Transcript Chapter 20 Organic Chemistry

Chemistry: A Molecular Approach, 1st Ed.
Nivaldo Tro
Chapter 20
Organic
Chemistry
Roy Kennedy
Massachusetts Bay Community College
Wellesley Hills, MA
2008, Prentice Hall
Structure Determines Properties
• Organic compounds all contain carbon
CO, CO2 , carbonates and carbides are inorganic
other common elements are H, O, N, (P, S)
• Carbon has versatile bonding patterns
chains, rings, multiple bonds
chain length nearly limitless
• Carbon compounds generally covalent
molecular; gases, liquids, or low melting solids;
varying solubilities; nonconductive in liquid
• C - C bonds unreactive (very stable)
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Bond Energies and Reactivities
C-C
S-S
Si-Si
N-N
O-O
347 kJ H3C-CH3
NONREACTIVE
IN AIR
214 kJ
213 kJ
159 kJ
138 kJ
EXTREMELY
REACTIVE
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HS-SH
SPONTANEOUS
3 BURNS IN AIR
H3Si-SiH
H2N-NH2
EXTREMELY
REACTIVE
HO-OH
REACTIVE
3
Allotropes of Carbon - Diamond
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Allotropes of Carbon - Graphite
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Carbon Bonding
• mainly forms covalent bonds
• C is most stable when it has 4 single covalent bonds,
but does form double and triple bonds
 C=C and C≡C are more reactive than C−C
 C with 4 single bonds is tetrahedral,
 2 singles and 1 double is trigonal planar
 2 doubles or 1 triple and 1 single is linear
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Hydrocarbons
• hydrocarbons contain only C and H
 aliphatic or aromatic
• insoluble in water
no polar bonds to attract water molecules
• aliphatic hydrocarbons
 saturated or unsaturated aliphatics
saturated = alkanes, unsaturated = alkenes or alkynes
 may be chains or rings
chains may be straight or branched
• aromatic hydrocarbons
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Uses of Hydrocarbons
Number of
C atoms
1-4
5-7
6-18
12-24
18-50
50+
State
Major Uses
heating and
cooking fuel
liquids,
solvents,
(low boiling) gasoline
gas
liquids
gasoline
jet fuel; camp
liquids
stove fuel
diesel fuel,
liquids,
lubricants,
(high boiling)
heating oil
petroleum jelly,
solids
paraffin wax
8
Saturated Hydrocarbons
• a saturated hydrocarbon has all C-C single
bonds
it is saturated with hydrogens
• saturated aliphatic hydrocarbons are called
alkanes
• chain alkanes have the general formula CnH2n+2
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Unsaturated Hydrocarbons
• unsaturated hydrocarbons have one of more C=C
•
double bonds or CC triple bonds
unsaturated aliphatic hydrocarbons that contain C=C
are called alkenes
 the general formula of a monounsaturated chain alkene is
CnH2n
 remove 2 more H for each additional unsaturation
• unsaturated aliphatic hydrocarbons that contain CC
are called alkynes
 the general formula of a monounsaturated chain alkyne is
CnH2n-2
 remove 4 more H for each additional unsaturation
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Unsaturated Hydrocarbons
H3C
H
C
CH3
C
H
CH3
H3C
C
C
CH3
HC
H2C
CH3
H3C
C
C
CH3
H2C
H2C
H2
C C
CH2
H2C
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C
H2
H
C
C
H2
H2
C C
H2
C
CH2
C
H2
H2C
C
H2
CH2
H2
C
CH2
CH2
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Aromatic Hydrocarbons
• contain benzene ring structure
• even though they are often drawn with C=C,
they do not behave like alkenes
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H2
C C
H2C
CH
3
H3C
C
C
CH
3
H
H2C CH
CH3
C
C
3
C
H3C
H3C
C CH2
H
H
C
2
CH
3 C
H2
H2
C C
H
C
C
H2
H2
C
CH22
HC
CH
H2C
H
H22C
CH2
C
CH
C
2
C H2
H2
alkanes
alkenes
alkynes
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Formulas
• molecular formulas just tell you what
•
•
kinds of atoms are in the molecule, but
they don’t tell you how they are attached
structural formulas show you the
attachment pattern in the molecule
models not only show you the attachment
