1. Organic Chemistry
Topic 11

2. What is Organic Chemistry?
The study of carbon and most carbon compounds
“The chemistry of life”
… but includes far more compounds than those made by living things.

3. Bonding of Carbon Atoms
Carbon can form so many compounds because carbon atoms easily form covalent bonds with other carbon atoms
Can be single, double, or triple covalent bonds

4. Bonding of Carbon Atoms
Lewis Dot Diagram of Carbon in ground state
Lewis dot diagram of bonded carbon atom
Enables four covalent bonds
Tetrahedral shape
Angles are actually

6. Some Terminology
Organic compounds containing only single bonds are said to be saturated.
Organic compounds containing one or more double or triple bonds are called unsaturated compounds.

7. More Terminology
Hydrocarbons - organic compounds that contain only hydrogen and carbon atoms
Homologous series - group of related compounds in which each member differs from the one before by one additional unit.
Alkanes
Alkenes
Alkynes

8. Chemistry Humor According to a chemist, why is the world so diverse?
Because it's made up of alkynes of people.

9. Alkanes All single bonds between carbon atoms
Therefore, all saturated.
As the number of carbon atoms in this homologous series increases, so does the boiling point
Names end with “-ane”

10. Alkanes Methane - Natural gas Ethane - Also natural gas
Propane - outdoor grills/home heating
Butane - lighters
Pentane, Hexane, Heptane, Octane, Nonane, Decane - all found in gasoline
Candle wax - 20 or more carbon atoms
Road Tar - 40 or more carbon atoms

11. General Formula For Alkanes
Each successive carbon adds two more hydrogen atoms
Let’s develop a general formula for alkanes…
CnH2n+2

12. Alkenes Each member of alkene series contains one double covalent bond
Names are same as for alkanes, except change ending to “-ene”.
Ethene - (common name “ethylene”)
Unsaturated

13. Alkenes
Let’s develop a general formula for “alkenes”….
CnH2n

14. Alkynes Contain one triple bond between carbon atoms
Names are same as for alkanes, except change ending to “-yne”.
Ethyne (common name “acetylene” - used in welding torches)

15. Alkynes Let’s develop a general formula for alkynes CnH2n-2
Pull out Reference Tables…
Table P - Organic Prefixes
Table Q - homologous series & general formulas

17. Homework
Review Book Page 197 #1-18.

18. Let’s Keep some terms straight…
Molecular formula - represents the actual atoms in a molecule
Reminder - empirical formula is the simplest integer ratio in which atoms combine in a compound.
Structural Formula - attempts to show the kinds and numbers of atoms, but also the bonding patterns and approximate shapes
Condensed structural formulas

19. Let’s Keep some terms straight…
Ball-and-stick model
Space-filling model (very similar to “molecular shape” model)

20. Isomers Get a model kit and build a ball-and-stick model of butane.
How many carbons and hydrogen did you need?
Use the same number of carbons and hydrogens, but build something different than the butane you built above.

21. Isomers
Starting with butane there’s more than one way to combine the carbon and hydrogen atoms.
When a molecular formula can be represented by more than one structural arrangement, the compounds are called isomers of one another.

22. Isomers
Even though they have the same molecular formula, isomers have different chemical and physical properties.
Different boiling points
Different reactivities
As the number of carbon atoms increases, so does the number of possible isomers.

24. Naming Organic Compounds
When carbon atoms in one continuous chain, called a “straight chain” hydrocarbon
Also called “normal form”
The letter “n-” precedes the name of straight chain hydrocarbons

25. Naming Organic Compounds
Compounds with branched chains must be given different names because they have different chemical and physical properties.
Naming rules are governed by IUPAC (International Union of Pure and Applied Chemistry)

26. Naming Organic Compounds
Step 1 - Find the longest continuous chain of carbon atoms
The compound will be named based on its longest chain.
For example, if the longest chain is 6, then the compound will be named as a hexane.

27. Naming Organic Compounds
Step 2 - Identify attached Alkyl Groups
An alkyl group contains one less hydrogen than an alkane with the same number of carbon atoms
Step 3 - Assign numbers to the carbon atoms in the longest chain.
They must be numbered from the end that will give the lowest number for the attached group.

28. Naming Organic Compounds
Step 4 - Name the compound by stating the location of the attached chain, the alkyl group, then the main branch name

29. Naming Organic Compounds
Some additional naming info…
If there is more than one of the same type of group attached to the parent chain, then a prefix is used
di- means two; tri- means three; tetra- means four
Commas are used to indicate the specific carbon to which each group is attached

30. Naming Organic Compounds
Worksheet - Isomers of octane
Worksheet 25-4 Apply “A Compound Problem”

31. Functional Groups
Functional Groups - are atoms or groups of atoms that replace hydrogen in a hydrocarbon, and give the compound distinctive chemical and physical properties.

32. Organic Acids Organic Acids are a homologous series
Functional group is carboxyl group (-COOH)
Name comes from corresponding hydrocarbon, but replace ending “-e” with “-oic acid”
Ethanoic acid (common name “acetic acid”, which is found in vinegar)

33. Organic Acids
Most organic compounds are nonelectrolytes, but organic acids are weak electrolytes.
Reference Table R

34. Alcohols
Alcohols - organic compounds where one hydrogen of a hydrocarbon is replaced by an -OH group (called a hydroxyl group)
The -OH group resembles the hydroxide ion, but it isn’t the same. It doesn’t form hydroxide ion in water.
Therefore, alcohols are nonelectrolytes

35. Alcohols
The hydroxyl group is polar, though, which allows alcohols to dissolve in water.
Name by changing corresponding alkane ending “-e” to “-ol”

36. Esters Esters are organic compounds whose type formula is R-CO-ORI
Part comes from an organic acid, and the RI part comes from an alcohol
Esters have strong, fragrant odors.

