chemistry chapter 20 lec
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Chapter 20Organic
Chemistry
2008, Prentice Hall
Chemistry: A Molecular Approach , 1 st Ed. Nivaldo Tro
Roy KennedyMassachusetts Bay Community College
Wellesley Hills, MA
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Tro, Chemistry: A Molecular Approach 2
Structure Determines Properties Organic compounds all contain carbon
CO, CO 2 , carbonates and carbides are inorganicother common elements are H, O, N, (P, S)
Carbon has versatile bonding patternschains, rings, multiple bondschain length nearly limitless
Carbon compounds generally covalentmolecular; 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 347 kJ H 3 C-CH 3 NONREACTIVEIN AIR
S-S 214 kJ HS-SH EXTREMELYREACTIVE
Si-Si 213 kJ H 3 Si-SiH 3SPONTANEOUS
BURNS IN AIR
N-N 159 kJ H 2 N-NH 2EXTREMELY
REACTIVE
O-O 138 kJ HO-OH REACTIVE
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Tro, Chemistry: A Molecular Approach 4
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 bondsC=C and C C are more reactive than CC C with 4 single bonds is tetrahedral,2 singles and 1 double is trigonal planar2 doubles or 1 triple and 1 single is linear
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Uses of Hydrocarbons Number of
C atomsState Major Uses
1-4 gasheating andcooking fuel
5-7liquids,
(low boiling)
solvents,
gasoline6-18 liquids gasoline
12-24 liquids jet fuel; campstove fuel
18-50liquids,
(high boiling)
diesel fuel,lubricants,heating oil
50+ solids petroleum jelly, paraffin wax
1-4 gasheating andcooking fuel
5-7liquids,
(low boiling)
solvents,
gasoline6-18 liquids gasoline
12-24 liquids jet fuel; campstove fuel
18-50liquids,
(high boiling)
diesel fuel,lubricants,heating oil
50+ solids petroleum jelly,
paraffin wax
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Tro, Chemistry: A Molecular Approach 9
Saturated Hydrocarbons
a saturated hydrocarbon has all C-C single bonds
it is saturated with hydrogens
saturated aliphatic hydrocarbons are calledalkanes
chain alkanes have the general formula C nH2n+2
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Tro, Chemistry: A Molecular Approach 10
Unsaturated Hydrocarbons
unsaturated hydrocarbons have one of more C=Cdouble bonds or C C triple bonds unsaturated aliphatic hydrocarbons that contain C=C
are called alkenesthe general formula of a monounsaturated chain alkene isCnH2n remove 2 more H for each additional unsaturation
unsaturated aliphatic hydrocarbons that contain C Care called alkynes
the general formula of a monounsaturated chain alkyne isCnH2n-2 remove 4 more H for each additional unsaturation
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Tro, Chemistry: A Molecular Approach 12
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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Tro, Chemistry: A Molecular Approach 13
alkanes
CH3
CH
C
H
CH3
CH3
CC
CH3
CH3
CH3
CH
CH2 C
H2
CH2
CH2
CH
alkenes
CH3
C C CH3
CH2
CH2
CH
2
C
H2
CH2
CH 2CH
2
C C C
H2
C
H2
CH2
CH2
CH
2
C
H2
CH2
alkynes
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Formulas molecular formulas just tell you what
kinds of atoms are in the molecule, butthey dont tell you how they are attached
structural formulas show you theattachment pattern in the molecule
models not only show you the attachment pattern, but give you an idea about theshape of the molecule
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Tro, Chemistry: A Molecular Approach 16
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 identicalgroup attached to same previous central
atom unless () group listed first in which case
attached to next central atom
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Tro, Chemistry: A Molecular Approach 17
Line-Angle Formulas
each angle, and beginning and end represent a Catom
H omitted on Cincluded on functional groups
multiple bonds indicateddouble line is double bond, triple line is triple bond
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Formulas
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FormulasCH4 C
H
H
H
H
C2H6 CH3CH3 C
H
C
H
H
H
H
H
C3H8 CH3CH 2CH 3 C
H
C
H
H
H
C
H
H
H
H
C4H10 CH3CH 2CH 2CH 3 C
H
C
H
H
H
C
H
H
C
H
H
H
H
C4H10 C(CH 3)2 C
H
C
H
H
H
C
C
H
H
H
H
H
H
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Tro, Chemistry: A Molecular Approach 20