pattern, but give you an idea about the
shape of the molecule
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Condensed Structural Formulas
• attached atoms listed in order
 central atom with attached atoms
• follow normal bonding patterns
 use to determine position of multiple bonds
• () used to indicate more than 1 identical
group attached to same previous central
atom
 unless () group listed first in which case
attached to next central atom
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Line-Angle Formulas
• each angle, and beginning and end represent a C
atom
• H omitted on C
included on functional groups
• multiple bonds indicated
double line is double bond, triple line is triple bond
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Formulas
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Formulas
H
H
CH4
C
H
H
C2H6
C3H8
C4H10
C4H10
CH3CH3
CH3CH2CH3
CH3CH2CH2CH3
C(CH3)2
H
H
H
H
H
H
C
C
H
H
H
H
H
C
C
C
H
H
H
H
H
H
H
C
C
C
C
H
H
H
H
H
H
H
C
C
C
C
H
H
H
H
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H
H
H
H
H
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Isomerism
• Isomers = different molecules with the same
•
molecular formula
Structural Isomers = different pattern of atom
attachment
 Constitutional Isomers
• Stereoisomers = same atom attachments, different
spatial orientation
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H
H
H
H
H
H
C
C C C H
H C C C
Structural
Isomers of
C4H10
H
HButane,
HH HHBPH= 0°C
C
C
C
H
H
H CH C C C H
H
H H H H
H H H H
H
H
H
HIsobutane,
H HH BP H
= -12°C
H C H
C C C
H HH H
H C C HC H
H
H
H
H
H C H
H C H
H
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H
H
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Rotation about a bond is not isomerism
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Possible Structural Isomers
Carbon Molecular Possible
Content Formula Isomers
4
C4H10
2
5
C5H12
3
6
C6H14
5
7
C7H16
9
8
C8H18
18
9
C9H20
35
10
C10H22
75
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Ex 20.1 – Write the structural formula and carbon
skeleton formula for C6H14
start by
connecting
the carbons
in a line
C C C C
CC CC C
C CC
C C
C
C C
C C
C
C C
C
determine
the C
skeleton of
the other
isomers
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Ex 20.1 – Write the structural formula and carbon
skeleton formula for C6H14
H
fill in the H
to give each
C 4 bonds
H
H
H
H
H C
C C
C
C
C H
C C
H
H
H
H
H
C
H C
H C
H
C
C H
C C
H
H
H
H
H
H C
C
C
C H
C C
H
H
H
C H H
C H
H H H H H
H C
H
H H H
H
H
H
H C
H C
H CC C
C
H C
H C
H
H
H
H
H
H
C C
C H
H
H
H
H
H
H
H
C CC C C CC C
C C
H
H
H C H H C H
H
H
H
Ex 20.1 – Write the structural formula and carbon
skeleton formula for C6H14
convert each
to a carbon
skeleton
formula –
each bend
and the ends
represent C
atoms
H
H
H
H
H
H
H
C
C
C
C
C
C
H
H
H
H
H
H
H H H H H
H
C
H
H
H
C
C
C
H H H
H
H
H
H
H
C
C
H
H
C
C
H
H
H
H
H
H
C
C
C
C
C
H
H
H
H
C
H
H
H
H
H
H
H
C
C
C
H
C
H
H
H
H
H
H
H
H
H
H
H
C
C
C
C
H
H
H C H H C H
H
H
H
Stereoisomers
• stereoisomers are different molecules whose
atoms are connected in the same order, but have
a different spatial direction
• optical isomers are molecules that are
nonsuperimposable mirror images of each other
• geometric isomers are stereoisomers that are
not optical isomers
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Nonsuperimposable Mirror Images
mirror image cannot be rotated so all its atoms align
with the same atoms of the original molecule
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Chirality
• any molecule with a nonsuperimposable mirror
image is said to be chiral
• any carbon with 4 different substituents will be
a chiral center
• a pair of nonsuperimposable mirror images are
called a pair of enantiomers
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Optical Isomers of 3-methylhexane
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Plane Polarized Light