37. Esterification
Esterification - The organic reaction between an organic acid and an alcohol to produce an ester plus water.
Esters are named by using the alkyl name of the alcohol followed by the acid group modified to end in “-oate”.

38. Esterification
Esterification Lab

39. More About Alcohols There are several different types of alcohols
Type depends on number of hydroxyl groups
Type depends on the position of each hydroxyl group on the chain

40. Alcohols
Alcohols are primary, secondary, or tertiary based on whether the hydroxyl group is attached to a primary, secondary, or tertiary carbon atom.
Primary carbon - attached to only one other carbon atom
Secondary Carbon - attached to two other carbon atoms
Tertiary Carbon - attached to three other carbon atoms

41. Alcohols
Primary Alcohol - has a hydroxyl group attached to primary carbon
Secondary Alcohol - hydroxyl group attached to secondary carbon
Tertiary Alcohol - hydroxy group attached to tertiary alcohol

42. Alcohols Monohydroxy alcohols - have one hydroxyl group
Dihydroxy alcohols - two hydroxyl groups
1,2 ethanediol
Trihydroxy Alcohols- three hydroxyl groups
1,2,3 propanetriol

43. Some Practice
Page 204 #34,35, 39, 41, 42, 43,45

44. Organic Halides (“Halocarbons”)
When a halogen (F, Cl, Br, or I) replaces a hydrogen on an alkane, the compound is called an organic halide (or halocarbon).
The functional group is the attached halogen.
Named by citing the location of the halogen attached to the chain.

45. Ethers
Series of organic compounds in which two carbon chains are joined together by an oxygen atom bonded between two carbon atoms.
Named using alkyl group names followed by “ether”.

46. Worksheet 26-1 Apply
Halocarbon, Alcohol, or Ether?

47. Amines
Amines are formed when one of the hydrogens of ammonia is replaced by an alkyl group.
Named by taking the alkane name and change the ending “-e” to “-amine”, and number the alkane chain to show the location of the amine group.

48. Carbonyl Group
When an oxygen is bound to a carbon by a double bond, it is called a carbonyl group.
Overhead “Functional Groups of Organic Compounds”

49. Aldehydes
Aldehydes are organic compounds in which the carbonyl group is on the end carbon
Named by substituting “-al” for the final “-e” of the corresponding alkane name.
Methanal’s common name is “formaldehyde”

50. Ketones
Ketones formed when carbonyl group is attached to an interior carbon atom that is attached to two other carbon atoms.
Named by replacing final “-e” of corresponding alkane name with “-one”
Propanone’s common name is “acetone” - nail polish remover.
Ketones are often used as solvents (because both polar and nonpolar

51. Amino Acids
Amino acids contain the carboxylic group (-COOH) and an amine.
The amine group is attached to the carbon adjacent to the acid group.
Amino acids are the building blocks of protein.
The body must take in (ingest) 10 essential amino acids, because the body can’t produce them. The remaining amino acids can be synthesized.

52. Amides Amides are compounds formed by combination of two amino acids.
Look at Figure page 166.
Also called a “peptide bond”.
Additional amino acids can be linked, forming “polypeptides”, and eventually, proteins.

53. Saponification The name of the organic reaction that makes soap.
An ester reacts with an inorganic base to produce an alcohol and soap.

54. Polymerization
Polymers - organic compounds made up of chains of smaller units covalently bonded together
The formation of these large polymer molecules is called polymerization

55. Polymerization Each individual unit is called a monomer.
Synthetic Plastics (nylon, rayon, polyethylene, etc..) are polymers

56. Polymerization Two General Types of Polymerization Reactions
Addition Polymerization - involves the joining of monomers of unsaturated compounds
Condensation Polymerization - result from the bonding of monomers by removing water from hydroxyl groups and joining the monomers by an ester or ether linkage.

57. Addition Polymerization
An addition reaction is one in which two or more molecules join together to give a single product. During the polymerisation of ethene, thousands of ethene molecules join together to make poly(ethene) - commonly called polyethylene.
The number of molecules joining up is very variable, but is in the region of 2000 to

58. Addition Polymerization
The mechanism
The over-all process is known as free radical addition.
Chain initiation
The chain is initiated by free radicals, Ra, produced by reaction between some of the ethene and the oxygen initiator.
Chain propagation
Each time a free radical hits an ethene molecule a new longer free radical is formed.
etc

59. Substitution Reactions
A substitution reaction involves the replacement of one or more of the hydrogen atoms in a saturated hydrocarbon with another atom or group.
CH4 + Cl2  CH3Cl + HCl

60. Substitution Reactions
If a mixture of methane and chlorine is exposed to a flame, it explodes - producing carbon and hydrogen chloride. This isn't a very useful reaction!
So how does the substitution reaction occur without an explosion?

61. Substitution Reaction
The mechanism involves a chain reaction.
The chain is initiated (started) by UV light breaking a chlorine molecule into free radicals.
Cl2  2Cl•
By the way, this is an example of a photochemical reaction.

62. Substitution Reaction
Chain propagation reactions - these are the reactions that keep the chain going…
CH4 + Cl• CH3• + HCl
CH3• + Cl2  CH3Cl + CL•
The chain terminates when one of these reactions occurs…
2Cl•  Cl2
CH3•  +  Cl•  CH3Cl
CH3•  +  CH3•  CH3CH3

63. Addition Reactions
Addition Reactions involve adding one or more atoms at a double or triple bond.
C2H4 + Cl2  C2H4Cl2 Or
C2H4 + H2  C2H6

64. Fermentation
Fermentation is a chemical process in which yeast cell secrete enzymes (zymase) and break sugar chains into carbon dioxide and water
C6H12O6  2C2H5OH + 2CO2