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Chapter TwelveChapter TwelveSaturated
Hydrocarbons
Chapter 12 | Slide 2 of 64
Saturated Hydrocarbons cont’d
© Bill Ross/CORBIS
CO 12.1
Chapter 12 | Slide 3 of 64
← Fig. 12.1 Sheer numbers is one reason why organic chemistry is a separate field of chemical study.
Saturated Hydrocarbons cont’d
Chapter 12 | Slide 4 of 64
Organic Chemistry
• The study of compounds containing ___________.
C
C
C
C
C
CC
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
CC
There are many more organic compounds than inorganic compounds. Why?
Chapter 12 | Slide 5 of 64
Properties of Organic Compounds
Typical organic compounds,
• Contain _____________
• Have ____________bonds
• Have low ____________________________– The bigger the molecule, _______________________________
• Have low ______________________– The bigger the molecule, _______________________________
• Are _______________
• Are soluble in ______________________
• Have a ______________ than water
Chapter 12 | Slide 6 of 64
The Bonding of Carbon
• To understand the bonding patterns of carbon, we must review what we know about carbon– Does carbon tend to form ionic or covalent compounds?
• .
– How many valence electrons does carbon have?• .
– How many electrons does carbon need to have an octet of electrons in its valence shell?
• .
Chapter 12 | Slide 7 of 64
Filling the Octet
• Carbon’s octet is filled when:
– .
Chapter 12 | Slide 8 of 64
Chemical Bonding of Carbon
• Carbon bonds in a ___________:
• Wedges: ___________________.• Dashed lines: ________________
__________.
C
Chapter 12 | Slide 9 of 64
Learning Check
• Complete the structure by adding the correct number of hydrogen atoms. Identify the molecular shape around each of the carbon atoms.
• C-C-C
• C=C-C
• C=C=C
Chapter 12 | Slide 10 of 64
Learning Check
• Complete the structure by adding the correct number of hydrogen atoms. Identify the molecular shape around each of the carbon atoms.
C
C
C
C
C
CC
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
CC
Chapter 12 | Slide 11 of 64
Representations of Organic Compounds
• Chemical Formulas show:
• Expanded structural formulas show:
• Condensed structural formulas show:
• Line drawings:
Chapter 12 | Slide 12 of 64
Converting Between Structural, Condensed, and Line Formulas
CC
CC
C
H
HH
C H
H
HH
H
H
H
Chapter 12 | Slide 13 of 64
Learning Check
• Convert the following structural formulas to condensed structural formulas and line drawings.
C
C
C
H
H
H
HH
H
C C CC
H
H
H
HH
H
H
H
H
H
C C
C
C
C
H
HH
H
H
H
H H
H
H
C
C
C
CC
C C
H
H
H
H
H
H
H
H
H H
H
H
Chapter 12 | Slide 14 of 64
Learning Check
• Convert the following line drawings to condensed structural formulas and complete structural formulas
Chapter 12 | Slide 15 of 64
Saturated v. Unsaturated
• Saturated Organic Compounds– .
• Unsaturated Organic Compounds– .
• Which compounds on the previous learning checks represent saturated organic compounds? Unsaturated organic compounds?
Chapter 12 | Slide 16 of 64
Learning Check
• Which are saturated organic compounds, which are unsaturated organic compounds?
Chapter 12 | Slide 17 of 64
← Fig. 12.3 Molecular structures of (a) methane, (b) ethane, and (c) propane, the three simplest alkanes.
Chapter 12 | Slide 18 of 64
Fig. 12.4 Models of (a) pentane, (b) isopentane, and (c) neopentane.
Chapter 12 | Slide 19 of 64
Alkanes
• Saturated hydrocarbons– Contain only __________________________– .– All carbon-carbon bonds are ____________________
• Determine the chemical formulas for the alkanes containing 3, 5, 7, and 9 carbons (separately)
• What is the relationship between the number of carbons and the number of hydrogens in these alkanes?– .
Chapter 12 | Slide 20 of 64
Fig. 12.2 Terms for organic compounds.
Chapter 12 | Slide 21 of 64
• Alkanes with four or more carbons can be drawn and can exist in more than one configuration:
• Structural isomers –
– The properties of compounds depend on ____________________________________________
C4H10
Isomers
Chapter 12 | Slide 22 of 64
Table 12.1 Selected Physical Properties of C4 and C5 Alkanes.
Chapter 12 | Slide 23 of 64
Conformations of Alkanes
• Single bonds are not locked in place. There is rotation around single bonds. As a result, alkanes exist in different conformations.– Conformation:
– Different conformations of the same molecule have the same condensed structural formula
– Show some examples:
Chapter 12 | Slide 24 of 64
Conformations of the Same Molecule or Different Molecules?
