1. Organic Chemistry

2. Organic Chemistry
Organic Chemistry: The chemistry of carbon and carbon-based compounds
Organic Chemistry in everyday life:
Smells & tastes: fruits, chocolate, fish, mint
Medications: Aspirin, Tylenol, Decongestants, Sedatives
Addictive substances: Caffeine, Nicotine, Alcohol
Hormones/Neurotransmitters: Adrenaline, Epinephrine
Food/Nutrients: Carbohydrates, Protein, Fat, Vitamins
Genetics: DNA, RNA
Consumer products: Plastics, Nylon, Rayon, Polyester

3. Organic Chemistry Also the “weed-out” class for pre-med students!
Notoriously difficult college class.

4. Question: What makes a molecule an organic molecule?
The presence of carbon-hydrogen bonds!

6. The simplest hydrocarbons: Alkanes
Compounds containing only C and H
All bonds are single bonds
Names end in -ane

7. Expanded and Condensed Structures

8. Structural Formulas “Lazy” way to write the Hydrogens
Instead of drawing the bonds, just state how many hydrogens are attached
NOTE: The bonds are between CARBONS in a parent chain, and not hydrogens!
Structural Formula
Expanded Structural formula

9. Names of Alkanes The names of alkanes
are determined by the IUPAC (International Union of Pure and Applied Chemistry) system.
end in –ane.
with 1-4 carbons in a chain use prefixes as follows.
Name # Carbons Structural Formula
Methane 1 CH4
Ethane 2 CH3CH3
Propane 3 CH3CH2CH3
Butane 4 CH3CH2CH2CH3

10. Prefixes for # of Carbons1
Meth 6
Hex 2
Eth 7
Hept 3
Prop 8
Oct 4
But 9
Non 5
Pent 10
Dec

11. Learning Check H C C C C C H H H H H H
A. Write the condensed formula for:
H H H H H
H C C C C C H
H H H H H
What is its molecular formula?
(Gives total # of each atom, does not indicate how they are arranged)
C. What is its name?
CH3─CH2─CH2─CH2─CH3
C5H12
pentane

12. ALKANES
(a “family” of hydrocarbons)
  CnH2n+2 CH4
C2H6
C3H8
C4H10
etc.
What would be the formula for decane, which has 10 carbons?

13. Some Structures for Butane: All these structures mean the same thing!

14. Cycloalkanes Cycloalkanes are alkanes that form a loop.
have two hydrogen atoms fewer than the open chain. (remember each carbon has 4 bonds)
Formula will be CnH2n
are named by using the prefix cyclo- before the name of the alkane chain with the same number of carbon atoms.

15. Examples of Cycloalkanes
Cyclopentane CH2 CH2 CH2 CH2 CH2 Cyclohexane CH2

16. Some Properties of Alkanes
Alkanes with 1-4 carbon atoms are:
methane, ethane, propane, and butane.
gases at room temperature.
used as heating fuels.

17. Trivia question: Can you name a famous propane salesman
Trivia question: Can you name a famous propane salesman? (He also sells propane-related accessories!)

18. Trivia question: Can you name a famous propane salesman?

19. Some Properties of Alkanes
Alkanes with 5-8 carbon atoms are
liquids at room temperature.
pentane, hexane, heptane, and octane.
very volatile.
used to make gasoline.
Alkanes with 9-17 carbon atoms
are liquids at room temperature
have higher boiling points.
are found in kerosene, diesel, and jet fuels.

20. Combustion In combustion reactions, alkanes react with oxygen.
CO2, H2O and energy are produced.
Alkane + O CO2 + H2O + heat

21. Learning Check Write a balanced equation for the
complete combustion of propane.

22. Isomers
Compounds with the same formula, but different structures

23. Are these isomers?

24. Structural isomers
same molecular formulas
different structural formulas

25. Pentane C5H12
3 structural isomers
No other arrangements of C5H12 possible

26. Chemists needed to expand the system of nomenclature to allow naming of individual structural isomers
Compounds without branches are called ‘straight chain’ alkanes
Branched compounds are named as derivatives of the longest straight chain in the molecule
The length of the longest chain provides the parent name
The straight chain is numbered to allow indication of the point of branching
The branches are named from the corresponding alkanes