• light that has been filtered so that only those
waves traveling in a single plane are allowed
through
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Optical Activity
• a pair of enantiomers have all the same physical
properties except one – the direction they rotate the
plane of plane polarized light
 each will rotate the plane the same amount, but in opposite
directions
 dextrorotatory = rotate to the right
 levorotatory = rotate to the left
• an equimolar mixture of the pair is called a racemic
mixture
 rotations cancel, so no net rotation
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Chemical Behavior of Enantiomers
• a pair of enantiomers will have the same
chemical reactivity in a non-chiral environment
• but in a chiral environment they may exhibit
different behaviors
enzyme selection of one enantiomer of a pair
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•
•
•
•
•
Alkanes
aka paraffins
aliphatic
general formula CnH2n+2 for chains
very unreactive
come in chains or/and rings
CH3 groups at ends of chains, CH2 groups in
the middle
chains may be straight or branched
• saturated
• branched or unbranched
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Name
Lewis
Structure
H
Methane
H
C
H
Ethane
Propane
H
H
Pentane
Hexane
H
H
H
H
H
H
C
C
H
H
C
H
Butane
Formula
H
CH4
Boiling
Point
-162°C
CH3CH3
-89°C
CH3CH2CH3
-42°C
CH3CH2CH2CH3
0°C
CH3CH2CH2CH2CH3
36°C
CH3CH2CH2CH2CH2CH3
69°C
H
H
H
C
C
H
H
H
H
H
H
H
C
C
C
C
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
C
C
C
C
C
C
H
H
H
H
H
H
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H
H
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Naming
• each name consists of 3 parts
 prefix
indicates position, number, and type of branches
indicates position, number, and type of each functional group
 parent
indicates the length of the longest carbon chain or ring
 suffix
indicates the type of hydrocarbon
– ane, ene, yne
certain functional groups
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Naming Alkanes
1) Find the longest continuous carbon chain
2) Number the chain from end closest to a branch
 if first branches equal distance use next in
3) Name branches as alkyl groups
 locate each branch by preceding its name with
the carbon number on the chain
4) List branches alphabetically
 do not count n-, sec-, t-, count iso
5) Use prefix if more than one of same group
present
 di, tri, tetra, penta, hexa
 do not count in alphabetizing
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Alkyl Groups
H
H C
H
CH3-, METHYL
H H
H C C
H H
CH3CH2-, ETHYL
H H H
H C C C
H H H
CH3CH2CH2-, PROPYL
H CH3
H C C
H H
(CH3)2CH-, ISOPROPYL
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More Alkyl Groups
H H H H
H C C C C
H H H H
CH3CH2CH2CH2-, n-BUTYL
H H CH3
H C C C
H H H
CH3CH2(CH3)CH-, sec-BUTYL
H
H C
H
(CH3)2CHCH2-, ISOBUTYL
CH3 H
C
C
H
H
CH3
H 3C C
CH3
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(CH3)3C-, tert- BUTYL
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Examples of Naming Alkanes
2-methylpentane
3-isopropyl-2,2-dimethylhexane
H
H
H
H
H
H
H
C
C
C
C
C
H
CH3 H
H
H
H
CH3 H
H
H
H
C
C
C
C
C
H
CH3 CH
H
H
H
C
H
H
CH3 CH3
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Example – Name the alkane
CH3CHCH2CHCH3
CH3
CH3
1) find the longest continuous C chain and use it
to determine the base name
CH3CHCH2CHCH3
CH3
CH3
since the longest chain has 5 C
the base name is pentane
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Example – Name the alkane
CH3CHCH2CHCH3
CH3
CH3
2) identify the substituent branches
CH3CHCH2CHCH3
CH3
CH3
there are 2 substituents
both are 1 C chains, called methyl
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Example – Name the alkane
3) number the chain from the end closest to a
substituent branch
 if first substituents equidistant from end, go to next
substituent in
then assign numbers to each substituent based