H2C
H2C
CH
H2C
CH2
CH2
CH3
H2C
CH
CH2
CH2
CH2
H2C
H3C
H3C
H2C
CH
CH3
CH3H2C
H2C
CH3
CH2
CH3
H3C
H2C
CH
CH3
CH3
H3C
CH
CH2
CH3
CH3
Chapter 12 | Slide 25 of 64
What are the two isomers of C2H6O?
CH
HH C
H
HOH C
H
HHO C
H
HH
CH
HH C
H
OHH C
H
HH C
H
HHO
Chapter 12 | Slide 26 of 64
Structural Isomers
• How many structural isomers can you draw for hexane?
Chapter 12 | Slide 27 of 64
• The number of carbon atoms attached to a branched carbon are designated by:– Primary:– Secondary:– Tertiary: – Quaternary:
Chapter 12 | Slide 28 of 64
CH
HHR C
H
RHR C
R
RHR C
R
RRR
primary
(R represents a general alkyl group.)
secondary
tertiary quaternary
Chapter 12 | Slide 29 of 64
Naming Alkanes
• We will use the IUPAC system (International Union of Pure and Applied Chemistry).– In this system, we name both the ____________ and
any ___________________ on the chain• Parent chain:
• Substituents:
– Alkyl groups
– Halogen groups
Chapter 12 | Slide 30 of 64
Naming the Parent Chain
• Depends on the length of the chain– 1 carbon: __________: CH3
– 2 carbons: _________ : CH3CH3
– 3 carbons: _________ : CH3CH2CH3
– 4 carbons: _________ : CH3CH2CH2CH3
– 5 carbons: _________ : CH3CH2CH2CH2CH3
– 6 carbons: _________ : CH3CH2CH2CH2CH2CH3
– 7 carbons: _________ : CH3CH2CH2CH2CH2CH2CH3
– 8 carbons: _________ : CH3CH2CH2CH2CH2CH2CH2CH3
– 9 carbons: _________ : CH3CH2CH2CH2CH2CH2CH2CH2CH3
– 10 carbons: _________ : CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3
Chapter 12 | Slide 31 of 64
Learning Check
A. What is the condensed formula for:
H H H H
H C C C C H
H H H H
B. What is its molecular formula?C. What is its name?
Chapter 12 | Slide 32 of 64
• Step 1:– Find the longest continuous carbon chain: The
longest chain is the parent.
CH3CH2CCH2CH3
CH2CH3
CH3CH2CH2CHCH3
Chapter 12 | Slide 33 of 64
• Step 2:– Number the carbon atoms in the main chain
beginning at the end near the first branch point.
CH3CH2CCH2CH3
CH2CH3
CH3CH2CH2CHCH3
Chapter 12 | Slide 34 of 64
Alkane Name Alkyl Group Name
CH4 Methane CH3 Methyl
CH3CH3 Ethane CH2CH3 Ethyl
CH3CH2CH3 Propane CH2CH2CH3
CH3CHCH3
Propyl
Isopropyl
• Step 3:– Identify and number the substituents.– Alkyl groups: occur when a hydrogen atom is
removed from an alkane. Replace “ane” with “yl”.
Chapter 12 | Slide 35 of 64
Fig. 12.5 The four most common branched-chain alkyl groups and their IUPAC names.
Naming Substituents
Chapter 12 | Slide 36 of 64
• Step 3:– Identify and number the substituents.– Use di, tri, tetra to name two like groups in an organic
molecule.
CH3CH2CCH2CH3
CH2CH3
CH3CH2CH2CHCH3
Chapter 12 | Slide 37 of 64
• Step 4:– Name the alkane as one word.
• Note: if two or more side chains, write in alphabetical order.
CH3CH2CCH2CH3
CH2CH3
CH3CH2CH2CHCH3
Chapter 12 | Slide 38 of 64
• Step 4:– Name the alkane as one word.
• Note: if two or more side chains, write in alphabetical order.
CH3CH2CCH2CH3
CH2CH3
CH3CH2CH2CHCH3
12
3
4567
Parts:heptane 3,3-diethyl4-methyl
Chapter 12 | Slide 39 of 64
Naming Conventions
• Carbons are numbered so the substituents get _____________________________
• Substituents are named ________________• Numbers are separated from each other by
_______________• Numbers are separated from letters by
__________________• There are _____________ in the name
Chapter 12 | Slide 40 of 64
Name this alkane.
