for 5 and 6 carbon Alkanes.
•Be sure you have the correct number of hydrogens.
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What are the various
Functional Groups?
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Functional Groups
• Atoms or groups of atoms that replace
hydrogen atoms in a hydrocarbon.
• This will form new compounds?
• They have distinct physical and chemical
properties.
• There are 9 functional groups
• All found on Table R!
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C, H and O
• Alcohols (R-OH)
– ethanol, isopropyl alcohol, (rubbing alcohol)
• Ethers (R-O-R)
– dimethyl ether (old anaesthetic) H C
O
3
O
• Ketones
– acetone (nail polish remover) C
H3C
CH3
• Aldehydes (a ketone with at least one R = H)
– formaldehyde
CH3
O
R
O
• Esters
R
– many fine odours R
O
O
• Carboxylic acids
– acetic acid H C C OH
• Carbohydrates
– (CH2O)n, glucose, starch, cellulose
R
3
HOH2C
H
H
OH
H
C
C
C
C
OH
OH
H
OH
CHO
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1. Halides
• A Halogen (F, Cl, Br, or I) replaces a hydrogen on a
hydrocarbon.
• Used as organic solvents
• General Formula: R-X (X= Halogen & R= Alkyl group)
• Add fluoro for F
Designate the location of
• Chloro for Cl
• Bromo for Br
• Iodo for I
the halide with 1,2 etc
2-fluoropropane
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2. Alcohols
 Organic compounds in which one or more hydrogen
atoms are replaced by an –OH group.
 -OH group is called a hydroxyl group.
 NOT A BASE!
 They are nonelectrolytes (Do not form ions in solution).
 Polar substances
 General Formula: R-OH
 Naming: Position of OH group must be assigned & -ANE
ending changes to –OL.
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Classification of Alcohols
 There are primary, secondary, and tertiary carbon
atoms:
 Primary Carbon: Attached to one carbon only
 Secondary: Attached to two carbon atoms
 Tertiary: Attached to three carbon atoms.
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Alcohols
“ol” ending
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3. Aldehydes
• Organic compounds in which a carbonyl group
(C=O) is found on the end carbon (a primary
carbon):
Propanal
• Naming: Substitute –AL in place of final –E of
alkane name.
• General Formula
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4. Ketones
• C=O group is on the inside of a hydrocarbon:
Propanone
• Naming: Substitute –ONE in place of final –E
of alkane name.
• General Formula:
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5. Ethers
• Two carbon chains are joined together by an
oxygen atom:
Methyl ethyl
Ether
• Naming: name the alkyl groups and add ether
at the end.
• General Formula: R-O-R
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6. Organic Acids
• Organic compounds that have a Carboxyl
group (-COOH):
Ethanoic Acid
• Naming: Substitute –OIC ACID in place of final
–E in alkane name.
• Ethanoic acid= Acetic acid
• General Formula:
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Carboxylic Acids
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3-methyl-2-hexanoic acid
armpit in a jar
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Isovaleric acid
“locker room concentrate”
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4-ethyloctanoic acid
“wet male goat”
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7. Esters
• General Formula:
• Have strong aromas; for example, flavorings in
bananas, wintergreen, oranges.
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The fine smell of esters
O
O
O
O
PINEAPPLE
APRICOT
O
O
H
O
BANANA
O
ARTIFICIAL RUM FLAVOUR
O
O
ORANGE
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8. Amines
• Formed when one or more of the hydrogen’s in
ammonia is replaced by an alkyl group:
• Naming: Substitute –AMINE in place of final –E of
alkane name.
• General Formula:
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9. Amides
• Formed by the combination of 2 amino acids:
• General Formula:
• Form proteins
• Naming: Replace final –E with -AMIDE
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Functional Groups
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Packet Pages 13-15
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Aim: How do organic
compounds react?
Do Now: Name the Functional Group:
1. CH3COOH
2. CH3COOCH3
3. CH3CHO
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Which one is faster?
• Making Wine or Dissolving Alka Seltzer in
water?