on the number of the main chain C it’s attached to
1
2
3
4
5
CH3CHCH2CHCH3
both substituents are
equidistant from the end
CH3
2
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CH3
4
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Example – Name the alkane
4) write the name in the following order
1) substituent number of first alphabetical substituent
followed by dash
2) substituent name of first alphabetical substituent followed
by dash
 if it’s the last substituent listed, no dash
 use prefixes to indicate multiple identical substituents
3) repeat for other substituents alphabetically
4) name of main chain
CH3CHCH2CHCH3
CH3
2
2,4 – dimethylpentane
CH3
4
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Practice – Name the Following
CH3
CH3 CHCHCH2 CH3
CH2 CH3
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Practice – Name the Following
CH3
CH3 CHCHCH2 CH3
CH2 CH3
3-ethyl-2-methylpentane
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Drawing Structural Formulas
• draw and number the
•
•
base chain carbon
skeleton
add the carbon skeletons
of each substituent on the
appropriate main chain C
add in required H’s
4-ethyl-2-methylhexane
C C C C C C
1 2 3 4 5 6
C C C C C C
C
CH3 CH CH2 CH CH2 CH3
CH3
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C C
H2C CH3
47
Practice – Draw the structural formula of 4isopropyl-2-methylheptane
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Practice – Draw the structural formula of 4isopropyl-2-methylheptane
CH3 CH CH2 CH CH2 CH2 CH3
CH3
HC CH3
CH3
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Alkenes
• also known as olefins
• aliphatic, unsaturated
C=C double bonds
• formula for one double bond = CnH2n
subtract 2 H from alkane for each double bond
• trigonal shape around C
flat
• much more reactive than alkanes
• polyunsaturated = many double bonds
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Alkenes
ethene = ethylene
H
H
propene
H
C C
C C
H
H
H
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H
CH3
52
Physical Properties of Alkenes
Molar Mass BP, °C Density, g/cm 3
28
-104
0.52
Name
ethene
Formula
CH2=CH2
propene
CH2=CHCH3
42
-47
0.59
1-butene
CH2=CHCH2CH3
56
-6
0.59
1-pentene
CH2=CH(CH2)2CH3
70
30
0.64
1-hexene
CH2=CH(CH2)3CH3
84
64
0.68
1-heptene
CH2=CH(CH2)4CH3
98
93
0.70
1-octene
CH2=CH(CH2)5CH3
112
122
0.72
1-nonene
CH2=CH(CH2)6CH3
126
146
0.73
1-decene
CH2=CH(CH2)7CH3
140
171
0.74
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Alkynes
•
•
•
•
also known as acetylenes
aliphatic, unsaturated
CC triple bond
formula for one triple bond = CnH2n-2
subtract 4 H from alkane for each triple bond
• linear shape
• more reactive than alkenes
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Alkynes
ethyne = acetylene
H C C H
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propyne
H C C CH3
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Physical Properties of Alkynes
Name
Formula
Molar Mass BP, °C Density, g/cm 3
ethyne
CHCH
28
-104
0.52
propyne
CHCCH3
42
-47
0.59
1-butyne
CHCCH2CH3
56
-6
0.59
1-pentyne
CHC(CH2)2CH3
70
30
0.64
1-hexyne
CHC(CH2)3CH3
84
64
0.68
1-heptyne
CHC(CH2)4CH3
98
93
0.70
1-octyne
CHC(CH2)5CH3
112
122
0.72
1-nonyne
CHC(CH2)6CH3
126
146
0.73
1-decyne
CHC(CH2)7CH3
140
171
0.74
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Naming Alkenes and Alkynes
• change suffix on main name from -ane to -ene
for base name of alkene, or to -yne for the base
name of the alkyne
• number chain from end closest to multiple bond
• number in front of main name indicates first
carbon of multiple bond
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Examples of Naming Alkenes
2-methyl-1-pentene
H
3-isopropyl-2,2-dimethyl-3-hexene H
H
H
H
C
C
C
C
C
H
CH3 H
H
H
H
CH3
C
C
H
CH3 CH
C
H
H
H
C
C
C
H
H
H
H
CH3 CH3
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Examples of Naming Alkynes
3-methyl-1-pentyne
H