Isomerism Isomers = different molecules with the same
molecular formula Structural Isomers = different pattern of atom
attachmentConstitutional Isomers
Stereoisomers = same atom attachments, differentspatial orientation
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Tro, Chemistry: A Molecular Approach 21
Structural Isomers of C 4H10
Butane, BP = 0C Isobutane, BP = -12C
C C C C
H
H
H H
H H
H H
H
HC
H
H
H
H H
H
C HC
CH H
H
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Tro, Chemistry: A Molecular Approach 22
Rotation about a bond is not isomerism
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Possible Structural IsomersCarbon
Content
Molecular
Formula
Possible
Isomers
4 C 4 H 10 2
5 C5H
12 3
6 C 6 H 14 5
7 C 7 H 16 9
8 C 8 H 18 189 C 9 H 20 35
10 C 10 H 22 75
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Ex 20.1 Write the structural formula and carbon
skeleton formula for C 6H14 start byconnecting
the carbonsin a line
determine
the Cskeleton ofthe otherisomers
C C C C C CC C C C C
C
C C C C C
CC C C C
C
CC C C C
C C
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fill in the Hto give eachC 4 bonds
C C C C
C
CH
H
H
H H H
H
H
HHH
HH
H
C C C C
C
C
H
H
H H H
HH
HH
H
H
H
H
H
C C C C C CH
H
H
H
H
H
H
H
H
H H
H
HH
Ex 20.1 Write the structural formula and carbonskeleton formula for C 6H14
C C C C
C
H
H
H H
HH
HH
H
HH
C H
H
H
C C C C C C
C C C C C
C
C C C C C
C
C C C C
C
CC C C C
C C
C C C C
C
H
H
H H
H
CHH
H
HHH
H
H
H
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convert eachto a carbonskeletonformula each bendand the endsrepresent Catoms
C C C C
C
CH
H
H
H H H
H
H
HHH
HH
H
C C C C
C
C
H
H
H H H
HH
HH
H
H
H
H
H
C C C C C CH
H
H
H
H
H
H
H
H
H H
H
HH
Ex 20.1 Write the structural formula and carbonskeleton formula for C 6H14
C C C C
C
H
H
H H
HH
HH
H
HH
C H
H
H
C C C C
C
H
H
H H
H
CHH
H
HH
H
H
H
H
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Tro, Chemistry: A Molecular Approach 27
Stereoisomers
stereoisomers are different molecules whoseatoms 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 arenot optical isomers
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Tro, Chemistry: A Molecular Approach 28
Nonsuperimposable Mirror Images
mirror image cannot be rotated so all its atoms alignwith the same atoms of the original molecule
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Chirality
any molecule with a nonsuperimposable mirrorimage 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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Tro, Chemistry: A Molecular Approach 30
Optical Isomers of 3-methylhexane
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Plane Polarized Light
light that has been filtered so that only thosewaves traveling in a single plane are allowedthrough
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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 lighteach will rotate the plane the same amount, but in oppositedirectionsdextrorotatory = 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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Tro, Chemistry: A Molecular Approach 33
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 behaviorsenzyme selection of one enantiomer of a pair
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Tro, Chemistry: A Molecular Approach 35
Name L ewis Structure
F ormula Boilin Point
Methane C H
H
H
HCH 4 -162C
Ethane C
H
H
H C H
H
H
CH 3CH 3 -89C
Propane CH
H
H
C
H
H
C
H
H
HCH 3CH 2CH 3 -42C
Butane CH
H
H
C
H
H
C
H
H
C
H
H
H CH3CH 2CH 2CH 3 0C
Pentane CHH
H
C
H
H
C
H
H
C
H
H
C
H
H
H CH 3CH 2CH 2CH 2CH 3 36C
Hexane CHH
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
H CH3CH 2CH 2CH 2CH 2CH 3 69C
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Tro, Chemistry: A Molecular Approach 36
Naming
each name consists of 3 parts prefix
indicates position, number, and type of branchesindicates position, number, and type of each functional group
parentindicates the length of the longest carbon chain or ring
suffixindicates the type of hydrocarbon
ane, ene, yne
certain functional groups
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Naming Alkanes1) Find the longest continuous carbon chain
2) Number the chain from end closest to a branchif first branches equal distance use next in
