Lecture #4-Alkenes and Alkynes, Structure and Nomenclature...
Transcript of Lecture #4-Alkenes and Alkynes, Structure and Nomenclature...
![Page 1: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/1.jpg)
Unsaturated Hydrocarbons
![Page 2: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/2.jpg)
Chemical Formulas and Unsaturation
C C C C C
C C C C C
H H H H H
H H H H H
H C C C C C H
H H H H H
H H H H H
H C C C C
H H H H
H H
C
H
H
H
H
H
Cn
CnH2n
CnH2n+2
CnH2n+2
![Page 3: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/3.jpg)
Chemical Formulas and Unsaturation
C C C C C
Cn
C C C C C
Cn
C C C C C
Cn
CnH2n
H C C C C C H
H H H
H H H H H
C
C
C C
C
CnH2n
C
C
C C
C
HH
H
H
H
H H
H
H
H
![Page 4: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/4.jpg)
Chemical Formulas and Unsaturation
Hydrocarbons
SaturatedHydrocarbons
UnsaturatedHydrocarbons
AlkanesCnH2n+2
CycloalkanesCnH2n
(one ring)
AlkenesCnH2n
(one C=C)
AlkynesCnH2n-2
(one C C)
BenzeneC6H6
CnH2n-6
![Page 5: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/5.jpg)
Review of Carbon Bonding Patterns
![Page 6: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/6.jpg)
Classes of “Unsaturated” Hydrocarbons
120º120º 180º
![Page 7: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/7.jpg)
Lewis Representation of Ethene
C C
H
H
H
HC
H
H C
H
H
N o t e : B o t h o f t h e s e representations picture the two components of the double bond as being identical. This is not the case.
![Page 8: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/8.jpg)
Covalent Bonding in Ethene
The two carbons and all four hydrogens all lie within the same plane. The bond angles are all 120º.
Note: Though the two components of the double bond are pictured the same, one of the bonds is actually weaker than the other.
![Page 9: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/9.jpg)
Supplement on Hybridization
in Ethene
![Page 10: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/10.jpg)
Hybrid Orbitals - Bonding in Methane
Recall that the four orbitals associated with the bonding in an alkane or cycloalkane are the result of “sp3 hybridizaton.”
![Page 11: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/11.jpg)
Hybrid Orbitals - Alkenes
The four orbitals associated with the
bonding in alkenes or cycloalkenes are the result
of “sp2 hybridizaton.”
![Page 12: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/12.jpg)
Covalent Bonding in Ethene
C2H4, ethene, is formed from two sp2 hybridized carbon atoms and four hydrogen atoms:
Lateral overlap of the unhybridized p orbitals, above and below the triangular planes, results in a π bond of the double bond.
![Page 13: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/13.jpg)
Nomenclature of Alkenes
1. Select the longest carbon chain containing the double bond as the parent chain. Replace the “-ane” ending with “-ene.
2. Number the parent chain beginning at end closest to the double bond beginning with the first carbon in the chain.
3. Locate and name the substituents in alphabetical order.
4. Compounds with two double bonds are called dienes.
5. Cyclic compounds are named as cycloalkenes. Carbons in the double bond are always numbered first. Then the ring is numbered in the direction so as to give the lowest numbers to substituents.
![Page 14: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/14.jpg)
Isomerism in Alkenes
H2C CH CH2CH2 CH3
H3C CH CH CH2 CH3
H3C CH2 CH CH CH3
Positional Isomerism
1-pentene
2-pentene
????also
2-pentene
Geometric Isomerism (a form of stereoisomerism)
![Page 15: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/15.jpg)
Alkenes-Nomenclature
![Page 16: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/16.jpg)
Alkenes-Nomenclature
2-hexene 2-methyl-3-hexene
![Page 17: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/17.jpg)
2,3-dimethyl-1-pentene
Alkenes-Nomenclature Practice
2,3-dimethyl-2-hexene
![Page 18: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/18.jpg)
Alkenes-Nomenclature
4-methylcyclohexene
![Page 19: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/19.jpg)
Alkenes-Nomenclature Practice
2,5-dimethyl-2-heptene 3,3-dimethylcyclopentene
![Page 20: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/20.jpg)
Exercises on Alkene Nomenclature
![Page 21: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/21.jpg)
H3C CH2 CH2 C CH2 CH3
CH2
H3C CH CH CH CH CH
CH2 CH3
CH3
CH3
CH3
CH3Cl
CH2CH3
1a)
b)
c)
![Page 22: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/22.jpg)
Geometric Isomerism (a form of stereoisomerism)
Isomerism in Alkenes
Exists for the following cases:
C C
X
Y
A
B
A≠B and E≠D
C C
X
Y
A
B
C C
Y
X
A
B
A result of lack of free rotation around the double bond
X
E
D
E
D
D
E
![Page 23: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/23.jpg)
Isomerism in Alkenes
![Page 24: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/24.jpg)
Isomerism in Alkenes Cis/trans isomers have different physical properties
![Page 25: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/25.jpg)
Isomerism in Alkenes
Cis/trans isomers are not possible for some alkenes.