4-isopropyl-5,5-dimethyl-2-hexyne H
C
C
H
H
H
C
C
C
CH3 H
H
H
CH3 H
C
C
H
CH3 CH
C
H
H
C
C
C
H
H
CH3 CH3
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Name the Alkene
1) find the longest, continuous C chain that
contains the double bond and use it to determine
the base name
H2C CH3
H3C CH
C CH CH3
H2C CH3
since the longest chain with the double bond has 6 C
the base name is hexene
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Name the Alkene
2) identify the substituent branches
H2C CH3
H3C CH
C CH CH3
H2C CH3
there are 2 substituents
one is a 1 C chain, called methyl
the other one is a 2 C chain, called ethyl
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Name the Alkene
3) number the chain from the end closest to the
double bond
then assign numbers to each substituent based
on the number of the main chain C it’s attached to
3
H2C CH3
4
H3C CH
C CH CH3
4
3
2
1
H2C CH3
5
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6
63
Name the Alkene
4) write the name in the following order
1) substituent number of first alphabetical substituent –
substituent name of first alphabetical substituent –
 use prefixes to indicate multiple identical substituents
2) repeat for other substituents
3) number of first C in double bond – name of main chain
3
H2C CH3
4
H3C CH
3–ethyl– 4–methyl–2–hexene
C CH CH3
4
3
2
1
H2C CH3
5
6
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Practice – Name the Following
CH3
H3C C
C CH2 CH3
H2C CH3
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Practice – Name the Following
CH3
H3C 3C
C4 CH2 CH3
5
6
H2C CH3
2
1
3,4-dimethyl-3-hexene
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Name the Alkyne
1) find the longest, continuous C chain that
contains the triple bond and use it to determine
the base name
CH3 CH CH2 CH C
CH3
C CH3
HC CH3
CH3
since the longest chain with the triple bond has 7 C
the base name is heptyne
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Name the Alkyne
2) identify the substituent branches
CH3 CH CH2 CH C
CH3
HC
C
CH3
CH3
CH3
there are 2 substituents
one is a 1 C chain, called methyl
the other one is called isopropyl
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Name the Alkyne
3) number the chain from the end closest to the
triple bond
then assign numbers to each substituent based
on the number of the main chain C it’s attached to
CH3 CH CH2 CH C
7
6
5
4
3
6 CH3
HC
4
C
2
CH3
1
CH3
CH3
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Name the Alkyne
4) write the name in the following order
1) substituent number of first alphabetical substituent –
substituent name of first alphabetical substituent –
 use prefixes to indicate multiple identical substituents
2) repeat for other substituents
3) number of first C in double bond – name of main chain
CH3 CH CH2 CH C
7
6
5
4
3
6 CH3
HC
4
C
2
CH3
1
CH3
CH3
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4–isopropyl–6–methyl–2–heptyne
70
Practice – Name the Following
CH3
H3C C C
CH
CH2CH3
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Practice – Name the Following
CH3
H3C C C
3
2
CH
1
CH2CH3
4
5
3,3-dimethyl-1-pentyne
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Geometric Isomerism
• because the rotation around a double bond is highly
•
•
•
restricted, you will have different molecules if groups
have different spatial orientation about the double bond
this is often called cis-trans isomerism
when groups on the doubly bonded carbons are cis,
they are on the same side
when groups on the doubly bonded carbons are trans,
they are on opposite sides
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73
Free Rotation Around
C─C
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74
Cis-Trans Isomerism
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75
Reactions of Hydrocarbons
• all hydrocarbons undergo combustion
• combustion is always exothermic
about 90% of U.S. energy generated by combustion
