1. Hydrocarbons

2. Straight Chain Alkanes aren’t “Straight”
C – C bonds are sp3 hybridized
Butane, C4H10

3. Structural Shorthand
Explicit hydrogens (those required to complete carbon’s valence) are usually left off of drawings of hydrocarbons C1 C2 C3 C4 C1 C2 C3 C4
Line intersections represent carbon atoms

4. Structural Isomers
Isomers are molecules with the same chemical formula, but different organization of atoms (different bonding)
n-Pentane, C5H12
Isopentane, C5H12
Neopentane, C5H12

5. Cyclic Alkanes Cyclopropane, C3H6 Cyclobutane, C4H8
Cyclopentane, C5H10
Cyclohexane, C6H12
Cycloheptane, C7H14
Remember, explicit hydrogens are left out

6. Rules for Naming Alkanes (Nomenclature)
For a branched hydrocarbon, the longest continuous chain
of carbon atoms gives the root name for the hydrocarbon 1 2 3 4
4 carbon chain = butane

7. Rules for Naming Alkanes (Nomenclature)
When alkane groups appear as substituents, they
are named by dropping the -ane and adding -yl.
—CH3 Methyl
—CH2CH3 Ethyl
—CH2CH2CH3 Propyl
—CH2CH2CH2CH3 Butyl
Methyl

8. Rules for Naming Alkanes (Nomenclature)
The positions of substituent groups are specified
by numbering the longest chain of carbon atoms
sequentially, starting at the end closest to the
branching. 1 2 3 4
Methyl

9. Rules for Naming Alkanes (Nomenclature)
The location and name of each substituent are
followed by the root alkane name. The substituents
are listed in alphabetical order (irrespective of any
prefix), and the prefixes di-, tri-, etc. are used to
indicate multiple identical substituents. 1 2 3 4
Name:
2-methylbutane
Methyl

10. Nomenclature Practice
Name this compound 1
9 carbons = nonane 2 4 3 5 6 7 8 9
Step #1: For a branched hydrocarbon, the longest continuous chain of carbon atoms gives the root name for the hydrocarbon

11. Nomenclature Practice
Name this compound
9 carbons = nonane 1 2 4 3 5 6
CH3 = methyl 7
chlorine = chloro 8 9
Step #2: When alkane groups appear as substituents, they are named by dropping the -ane and adding -yl.

12. Nomenclature Practice
Name this compound
9 carbons = nonane 1 2 4 3 5 6
CH3 = methyl 7
chlorine = chloro 8 9 1 9
NOT 9 1
Step #3: The positions of substituent groups are specified by numbering the longest chain of carbon atoms sequentially, starting at the end closest to the branching.

13. Nomenclature Practice
Name this compound
9 carbons = nonane 1 2 4 3 5 6
CH3 = methyl 7
chlorine = chloro 8 9
2-chloro-3,6-dimethylnonane
Step #4: The location and name of each substituent are followed by the root alkane name. The substituents are listed in alphabetical order (irrespective of any prefix), and the prefixes di-, tri-, etc. are used to indicate multiple identical substituents.

14. Properties of Hydrocarbons
Made up of mostly C and H
Relatively nonpolar
Low solubility in polar solvents (e.g. water)
Good solvents for other nonpolar molecules
Mostly london-dispersion forces (weak)
Low boiling and melting points

15. Reactions of Hydrocarbons
Combustion:
Hydrocarbons burn readily in air to produce carbon dioxide and water.
C3H8(g) O2(g) --> 3CO2(g) + H2O(g)

16. Reactivity of Hydrocarbons
Alkanes are generally less reactive than alkenes or alkynes
Aromatic compounds are more reactive than alkanes, but less reactive than alkenes and alkynes.
Alkanes < aromatics < alkenes < alkynes

17. Reactions of Alkanes
Single bonds between carbon atoms are difficult to break. (This is why alkanes are relatively unreactive)
Can undergo combustion reactions

18. Reactions of Alkanes Substitution Reactions:
Hydrogen atoms may be substituted by a halogen.
The product is a halogenated alkane (alkyl halides)

19. Reactions of Alkenes and Alkynes
Addition Reactions:
Reactions in which a molecule is added to a double or triple bond.
No loss of hydrogen atoms from the hydrocarbon

20. Hydrogenation
Halogenation

21. Hydrohalogenation
Hydration

22. Markovnikov’s Rule
When molecules with two identical atoms (e.g. H2) are added to a double bond, only one possible product is formed.
When molecules of nonidentical atoms (e.g. HBr) are added, two different products are theoretically possible

23. Markovnikov’s Rule
However, experiments show that only one main product is formed.
This product can be predicted by Markovnikov’s rule
“The rich get richer”
When a hydrogen halide is added to an alkene or alkyne, the hydrogen atom bonds to the carbon atom that already has more hydrogen atoms.
Carbon 1 has 2 H’s
Carbon 2 has 1 H

24. Benzene Ring Does not act as 3 single bonds and 3 double bonds
It’s 6 identical bonds of intermediate length
Due to hybridization (delocalized, shared electrons)

25. Reactions of Aromatic Hydrocarbons
Less reactive than alkenes and do not undergo addition reactions unless under conditions of extreme temperature or pressure
Do undergo substitution reactions (more reactive than alkanes)