Unit 3Organic Chemistry

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Unit 3 Organic Chemistry

• Chemistry 2202

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Introduction

• Organic Chemistry is the study of the molecular
  compounds of carbon.
• eg. CH4 CH3OH CH3NH2
• Organic compounds exclude oxides of carbon and
  ions containing carbon.
• ie. CO, CO2, KCN, CaCO3
• are NOT organic compounds!!

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History of Organic Chemistry

• Organic chemistry can be traced back to ancient
  times when medicine men extracted chemicals from
  plants and animals to treat members of their
  tribes
• Organic chemistry was first defined as a branch
  of modern science in the early 1800's by Jon
  Jacob Berzelius

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• Berzelius believed in Vitalism - organic
  compounds could only originate from living
  organisms through the action of some vital force
• organic compounds originate in living or
  once-living matter
• inorganic compounds come from "mineral" or
  non-living matter

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• In 1828, Friedrich Wöhler discovered that urea -
  an organic compound - could be made by heating
  ammonium cyanate (an inorganic compound).
• NH4OCN(aq) ? (NH2)2CO(s)

organic
inorganic
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• organic chemistry branched into disciplines such
  as polymer chemistry, pharmacology,
  bioengineering and petro-chemistry
• 98 of all known compounds are organic

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• The huge number of organic compounds is due
  mainly to the ability of carbon atoms to form
  stable chains, branched chains, rings, branched
  rings, multiple rings, and multiple bonds (double
  and triple bonds) to itself and to many other
  non-metal atoms.

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Sources of Organic Compounds

• 1. Carbonized Organic Matter
• - fossil fuels such as coal, oil, and natural gas
  
• - basis for the petrochemical industry
• 2. Living Organisms
• eg - penicillin from mold
• - ASA from the bark of a willow tree

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• 3. Invention
• - antibiotics, aspirin, vanilla flavoring, and
  heart drugs are manufactured from organic
  starting materials
• - plastics

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Structural Isomers

• Structures that have the same molecular formula
  but different structural formulas are called
  structural isomers
• eg. C4H10
• Practice Draw all structural isomers of
  C5H12 and C6H14

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Structural Isomers

• structural isomers have the same chemical formula
  but have different chemical and physical
  properties.

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Classifying Organic Compounds
Organic Compounds
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• hydrocarbons consist of carbon and hydrogen atoms
  only
• eg. Methane - CH4
• hydrocarbon derivatives have one or more hydrogen
  atoms replaced by another nonmetallic atom
• eg. bromomethane - CH3Br
• methanol - CH3OH

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Hydrocarbons
AlkAnes
AlkEnes
AlkYnes
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• aliphatic hydrocarbons have carbon atoms bonded
  in chains or rings with only single, double, or
  triple bonds
• aromatic hydrocarbons contain at least one 6
  carbon benzene ring

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Aliphatic Hydrocarbons

• 1. Alkanes
• Alkanes are hydrocarbons that have only single
  bonds between carbon atoms
• general formula CnH2n2
• eg. C3H8 C6H14

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IUPAC prefixes
Prefix of carbon atoms
meth 1
eth 2
prop 3
but 4
pent 5
hex 6
hept 7
oct 8
non 9
dec 10
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Complete this table for the first 10 alkanes
methane CH4
ethane
propane







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• A series of compounds which differ by the same
  structural unit is called a homologous series
• eg. each successive member of the alkanes
  increases by CH2

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Representing Alkanes (4 ways)

• 1. Structural formulas
• eg. propane

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• Hydrogen atoms may be omitted from structural
  formulas
• eg. propane

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• 2. Condensed Structural Formula
• eg. propane
• CH3-CH2-CH3

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• 3. Line Structural Diagrams
• eg propane
• (the endpoint of each segment is a carbon atom)

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• 4. Expanded Molecular Formulas
• eg. propane
• CH3CH2CH3

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Alkyl Groups

• An alkyl group has one less hydrogen than an
  alkane.
• General Formula CnH2n 1
• To name an alkyl group, use the prefix to
  indicate the of carbon atoms followed by the
  suffix yl
• eg. -C7H15 heptyl

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Alkyl Groups

• methyl  -CH3
• ethyl  -C2H5  or  -CH2CH3
• propyl  -C3H7  or  -CH2CH2CH3

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Alkyl Groups

• Branched alkanes are alkanes that contain one or
  more alkyl groups
• eg.

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Naming Branched Alkanes

1. Find the longest continuous chain of carbons and
   name it using the alkane name. This is the parent
   chain.
2. Number the carbons in the parent chain starting
   from the end closest to branching. These numbers
   will indicate the location of alkyl groups.

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Naming Branched Alkanes

• List the alkyl groups in alphabetical order. Use
  Latin prefixes if an alkyl group occurs more than
  once.
• (di 2, tri 3, tetra 4, etc.)
• Use a number to show the location of each alkyl
  group on the parent.