2 CH3CH2CH2CH3(g) + 13 O2(g) → 8 CO2(g) + 10 H2O(g)
CH3CH=CHCH3(g) + 6 O2(g) → 4 CO2(g) + 4 H2O(g)
2 CH3CCCH3(g) + 11 O2(g) → 8 CO2(g) + 6 H2O(g)
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76
Other Alkane Reactions
• Substitution
replace H with a halogen atom
initiated by addition of energy in the form of
heat or ultraviolet light
to start breaking bonds
generally get multiple products with multiple
substitutions
H H
H C C H + Cl Cl
H H
Tro, Chemistry: A Molecular Approach
heat or
UV light
H Cl
H C C H + H Cl
H H
77
Other Alkene and Alkyne Reactions
• Addition reactions
 adding a molecule across the multiple bond
• Hydrogenation = adding H2
 converts unsaturated molecule to saturated
 alkene or alkyne + H2 → alkane
• Halogenation = adding X2
• Hydrohalogenation = adding HX
 HX is polar
 when adding a polar reagent to a double or triple
bond, the positive part attaches to the carbon with
the most H’s
78
Addition Reactions
HH
CC
HH
C
CC
HCl + ++ H-Cl
22
CH
CH333
CH
Tro, Chemistry: A Molecular Approach
HH
HH
Cl
H
H
H
CC
HH
HH
CH
CH
3 33
CC
ClCl
H
79
Aromatic Hydrocarbons
• contain benzene ring structure
• even though they are often drawn with C=C,
they do not behave like alkenes
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Resonance Hybrid
• the true structure of benzene is a resonance
hybrid of two structures
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81
Naming Monosubstituted
Benzene Derivatives
• (name of substituent)benzene
 halogen substituent = change ending to “o”
F
CH2CH2CH3
propylbenzene
fluorobenzene
• or name of a common derivative
CH3
NH2
toluene
aniline
Tro, Chemistry: A Molecular Approach
OH
phenol
HC CH2
styrene
82
Naming Benzene as a Substituent
• when the benzene ring is not the base name, it is
called a phenyl group
H2C
CH CH2
CH CH2
CH3
4-phenyl-1-hexene
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83
Naming Disubstituted
Benzene Derivatives
• number the ring starting at attachment for first
substituent, then move toward second
order substituents alphabetically
use “di” if both substituents the same
CH3
F
3
1
2
1 Br
1-bromo-3-fluorobenzene
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2
CH3
1,2-dimethylbenzene
84
Naming Disubstituted
Benzene Derivatives
• alternatively, use relative position prefix
ortho- = 1,2; meta- = 1,3; para- = 1,4
CH3
CH3
CH3
Cl
Cl
Cl
2-chlorotoluene
ortho-chlorotoluene
o-chlorotoluene
Tro, Chemistry: A Molecular Approach
3-chlorotoluene
meta-chlorotoluene
m-chlorotoluene
4-chlorotoluene
para-chlorotoluene
p-chlorotoluene
85
Practice – Name the Following
F
Br
Br
Cl
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86
Practice – Name the Following
F
Br
Br
Cl
1-chloro-4-fluorobenzene
Tro, Chemistry: A Molecular Approach
1,3-dibromobenzene
or meta-dibromobenzene
or m-dibromobenzene
87
Polycyclic Aromatic Hydrocarbons
• contain multiple benzene rings fused together
fusing = sharing a common bond
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88
Reactions of Aromatic Hydrocarbons
• most commonly, aromatic hydrocarbons
undergo substitution reactions – replacing H
with another atom or group
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89
Functional Groups
• other organic compounds are hydrocarbons in which
•
functional groups have been substituted for hydrogens
a functional group is a group of atoms that show a
characteristic influence on the properties of the
molecule
 generally, the reactions that a compound will perform are
determined by what functional groups it has
 since the kind of hydrocarbon chain is irrelevant to the
reactions, it may be indicated by the general symbol R
R group
Tro, Chemistry: A Molecular Approach
CH3—OH
functional group
90
91
Alcohols
• R-OH
• ethanol = CH3CH2OH
 grain alcohol = fermentation of sugars
 alcoholic beverages
 proof number = 2X percentage of alcohol
 gasohol
• isopropyl alcohol = (CH3)2CHOH