CH3CH2CH2C CHCH3
CH3
• Longest chain?• Number the chain.• Substituents?• Name the alkane.
Chapter 12 | Slide 41 of 64
Name this alkane.
CH3CHCH2CCH3
CH2CH2CH3
CH3
• Longest chain?• Number the chain.• Substituents?• Name the alkane
CH3
Chapter 12 | Slide 42 of 64
Name this alkane.
CH3CH2CHCH2CHCH3
CH2CH3
CH3
• Longest chain?• Number the chain.• Substituents?• Name the alkane
Chapter 12 | Slide 43 of 64
Name this alkane.
CH3CH2CH2CH2C CHCH2CH3
CH2CH3
CH3
CH2CH3
• Longest chain?• Number the chain.• Substituents?• Name the Alkane
Chapter 12 | Slide 44 of 64
Draw the alkane.
• 2-methylheptane
• 4-ethyl-3,4-dimethyloctane
Chapter 12 | Slide 45 of 64
Draw the alkane.
• 2,3-dimethylhexane
• 4-ethyl-2,4-dimethylhexane
Chapter 12 | Slide 46 of 64
Cycloalkanes
• Saturated hydrocarbons in which ______________ _________________________________________
• Draw the structural formulas for the cycloalkanes with 4, 6, and 8 carbons.
• What is the relationship between the number of carbons and the number of hydrogens in a cycloalkane?– .
Chapter 12 | Slide 47 of 64
Cycloalkanes
• Properties:– .
cyclopropane cyclobutane cyclopentane cyclohexane
Chapter 12 | Slide 48 of 64
Fig. 12.6 Simple cycloalkanes
Chapter 12 | Slide 49 of 64
• Naming:– Count the carbons and add the prefix __________– For substituted cycloalkanes, start at point of
attachment and number around the ring to give any other substituent the ____________________.
– _______________________ has priority.
CH2CH3
CH3
Chapter 12 | Slide 50 of 64
CH2CH2CH3
CH3
Name this compound.
Chapter 12 | Slide 51 of 64
Learning Check
Chapter 12 | Slide 52 of 64
Isomerism in Cycloalkanes
• Cis-trans isomers:– Isomers that have the same molecular and structural
formulas but different ______________ ________________________________________ ________________________________________
• Cis isomer:
• Trans isomer:
Chapter 12 | Slide 53 of 64
H3C
H
H
H
CH3
H
H3C
H
H
CH3
H
H
cis (same) trans (opposite)
trans-1,2-dimethylcyclopropane cis-1,2-dimethylcyclopropane
Can also draw as:
Chapter 12 | Slide 54 of 64
Learning Check
• Determine whether cis-trans isomerism is possible for each of the following cycloalkanes. If so, then draw structural formulas for the cis and trans isomers– A. 1-ethyl-1-methylcyclopentane– B. Ethylcyclohexane– C. 1,4-dimethylcyclohexane– D. 1,1-dimethylcyclooctane
Chapter 12 | Slide 55 of 64
Chemical Reactions of Alkanes, I
• Combustion
In combustion reactions,
• Alkanes react with _____________.
• _________________________ are produced.
• Alkane + O2
Chapter 12 | Slide 56 of 64
Chemical Reactions of Alkanes, II
• Halogenation– .– In halogenation reactions,
– Requires _________________
– Reaction:
Chapter 12 | Slide 57 of 64
Figure 12.14 In an alkane substitution reaction, an incoming atom or group of atoms (represented by the orange sphere) replaces a hydrogen atom in
the alkane model.
Chapter 12 | Slide 58 of 64
An alkane in which one or more H atoms is replaced with a halogen (F, Cl, Br, or I)
CH3Br
Br
CH3CH2CHCH3
Cl
Haloalkanes
Chapter 12 | Slide 59 of 64
Name the following:Br
Cl
Cl
Learning Check
Chapter 12 | Slide 60 of 64
List other attached atoms or group ___________ ___________________
Br = bromo, Cl = chloro
Cl Br
CH3CHCH2CHCH2CH2CH3
Substituents
Chapter 12 | Slide 61 of 64
The name of this compound is:
Cl CH3
CH3CH2CHCH2CHCH3
1) 2,4-dimethylhexane
2) 3-chloro-5-methylhexane
3) 4-chloro-2-methylhexane
Learning Check
Chapter 12 | Slide 62 of 64
Table 12.4
Saturated Hydrocarbons cont’d
Chapter 12 | Slide 63 of 64
Fig. 12.15 Models of four ethyl halides.
Saturated Hydrocarbons cont’d
Chapter 12 | Slide 64 of 64
CAG 12.1
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