CHE 102 Chap 196
IUPAC Rules for Naming Alkenes
• Select the longest continuous carbon-carbon chain that contains the double bond.
• Name this parent compound as you would an alkane but change the –ane ending to -ene; for example, propane is changed to propene.
CH3CH2CH3propane
CH2CHCH3propene
CHE 102 Chap 197
IUPAC Rules Continued
• Number the carbon chain of the parent compound starting with the end nearer to the double bond. Use the smaller of the two numbers to indicate the position of the double bond. Place this number in front of the alkene name; for example, 2-butene means that the carbon-carbon double bond is between carbons 2 and 3.
CHE 102 Chap 198
IUPAC Rules Continued
• Branch chains and other groups are treated as in naming alkanes, by numbering and assigning them to the carbon atom to which they are bonded.
CHE 102 Chap 199
Two or more C=C double bonds
CH2CHCHH2C
1,3-butadiene
Fourcarbon atoms
InsertedTo ease
pronunciation
TwoDoublebonds
Positionof thedoublebonds
CHE 102 Chap 1910
Cycloalkenes
• Just like normal cycloalkanes except the numbering always starts at the double bond.
CH
CHCH2
H2C
H2CCH2
cyclohexene
Cl
1
2
3
4
5
6
3-chlorocyclohexene
CHE 102 Chap 1911
Geometric Isomers (Cis/Trans)
• Structural Isomers– Same formula
– Different structure
• Geometric Isomers– Same formula
– Same structure
– Different geometry
CHE 102 Chap 1913
Different Properties = Different Molecules
Cis-1,2-dichloroethene
CCCl Cl
HH
trans-1,2-dichloroethene
CCH Cl
HCl
(bp=60.1°C) (bp= 48.4°C)
CHE 102 Chap 1915
CCH
H
H
H
Two groupsthe same
CCCH3
H
H
H
• cis and trans cannot be used if 2 of the same groups are on one side of the double bond.
– These do not have isomerism
CHE 102 Chap 1918
Reactions of Alkenes
• Alcohols– Dehydration/Hydration
• Oxidation
• Addition– Hydrogenation
– Halogenation x2
– Hydration
– Markovnikov’s Rule
CHE 102 Chap 1919
Alkenes and Alcohols
CC CH3
H
OH
CH3
H
H
conc. H2SO4 CC CH3
H
CH3
H
+ H2O
Dehydration
Hydration
CH2 CH2 + HOH H+
CH3CH2OH Ethanol
CHE 102 Chap 1920
Oxidation
ethene
CH2H2C + KMnO4 + H2O
ethylene glycol
CH2H2C
OHOH
+ MnO2 + KOH
Purple Brown
“Bayer Test for C=C”
CHE 102 Chap 1925
Carbocations
C+
H
H
H
MethylCarbocation
C+
H
H
CH3
EthylCarbocation (primary)
C CH3CH3
H
+
IsopropylCarbocation(secondary)
C
CH3
CH3
CH3
+
t-ButylCarbocation (tertiary)
Stability of carbocations: 3o > 2 o > 1o > CH 3+
CHE 102 Chap 1926
Markovnikov’s Rule
When an unsymmetrical molecule such as HX(HCl)adds to a carbon-carbon double bond, the hydrogen from HX goes to the carbon atom that has the greaternumber of hydrogen atoms.
CHE 102 Chap 1928
Alkynes• IUPAC Rules for Naming• ane yne• Use # to indicate position of triple bond• Reactions:
– Combustion
– Halogenation
– Addition
• Properties– Low Bp/Mp (Lower Mass)
– Non-polar
– Very reactive
CHE 102 Chap 1930
Naming
• Sidechains:
CH
CH3
CHClCH2CH3
3-Chloro-2-phenylpentane
CH2
diphenylmethane
CHE 102 Chap 1931
Special Aromatics
Nitrobenzene
O2N
CH3
TolueneMethylbenzene
OH
PhenolHydroxybenzene
C OOH
Benzoic acid
C OH
Benzaldehyde
NH2
Aniline
(aminobenzene)
CHE 102 Chap 1933
Examples
Cl
Cl
Ortho-dichlorobenzene1,2-dichlorobenzene
Cl
Cl
meta-dichlorobenzene1,3-dichlorobenzene
Cl
Cl
para-dichlorobenzene1,4-dichlorobenzene
Cl
Br
o-bromochlorobenzene
NO2
CH2CH3
m-ethylnitrobenzene
CHE 102 Chap 1934
Special CasesCH3
CH3
o-xylene
CH3
CH3
m-xylene
CH3
CH3
p-xylene
OH
NO2
o-nitrophenol
NH2
Br
p-bromoaniline
CH3
NO2
m-nitrotoluene
o-xylenep-xylenem-xylene
CHE 102 Chap 1935
Poly Substituted
• # ring to give lowest overall numbers• Special groups always labeled #1
NO2
NO2NO2
1,3,5-trinitrobenzene
1
2
3
4
5
6
Br
Br
Br
1,2,4-tribromobenzene
12
3
4
5
6
CH3
NO2
NO2
NO2
2,4,6-trinitrotoluene(TNT)
12
3
4
5
6 Br OH
Cl
5,bromo-2-chlorophenol
1
2
3
4
56
CHE 102 Chap 1937
Halogenation
+ X2 FeX3
Benzene Chlorine orBromine
X+ HX
Chlorobenzene orBromobenzene
Top Related