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Copyright 2011 Pearson Education, Inc.
Chapter 20Organic
Chemistry
Roy KennedyMassachusetts Bay Community College
Wellesley Hills, MA
Chemistry: A Molecular Approach, 2nd Ed.Nivaldo Tro
Copyright 2011 Pearson Education, Inc.
Odors• Our sense of smell helps us identify food, people, and
other organisms, and alerts us to dangers such as polluted air or spoiled food
• Odorants must be volatile
• However, many volatile substances have no scent at all
• Most common smells are caused by organic molecules
• The study of compounds containing carbon combined with one or more of the elements hydrogen, nitrogen, oxygen, and sulfur, including their properties and their reactions, is known as organic chemistry
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What Is Organic Chemistry?
• Organic chemistry is a branch of chemistry that focuses on compounds that contain carbonexcept CO, CO2, carbonates, and carbides
• Even though organic compounds only contain a few elements, the unique ways carbon atoms can attach together to form molecules leads to millions of different organic compounds
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The Chemistry of Life
• Life as we know it is because of organic chemistry
• Organic molecules can be very large and complex
• It is this complexity of large organic molecules that allows the complex functions of the cells to occur
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Differences Between Organic and Inorganic Compounds
• Organic compounds are easily decomposed into simpler substances by heating, but inorganic substances are not
• Inorganic compounds were readily synthesized in the lab, but synthesis of organic compounds in the lab is hard
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What’s Special About Organic Compounds?
• Organic compounds tend to be molecular• Mainly composed of just six nonmetallic elements
C, H, O, N, S, and P
• Compounds found in all three statessolids, liquids, and gasessolids tend to have low melting points
• Solubility in water varies depending on which of the other elements are attached to C and how many there areCH3OH is miscible with water; C10H21OH is insoluble
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What’s So Special About Carbon?
• Carbon atoms can do some unique things that other atoms cannot
• Carbon can bond to as many as four other atoms
• Bonds to carbon are very strong and nonreactive
• Carbon atoms can attach together in long chains
• Carbon atoms can attach together to form rings
• Carbon atoms can form single, double, or triple bonds
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Bond Energies and Reactivities
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Carbon Bonding
• Carbon forms four bonds
• When C has four single bonds, the shape is tetrahedral
• When C has one triple + one single or two double bonds, the shape is linear
• When C has two single + one double bond, the shape is trigonal planar
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linear, sp
all tetrahedral, sp3
Practice – Predict the shape and hybridization around each C aAtom
trigonal planar, sp2
CH3CN
CH3CH2CH3
H2CNH
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Hydrocarbons
• Hydrocarbons contain only C and H aliphatic or aromatic
• Insoluble in waterno polar bonds to attract water molecules
• Aliphatic hydrocarbons saturated or unsaturated aliphatics
saturated = alkanes, unsaturated = alkenes or alkynes may be chains or ringschains may be straight or branched
• Aromatic hydrocarbons
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Uses of Hydrocarbons
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Physical Properties of Aliphatic Hydrocarbons
• Boiling points and melting points increase as the size of the molecule increasesnonpolar moleculesmain attractive forces are dispersion forces
• Less dense than water
• Insoluble in water
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Saturated Hydrocarbons
• A saturated hydrocarbon has all C─C single bondsit is saturated with hydrogens
• Saturated aliphatic hydrocarbons are called alkanes
• Chain alkanes have the general formula CnH2n+2
• Ring alkanes have all C─C single bonds, but have fewer hydrogens than a chain with the same number of carbons
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Unsaturated Hydrocarbons
• Unsaturated hydrocarbons have one or more C=C double bonds or CC triple bonds
• Unsaturated aliphatic hydrocarbons that contain C=C are called alkenes the general formula of a monounsaturated chain alkene
is CnH2n
remove two more H for each additional double bond
• Unsaturated aliphatic hydrocarbons that contain CC are called alkynes the general formula of an alkyne with one triple bond is
CnH2n−2
remove four more H for each additional triple bond
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Aromatic Hydrocarbons
• Aromatic hydrocarbons contain a ring structure that seems to have C=C, but doesn’t behave that way
• The most prevalent example is benzene.C6H6
Other compounds have the benzene ring with other groups substituted for some of the Hydrogens
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alkanes
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Practice—Assuming only chains with a maximum of one unsaturation, decide if each of the following molecular formulas represents an
alkane, alkene, or alkyne
C14H28
C25H52
C12H22
Alkene
Alkane
Alkyne
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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 one identical group attached to same previous central atom unless () group listed first in which case