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Naming Branched Alkanes

• Use commas to separate numbers, and hyphens to
  separate numbers and letters. 

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Naming Branched Alkanes
ethyl

• eg.

7 6 5 4 3
2 1
methyl
4-ethyl-3-methylheptane
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Naming Branched Alkanes

• Practice
• p. 336 - 339 s 5 - 11

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Alkenes and Alkynes

• saturated compounds contain only single bonds
  between carbon atoms
• eg. alkanes
• saturated compounds have the maximum number of
  hydrogen atoms bonded to carbon atoms

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Alkenes and Alkynes

• unsaturated compounds contain double or triple
  bonds between carbon atoms
• eg. alkenes and alkynes

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Alkenes and Alkynes

• General Formulas
• Alkenes CnH2n
• Alkynes CnH2n - 2

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Naming Alkenes and Alkynes

• Name the longest continuous chain that contains
  the double/triple bond. Use the smallest
  possible number to indicate the position of the
  double or triple bond.

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Naming Alkenes and Alkynes

• Branches are named using the same rules for
  alkanes. Number the branches starting at the
  same end used to number the multiple bond.

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Naming Alkenes and Alkynes

• p. 347 s 17 - 19
• p. 354 s 28 29

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Cyclic Hydrocarbons

• Pp. 356 358
• questions 30 31

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3-ethyl-1-methylcyclopentane
cyclopentane
ethyl
methyl
1-ethyl-3-methylcyclopentane
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methyl
1,2,3,4-tetramethylcyclohexane
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Aromatic Compounds

• Aromatic hydrocarbons contain at least one
  benzene ring.
• The chemical formula for benzene, C6H6 , was
  determined by Michael Faraday in 1825.
• Structural formula was determined by August
  Kekulé in 1865.

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Aromatic Compounds

• benzene ring consists of six carbon atoms, each
  of which is bonded to a hydrogen atom
• (Try to draw this!!)
• C6H6 can be drawn with alternating single and
  double bonds.

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Aromatic Compounds

• While CC double bonds are shorter than C-C
  single carbon bonds, x-ray crystallography shows
  that all six C-C bonds in benzene are the same
  length.
• Benzene molecules behave like alkanes in chemical
  reactions, not like the alkenes

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Aromatic Compounds

• Kekulé thought benzene could exist in two forms
  and used the idea of resonance to explain its
  structure.
• The resonance structure is an average of the
  electron distributions.

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Aromatic Compounds
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Aromatic Compounds

• bonding electrons that were thought to be in the
  double bonds are delocalized and shared equally
  over the 6 carbon atoms
• the bonds in benzene are like 1 ½ bonds
  somewhere between single and double.

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Naming Aromatic Compounds

• an alkyl benzene has one or more H atoms replaced
  by an alkyl group.
• name the alkyl groups, using numbers where
  necessary, followed by the word benzene.

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Aromatic Compounds
methylbenzene
ethylbenzene
propylbenzene
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Aromatic Compounds
1,3-dimethylbenzene
1,4-dimethylbenzene
1,2-dimethylbenzene
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Aromatic Compounds

• ortho- means positions 1 and 2 and is represented
  by an italicized "o"
• meta- means positions 1 and 3 and is represented
  by an italicized "m"
• para- means positions 1 and 4 and is represented
  by an italicized "p"

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Aromatic Compounds
m-dimethylbenzene
p-dimethylbenzene
o-dimethylbenzene
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Aromatic Compounds

• Benzene is treated as a branch if it is not
  attached to the terminal carbon of an alkyl group
• Benzene as a branch is called phenyl

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Aromatic Compounds
2-phenylpropane
propylbenzene
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Aromatic Compounds
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Aromatic Compounds
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Aromatic Compounds

• p. 361 s 32 35
• Hydrocarbons Practice
• pp. 363, 364
• s 4 9
• Test!!

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Hydrocarbon Derivatives

• Hydrocarbon Derivatives have one or more H atoms
  replaced by another nonmetallic atom
• Types of derivatives

• alcohols
• ethers
• aldehydes
• ketones

• carboxylic acids
• organic halides
• esters

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Hydrocarbon Derivatives

• A functional group is the reactive group of atoms
  that gives a family of derivatives its distinct
  properties.
• The general formula for a derivative is
• R - functional group
• where R stands for any alkyl group.

Bonded to
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Hydrocarbon Derivatives
hydroxyl group

• eg. ALCOHOLS R-OH
• ethanol C2H5OH
• propanol C3H7OH
• CARBOXYLIC ACIDS R-COOH
• ethanoic acid CH3COOH
• propanoic acid C2H5COOH

carboxyl group
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Hydrocarbon Derivatives

• Types of derivatives (See p. 378)
• Alcohols pp. 386 - 388
• Ethers pp. 394 396
• Aldehydes Ketones pp. 402,403
• Carboxylic Acids pp.405, 406
• Alkyl Halides pp. 390, 391
• Esters pp. 410, 411