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Organic Reactions
• Occur more slowly than inorganic reactions
because of the covalent bonds.
• There are 7 types of Organic Reactions.
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Substitution
• Involves the replacement of 1 or more of the
hydrogen atoms in a saturated hydrocarbon
with another atom or group:
• C2H6 + Cl2
C2H5Cl + HCl
+
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Addition
• Involves adding 1 or more atoms at a
double or triple bond:
• Ethene + Chlorine
1,2
dichloroethane
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Fermentation
• A chemical process in which yeast cells secrete
the enzyme zymase and break down glucose
into carbon dioxide and ethanol:
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Esterification
• Reaction between an organic acid and an
alcohol to produce an ester plus water:
Ethanoic acid + Ethanol
Water + Ethyl ethanoate
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Saponification
• When an ester reacts with an inorganic base
to produce an alcohol and a soap:
Fat +
Base
Glycerol + Soap
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Combustion
• Almost all organic compounds will combust , or
burn:
• Compound + Oxygen
Carbon Dioxide + Water
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Polymerization
• Polymers: Organic compounds made up of
chains of smaller units (monomers) covalently
bonded together.
• Polymerization: Formation of these large
polymer molecules.
• Examples of Natural Polymers: Cellulose,
Proteins, & Starch
• Synthetic Polymers: Nylon & Rayon
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Addition Polymerization
• Joining of monomers of unsaturated
compounds:
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Condensation Polymerization
• Bonding of monomers by removing water
from hydroxyl groups and joining
monomers by an ether or ester linkage:
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Summary: Identify the Reaction
1. C2H6 + Cl2
C2H5Cl + HCl
2. C6H12O6
2C2H5OH + 2CO2
3. CH3COOH + CH3OH
CH3COOCH3 +
H2O
4. nC2H4
(C2H4)n
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Packet Pages 29-32
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Aim: How can we review Organic
Chemistry for our test?
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Carbon
• Carbon forms four bonds always!
• Carbon can form single, double, or triple
bonds.
• Single = Saturated
• Double or Triple = Unsaturated
• Carbon can covalently bond to other
carbon atoms.
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Hydrocarbons
• Have hydrogen and carbon atoms only!
• Homologous Series: Members that have
similar properties.
• 3 Types: Alkanes, Alkenes, and Alkynes
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Alkane
• All single bonds
• All end in –ane
• Each member differs by 1 carbon and 2
hydrogen atoms.
• General Formula: Cn H2n + 2
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Alkene
• Has at least one double bond
• All end in –ene.
• General Formula: CnH2n
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Alkyne
• Has at least one triple bond
• All end in –yne.
• General Formula: CnH2n-2
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Formulas
• Molecular:
• Shows the kind and
number of atoms in a
compound.
• Example: CH4 or C2H6
• Structural:
• In addition, shows the
bonding patterns and
two-dimensional view.
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Isomers
• Isomers: When a molecular formula can
be represented by more than one
structural arrangement
• Isomers have the same molecular
formula, but different physical and
chemical properties.
• As the # of carbon atoms increases, so
does the # of possible isomers
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Functional Groups
• Found on Table R!
• Alcohols: Can be classified in two ways:
1. Primary, Secondary, or Tertiary (with
ONE -OH group only)!
2. 1 –OH: Monohydroxy
• 2 -OH: Dihydroxy
• 3 –OH: Trihydroxy
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Organic Reactions
 7 Types: Need to know reactants & products.
 Combustion
 Substitution
 Addition
 Esterification
 Saponification
 Fermentation
 Polymerization: Addition & Condensation
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Organic Reactions
• Occur more slower than inorganic reactions.
Why?
• Review: Covalent bonds have low melting and
boiling points, are poor conductors, and are
nonpolar substances.
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Number of Possible Isomers for Selected Alkanes
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Some Common Alkyl Groups
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Naming Alkanes
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Cis-Trans Isomerism
Does the term “trans” have anything to do with
the topic of “trans-fats” we have been hearing
a lot about recently?
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Different Ways of Representing
the Alkane Ethyne
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