Unit 3 Organic 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

• Started when medicine men extracted chemicals
  from plants and animals as treatments and cures
• 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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• Whats this?
• (NH2) 2CO - (NH2)2CO

di-urea
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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.
• Some more Organic notes

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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
Hydrocarbons
Hydrocarbon Derivatives

• Alcohols
• Ethers
• Aldehydes
• Ketones
• Carboxylic Acids
• Alkyl Halides
• Esters
• Amines
• Amides

Aromatic (benzene based)
Aliphatic
AlkAnes
AlkEnes
AlkYnes
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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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• 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 alkane increases by CH2
• What is the next member of this homologous
  series?
• SiO2 Si2O3 Si3O4 _____

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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
• octane CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH3
• OR
• CH3-(CH2)6-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
• p. 333

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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(parent chain) and name it using the
   alkane name.
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
• (Answers on p. 375)

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2. Alkenes and Alkynes

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

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Alkenes and Alkynes

• unsaturated hydrocarbons 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

At least one double bond
At least one triple bond
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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
1-ethyl-3-methylcyclopentane
cyclopentane
ethyl
methyl
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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 formula for benzene, C6H6 , was determined by
  Michael Faraday in 1825.
• The structural formula was determined by August
  Kekulé in 1865.

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Aromatic Compounds

• Proposed formula

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Conflicting Evidence

• CC double bonds are shorter than C-C single
  bonds. X-ray crystallography shows that all C-C
  bonds in benzene are the same length.
• Benzene reacts like an alkane, not like an
  alkene.

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Modified structure

• Kekulé proposed a resonance structure for
  benzene.
• The resonance structure is an average of the
  electron distributions.

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Aromatic Compounds
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Aromatic Compounds

• bonding electrons, once believed to be in double
  bonds, are delocalized and shared equally over
  the 6 carbon atoms
• the bonds in benzene are like 1½ 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 "o"
• meta- means positions 1 and 3 and is represented
  by "m"
• para- means positions 1 and 4 and is represented
  by "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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cis and trans isomers (p. 348)
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Properties of aliphatic hydrocarbons

• Because they are nonpolar, all hydrocarbons are
  insoluble in water.
• The boiling point of alkanes is somewhat higher
  than alkenes but lower than alkynes.
• As the number of atoms in the hydrocarbon
  molecule increases, the boiling point increases.

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Reactions

• Complete the aliphatic hydrocarbons worksheet
  using these references
• a) complete combustion (p. 340)
• b) incomplete combustion (p. 340)
• c) substitution reaction (p. 344, 362)
• d) addition reaction (p. 349)

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Hydrocarbon Derivatives

• Hydrocarbon Derivatives contain other nonmetal
  atoms such as O, N, or halogen atoms.
• 9 types of derivatives
• (See p. 378 ethers and organic halides)
• the reactive group of atoms that gives a family
  of derivatives its distinct properties is a
  functional group

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Hydrocarbon Derivatives

• The general formula for a derivative is
• R - functional group
• where R stands for any alkyl group.

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Hydrocarbon Derivatives

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

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1. Alcohols

• Have the hydroxyl functional group
• General Formula R - OH

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Naming Alcohols (p. 387)

• The parent alkane is the longest chain that has
  an -OH group
• Replace the last -e in the alkane name with the
  suffix -ol.
• Add a number to indicate the location of the -OH
  group.

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methanol
ethanol
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• eg.

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Properties of Alcohols (p. 389)

• Alcohols have H-bonding which makes their mp and
  bp higher than the corresponding alkane.
• Polarity decreases as the of carbon atoms
  increases
• Long chain alcohols are less soluble in water
  than short chain alcohols.

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Reactions of alcohols

• Combustion
• R-OH O2 ? CO2 H2O
• eg. Write the equation for the burning of
  butanol.

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Reactions of alcohols

• Substitution
• R-OH H-X ? R-X H2O
• eg. Use structural formulas to show the reaction
  between 2-pentanol and HBr.

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Reactions of alcohols

• Elimination (Dehydration)
• eg.

H2SO4
H2O
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• P. 393 16 a), d), 18 a), b), d) e)
• (Draw structural formulas for the products in 18)

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2. Ethers

• Composed of two alkyl groups bonded to an oxygen
  atom.
• General Formula R1-O-R2
• Naming ethers p. 395
• IUPAC name
• Common name

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(No Transcript)
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P. 395, 396 s 20 23 Worksheet Ethers
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3. Aldehydes (p. 402)

• Contain a carbonyl functional group at the end of
  a carbon chain.
• General Formula

O
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• Naming
• Use the alkane name for the longest continuous
  chain.
• Remove the e and add the suffix al
• eg.
• butane ? butanal

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4. Ketones (p. 402)

• Contain a carbonyl functional group in the
  middle of a carbon chain.
• ie. NOT on carbon 1
• General Formula

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• Naming
• Use the alkane name for the longest continuous
  chain.
• Replace the e with the suffix one
• Use the smallest possible number for the position
  of the CO group.

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p. 403 s 28 - 31 Handout Aldehydes and
Ketones
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5. Carboxylic Acids (p. 405)

• Contain a carboxyl functional group
• ie. -COOH
• General Formula
• AKA Organic Acids

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• Naming
• Use the alkane name for the LCC that contains the
  COOH group.
• Replace the e with the suffix oic acid

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Text p. 406 s 32 - 35
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6. Alkyl Halides (p. 390, 391)

• Contain at least one halogen atom
• General Formula R X
• (X is F, Cl, Br, or I)

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Text p. 391 s 12 - 15
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• Elimination - Alcohols
• eg.

H2SO4
?
H2O
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• Elimination Alkyl Halides
• eg.

OH- ?
H2O I-
p.393 s 18 c) and f)
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7. Esters (pp. 410, 411)

• Form when a carboxylic acid reacts with an
  alcohol
• General Formula
• Esterification Reaction
• carboxylic acid alcohol ? ester water

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pp. 411, 412 s 36 - 40
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Cracking Reforming

• Cracking is a reaction that break long chain
  hydrocarbons into smaller fragments.
• eg.
• decane H2 ? ethane octane

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Reactions Organic Compounds

• Combustion (p. 340)
• Substitution (p. 344)
• Esterification (p. 410)
• Elimination (p. 390)

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Cracking Reforming

• Reforming is a reaction that combines smaller
  hydrocarbons to make long chain hydrocarbons
• eg.
• ethane butane ? hexane H2

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Review - Derivatives

• pp. 400, 401
• Omit 1a), 2c) d), 3b) e), 5b),
• 8, 10b) c), 11b) d)
• pp. 419, 420
• Omit 1g), 3d), 4a), 7, 8c), 10