1. Lecture 6 – Chapter 11 Intro to Organic Chemistry

2. What is organic chemistry?
Chemistry of carbon compounds
Originally term described chemistry of compounds in life. However, what is life?? Martin Hanczyc suggests that there is a fine line between life and not-life
Important chemicals of living organisms organic – carbohydrates, proteins, nucleic acids, vitamins, hormones, etc.
Organic compounds isolated from nature or synthesized
has many H atoms
may also contain O, S, N, P, and halogens

3. Comparing Properties of Organic and Inorganic Compounds
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4. Organic versus Inorganic Compounds
Propane, C3H8, is an organic compound used as a fuel.
NaCl, salt, is an inorganic compound composed of Na+ and Cl– ions.
Question: Why is propane
an organic compound, but
NaCl is not?
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5. Writing Formulas for Carbon Compounds – periodic table next slide
In carbon compounds,
carbon has 4 valence electrons, and hydrogen has 1 •
• C • H •
to achieve an octet, C forms four bonds
H H
 
H  C  H H C H
H H CH4 (methane)
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6. Tetrahedral Structure of Carbon
Valence Shell Electron Pair Repulsion (VSEPR) theory predicts that a carbon atom with four single, covalent bonds is tetrahedral as shown in a
(a) tetrahedron
(b) ball-and-stick model
(c) space-filling model
(d) expanded structural formula
VSEPR – Valence electron pairs repulse each other. Molecules adopt a geometry so that electron pairs are as far apart as possible.
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7. Organic Compounds with More Carbon Atoms
In organic molecules with more carbon atoms,
valence electrons are shared
covalent bonds form between carbon atoms
covalent bonds form between carbon and hydrogen atoms
H H H H
• • • •
H  C  C  H H C C H
H H H H CH3─CH3 (ethane)
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8. Tetrahedral Structure of Ethane
In VESPR, two carbon atoms in ethane each has a tetrahedral shape as shown in a
(a) tetrahedron
(b) ball-and-stick model
(c) space-filling model
(d) expanded structural formula
ethane in Chemspider
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9. Examples of covalent compounds of carbon - atomic orbitals (p122) become hybrid orbitals when atoms bond. Shapes dictated by orbitals and VSEPR theory
Three types of carbon bonds –1. Single bond (tetrahedral), 2. double bonds (trigonal planar) and 3. triple bond (linear)
Single bonds
Tetrahedral, Bond angle 109.5o
Example: Formaldehyde-an aldehyde
Example: ethylene -an alkene
Double bonds
Trigonal planar
Bond angle 120o
Example:
Ethyne- an alkyne
Triple bonds
Linear
Bond angle 180o
Example:
Ethane – an alkane
Lewis dot of ethane
Lewis dot of ethyne
Lewis dot of ethene
3D model of ethane

10. Names of Alkanes The names of alkanes
are determined by the IUPAC (International Union of Pure and Applied Chemistry) system
use a prefix to indicate the number of carbons in a chain
end in -ane
IUPAC naming rules
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11. Learning Check A. Give the name of each compound: 1) CH3—CH3
2) CH3—CH2—CH3
3) CH3—CH2—CH2—CH2—CH2—CH3
Write the condensed structural formula of pentane.
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12. Solution A. Give the name of each compound: 1) CH3—CH3 ethane
2) CH3—CH2—CH3 propane
3) CH3—CH2—CH2—CH2—CH2—CH3 hexane
B. Write the condensed structural formula of pentane.
CH3—CH2—CH2—CH2—CH3
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13. General, Organic, and Biological Chemistry
Types of Structural Formulas (molecular formulas of alkanes are CnH2n+2
Tetrahedral
Bond angles all 109.5
C6H14
hexane chemspider
shows each carbon atom and the attached hydrogen atoms
shows each bond
C atom = tetrahedral, atoms not straight line, but zigzag
line-bond formula abbreviates the carbon atoms and shows only the zigzag pattern of bonds from carbon atom to carbon atom.
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14. Learning Check A. Draw the condensed structural formula of H H H H H
H C C C C C H
H H H H H
B. What is its molecular formula?
C. What is its name?
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15. Solution A. Draw the condensed structural formula: CH3─CH2─CH2─CH2─CH3
B. What is its molecular formula? C5H12
C. What is its name? pentane
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16. Learning Check Draw the condensed structural formula for: A. Ethane
B. Heptane
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17. Solution Draw the condensed structural formula for: A. Ethane CH3─CH3
B. Heptane CH3─CH2─CH2─CH2─CH2─CH2─CH3
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18. Cycloalkanes cyclic alkanes 2H fewer than the alkane (CnH2n)
Use the prefix cyclo- before the name
The structural formulas
geometric figures
carbons:
Cyclopropane Cyclobutane Cyclopentane Cyclohexane
cyclohexane chemspider ring pucker
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19. Learning Check Name the following: A. CH3─CH2─CH2─CH3 B.
C. CH3─CH2─CH2─CH2─CH2─CH2─CH2─CH3 D.
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20. Solution Name the following: A. CH3─CH2─CH2─CH3 butane B. cyclopropane
C. CH3─CH2─CH2─CH2─CH2─CH2─CH2─CH3 octane D.
cyclohexane
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21. Alkanes with Substituents
Chapter 2
Alkanes with Substituents
butane chemspider
Constitutional Isomers
same molecular formula
different structural arrangements (connectivity)
a straight chain with branched chain(s)
Branch or substituent
2-methylpropane chemspider
GOB: 11.4 constitutional isomers exercise/tutorial
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22. General, Organic, and Biological Chemistry
Substituents
Substituents are
attached to carbon chains
carbon branches that are missing one H and named as alkyl groups
halogen atoms that are named as halo substituents
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23. **Branched Substituents