![Page 26: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/26.jpg)
cis-4-methyl-2-hexene
Alkenes-Nomenclature Practice
trans-5,6-dimethyl-3-heptene
![Page 27: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/27.jpg)
2a) cis-1-chloro-1-butene
b) trans-3-hexene
c) trans-4,4-dimethyl-2-pentene
d) cis-1,3-dichlorocyclohexane
C C
Cl CH2 CH3
H H
C C
CH2
CH2 CH3
H3C H
H
C C
H3C
C CH3
CH3
H3C
H
H
Cl
Cl
![Page 28: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/28.jpg)
Alkynes
![Page 29: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/29.jpg)
Supplement on Hybridization
in Ethyne
![Page 30: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/30.jpg)
Alkynes Structure of the Triple Bond
CH C H
N o t e : B o t h o f t h e s e representations picture the three components of the t r i p l e b o n d a s b e i n g identical. This is not the case.
C C HH
![Page 31: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/31.jpg)
7 sigma bonds
Ethane, CH3CH3The sp3 hybrid orbitals of
two carbons overlap
The remaining sp3 hybrid orbitals overlap with hydrogen s orbitals
![Page 32: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/32.jpg)
5 sigma bonds
Ethene, CH2CH2The sp2 hybrid orbitals of
two carbons overlap
The remaining sp2 hybrid orbitals overlap with hydrogen s orbitals
![Page 33: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/33.jpg)
Ethene, CH2CH2
The remaining unhybridized p
orbitals overlap to form a ∏ bond.
5 sigma bonds and 1 ∏ bond
![Page 34: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/34.jpg)
3 sigma bonds
Ethyne, CHCHThe sp hybrid orbitals of
two carbons overlap
The remaining sp hybrid orbitals overlap with hydrogen s orbitals
![Page 35: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/35.jpg)
Ethyne, CHCH
The remaining unhybridized p
orbitals overlap to form 2 ∏ bonds.
3 sigma bonds and 2 ∏ bonds
![Page 36: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/36.jpg)
Bonding in HCCHH C C H
H
C
C
H
![Page 37: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/37.jpg)
Summary of Hydrocarbon Bonding
![Page 38: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/38.jpg)
Alkynes Structure of the Triple Bond
CH C H
N o t e : B o t h o f t h e s e representations picture the three components of the t r i p l e b o n d a s b e i n g identical. This is not the case.
![Page 39: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/39.jpg)
Nomenclature of Alkynes
1. Select the longest carbon chain containing the triple bond as the parent chain. Replace the “-ane” ending with “-yne.
2. Number the parent chain beginning at end closest to the triple bond beginning with the first carbon in the chain.
3. Locate and name the substituents in alphabetical order.
![Page 40: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/40.jpg)
Alkynes-Nomenclature Practice
4,4-dimethyl-1-hexyne 2,7-dimethyl-4-octyne
![Page 41: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/41.jpg)
Alkynes-Nomenclature Practice
H3C
Cl
Cl
C C CH
CH3
CH3Excess Br2 in the dark
HC C CH2 CH2 C
CH3
CH3
CH3Excess HBr in the dark
![Page 42: Lecture #4-Alkenes and Alkynes, Structure and Nomenclature ...profkatz.com/courses/wp-content/uploads/2013/05/CH2210-Lecture-4... · Nomenclature of Alkenes 1. Select the longest](https://reader030.fdocuments.in/reader030/viewer/2022040110/5ec2a58f91801e352532ab6b/html5/thumbnails/42.jpg)
Properties of Alkenes and Alkynes
Nonpolar and insoluble in water as are alkanes.
Nonpolar, therefore Boiling points depend on size and shape.
Flammable.
Alkenes may display cis-trans isomerism.
Chemically reactive at the multiple bond.