3) Name branches as alkyl groups
locate each branch by preceding its name withthe carbon number on the chain4) 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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Tro, Chemistry: A Molecular Approach 39
More Alkyl Groups
C C C C
C C C
C
H
H
H
H
H
H
H
H
H
H
H
H
H
H H
C H 3
C H 3
C H 3
H3C
C C CC H 3H
H
H H
H
H
(C H 3)2C H C H 2- , IS OB U T Y L
C H3
C H2
(C H3
)C H - , s e c -B U T Y L
C H 3C H 2C H 2C H 2-, n - B U T Y L
(C H 3)3C - , tert-- B U T Y L
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Tro, Chemistry: A Molecular Approach 40
Examples of Naming Alkanes
2-methylpentane
H H H H H
H C C C C C H
H CH 3 H H H
3-isopropyl-2,2-dimethylhexane
H CH 3 H H H H
H C C C C C C H
H CH 3 CH H H H
CH 3 CH 3
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Tro, Chemistry: A Molecular Approach 41
Example Name the alkane
1) find the longest continuous C chain and use itto determine the base name
CH 3 CHCH 2 CHCH 3
CH 3 CH 3
CH 3CHCH 2CHCH 3
CH 3 CH 3since the longest chain has 5 C
the base name is pentane
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Example Name the alkane
2) identify the substituent branches
CH 3 CHCH 2 CHCH 3
CH 3 CH 3
there are 2 substituents both are 1 C chains, called methyl
CH 3CHCH 2CHCH 3
CH 3 CH 3
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CH 3CHCH 2CHCH 3
CH 3 CH 3
Example Name the alkane
3) number the chain from the end closest to asubstituent branchif first substituents equidistant from end, go to nextsubstituent in
both substituents areequidistant from the end
1 2 3 4 5
2 4
then assign numbers to each substituent basedon the number of the main chain C its attached to
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Practice Name the Following
CH3CHCHCH 2CH3
CH3
CH2CH3
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Practice Name the Following
CH3CHCHCH 2CH3
CH3
CH2CH3
3-ethyl-2-methylpentane
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Tro, Chemistry: A Molecular Approach 47
Drawing Structural Formulas
draw and number the base chain carbonskeleton
add the carbon skeletonsof each substituent on theappropriate main chain C
add in required Hs
4-ethyl-2-methylhexane
C C C CC C
C C C
CH3 CH2 CH2 CH3CH CHCH3 H2C CH 3
C C C C C C1 2 3 4 5 6
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Practice Draw the structural formula of 4-
isopropyl-2-methylheptane
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Practice Draw the structural formula of 4-
isopropyl-2-methylheptane
CH 3 CH 2 CH 2CH CH
CH 3 CH 3HC
CH 3
CH 2 CH 3
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Tro, Chemistry: A Molecular Approach 50
Alkenes also known as olefins aliphatic, unsaturated
C=C double bonds formula for one double bond = C nH2n
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
C CH H
HH
ethene = ethylene
C CH H
CH 3H
propene
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Tro, Chemistry: A Molecular Approach 54
Alkynes
also known as acetylenes aliphatic, unsaturated C C triple bond formula for one triple bond = C nH2n-2
subtract 4 H from alkane for each triple bond
linear shape more reactive than alkenes
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Alkynesethyne = acetylene propyne
C C HH C C CH 3H
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Tro, Chemistry: A Molecular Approach 58
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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Tro, Chemistry: A Molecular Approach 59
Examples of Naming Alkenes
2-methyl-1-pentene
3-isopropyl-2,2-dimethyl-3-hexene
H H H
H C C C C C H
H CH 3 H H H
H CH 3 H H
H C C C C C C H
H CH 3 CH H H H
CH 3 CH 3
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Examples of Naming Alkynes
3-methyl-1-pentyne
4-isopropyl-5,5-dimethyl-2-hexyne
H H H
H C C C C C H
CH 3 H H
H CH 3 H H
H C C C C C C H
H CH 3 CH H
CH 3 CH 3
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Name the Alkene
1)find the longest, continuous C chain thatcontains the double bond and use it to determinethe base name
since the longest chain with the double bond has 6 Cthe base name is hexene
H 3 C CH C
H 2 C CH 3
CH CH 3
H 2 C CH 3
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Name the Alkene
