Download Chapter 11 - Department of Chemistry and Physics

Chapter 11
Introduction to Organic Chemistry
Properties of Carbon and its
compounds
2
Properties of Carbon and its
compounds
3
Properties of Carbon and its
compounds
4
Properties of Carbon and its
compounds
5
Saturated Hydrocarbons
† Hydrocarbons are chemical
compounds that contain only C and H
atoms.
† Saturated hydrocarbons contain
only single bonds.
„ There are no double or triple bonds in
these compounds.
† The primary source of hydrocarbons
is petroleum and natural gas.
6
Alkanes
† The simplest saturated hydrocarbons are
called alkanes.
† Methane, CH4, is the simplest alkane.
† The alkanes form a series.
„ Each member of the series differs by a
specific number and kind of atoms.
H
C H
H
H
or CH4
7
Naming Saturated Hydrocarbons
† The International Union of Pure and Applied Chemistry (IUPAC)
names for the first 12 "straight-chain" or "normal" alkanes are
given in this table.
Number of carbon
atoms in chain
Name
1
Methane
2
Ethane
3
Propane
4
Butane
5
Pentane
6
Hexane
8
Naming Saturated Hydrocarbons
Number of carbon
atoms in chain
Name
7
Heptane
8
Octane
9
Nonane
10
Decane
11
Unidecane
12
Dodecane
9
Alkanes
† The alkanes differ from each other by a CH2 or
methylene group.
† The boiling points of the alkanes increase with molecular weight.
† All alkanes have this general formula.
CnH2n+2
† For example ethane, C2H6 , and propane, C3H8 , are
the next two family members.
H
H
H C
H
H
H
H
C
C
H
H
C2H6
H
H
H
H
H
C
C
C
H
H
H
H
H
H C
H
H
C3H8
10
Alkanes
† Isomers are chemical compounds that
have the same molecular formulas but
different structures.
† Two alkanes have the molecular formula C4H10.
„ They are a specific type of isomer called
structural (constitutional) isomers.
H
H
H
H
H
C
C
C
C
H
H
H
H
H
H
H
H
C
C
C
H
H
H
H C
H
H
H
n-butane
H
H
C
H
H
H
H C
H
H
2-methylpropane
11
Alkanes
† Three alkanes have the formula C5H12.
„ There are three structural isomers of pentane.
H2
C
H3C
C
H2
H2
C
H
H C
H
H
CH3
CH
CH3
H3C
C
H2
CH3
CH3
H
n-pentane
H C
H
H
C
H3C
CH3
CH3
H
2-methylbutane
H C
H
H
2,2-dimethylpropane
†The number of structural isomers increases rapidly
with increasing numbers of carbon atoms.
12
Alkanes
† There are five isomeric hexanes, C6H14.
You draw them!
H3C
H2
C
C
H2
H2
C
C
H2
CH3
n-hexane
13
Constitutional Isomers
† There are five isomeric hexanes, C6H14.
H3C
C
H2
H2
C
C
H2
H2
C
CH3
H2
H3C
C H CH3
C
C
H2
CH3
2-methylpentane
n-hexane
H3C
CH3
C C CH3
H2
CH3
2,2-dimethylbutane
CH3
H3C
C
CH3
C H C
H2
H2
3-methylpentane
CH3
H3C
HC CH
CH3
H3C
2,3-dimethylbutane
14
Naming Saturated Hydrocarbons
† Other organic compounds are named as
derivatives of the alkanes.
† Branched-chain alkanes are named by the
following rules.
1. Choose the longest continuous chain of carbon
atoms which gives the basic name or stem.
15
Naming Saturated Hydrocarbons
2
3
Number each carbon atom in the basic chain, starting at the
end that gives the lowest number to the first group attached
to the main chain (substituent).
For each substituent on the chain, we indicate the position
in the chain (by an Arabic numeric prefix) and the kind of
substituent (by its name).
‰ The position of a substituent on the chain is indicated by the lowest
number possible.
‰The number precedes the name of the
substituent.
16
Naming Saturated Hydrocarbons
4 When there are two or more substituents of a given kind, use
prefixes to indicate the number of substituents.
‰ di = 2, tri = 3, tetra = 4, penta = 5, hexa = 6, hepta = 7, octa = 8,
and so on.
5 The combined substituent numbers and names serve as a
prefix for the basic hydrocarbon name.
6 Separate numbers from numbers by commas and numbers
from words by hyphens.
‰ Words are "run together".
17
Naming Saturated Hydrocarbons
† Alkyl groups (represented by the symbol R) are common
substituents.
„ Alkyl groups are fragments of alkanes in which one H
atom has been removed for the connection to the main
chain.
„ Alkyl groups have the general formula CnH2n+1.
† In alkyl groups the -ane suffix in the name of the parent
alkane is replaced by -yl.
„ A one carbon group is named methyl.
„ A two carbon group is named ethyl.
„ A three carbon group is named propyl.
