Transcript Ch. 13 Hydrocarbons

Ch. 13
Hydrocarbons
Milbank High School
Objectives
1. What is organic chemistry? In general, how do organic
compounds differ from inorganic compounds?
2. Why are there so many more organic compounds than
inorganic compounds?
3. What are hydrocarbons? What structural features identify
alkanes? Alkenes? Alkynes? Aromatic hydrocarbons?
4. How are alkanes, alkenes, alkynes, and aromatic hydrocarbons
named using IUPAC nomenclature?
5. What are the physical and chemical properties of alkanes,
alkenes, alkynes, and aromatic hydrocarbons?
Objectives
6. What is an alkyl group?
7. What are some products from reactions of alkanes?
How are they formed?
8. What are the major reactions of alkenes? What are
the products of those reactions?
9. What are polymers? How are they formed and
utilized?
10. What is petroleum and how is it utilized?
Organic Chemistry
• Chemistry of compounds that contain
carbon
– Combine mainly with hydrogen, oxygen, and
nitrogen
– Over 10 million compounds made with these
4 elements
• 95% of compounds contain carbon
– Form stable, covalent bonds with each other
Properties
• Organic (Benzene)
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Low melting pts
Low boiling pts
Low solubility in water
Highly flammable
Nonconductive
Covalent bonds
• Inorganic (NaCl)
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High melting pts
High boiling pts
Soluble in water
Nonflammable
Conductive
Ionic bonds
Hydrocarbons
• Compounds containing only two elements
– Carbon and hydrogen
Sec. 13.1
Alkanes: Structures and Names
• Objectives
– Identify an alkane
– Determine what an isomer of an alkane is
– Identify different types of alkanes
Alkanes
• Saturated Hydrocarbons
• Called saturated because each carbon is
bonded to four other atoms
• Only single bonds
• Methane
• Ethane
• Propane
Homology
• Related compounds
• Homologs
– Have properties that vary in a regular and
predictable manner
– A manner of organization
– Similar to P.T.
Isomers
• Different compounds having the same
molecular formula
• Butane
• Isobutane (isolated branched chain)
Isomers
• Pentane
• Isopentane
• Neopentane
Alkanes
• CnH2n+2
• Representation
– Structural Formulas
– Condensed Structural Formulas
– Butane
Alkyl Group
• A group of atoms that results when one
hydrogen atom is removed from an alkane
• CnH2n+1
• Change –ane ending to –yl
• Methyl
• Ethyl
• Propyl
Sec. 13.2
IUPAC Nomenclature
• Define IUPAC
• Examine the rules for IUPAC naming
• Determine the correct names of alkanes
IUPAC Nomenclature
• Geneva, Switzerland 1892
• International Union of Pure and Applied
Chemistry
• IUPAC System of Nomenclature
– (isobutane, isopentane are common names)
IUPAC Rules
• 1. Name the longest chain in the parent
compound. End in –ane. (Root name)
– Number each carbon
– See Example
• 2. Note the alkyl groups attached
• 3. Number the carbon that the group is
attached to.
– Must use the lowest number possible.
– See Example
IUPAC Rules Con’t
• 4. Use prefixes to indicate the amount of
attached groups
– See Example
• 5. If there are more than two or more
different substituents, list them in
alphabetical order. If at equal points,
lower alphabetical order given lowest
number
– See Example
IUPAC Rules Con’t
• 6. Prefixes not included in alphabetizing
– See Example
Name each of the following
Name each of the following
A.
B.
C.
D.
Answers
a. 3-ethylhexane
b. 2,4-dimethylpentane
c. c. 3-methylhexane
d. 4-isopropylheptane
Draw the structural formulas for
each of the following
• 4-propylheptane
• 3-ethyl-2-methylpentane
• 3-isopropyl-3-methyloctane
Answers
•
Sec. 13.3
Properties of Alkanes
• Objectives
– Determine the physical and physiological
properties of alkanes
Physical Properties
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Nonpolar
– Insoluble in water
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Less dense than water
– Less than 1.0g/ml
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Related to one another
– See chart
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Boiling points
– Increase with higher molar mass
Physiological Properties
• Gases serve as anesthetics
• Liquid alkanes
– Light liquids
– Harmful to lungs
– Heavy liquids
• Mineral oil
• Petroleum jelly
Sec. 13.4
Chemical Properties: Reactions
of Alkanes
• Objectives
– Determine the chemical properties of alkanes
Chemical Properties
• Do not react with many laboratory agents
• Usually very flammable
– Undergo combustion reactions
CH4 + 2 O2  CO2 + 2 H2O + Heat
2 CH4 + 3 O2  2 CO + 4 H2O
(Harmful carbon monoxide reaction)
Sec. 13.5
Halogenated Hydrocarbons
• Objectives
– Define what halogenated hydrocarbons are
– Name halogenated hydrocarbons using
common and IUPAC names
Halogenated Hydrocarbons
• Have one or more hydrogen atoms
replaced by halogen atoms
– Usually these are formed under UV light or
very high temps
– Results in an alkyl halide
Common Names
• First part of name is alkyl group
• Second part is the halogen, ending in –ide
• Name these:
– CH3CH2Br
– (CH3)2CHCl
– CH3I
– CH3CH2CH2F
Answers
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Ethyl bromide
Isopropyl chloride
Methyl iodide
Propyl flouride
IUPAC Names
• Rules similar to those used for naming
alkanes
• Substitute in the prefixes fluoro-, chloro-,
bromo-, and iodo-
Give the IUPAC name for each
of the following compounds
Answers
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2-chloropentane
4-bromo-2-methylhexane
2-chloro-3-methylbutane
1-bromo-3-chloro-4-methylpentane
Sec. 13.6
Cycloalkanes
• Define what a cycloalkane is
• Name and draw cycloalkanes
Cycloalkanes
• Carbon atoms that are joined in a ring or
circle
• Simplest: cyclopropane
• Another: cyclohexane
Naming
• Add cyclo• Otherwise fairly similar to regular naming
• Draw structures for the following
compounds
– Cyclooctane
– Ethylcyclohexane
– 1,1,2-trimethylcyclobutane
Answers
• A.