2) identify the substituent branches
there are 2 substituents
one is a 1 C chain, called methylthe other one is a 2 C chain, called ethyl
H 3 C CH C
H 2 C CH 3
CH CH 3
H 2 C CH 3
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H 3 C CH C
H 2 C CH 3
CH CH 3
H 2 C CH 3
Name the Alkene
3) number the chain from the end closest to thedouble bondthen assign numbers to each substituent basedon the number of the main chain C its attached to
1234
5 6
4
3
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Tro, Chemistry: A Molecular Approach 64
Name the Alkene4) 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 substituents2) repeat for other substituents3) number of first C in double bond name of main chain
3 ethyl 4 methyl 2 hexeneH 3 C CH C
H 2 C CH 3
CH CH 3
H 2 C CH 31234
5 6
4
3
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Name the Alkyne1) find the longest, continuous C chain that
contains the triple bond and use it to determinethe base name
since the longest chain with the triple bond has 7 Cthe base name is heptyne
CH3 CH2 CCH CH
CH3 CH3HC
CH3
C CH 3
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Name the Alkyne
2) identify the substituent branches
there are 2 substituents
one is a 1 C chain, called methylthe other one is called isopropyl
CH3 CH2 CCH CH
CH3 CH
3HC
CH3
C CH 3
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CH2 CCH CH
CH3 CH3HC
CH3
C CH 3CH3
Name the Alkyne
3) number the chain from the end closest to thetriple bondthen assign numbers to each substituent basedon the number of the main chain C its attached to
46
1234567
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Tro, Chemistry: A Molecular Approach 70
Name the Alkyne4) 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 substituents2) repeat for other substituents
3) number of first C in double bond name of main chain
4 isopropyl 6 methyl 2 heptyne
CH2 CCH CH
CH3 CH3HC
CH3
C CH3CH3
46
1234567
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Practice Name the Following
H3C C
CH 3
CH 2CH 3
C CH
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Free Rotation Around
C C
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Cis-Trans Isomerism
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Reactions of Hydrocarbons
all hydrocarbons undergo combustion combustion is always exothermic
about 90% of U.S. energy generated by combustion2 CH 3CH 2CH 2CH 3( g ) + 13 O 2( g ) 8 CO 2( g ) + 10 H 2O( g )
CH 3CH=CHCH 3( g ) + 6 O 2( g ) 4 CO 2( g ) + 4 H 2O( g )
2 CH 3C CCH 3( g ) + 11 O 2( g ) 8 CO 2( g ) + 6 H 2O( g )
Oth Alk R ti
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Other Alkane Reactions Substitution
replace H with a halogen atominitiated by addition of energy in the form ofheat or ultraviolet light
to start breaking bondsgenerally get multiple products with multiplesubstitutions
C CH H
H
HH
H
heat orUV light
H ClC CH Cl
H
HH
HCl Cl + H Cl+
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Other Alkene and Alkyne Reactions
Addition reactionsadding a molecule across the multiple bond Hydrogenation = adding H 2
converts unsaturated molecule to saturated
alkene or alkyne + H 2 alkane
Halogenation = adding X 2 Hydrohalogenation = adding HX
HX is polarwhen adding a polar reagent to a double or triplebond, the positive part attaches to the carbon withthe most Hs
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Addition Reactions
H
C C
H H
CH3
Cl2
C C
Cl
Cl
CH3
HH
H
+HC C
H H
CH3
C C
H
H
CH3
HH
H
+ H
2H
C C
H H
CH3
C C
H
Cl
CH3
HH
H
+ + H-Cl -
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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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Resonance Hybrid
the true structure of benzene is a resonancehybrid of two structures
Naming Monosubstituted
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Naming MonosubstitutedBenzene Derivatives
(name of substituent)benzenehalogen substituent = change ending to o
or name of a common derivative
F
fluorobenzene
CH 2CH 2CH 3
propylbenzene
CH 3 NH 2 OH HC CH 2
toluene aniline phenol styrene
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Naming Disubstituted
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Naming DisubstitutedBenzene Derivatives
alternatively, use relative position prefixortho- = 1,2; meta- = 1,3; para- = 1,4
