Transcript Hydrocarbon Compounds

Hydrocarbon Compounds
22.1 Hydrocarbons
22.2 Unsaturated Hydrocarbons
22.3 Isomerism
22.4 Hydrocarbon Rings
22.5 Hydrocarbons from Earth’s Crust
Updated 7/17/2015
Created by C. Ippolito July 2007
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Hydrocarbons
1.
2.
3.
Updated 7/17/2015
Objectives
Describe the relationship between the number of
valence electrons and bonding in carbon
Define and describe alkanes
Relate the polarity of hydrocarbons to their
solubility
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Organic Chemistry and
Hydrocarbons
• Organic Chemistry
– originally compounds thought to be made
only in living things
– now study of compounds with BOTH carbon
and hydrogen
• Hydrocarbons
– simplest organic compounds
– contain only carbon and hydrogen
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Alkanes
• only single covalent bonds between carbons
– Saturated Hydrocarbons
• contain the maximum number of hydrogen atoms per carbon
atom
– Straight Chain Alkanes
• homologous series – group of compounds that have a
constant incremental change
• 1 = meth• 3 = prop• 5 = pent• 7 = hept• 9 = nonUpdated 7/17/2015
• 2 = eth• 4 = but• 6 = hex• 8 = oct• 10 = dec-
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Formulas
• Molecular Formula – C4H10
• Structural Formula –
• Condensed Structural Formulas
CH3-CH2-CH2-CH3
CH3CH2CH2CH3
CH3(CH2)2CH3
• Carbon Skeleton – C-C-C-C
• Line Angle Formula Updated 7/17/2015
Created by C. Ippolito July 2007
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Branched Chains
• Parent Chain
– longest continuous carbon chain
• Substituents
– atoms or atom groups replacing a
hydrogen atom
• Alkyl Groups
– hydrocarbon substituents
» CH3― methyl group
» CH3CH2― ethyl group
» CH3CH2CH2― propyl group
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IUPAC Naming Rules for Alkanes
1. Find longest chain (parent)
2. Number carbons and use root name
with –ane ending
3. Add numbers to substituent groups
4. Use prefixes for multiple appearances of
same group
5. List substituents in alphabetical order
6. Use punctuation but no spaces
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Created by C. Ippolito July 2007
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Naming Branched Alkanes
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Created by C. Ippolito July 2007
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Drawing Branched-Chain Alkanes
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Properties of Alkanes
• Hydrocarbons are NONPOLAR
– weak van der Waals forces
• low mass tend to be gases or liquids with low
boiling points
– insoluble in water
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Created by C. Ippolito July 2007
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Unsaturated Hydrocarbons
1.
2.
Updated 7/17/2015
Objectives
Describe the difference between
unsaturated and saturated hydrocarbons
Distinguish between the structures of
alkenes and alkynes
Created by C. Ippolito July 2007
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Alkenes
• contain one or more carbon-carbon double
covalent bond
– Unsaturated Hydrocarbon
• contain less than the maximum number of
hydrogen per carbon atom
Updated 7/17/2015
Created by C. Ippolito July 2007
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IUPAC Naming Rules for Alkenes
1. Find longest chain with double bond
(parent)
2. Number carbons and use root name with
ending –ene so that double bond has lowest
number possible
3. Add numbers to substituent groups
4. Use prefixes for multiple appearances of
same group
5. List substituents in alphabetical order
6. Use punctuation but no spaces
Updated 7/17/2015
Created by C. Ippolito July 2007
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Alkenes
• contain one or more carbon-carbon triple
covalent bond
– Unsaturated Hydrocarbon
• contain less than the maximum number of
hydrogen per carbon atom
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Created by C. Ippolito July 2007
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IUPAC Naming Rules for Alkynes
1. Find longest chain with triple bond (parent)
2. Number carbons and use root name with
ending –yne so that double bond has lowest
number possible
3. Add numbers to substituent groups
4. Use prefixes for multiple appearances of
same group
5. List substituents in alphabetical order
6. Use punctuation but no spaces
Updated 7/17/2015
Created by C. Ippolito July 2007
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Isomerism
1.
2.
3.
Updated 7/17/2015
Objectives
Explain why structural isomers have different
properties
Describe the conditions under which geometric
isomers are possible
Identify optical isomers
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Structural Isomers
• compounds with the same molecular
formula but different structures
– different physical and chemical properties
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Created by C. Ippolito July 2007
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Stereoisomers
• atoms joined in same order but positions
in space are different
– Geometric Isomers
• related to rigid double bond
– Optical Isomers
• asymmetrical carbon
Updated 7/17/2015
Created by C. Ippolito July 2007
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Geometric Isomers
• Geometric Isomers
– orientation around rigid
double bond
• cis configuration
– groups on same side of double
bond
• trans configuration
– groups on different sides of
double bond
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Created by C. Ippolito July 2007
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Optical Isomers
• Optical Isomers
– four different groups attached to an
asymmetric carbon
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Hydrocarbon Rings
Objectives
1. Identify cyclic ring structures
2. Describe bonding in benzene
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Cyclic Hydrocarbons
• hydrocarbon chain forms a ring
–
–
–
–
cyclopropane
cyclobutane
cyclopentane
cyclohexane
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Created by C. Ippolito July 2007
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Aromatic Hydrocarbons
• contains a benzene ring
– electrons shared evenly
– “resonance”
• phenyl group
– benzene sub
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Substituted Benzene
• dimethyl benzene – 3 isomers
– ortho• 1,2 dimethyl benzene
– o-xylene
– meta• 1,3 dimethyl benzene
– m-xylene
– para• 1,4 dimethyl benzene
– p-xylene
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Created by C. Ippolito July 2007
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Hydrocarbons from Earth’s
Crust
1.
2.
3.
Updated 7/17/2015
Objectives
Identify three important fossil fuels and describe their
origins.
Describe the composition of natural gas, petroleum,
and coal.
Describe what happens when petroleum is refined
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Natural Gas
• source of alkanes of low molar mass
– 80% methane
– 10% ethane
– 4% propane
CH4(g) + 2O2(g)  CO2(g) + 2H2O(g) + heat
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Petroleum
• Fractional Distillation
– separation by boiling points
• Cracking
– heat to form smaller chains from
larger ones
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Coal
• Classified by its hardness and carbon content
– Peat
• soft, brown, spongy, fibrous material
• high water content
– Lignite
• harder, less fibrous, 50% carbon
– Bituminous Coal
• “soft” coal, 70%-80% carbon
– Anthracite Coal
• “hard” coal, over 80% carbon
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Created by C. Ippolito July 2007
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