1. Organic Chemistry
Mrs. Rose Marie Capanema Mansur

2. Organic Chemistry

3. Origins
Originally defined as the chemistry of living materials or originating from living sources.
Wohler synthesized urea from non organic sources (1800 – 1882)
Now generally defined as the chemistry of carbon and its compounds.

4. Hydrocarbons
Hydrocarbons are organic compounds that contain only hydrogen and carbon
Types :
Alkanes
Alkenes
Alkynes
Aromatic 4

5. WHAT DO ORGANIC COMPOUNDS LOOK LIKE?
Leaded gasoline: antiknock additives such as TEL, an organometallic compound with the formula (CH3CH2)4Pb.

6. Naming Hydrocarbons Using the IUPAC System
A series of prefixes are used to designate the number of carbon atoms in a carbon chain:
meth
1 C
hex
6 C
eth
2 C
hept
7 C
prop
3 C
oct
8 C
but
4 C
non
9 C
pent
5 C
dec
10 C 6

7. Alkane Structures Alkanes have only carbon to carbon single bonds.
General Formula CnH2n+2 7

8. Homologous Series: CH4 Methane C2H6 Ethane C3H8 Propane C4H10 Butane
Pentane
Definition:
Each compound in this series differs from the previous compound by a –CH2 –
A homologous series of alkanes

9. Alkane Structures
Structural Isomers are compounds with the same chemical formula but a different structural formula.
As the number of carbon atoms in an alkane molecule increases, so do the possibilities for isomerism of this kind. There are three isomeric pentanes, all with the C5H12, five isomeric hexanes, C6H14 9

10. Boiling Points of Alkanes
Longer-chain alkane molecules can touch each other over a much larger area than short-chain alkanes.
The London forces between them are corresponding larger, and the boiling point is higher. Similar remarks apply, though not so strongly, to a comparison between straight-chain and brand-chain isomers.

11. General Properties of Alkanes
The boiling points of alkanes are very low for their molecular mass. This is because the molecule is completely nonpolar( inertness)
It increases with an increase in mass.

12. Alkenes Alkenes have one carbon to carbon double bond C=C
Since there are fewer hydrogen atoms in alkenes as a result of the double bond, alkenes are referred to as unsaturated.
Alkanes on the other hand have the maximum number of hydrogen atoms. They are referred to as saturated. 12

13. Alkene Structures
Like alkanes, alkenes can have branched or consecutive chains. In the larger alkenes there are also multiple locations for the C=C. Hence multiple structural isomers are possible.
Straight chain. The double bond is between the second and third carbon
Straight chain. The double bond is between the first and second carbon
Branched
chain 13

14. Alkynes Alkynes have one (or more) carbon to carbon triple bonds
Since there are fewer hydrogen atoms in alkynes as a result of the triple bond, alkynes like alkenes are referred to as unsaturated. 14

15. Alkyne Structures
Like alkanes and alkenes, alkynes can have branched or consecutive chains. In the larger alkenes there are also multiple locations for the C=C. Multiple structural isomers are possible. The branch cannot originate on one of the carbons making up the triple bond
Branched chain. The triple bond can occur in one of the branches but branches cannot be attached to any carbon in the triple bond
Straight chain. The triple bond is between the first and second carbon
Straight chain. The triple bond is between the second and third carbon 15

16. Table of Functional Groups
Functional groups are collections of atoms in a molecule that participate in characteristic reactions.

17. Resonance –Polarity of Carboxylic acids

18. Ring Structures
Hydrocarbons that exist in chains are known as aliphatic hydrocarbons
The ends of a chain may be joined to form a ring structure.
These compounds are known as cyclic structures 18

19. Aromatic Structures
The benzene ring is a common structure in organic molecules
It consists of 6 carbon atoms and 6 hydrogen atoms.
One would predict that there should also be 3 C=C bonds in a benzene ring 19

20. Aromatic Structures
Further investigation reveals that the double bonds are not distinct in benzene. Rather it is a resonance hybrid.
Either of these structures could be used to represent benzene. 20

21. Aromatic Structures
Research shows that there are no differences in the C to C bonds in benzene.
The current view of benzene holds that there are 6 C-C single bonds and 3 pairs or 6 delocalized electrons 21

22. Aromatic Structures
The structure of benzene is shown as either of these two structures, or as a circle in a hexagon which depicts that the electrons are delocalized 22

23. Halogenoalkanes or Alkyl Halides
Halogenoalkanes are compounds in which one or more hydrogen atoms in an alkane have been replaced by halogen atoms (fluorine, chlorine, bromine or iodine).
Halogenoalkanes are commonly known as alkyl halides 23

24. Halogenoalkanes or Alkyl Halides
Depending on the location of the halogen atom, halogenoalkanes may be primary secondary or tertiary 24

25. Boiling Points of Halogenoalkanes
The boiling point depends on the halide
Cl < Br < I
The boiling points increase as the chain length increases 25

26. Solubility of Halogenoalkanes
The halogenoalkanes are only very slightly soluble in water.
The attractions between the halogenoalkane molecules (van der Waals dispersion and dipole-dipole interactions) are relatively strong
Halogenoalkanes are only slightly polar and do not effectively break the hydrogen bonds between water molecules.
Halogenoalkanes are soluble in non polar or less polar organic solvents such as alcohol, ether, and benzene . 26