CH 3
Cl
2-chlorotolueneortho -chlorotoluene
o-chlorotoluene
CH 3
Cl
CH 3
Cl
3-chlorotoluenemeta -chlorotoluene
m-chlorotoluene
4-chlorotoluene para -chlorotoluene
p-chlorotoluene
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Practice Name the Following
F
Cl
Br
Br
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Tro, Chemistry: A Molecular Approach 87
Practice Name the Following
F
Cl
Br
Br
1-chloro-4-fluorobenzene 1,3-dibromobenzeneor meta -dibromobenzene
or m-dibromobenzene
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Polycyclic Aromatic Hydrocarbons
contain multiple benzene rings fused togetherfusing = sharing a common bond
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Reactions of Aromatic Hydrocarbons
most commonly, aromatic hydrocarbonsundergo substitution reactions replacing Hwith another atom or group
Functional Groups
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Tro, Chemistry: A Molecular Approach 90
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 themolecule
generally, the reactions that a compound will perform aredetermined by what functional groups it hassince the kind of hydrocarbon chain is irrelevant to thereactions, it may be indicated by the general symbol R
CH 3 OHR group functional group
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91
Alcohols
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Tro, Chemistry: A Molecular Approach 92
Alcohols R-OH
ethanol = CH 3CH 2OHgrain alcohol = fermentation of sugarsalcoholic beverages
proof number = 2X percentage of alcoholgasohol
isopropyl alcohol = (CH 3)2CHOH2-propanolrubbing alcohol
poisonous
methanol = CH 3OHwood alcohol = thermolysis of wood paint solvent poisonous
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Ald h d Od d Fl
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96
Aldehyde Odors and Flavors
butanal = butter
vanillin = vanilla
benzaldehyde = almonds
cinnamaldehyde = cinnamon
O
HC CH 2CH 2CH 3
O
C
H
HC
O
C C
H
H
H
OO
HO
HO
Ketone Odors and Flavors
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97
Ketone Odors and Flavors acetophenone = pistachio
carvone = spearmint
ionone = raspberries
muscone = musk
OC
H3C
O CH 3
O
H3C
C
CH 3
CH 2
CH3
CH3H3C O
C CH 3CCH
H
R i
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Tro, Chemistry: A Molecular Approach 98
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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Tro, Chemistry: A Molecular Approach 99
Carbonyl Group
C=O group is highly polarmany reactions involve addition across C=O,
with positive part attached to O
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Addition to C=O
C b li A id
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Carboxylic Acids RCOOH sour tasting weak acids citric acid
found in citrus fruit
ethanoic acid = acetic acidvinegar
methanoic acid = formic acidinsect bites and stings
O
OHCH
O
OHCCH 3
OH
O
HO C C
CH2
C
C
O
O
OH
OH
CH2
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Tro, Chemistry: A Molecular Approach 102
Carboxylic Acids
made by the oxidation ofaldehydes and alcoholsOH on the end of the chain
always on main chainhas highest precedence
C of group always C1 position not indicated in name
change ending to oic acid
H3C CH 2
OH
H3C
O
C OHoxidation
ethanoic acidethanol
oxidation
O
CH
O
COH
benzaldehyde benzoic acid
Naming Carboxylic Acids
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Tro, Chemistry: A Molecular Approach 103
Naming Carboxylic Acids
Esters
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Tro, Chemistry: A Molecular Approach 104
Esters
R COO R sweet odor made by reacting carboxylic acid
with an alcoholR aCOOH + R bOH R aCOOR b + H 2O name alkyl group from alcohol, then
acid name with oate ending
precedence over carbonyls, but notcarboxylic acidnumber from end with ester group
O
COH
C CH 3
O
O
aspirin
methyl butanoate
Naming Esters
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Tro, Chemistry: A Molecular Approach 105
Naming Esters
Condensation Reactions
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Tro, Chemistry: A Molecular Approach 106
Condensation Reactions a condensation reaction is any organic reaction
driven by the removal of a small molecule, likewater esters are made by the condensation reaction