 2-propanol
 rubbing alcohol
 poisonous
• methanol = CH3OH
 wood alcohol = thermolysis of wood
 paint solvent
 poisonous
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92
Naming Alcohols
• main chain contain OH
• number main chain from end closest to OH
• give base name ol ending and place number of C
•
on chain where OH attached in front
name as hydroxy group if other higher precedence
group present
1CH 2CH
3
2
OH CH3
3CH 4 C 5CH 6CH
2
CH2CH3
4-ethyl-4-methyl-3-hex-5-enol
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93
Reactions of Alcohols
Nucleophilic Substitution
CH3
OH + HCl  CH3Cl + H2O
Acid Catalyzed Elimination (Dehydration)
CH3
CH2OH  CH2 CH2 + H2O
H2SO4
Oxidation
CH3
-2H
CH2OH  CH3
-2H
CHO CH3
COOH
with Reactive Metals
CH3
OH
Tro, Chemistry: A Molecular Approach
+ Na  CH3O−Na+ + ½ H2
94
•
•
•
•
•
•
Aldehydes and Ketones
contain the carbonyl group
aldehydes = at least 1 side H
ketones = both sides R groups
many aldehydes and ketones have
pleasant tastes and aromas
some are pheromones
formaldehyde = H2C=O
 pungent gas
 formalin = a preservative
 wood smoke, carcinogenic
• acetone = CH3C(=O)CH3
O
C
formaldehyde
acetone
 nail-polish remover
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95
Aldehyde Odors and Flavors
• butanal = butter
O
C CH2CH2CH3
H
O
• vanillin = vanilla
HO
O
H
HO
• benzaldehyde = almonds
O
H
C
• cinnamaldehyde = cinnamon
O
H
C C
H
C
H
96
Ketone Odors and Flavors
• acetophenone = pistachio
O
C
H3C
• carvone = spearmint
H3C
CH2
O
C
• ionone = raspberries
CH3
H3C
CH3
O
H
C C C CH3
H
CH3
• muscone = musk
O
CH3
97
Reactions
• aldehydes and ketones are generally synthesized
by the oxidation of alcohols
• therefore, reduction of an aldehyde or ketone
results in an alcohol
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98
Carbonyl Group
C=O group is highly polar
many reactions involve addition across C=O,
with positive part attached to O
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99
Addition to C=O
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100
Carboxylic Acids
•
•
•
•
RCOOH
sour tasting
weak acids
citric acid
O
O
CH2
C OH
HO C C OH
CH2
C OH
O
found in citrus fruit
• ethanoic acid = acetic acid
vinegar
O
CH3 C OH
• methanoic acid = formic acid
insect bites and stings
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O
H C OH
101
Carboxylic Acids
• made by the oxidation of
aldehydes and alcohols
OH on the end of the chain
• always on main chain
has highest precedence
• C of group always C1
O
C
O
H
oxidation
benzaldehyde
OH
H3C CH2
position not indicated in name ethanol
C
OH
benzoic acid
oxidation
O
H3C C OH
ethanoic acid
• change ending to oic acid
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102
Naming Carboxylic Acids
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103
Esters
• R–COO–R
• sweet odor
• made by reacting carboxylic acid
with an alcohol
methyl butanoate
RaCOOH + RbOH  RaCOORb + H2O
O
• name alkyl group from alcohol, then
C
OH
acid name with oate ending
 precedence over carbonyls, but not
carboxylic acid
 number from end with ester group
Tro, Chemistry: A Molecular Approach
O C CH3
O
aspirin
104
Naming Esters
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105
Condensation Reactions
• a condensation reaction is any organic reaction
driven by the removal of a small molecule, like
water
• acid
estersanhydrides
are made by
arethe
made
condensation
by the condensation
reaction
reaction
betweenbetween
a carboxylic
2 carboxylic
acid andacid
an alcohol
molecules

+
O
R
C
OH
the reaction is driven
acid catalyzed
by heat
O
HO
C
Tro, Chemistry: A Molecular Approach
O
R'
R
C
O
O
C
+
R'
HOH
106
Synthesis of Aspirin
(Acetylsalicylic Acid)
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107
Ethers
• R– O – R
• ether = diethyl ether = CH3CH2OCH2CH3
anesthetic
• to name ethers, name each alkyl group
attached to the O, then add the word ether
