1. Nomenclature, Properties, and Reactions of Hydrocarbons
This set of notes combines material from Chapters 10 and 11.
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2. Nomenclature A picture is worth a thousand words!
trans-2-[4-(Diphenyl-1-butenyl)phenoxy]-N,N-dimethylethylamine
a.k.a. Tamoxifen
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3. Nomenclature The basics: Prefix(es)  Root  Suffix
e.g. 2-methylpentane
Prefixes name and locate substituents
Root gives number of carbons in longest chain
Suffix names key functional group
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4. Nomenclature Roots are Greek numbers for 5 or more carbons # C’s Root
Alkane
Subst.
Alkene 1
meth
methane
methyl
N. A. 2
eth
ethane
ethyl
ethene 3
prop
propane
propyl
propene 4
but
butane
butyl
butene 5
pent
pentane
pentyl
pentene 6
hex
hexane
hexyl
hexene 7
hept
heptane
heptyl
heptene 8
oct
octane
octyl
octene
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5. Nomenclature Suffix identifies key functional group Group Structure
Example
alkane
-ane
pentane
alkene
-ene
pentene
alcohol
-anol
pentanol
carboxylic acid
-anoic acid
pentanoic acid
amine
-amine
pentamine
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6. Nomenclature Prefix(es) name and locate subtituent(s)
name = root + yl for alkyl substituents
number = location on main chain
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7. Naming Alkanes Find longest chain, name as root + ane
Find substituents, name as root + yl
Number longest chain, starting closest to a substituent
Name the compound
n -Prefix(es)  Root  Suffix
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8. Naming Alkanes 2-methylpentane
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9. Naming Alkanes The devil is in the details…
If two or more of the same substituent are present in a molecule, use Greek prefixes to indicate how many there are.
The prefix should contain a number for the position of each substituent.
Separate numbers with commas, separate numbers from letters with hyphens.
2,3-dimethylhexane 2,2-dimethylhexane
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10. Naming Alkanes The devil is in the details…
If there are more than two kinds of substit-uent in a molecule, number the longest chain starting closest to a substituent.
List the substituents alphabetically.
3-ethyl-2-methylpentane
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11. Naming Cycloalkanes Ring is named as cycloroot + ane
Find substituents, name as root + yl
Number substituents according to alphabet-ical priority, keeping numbers as low as pos-sible. If there is only one substituent, it is named without a number.
Name the compounds
n -Prefix(es)  Root  Suffix
Cyclobutane Methylcyclohexane
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12. Naming Alkenes Find longest chain, name as root + ene
Number longest chain containing double bond, starting at end closest to double bond
Number of first carbon of double bond is prefix
Name the compound
n -Prefix(es)  Root  Suffix
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13. Naming Alkenes cis-2-pentene trans-2-pentene
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14. Naming Alkenes The devil is still in the details…
If there are substituents in the molecule, number and name them as prefixes.
3-methyl-1-butene
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15. Naming Alkenes The devil is still in the details…
If there are several double bonds in a molecule, use Greek prefixes to indicate how many there are, and number them if necessary.
butadiene 2-methylbutadiene (isoprene)
3-methyl-1,4-pentadiene
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16. trans, trans-3,5-octadiene
Naming Alkenes
The devil is still in the details…
If there are internal double bonds, give their geometry (cis-, trans-) in the order in which they’re numbered in the molecule.
cis, cis-2,6-octadiene
trans, trans-3,5-octadiene
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17. Naming Aromatics
Give the name of the substituent, followed by the name of the ring system.
ethylbenzene butylbenzene
If there are several substituents, number the ring such that the substituents have the lowest possible numbers. If this can be done in more than one way, start with the substituent that’s first alphabetically.
1-ethyl-3,5-dimethylbenzene
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18. Naming Aromatics
Ortho, meta, para designations are still used, especially if both substituents are the same.
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19. Naming Organic Compounds
But organic chemists like to draw their molecules rather than naming them!
17-(1,5-Dimethylhexyl)-10,13-dimethyl-2,3,4,7,8,9,10,11, 12,13,14,15,16,17-tetradecahydro-1H-cyclopenta-[a]phenanthren-3-ol a.k.a. Cholesterol
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20. Properties of Hydrocarbons
Hydrocarbons are nonpolar molecules
Only dispersion forces between molecules
XC = 2.5 XH = 2.1
Melting points and boiling points are low
BP of pentane = 35
Hydrocarbons are not soluble in water or other hydrogen-bonding solvents.
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21. Reactions of Alkanes Alkanes are not very reactive.
Combustion is most important reaction
It gives energy. Alkanes burn cleanly.
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22. Reactions of Alkanes Alkanes react with halogens in light or heat.
Cl replaces H on a carbon atom.
The reactions involve free radicals.
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23. Reactions of Alkenes Alkenes are quite reactive
Combustion of alkenes is smoky.
Characteristic reaction of alkenes is addition across the double bond.
Electrons in  bond are above and below the plane of the molecule, available to reactive species.
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24. Reactions of Alkenes
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25. Reactions of Alkenes Reaction with halogens:
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26. Reactions of Alkenes Bromine is decolorized by reaction with alkenes
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27. Reactions of Alkenes Reaction with halogens:
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28. Reactions of Alkenes Polymerization: R1, R2 can be almost anything
So can X, Y
n can be huge, > 100,000
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30. Reactions of Aromatics
Aromatics are intermediate between alkanes and alkenes in reactivity.
Combustion of aromatics is very smoky.
Characteristic reactions of aromatics are substitutions; conjugated -bond system with resonance is maintained. Aromatics are less reactive than alkenes because there is a barrier to disrupting the  system.
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31. Reactions of Aromatics
Reaction with nitric acid (nitration):
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32. Reactions of Aromatics
Reaction with halogens requires a catalyst.
Product involves substitution of X for H.
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33. Reactions of Aromatics
Reaction with hydrogen requires forcing conditions; high pressure and temperature
Aromatic system is destroyed.
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34. Common Hydrocarbons Alkanes: Methane CH4 Fuel, Industrial Feed
Propane C3H8 Fuel, Industrial Feed
Butane C4H10 Fuel, Industrial Feed
2,2,4-trimethylpentane (iso-octane)
antiknock agent in gasoline
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35. Common Hydrocarbons Alkenes: Ethene C2H4 Monomer Propene C3H6 Monomer
Butadiene C4H6 Monomer (rubber)
Isoprene C5H8 Monomer (rubber)
Styrene C8H8 Monomer
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36. Common Hydrocarbons Aromatics Benzene C6H6 Industrial feed
Toluene C7H8 Solvent, Industrial feed
Xylenes C8H10 Solvent, Industrial feed
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