18
Unsaturated Hydrocarbons
† The three classes of unsaturated hydrocarbons
are:
1. alkenes, CnH2n
2. alkynes, CnH2n-2
3. aromatic hydrocarbons
19
Alkenes
† The simplest alkenes contain one C=C bond per
molecule.
„ The general formula for simple alkenes is CnH2n.
† The first two alkenes are:
„ ethene, C2H4
H
H
C C
H
H C
H
H
H
H
20
Alkenes
† The simplest alkenes contain one C=C bond per
molecule.
„ The general formula for simple alkenes is CnH2n.
† The first two alkenes are:
„ and propene, C3H6
H
H
H
H C
H
H
C
H
C
H
H
C
H
21
Alkenes
† The systematic naming system for alkenes uses the
same stems as alkanes.
† In the IUPAC system, the -ane suffix for alkanes is
changed to -ene.
„ Common names for the alkenes have the same stem but use
the suffix -ylene is used.
† In chains of four or more C atoms, a numerical prefix
shows the position of the lowest-numbered doubly
bonded C atom.
„ Always choose the longest chain that contains the C=C bond.
22
Alkynes
† Alkynes contain C≡C bonds.
† The simplest alkyne is C2H2, ethyne, or acetylene.
„ Alkynes with only one C ≡ C bond have the formula
CnH2n-2.
23
Alkynes
† Alkynes are named like the alkenes except that
the suffix -yne is used with the characteristic
stem
„ The alkyne stem is derived from the name of the
alkane with the same number of carbon atoms.
H
H
H
C
C
H
H
C
C
H
H
H
C
C
C
H
H
H
H
H C
H
H
H
H
H
C
C
H
C
H
H
H
H
H
C
C
C
C
C
H
H
H
H
H
H
H
3-heptyne
H C
H
H
2-octyne
24
Aromatic Hydrocarbons
† Historically, aromatic was used to describe
pleasant smelling substances.
† Now it refers to benzene, C6H6, and derivatives
of benzene.
„ Other compounds that have similar chemical
properties to benzene are also called aromatic.
25
Benzene
† The structure of benzene, C6H6, is:
H
H
H
H
H C
H
H
C
C
C
C
C
C
H
H
H
26
Functional Groups
† Functional groups are groups of atoms that
represent potential reaction sites.
† Compounds that contain a given functional
group usually undergo similar reactions.
† Functional groups influence physical properties
as well.
27
Organic Halides
† A halogen atom may replace almost any hydrogen
atom in a hydrocarbon.
† The functional group is the halide (-X) group.
† Examples include:
„ chloroform, CHCl3
Cl
Cl
C
H
Cl
28
Organic Halides
† 1,2-dichloroethane, ClCH2CH2Cl
H Cl
H C C H
H
H C
H
H
Cl H
29
Alcohols and Phenols
† The functional group in alcohols and phenols is
the hydroxyl (-OH) group.
† Alcohols can be considered derivatives of
hydrocarbons in which one or more H atoms have
been replaced by -OH groups.
† Alcohols are considered neutral compounds because
they are only very slightly acidic.
„ Alcohols can behave as acids but only in the presence of
very strong bases.
30
Alcohols and Phenols
† Ethyl alcohol (ethanol), C2H5OH, is the most
familiar alcohol.
H H
H C C OH
H
H C
H
H
H H
31
Alcohols
† Alcohols can be classified into three classes:
1. Primary (1°) alcohols like ethanol have the -OH
group attached to a C atom that has one bond to
another C atom.
H3C
C OH
H2
32
Alcohols and Phenols
2. Secondary(2°) alcohols have the –OH group
attached to a C atom that has bonds to 2 other C
atoms.
† For example,2-propanol:
H3C
HC OH
H3C
33
Alcohols and Phenols
3. Tertiary (3°) alcohols have the –OH group
attached to a C atom that is bonded to 3 other C
atoms.
† For example, 2-methyl-2-propanol
OH
H3C C CH3
CH3
34
Alcohols and Phenols
† The stem for the parent hydrocarbon plus an -ol
suffix is the systematic name for an alcohol.
† A numeric prefix indicates the position of the -OH
group in alcohols with three or more C atoms.
† Common names are the name of the appropriate alkyl
group plus alcohol.
35
Alcohols
H2C
OH
H2
C
C
H2
H2
C
OH
C H3
1-pentanol
1-pentyl alcohol
C
H3C H C
H2
H2
C
C H3
2-pentanol
2-pentyl alcohol
H2
H2
C H C
H3C
C
C H3
OH
3-pentanol
3-pentyl alcohol
36
Alcohols
OH
H2
C
HO
H
H C
H
H
H2
C
C
H2
CH
H3C
CH3
CH3
H
1-butanol
H C
H
H
2-butanol
OH
HO
CH2
H3C
CH
H3C
CH2
C
CH3
CH3
CH3
H
H
H C
H
H
2-methyl-1-propanol
H C
H
H
2-methyl-2-propanol
37
Alcohols
† Because the -OH group is quite polar, the properties of
alcohols depend upon the number of -OH groups per
molecule and the size of the organic group.