27. Naming the branches

28. Alkane Alkyl group
Methane Methyl (CH3-)
Ethane Ethyl (CH3CH2-)
Propane Propyl (CH3CH2CH2-)
Butane Butyl (CH3CH2CH2CH2-)
Etc.
2-Methylbutane
[Straight chain numbered so as to give the lower branch number]

29. IUPAC rules for naming alkanes:
parent chain = longest continuous carbon chain  “alkane”.
branches on the parent chain are named as “alkyl” groups.
number the parent chain starting from the end that gives you the lower number for the first branch (principle of lower number).
assign numbers to the alkyl branches to show where they are in the parent chain
if an alkyl group appears more than once use prefixes: di, tri, tetra, penta…; each alkyl group must have a number!
the name is written as one word with the parent name last. The names and locants for the alkyl branches are put in alphabetic order (ignore all prefixes) separating numbers from numbers with commas and letters from numbers with hyphens.

30. Step 1. Find the parent chain.
Where is the longest continuous chain of carbons?

31. Step 2. Number the parent chain.
Number the parent chain so that the attached groups are on the lowest numbers
Methyl is on carbon #2 of the parent chain
Methyl is on carbon #4 of the parent chain
GREEN is the right way for this one! 2 7 1
Groups on 2 and 5
Groups on 4, 6, and 7
Groups on 2, 3, and 5
Groups on 3 and 6

32. Step 3. Designate where the group is attached to the parent chain.
Use the numbers of the parent chain from step 2 to designate the location of the attached groups to the parent chain.
2-methyl

33. 6-ethyl,3,6-Dimethylnonane
First, identify longest straight chain
‘…nonane’
Number so as to give lower numbers for branch points
Branches at C3 and C6
Not at C4 and C7
6-ethyl,3,6-Dimethylnonane

34. Identical substituents grouped together with a prefix
‘di…’ for two identical
‘tri…’ for three
‘tetra…’ for four
Substituents named in alphabetical order

35. hexanes C6H IUPAC names
CH3
CH3CH2CH2CH2CH2CH CH3CHCH2CH2CH3
hexane 2-methylpentane
CH CH3
CH3CH2CHCH2CH3 CH3CCH2CH3
3-methylpentane ,2-dimethylbutane
CH3CHCHCH3
2,3-dimethylbutane

36. Draw Some Simple Alkanes
3-ethylhexane
2,2-dimethylbutane
2,3-dimethylbutane

37. Alkanes
Now that we know how to name alkanes, let’s learn something about their chemical properties.

38. Alkanes – chemical properties
The main chemical property of alkanes is that they have very low reactivity.
Why? Know these two reasons:
1. Ionic and polar compounds tend to be more reactive than non-polar compounds.
Non-polar compounds don’t attract other molecules to react with.
2. C-C and C-H bonds are relatively strong. It takes a lot of energy to break them.

39. Alkanes – chemical properties
The net effect is that alkanes have a fairly restricted set of reactions.
You can:
burn them - destroying the whole molecule
react them with some of the halogens, breaking carbon-hydrogen bonds;
crack them, breaking carbon-carbon bonds.

40. Cracking?
Cracking is the name given to breaking up large hydrocarbon molecules into smaller and more useful bits.

41. Cracking
There isn't any single unique reaction happening in the cracker. The hydrocarbon molecules are broken up in a fairly random way to produce mixtures of smaller hydrocarbons, some of which have carbon-carbon double bonds. One possible reaction involving the might be:

42. Alkanes – chemical properties
One chemical reaction that alkanes will readily undergo is combustion!
CH4 is methane – a main component of natural gas. Used to heat homes.
C2H4 (ethane) is also a main component of natural gas.
C3H8 (propane) – sold as fuel for camp stoves
C4H8 (butane) – used in lighters
C8H18 (octane) – major component of gasoline

43. New topic: Functional Groups

44. Functional Groups As we’ve seen, alkanes don’t do much, except burn.
The chemistry of hydrocarbons is really controlled by what is attached to the alkanes.
Those attachments are called functional groups.

45. Big Idea in Organic Chemistry
Structure controls Function
Each functional group has predictable reactivity

46. Types of Organic Compounds
Classified according to functional group
Alkane
Alkene
Alkyne
Haloalkane
Alcohol
Ether
Ketone
Aldehyde
Carboxylic acid
Amine
Amino acid
Amide

47. Naming Alkenes & Alkynes
Using the IUPAC alkane names:
Alkene names change the end to -ene.
Alkyne names change the end to -yne
Ignore the names in parentheses – those are the old-fashioned names from before the naming rules!