to the end
diethyl ether
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108
Amines
•
•
•
•
•
N containing organic molecules
very bad smelling
form when proteins decompose
organic bases
name alkyl groups attached to the N, then add
the word amine to the end
NH2
H3C CH2
ethylamine
H3C NH
H3C
CH2
ethylmethylamine
Tro, Chemistry: A Molecular Approach
H2NCH2CH2CH2CH2NH2
putrescine
H2NCH2CH2CH2CH2CH2NH2
cadaverine
109
Amines
• many amines are biologically active
 dopamine – a neurotransmitter
 epinephrine – an adrenal hormone
 pyridoxine – vitamin B6
HO
CH2CH2NH2
HO
dopamine
• alkaloids are plant products that are
alkaline and biologically active
 toxic
 coniine from hemlock
 cocaine from coca leaves
 nicotine from tobacco leaves
 mescaline from peyote cactus
 morphine from opium poppies
Tro, Chemistry: A Molecular Approach
N
N
CH3
nicotine
110
Amine Reactions
• weak bases
react with strong acids to form ammonium salts
RNH2 + HCl → RNH3+Cl−
• react with carboxylic acids in a condensation
reaction to form amides
RCOOH + HNHR’  RCONHR’ + H2O
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111
Macromolecules
• polymers are very large molecules made by
repeated linking together of small molecules
 monomers
• natural
• modified natural polymers
• synthetic
 plastics, elastomers (rubber), fabrics, adhesives
• composites
 additives such as graphite, glass, metallic flakes
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112
Natural Polymers
• polysaccharides
 cellulose (cotton)
 starch
•
•
•
•
•
•
proteins
nucleic acids (DNA)
natural latex rubber, etc.
shellac
amber, lignin, pine rosin
asphalt, tar
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Modified Natural Polymers
• Cellulose Acetate
 Rayon
 film
• Vulcanized Rubber
• Gun Cotton
• Celluloid
 ping-pong balls
• Gutta Percha
 fill space for root canal
• Casein
 buttons, mouldings, adhesives
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114
Polymerization
• the process of linking the monomer units together
• two processes are addition polymerization and
•
condensation polymerization
monomers may link head-to-tail, or head-to-head, or
tail-to-tail
 head-to-tail most common
 regular pattern gives stronger attractions between chains than
random arrangements
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115
H
H
H
H
H
C
C
C
C
Cl
H
Cl
H
Head-to-Tail
Head Tail Head Tail
H
H
H
H
H
C
C
C
C
H
Cl Cl
Tail
H
Head Head Tail
Head-to-Head,
Tail-to-Tail
116
Addition Polymerization
• monomers add to the growing chain in
such a manner that all the atoms in the
original monomer wind up in the chain
no other side products formed, no atoms
eliminated
• first monomer must “open” to start
reaction
done with heat or addition of an initiator
• chain reaction
each added unit ready to add another
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117
Addition Polymerization
initiator
H
H
C
H
etc.
initiator
C
Cl
H
H
C
C
Cl
H
H
H
H
H
C
C
C
Cl
H
H
H
H
H
H
C
C
C
Cl
H
Cl
•
H
C
Cl
H
H
H
H
+
H
C +
H
C
Cl
H
C
H
H
H
H
H
C
C
C
C
Cl
H
Cl
H
•
H
H
H
H
H
H
C
C
C
C
C
C
Cl
H
Cl
H
Cl
H
•
Condensation Polymerization
• monomer units are joined by removing small
molecules from the combining units
polyesters, polyamides lose water
• no initiator needed
• chain reaction
• each monomer has two reactive ends, so chain
can grow in two directions
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119
Condensation Polymerization
+
HO
HO
+
O
O
C
C
O
O
C
C
Tro, Chemistry: A Molecular Approach
OH + HO
O
CH2
CH2
CH2
OH
CH2
OH
+ H2O
120
Nylon
• polyamides
• good physical properties
 affected by moisture
•
•
•
•
very good heat resistance
excellent chemical resistance
excellent wear resistance
nylon 6,6 made by condensing
1,6–hexandiamine, H2N–(CH2)6–NH2, with
hexandioic acid, HOOC–(CH2)4–COOH
O
O
HN (CH2)6 NH
Tro, Chemistry: A Molecular Approach
C
(CH2)4
C
121
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122