24. Naming Alkanes with Substituents
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25. Example of Naming Alkanes
Give the name of CH3
CH3─CH─CH2─CH3
STEP 1 Write the name of the longest chain: butane
STEP 2 Number the chain from the end nearer a branch: CH3
STEP 3 Give location and names of substituents:
2-Methylbutane
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26. Learning Check Write the IUPAC name for: Cl CH3 CH3─CH2─CH─CH─CH3
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27. Solution STEP 1 Write the name of the longest chain: pentane
STEP 2 Number chain from end nearer substituents:
Cl CH3 (nearer end)
CH3─CH2─CH─CH─CH3
STEP 3 Give location and name substituents alphabetically:
3-Chloro-2-methylpentane
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28. Learning Check Give the IUPAC name for each of the following:
A CH CH3
| |
CH3─CH─CH2 ─CH─CH2─CH3
B Cl CH3
| |
CH3─CH2─CH─CH2─C─CH2─CH3 | Cl
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29. Solution A. CH3 CH3 | | CH3─CH─CH2 ─CH─CH2─CH3 2,4-dimethylhexane
| |
CH3─CH─CH2 ─CH─CH2─CH3 2,4-dimethylhexane
B Cl CH more substituents on C3
| |
CH3─CH2─CH─CH2─C─CH2─CH3 | Cl
3,5-dichloro-3-methylheptane
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30. Guide to Drawing Alkane Structures
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31. What Is in a Name?
The structural formula is drawn from the IUPAC name.
2,4-dimethylhexane
2, dimethyl hexane
Location of Two CH3-groups carbon main chain
branches on attached with single C—C
bonds main chain
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32. Learning Check Draw the condensed structural formula for
3-bromo-1-chlorobutane.
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33. Solution STEP 1 Draw a chain with 4 carbon atoms: C─C─C─C
STEP 2 Number the chain and add substituents: Br 
C ─ C ─ C ─ C ─ Cl
STEP 3 Add hydrogen (H) to give four bonds to each C:
CH3─CH─CH2─CH2─Cl
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34. Naming Cycloalkanes with Substituents
The name of a substituent is placed in front of the
cycloalkane name.
CH3
Methylcyclobutane
When there are two substituents, number the ring
1-bromo-2-chlorocyclopentane Br Cl
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35. Learning Check Name each of the following: 1. CH3 CH2─CH3 2. Cl
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36. Solution Name each of the following: 1. CH3 methylcyclopropane CH2─CH32.
Cl Chloro-1-ethylcyclohexane
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37. Learning Check Write three isomers of C5H12, and name each.
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38. Solution A chain of 5 carbon atoms: CH3─CH2─CH2─CH2─CH3 pentane
A chain of 4 carbon atoms and 1 carbon branch:
CH3 │
CH3─CH─CH2─CH methylbutane
A chain of 3 carbon atoms and 2 carbon branches:
CH3─C─CH ,2-dimethylpropane
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39. Cis-trans isomers in cycloalkanes
Cis-trans isomers are stereoisomers
Stereoisomers have same connectivity (unlike constitutional isomers) but different orientation of atoms in space.
Cis – substituents on same side of C-C bond
Trans (cross) – substituents on opposite side of bond

40. Some Properties of Alkanes
The properties of alkanes include being
nonpolar
insoluble in water
less dense than water
Very low boiling points
Two main reactions:
Highly flammable in air (combustion, oxidation)
Halogenation
Alkane + O2(g) CO2(g) + H2O(g) + energy
Alkane + X2(g) Haloalkane + HX
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41. Increase C chain increase boiling points
Increase C chain increase boiling points - chains interact with each other through London dispersion forces Adding a branch to chain decreases boiling points
1–4 carbon atoms are methane, ethane, propane, and butane
gases at room temperature
used as heating fuels
5–17 carbon atoms are
liquids at room temperature
pentane, hexane, heptane, and octane
very volatile
Shorter chains used to make gasoline
Longer chains (higher boiling points) kerosene, diesel, and jet fuels
18 or more carbon atoms
are waxy solids at room temperature
are used in waxy coatings of fruits and vegetables

42. Unsaturated Hydrocarbons
have fewer hydrogen atoms attached to the carbon chain than do alkanes
are alkenes with double C=C bonds
are alkynes with triple C≡C bonds

43. Naming Alkenes The names of alkenes use the corresponding alkane name
change the ending from -ane to –ene
Alkene  IUPAC 
H2C=CH2  Ethene  
H2C=CH─CH3  Propene  
  Cyclohexene

44. Cis–Trans Isomers Cis–trans isomers occur when
different groups are attached to
the double bond.
In a cis isomer, groups are attached on the same side of the double bond. 
In the trans isomer, the groups are attached on opposite sides of the double bond. 

45. Benzene Structure Benzene
has 6 electrons shared equally among the 6 C atoms (delocalized)
Can be represented by resonance structures
is also represented as a hexagon with a circle drawn inside

46. (or carbon groups)

47. behave in a predictable way Have atom or group of atoms
Functional groups
behave in a predictable way
Have atom or group of atoms
groups replace a H in the corresponding alkane
classify families of organic compounds
R, R’, etc. refer to general hydrocarbon
Naming priorities