chemistry 2100 lecture 2. alkynes and alkenes alkene (olefins): c n h 2n alkyne (acetylenes): c n h...
TRANSCRIPT
Alkynes and Alkenesalkene (olefins): CnH2n
alkyne (acetylenes): CnH2n-2 CC
H
HH
H HCCH
Ethene Ethyne
Ethylene Acetylene
Naming Alkenes and Alkynes
• Parent name is that of the longest chain that contains the C=C or C≡C.
• Number the chain from the end that gives the lower numbers to the carbons of the C=C or C≡C.
• Locate the C=C or C≡C by the number of its first carbon.
• Use -eneene to show C=C, -yne for C≡C.• For cycloalkenes:
– Number ring carbons to give carbon 1 and 2 to the C=C bond.
– Because of this convention, no need to specify the number of the C=C.
CH2CCH3 CH
CH2
CH3
Br CH3 C C C CH3
CH3
CH3
Constitutional
IsomersStereoisomers
ConformationalIsomers
GeometricIsomers
Enantiomers Diastereomers
single bond rotation
chiral achiral
sameconnections
differentconnections
notmirrorimages
mirrorimages
Isomers
Alkene Isomerism
C=CH3C
H H
HC=C
H3C
H CH3
Htrans-2-Butene
mp -106°C, bp 1°Ccis-2-Butene
mp -139°C, bp 4°C C C
H H
CH3 CH3
C C
CH3 H
H CH3
CH3CH2
CH3CH2
3-methyl-cis-2-pentene3-methyl-trans-2-pentene
2-methyl-2-pentene
C C
CH3 H
CH3 CH2CH3
Terpenes – natural polyenes isoprene
(2-methyl-1,3-butadiene)
CH3
CHCCH2 CH2
limonene(orange, dill)
myrcene(bay)
geraniol(rose)
menthol(mint)
carvone(spearmint, dill)
OH
OH
O
zingiberene
(ginger)
-selinene(celery)
caryophyllene(cloves)
Making Alkenes B""A
B
CC
A
+CC
tetra tri di mono
CC
R
RR
R
>
'''
'''
CC
R
HR
R
>
'''
CC
H
HR
R
>
'
CC
H
HR
H
Reactions of Alkenes C C
BA
+ BACC
Hydrogenation
(cis or trans)
CH3
CH3 CH CH2CH3 CH3CH CHCH2CH3 Pt
H2 CH3CH2 CH2CH2CH3
CH3
CCH2 CH2CH3
CH3
CHCH3CCH3orPt
H2
Partially Hydrogenated Vegetable Oil
"partially hydrogenated vegetable oil"
+
COOH
COOH
COOH
H2 catalyst
• •
Acid Addition
CH2Cl2
H ClCHCH3CH3CH + CHCH3
Cl
CH3CH
H
CH3CH
Cl
CHCH3
H
minor major
H BrCH2CH3CH2CH + +CH2CH3CH2CH
BrH
CH2CH3CH2CH
HBr
H2SO4
H2SO4
H OH CH3 CH2 OHCH2 CH2 +
CH2 + H OHCH3
OH
Polymerization
Z = CH3 polypropylene
Z = Cl PVC
Z = CN polyacrylonitrile
Z = OH polyvinyl alcohol
polypropylene
PVC
polyacrylonitrile
polyvinyl alcohol
CH2 CH
Z
n CH2CHCH2CHCH2CH CH2CH
Z Z Z Z