between a carboxylic acid and an alcohol the reaction is acid catalyzed
acid anhydrides are made by the condensation
reaction between 2 carboxylic acid molecules the reaction is driven by heat
R C
O
OH OH C
O
R' R C
O
O C
O
R'
+ + HOH
Synthesis of Aspirin
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Tro, Chemistry: A Molecular Approach 107
Synthesis of Aspirin(Acetylsalicylic Acid)
Ethers
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Tro, Chemistry: A Molecular Approach 108
Ethers R O R ether = diethyl ether = CH 3CH 2OCH 2CH 3
anesthetic
to name ethers, name each alkyl groupattached to the O, then add the word ether to the end
diethyl ether
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Amines
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Tro, Chemistry: A Molecular Approach 110
Amines many amines are biologically active
dopamine a neurotransmitterepinephrine an adrenal hormone
pyridoxine vitamin B 6
alkaloids are plant products that arealkaline and biologically active
toxicconiine from hemlockcocaine from coca leavesnicotine from tobacco leavesmescaline from peyote cactusmorphine from opium poppies
HO
HO
CH 2CH 2 NH 2
dopamine
N
N
CH 3
nicotine
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Tro, Chemistry: A Molecular Approach 111
Amine Reactions
weak basesreact with strong acids to form ammonium salts
RNH 2 + HCl RNH 3+Cl react with carboxylic acids in a condensation
reaction to form amides
RCOOH + HNHR RCONHR + H 2O
M l l
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Tro, Chemistry: A Molecular Approach 112
Macromolecules
polymers are very large molecules made byrepeated linking together of small molecules
monomers natural modified natural polymers synthetic
plastics, elastomers (rubber), fabrics, adhesives composites
additives such as graphite, glass, metallic flakes
Nat ral Pol mers
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Tro, Chemistry: A Molecular Approach 113
Natural Polymers
polysaccharidescellulose (cotton)starch
proteins nucleic acids (DNA) natural latex rubber, etc. shellac amber, lignin, pine rosin asphalt, tar
Modified Natural Polymers
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Tro, Chemistry: A Molecular Approach 114
Modified Natural Polymers
Cellulose AcetateRayonfilm
Vulcanized Rubber Gun Cotton Celluloid
ping-pong balls Gutta Percha
fill space for root canal Casein
buttons, mouldings, adhesives
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Addition Polymerization
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Tro, Chemistry: A Molecular Approach 117
Addition Polymerization
monomers add to the growing chain insuch a manner that all the atoms in theoriginal monomer wind up in the chain
no other side products formed, no atomseliminated
first monomer must open to startreaction
done with heat or addition of an initiator chain reactioneach added unit ready to add another
Addition Polymerization
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initiatorC C
H
H
H
ClCl
C CH
H H
H
Cl
C CH
H H
H
+ C C
H
H
H
ClCl
C CH
H H
H Cl
C C
H H
H
Cl
C CH
H H
H Cl
C C
H H
H
+ C C
H
H
H
Cl Cl
C CH
H H
H Cl
C C
H H
H Cl
C C
H H
H
initiatoretc.
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Tro, Chemistry: A Molecular Approach 119
Condensation Polymerization
monomer units are joined by removing smallmolecules from the combining units
polyesters, polyamides lose water no initiator needed chain reaction
each monomer has two reactive ends, so chaincan grow in two directions
Condensation Polymerization
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Tro, Chemistry: A Molecular Approach 120
+ +
+C C
O O
H O O H H O C H 2 C H 2 O H
H C C
O O
O O C H 2 C H 2 O H + H2O
Nylon
http://wps.prenhall.com/wps/media/objects/167/171580/SynthesisofNylon610.htmlhttp://wps.prenhall.com/wps/media/objects/167/171580/SynthesisofNylon610.html -
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Nylon polyamides
good physical propertiesaffected by moisture very good heat resistance excellent chemical resistance excellent wear resistance nylon 6,6 made by condensing
1,6 hexandiamine, H 2 N (CH 2)6 NH 2, withhexandioic acid, HOOC (CH
2)
4 COOH
( C H2 ) 6 N H C
O
( CH2 ) 4 C
O
H N
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