View
247
Download
3
Category
Tags:
Preview:
Citation preview
LecturePLUS Timberlake 1
Chapter 11Haloalkanes, Alkenes, and Alkynes
Alkenes and Alkynes
Geometric Isomers of Alkenes
Addition Reactions
LecturePLUS Timberlake 2
Saturated and Unsaturated Compounds
Saturated compounds (alkanes) have the maximum number of hydrogen atoms attached to each carbon atom
Unsaturated compounds have fewer hydrogen atoms attached to the carbon chain than alkanes
Unsaturated compounds contain double or triple bonds
LecturePLUS Timberlake 3
Alkenes
Carbon-carbon double bonds Names end in -ene
H2C=CH2 ethene (ethylene)
H2C=CH-CH3 propene (propylene)
cyclohexene
LecturePLUS Timberlake 4
Alkynes
Carbon-carbon triple bonds Names end in -yne
HCCH ethyne(acetylene)
HCC-CH3 propyne
LecturePLUS Timberlake 5
Naming Alkenes and Alkynes
When the carbon chain has 4 or more C atoms, number the chain to give the lowest number to the double or triple bond.
1 2 3 4
CH2=CHCH2CH3 1-butene
CH3CH=CHCH3 2-butene
CH3CHCHCH3 2-butyne
LecturePLUS Timberlake 6
Learning Check HA3
Write the IUPAC name for each of the following unsaturated compounds:
A. CH3CH2CCCH3
CH3
B. CH3C=CHCH3 C.
CH3
LecturePLUS Timberlake 7
Solutions HA3
Write the IUPAC name for each of the following unsaturated compounds:
A. CH3CH2CH=CHCH3 2-pentyne
CH3
B. CH3C=CHCH3 C.
2-methyl-2-butene 3-methylcyclopentene
CH3
LecturePLUS Timberlake 8
Cis and Trans Isomers
Double bond is fixed Cis/trans Isomers are possible
CH3 CH3 CH3
CH = CH CH = CH
cis trans CH3
LecturePLUS Timberlake 9
Hydrogenation
Adds a hydrogen atom to each carbon atom of a double bond
H H H H
Ni
H–C=C–H + H2 H–C–C–H
H H
ethene ethane
LecturePLUS Timberlake 10
Products of Hydrogenation
Adding H2 to vegetable oils produces
compounds with higher melting points
Margarines
Soft margarines
Shortenings (solid)
LecturePLUS Timberlake 11
Learning Check HA4
What is the product of adding H2 (Ni catalyst) to 1-butene?
LecturePLUS Timberlake 12
Solution HA4
What is the product of adding H2 (Ni catalyst) to 1-butene?
Ni
CH2=CHCH2CH3 + H2
CH3CH2CH2CH3
LecturePLUS Timberlake 13
Adding Halogens
Halogens also add to the double bond of an alkene.
H2CCH2 + Cl2
H2C CH2
Cl Cl
CH3C CCH2CH3 + Br2 CH3C CCH2CH3
Br Br
Br Br
LecturePLUS Timberlake 14
Learning Check HA5
Write the product of the following addition reactions:
CH3CH=CHCH3 + H2
+ Br2
LecturePLUS Timberlake 15
Solution HA5
Write the product of the following addition reactions:
CH3CH=CHCH3 + H2 CH3CH2CH2CH3
+ Br2Br
Br
LecturePLUS Timberlake 16
Unsaturated Fatty Acids
Fatty acids in vegetable oils are omega-6 acids (the first double bond occurs at carbon 6 counting from the methyl group)
A common omega-6 acid is linoleic acid
CH3CH2CH2CH2CH2CH=CHCH2CH=CH(CH2)7COOH
6
linoleic acid, a fatty acid
LecturePLUS Timberlake 17
Trans Fats
In vegetable oils, the unsaturated fats usually contain cis double bonds.
During hydrogenation, some cis double bonds are converted to trans double bonds (more stable) causing a change in the fatty acid structure
If a label states “partially” or “fully hydrogenated”, the fats contain trans fatty acids.
LecturePLUS Timberlake 18
Trans Fats
In the US, it is estimated that 2-4% of our total Calories is in the form of trans fatty acid.
trans fatty acids behave like saturated fatty acids in the body.
Several studies reported that trans fatty acids raise LDL-cholesterol. Some studies also report that trans fatty acid lower HDL-cholesterol
The trans fatty acids controversy will continue to be debated.
LecturePLUS Timberlake 19
Fats and Atheroschlerosis
Inuit people of Alaska have a high fat diet
and high blood cholesterol levels, but a
very low occurrence of atherosclerosis
and heart attacks.
Fat in the Intuit diet was primarily from
fish such as salmon, tuna and herring
rather than from land animals (as in the
American diet).
LecturePLUS Timberlake 20
Omega-3 Fatty Acids
Fatty acids in the fish oils are mostly the omega-3 type (first double bond occurs at the third carbon counting from the methyl group).
linolenic acid 18 carbon atoms
CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7COOH
eicosapentaenoic acid (EPA) 20 carbon atoms
CH3CH2(CH=CHCH2)5(CH2)2COOH
LecturePLUS Timberlake 21
Atherosclerosis
Plaques of cholesterol adhere to the walls of the
blood vessels
Blood pressure rises as blood squeezes through
smaller blood vessels
Blood clots may form
Omega-3 fatty acids decrease the “sticking” of
blood platelets (fewer blood clots)
Omega-3 fatty acids can increase bleeding time
LecturePLUS Timberlake 22
Learning Check HA6
(1) Ture or (2) False
A. ____ There are more unsaturated fats in vegetable oils.
B. ____ Vegetable oils have more omega-3 oils than found in fish.
C. ____ Hydrogenation of oils converts some cis-double bonds to trans- double bonds.
D. ____ Animal fats have more saturated fats.
LecturePLUS Timberlake 23
Solution HA6
(1) True or (2) False
A. _T__ There are more unsaturated fats in vegetable oils.
B. _F__ Vegetable oils have more omega-3 oils than found in fish.
C. _T__ Hydrogenation of oils converts some cis-double bonds to trans- double bonds.
D. _T__ Animal fats have more saturated fats.
Recommended