• B.
C.
Draw these structures
• Cyclopentane
• 1-ethyl-2-methylcyclopentane
• 1-ethyl-1,2,5,5-tetramethylcycloheptane
Answers
• A.
• B.
• C.
Sec. 13.7
Alkenes
• Objectives
– Define alkene
– Name alkenes using IUPAC rules
Alkenes
• End in -ene
• Unsaturated hydrocarbons
• Have a double bond (CH3=CH2)
IUPAC Rules
1. Name the longest chain.
2. Indicate the position of the double bond
with the lowest number possible.
3. Substituent groups named like alkanes
5-methyl-2-hexene
Name each of the following
Answers
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6-dimethyl-2-heptene
2-ethyl-1-butene
4-ethyl-2-methyl-2-hexene
1-methylcyclohexene
2,4,4-trimethyl-2-pentene
Draw the structure for the
following
• 3,4-dimethyl-2-pentene
• 3-ethyl-2-methyl-1-hexene
• 3-isopropylcyclopentene
Answers
• A.
• B.
• C.
Sec. 13.8
Properties of Alkenes
• Objectives
– Determine the properties of alkenes
Properties of Alkenes
• Similar to alkanes
• Occur widely in nature
• Ethylene
– Triggers fruit ripening
– Can be used artifically
• Others
– Carotene
• Vitamin A
– Fruit coloring
Sec. 13.9
Chemical Properties: Reactions
of Alkenes
• Define addition reactions
• Discuss hydrogenation and hydration
• Write equations for reactions between
alkenes and other substances
Addition Reactions
• One of the bonds in the double bond is broken
and each of the involved carbon atoms then
bonds to another atom or group
• Hydrogenation—addition of hydrogen to an
unsaturated molecule
Halogen addition
• Alkenes readily add halogen molecules
Hydration
• Addition of water to an alkene
Equations
• Write equations for the reaction between
CH3CH=CHCH3 and each of the following
• H2
• Br2
• H2O (H2SO4 catalyst)
Answers
• Write equations for the reaction of
each of the following.
• H2 (Ni catalyst)
• Cl2
• H2O (H2SO4 catalyst)
with
.
Answers
Sec. 13.11
Alkynes
• Define alkyne
• Name alkynes using IUPAC naming rules
Alkynes
• Carbon atoms share 3 pairs of electrons,
forming a triple bond
• Acetylene
• Alkynes have similar properties to those of
alkanes and alkenes
• Naming is the same, except they end in
-yne
Sec. 13.12
Benzene
• Objectives
– Recognize the versatile structure of a
benzene ring
Benzene
• Recognized by Michael Faraday in 1825
• Six sided structure with single and double
mobile bonds
Figure
• Resonance—a word
used to describe the
13.13
phenomenon in which no single Lewis
structure can be used
Sec. 13.13
Structure and Nomenclature of
Aromatic Compounds
• Define and name aromatic hydrocarbons
and aliphatic compounds
• Determine the difference between ortho,
meta, and para distribution
Aromatic Compounds
• Benzene
• Named because thought to have strong
aroma
• Now define as anything that has a
benzene ring
• Aliphatic compounds—nonaromatic
Naming
• One substituent…easy
Naming
• 2 substituents…2 different ways
• One way…same as before
• Other way…uses the terms ortho, meta,
and para
– Ortho (1,2 distribution)
– Meta (1,3 distribution)
– Para (1,4 distribution)
Examples
Aryl Groups
• Sometimes Benzene rings attach to
alkanes or alkenes
• Known as aryl groups
• Most common one is phenyl
Sec. 13.14
Uses of Benzene and Benzene
Derivatives
• Objectives
– Discuss some of the uses of benzene
Uses of Benzene
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Most comes from petroleum
Used as a starting material
Added to fuels to improve octane rating
Cigarette smoke
Very toxic
In Nature..
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Tryptophan
Vitamin K
Folic acid
Many drugs…Table 13.12