† The boiling points of alcohols increase with increasing
molecular weight.
† The solubility of alcohols in water decrease with increasing
molecular weight
38
Ethers
† Ethers may be thought of as derivatives of water in
which both H atoms have been replaced by alkyl or
aryl groups.
H
O
H
water
H3C
O
H
an alcohol
H3C
O
CH3
an ether
39
Ethers
† Ethers are not very polar and not very reactive.
† They are excellent solvents.
† Common names are used for most ethers.
H3C
O
C
H2
CH3
H3C
O
CH3
H2
C
H3C
O
H2
C
CH3
H
H
H C
H
H
ethylmethyl ether
H C
H
H
dimethyl ether
H
H C
H
H
diethyl ether
40
Aldehydes and Ketones
† The functional group in aldehydes and ketones is
the carbonyl group.
O
R1
R2 or H
carbonyl group
41
Aldehydes and Ketones
† Except for formaldehyde, aldehydes have one H
atom and one organic group bonded to a carbonyl
group.
O
O
H3C
H
H C
H
H
H
ethanal
or
acetaldehyde
H
H
H C
H
H
O
H3C
H
methanal
or
formaldehyde
H
H C
H
H
C
H2
H
propanal
or
propionaldehyde
42
Aldehydes and Ketones
† Ketones have two organic groups bonded to a
carbonyl group.
O
O
C
C
H3C
H
H C
H
H
O
H2C
CH3
propanone
or
acetone
C
CH3
H2C
CH3
H
H C
H
H
2-butanone
or
ethylmethylketone
CH3
H
H C
H
H
CH2
CH3
3-pentanone
or
diethylketone
43
Aldehydes and Ketones
† Common names for aldehydes are derived from the
name of the acid with the same number of C atoms.
† IUPAC names are derived from the parent
hydrocarbon name by replacing -e with -al.
H3C
C
H2
H2
C
O
C
H2
C
pentanal
or
pentyl aldehyde
H3C
H
H3C
C
O
O
C
C
H
H
CH 3
2,3-dimethylproponal
or
2,3-dimethylpropionaldehyde
benzanal
or
benzyl aldehyde
44
Aldehydes and Ketones
† The IUPAC name for a ketone is the characteristic stem
for the parent hydrocarbon plus the suffix -one.
† A numeric prefix indicates the position of the carbonyl
group in a chain or on a ring.
O
H3C
C
H2
H2
C
O
C
H2
C
CH 3
2-hexanone
or
methyl pentyl ketone
H3C
H2
C
O
C
H2
C
C
H2
C
CH 3
CH 3
3-hexanone
or
ethyl propyl ketone
acetophenone
or
methyl phenyl ketone
45
Amines
† Amines are derivatives of ammonia in which one or
more H atoms have been replaced by organic groups
(aliphatic or aromatic or a mixture of both).
† There are three classes of amines.
H
N
H
H
ammonia
H3C
N
H
primary
amine
H
H3C
N
H
CH3
secondary
amine
H3C
N
CH3
CH3
tertiary
amine
46
Carboxylic Acids
† Carboxylic acids contain the carboxyl functional
group.
O
C
OH
47
Carboxylic Acids
† IUPAC names for a carboxylic acid are derived
from the name of the parent hydrocarbon.
„ The final -e is dropped from the name of the
parent hydrocarbon
„ The suffix -oic is added followed by the word
acid.
† Many organic acids are called by their common
(trivial) names which are derived from Greek or
Latin.
48
Carboxylic Acids
O
O
C
C
H
H
H C
H
H
H3C
OH
methanoic acid
or
formic acid
H
H C
H
H
OH
ethanoic acid
or
acetic acid
O
H3C
H
H C
H
H
O
H2
C
C
C
H2
OH
propanoic acid
or
propionic acid
H3C
H
H C
H
H
C
C
H2
OH
butanoic acid
or
butyric acid
49
Esters
† Esters are usually called by their common names.
† Many simple esters occur naturally and have pleasant
odors.
„ Esters are frequently used in fragrances and as artificial
flavors.
H3C
H2
C
O
C
H2
C
O
H2
C
O
CH3
ethyl butanoate
or
ethyl butyrate
odor of pineapples
H3C
O
H2
C
C
H2
H2
C
C
H2
H2
C
C
H2
H2
C
CH3
octyl ethanoate
or
octyl acetate
odor of oranges
50
Amides
† Amides are derivatives of organic acids and primary or
secondary amines.
† The functional groups of amides are:
O
O
R1
C
N
H
H
or
R1
C
O
N
H
R2
or
R1
C
N
R3
51
R2
Some Derivatives of
Carboxylic Acids
† Amides are also named as derivatives of carboxylic
acids.
† The suffix -amide is substituted for -ic acid or -oic
acid.
O
O
H3C
C
N
C
NH2
H
H
ethanamide
or
acetamide
benzamide
52
Overview of Functional Groups
53
Overview of Functional Groups
54