48. IUPAC Nomenclature for alkenes
Parent is longest chain containing the double bond.
-ane changes to -ene.
Number the chain so that the double bond has the lowest possible number.
Chapter 7

49. Naming Alkenes & Alkynes
CH2= CH ─ CH2─ CH3 1-Butene
CH3─ CH=CH─ CH3 2-Butene
CH3 |
CH3─ CH=C─CH3 2-Methyl-2-butene
CH3─ CC ─ CH3 2-Butyne 1 2 3 4 1 2 3 4 4 3 2 1 1 2 3 4

50. Naming Alkenes & Alkynes
CH3─ CH2─ CC ─ CH Pentyne
CH3
CH3─ CH2─ C=CH ─ CH Methyl-2-pentene
CH2 – CH3
CH3─ CH2─ C=CH ─ CH Ethyl-2-pentene 5 4 3 2 1 5 4 3 2 1 5 4 3 2 1

51. Reactions of alkenes and alkynes
The presence of a double or triple bond in a hydrocarbon makes them much more reactive.
The double or triple bond indicates the presence of extra electrons, providing a good site for reactivity.

52. Addition reactions of alkenes and alkynes
In addition reactions, a reactant is added to the two atoms that form the multiple bond.
Example: Reaction of ethene with bromine:

53. Addition of hydrogen: Hydrogenation
Hydrogenation of alkenes produces the corresponding alkanes.
CH2=CH2 + H2 → CH3-CH3

54. Hydrogenation Notice that the reactant can hold extra hydrogens,
but the product is full of hydrogen.

55. Hydrogenation
Hydrogenation turns unsaturated hydrocarbons into saturated hydrocarbons
Saturated?
Remember what a saturated solution is? (It’s holding all the solute it can possibly hold.)
A saturated hydrocarbon is holding all the hydrogens it can possibly hold.
Saturated hydrocarbons are alkanes – no double or triple bonds!
Unsaturated hydrocarbons are alkenes or alkynes – more hydrogen could be added.

56. Saturated and unsaturated hydrocarbons

57. A related term: saturated fat

58. Saturated fats don’t have any double bonds.
Monounsaturated fats have one double bond,
polyunsaturated have more than one double bond.

59. Saturated and unsaturated fats
When one of the carbon bonds in the chain is a double bond, there are two less hydrogens than there would be in a saturated fat, so it is called a mono-unsaturated fat. When there is more than one double bond it is called a poly-unsaturated fat.
Unsaturated fats are better than saturated because the body can break them down easier and so they are used more quickly in the body’s metabolism.

60. Structure - Alcohols
The functional group of an alcohol is an -OH group bonded to a carbon

61. Nomenclature-Alcohols
IUPAC names
the parent chain is the longest chain that contains the OH group
number the parent chain to give the OH group the lowest possible number
change the suffix -e to -ol

62. Name these:
2-methyl-1-propanol
2-butanol
2-methyl-2-propanol

63. Physical Properties Alcohols are polar compounds
So – is this alcohol soluble in water?

64. Solubility in Water
Solubility decreases as the size of the alkyl group increases =>

65. Methanol
Can you draw the structure of methanol?

66. Ethanol Distillation produces “hard” liquors
Denatured alcohol used as solvent
10% ethanol in gasoline

67. Chemical Properties of alcohols

68. Dehydration Reactions
An alcohol can be converted to an alkene by dehydration.
Dehydration is just what is sounds like – removal of water.

69. Dehydration of alcohols2 S O 4 C H 3 2 O C H 2 = + O
180°C O H H 2 S O 4 + H 2 O
140° C
Cyclohexanol
Cyclohexene C H 3 C H 3 H 2 S O 4 C H 3 O C H 3 = 2 + H 2 O
50° C C H 3
2-Methyl-2-propanol
2-Methylpropene

70. As we’ve seen, alkanes have similar chemical properties, alkenes have
similar chemical properties, and alcohols have similar chemical properties.
Remember – it’s the functional group that controls the chemical properties.

71. One last example of a functional group:
Ketones

72. Ketones:
Can you find the functional group?

73. Memory trick for ketones:
The ketone functional group looks like a key hole. Right?

74. Ketones:
Ketones are named by dropping the -e ending of the parent name and adding -one.
5-methyl-3-hexanone
2-pentanone