attached to next central atom
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Example – Write the structural and condensed formula for the n-Alkane C8H18
• Connect the C atoms in a rowCarbon backbone
• Add H to complete four bonds on each C.middle C gets 2 Hs end C gets 3 Hs
• The condensed formula has the H attached to each C written directly after it
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Example – Draw a complete structural formula for CH2CHCH2CH(CH3)CH2CH3
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start by writing the first C with its attached H’scontinue adding each successive C with its
attached H’s or branch chainsafter the entire chain is constructed, apply the rule
4 bonds per C to identify double or triple bonds
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Practice – Write a complete structural formula for the straight chain isomer of C7H16
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Practice – Draw a complete structural formula for CHCCH2C(CH3)2CH3
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Carbon Skeleton Formulas
• Each angle, and beginning and end, represent a C atom
• H omitted on Cincluded on functional groups
• Multiple bonds indicateddouble line is double bond, triple line is triple bond
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Practice – Draw a complete structural formula for each of the following
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Formulas
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Isomerism• Isomers are different molecules with the same molecular
formula• Structural isomers are isomers that have a different pattern of
atom attachmentaka Constitutional Isomers
• Stereoisomers are isomers with the same pattern of atom attachments, but the atoms have a different spatial orientation
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Structural Isomers of C4H10
Butane, BP = 0 °C Isobutane, BP = −12 °C
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Rotation about a Bond Is Not Isomerism
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Possible Structural Isomers
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Example 20.1: Write the structural formula and carbon skeleton formula for C6H14
start by connecting the carbons in a line
determine the C skeleton of the other isomers
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fill in the H to give each carbon four bonds
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Example 20.1: Write the structural formula and carbon skeleton formula for the 5 structural isomers of C6H14
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convert each to a carbon skeleton formula – each bend and the ends represent C atoms
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n-hexaneBP 69 ºC
2-methylpentaneBP 60 ºC
3-methylpentaneBP 63 ºC
2,2-dimethylbutaneBP 50 ºC
2,3-dimethylbutaneBP 58 ºC
Example 20.1: Write the structural formula and carbon skeleton formula for the 5 structural isomers of C6H14
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Practice – Draw the three structural isomers of pentane
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Stereoisomers
• Stereoisomers are different molecules whose atoms are connected in the same order, but with a different spatial direction
• Optical isomers are stereoisomers that are nonsuperimposable mirror images of each other
• Geometric isomers are stereoisomers that are not optical isomers
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Nonsuperimposable Mirror Images
the 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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Practice – Draw the mirror image of the molecule and decide if they are enantiomers
Enantiomers
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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• Enantiomers have all the same physical
properties except one – the direction they rotate the plane of plane-polarized lighteach one of the enantiomers will rotate the plane
the same amount, but in opposite directionsdextrorotatory = rotates the plane to the rightlevorotatory = rotates the plane to the left
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Mixtures of Enantiomers
• An equimolar mixture of a pair of enantiomers is called a racemic mixture
• Because half the molecules are rotating the plane to the left and the other half are rotating it to the right, the rotations cancel, and the racemic mixture does not rotate the plane
• If the mixture is non-racemic, the amount of rotation can be used to determine the percentages of each enantiomer in the mixture
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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 behaviorsenzyme 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 ringsCH3 groups at ends of chains, CH2 groups in the middle
• Saturated
• Branched or unbranched
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Physical Properties of n–Alkanes
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Alkane Boiling Points
• Branched chain alkanes have lower boiling points than straight chain alkanes
• Ring alkanes have higher boiling points than straight chain alkanes
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Naming• Each name consists of three parts
prefix indicates position, number, and type of branches indicates position, number, and type of each functional group
parentindicates the length of the longest carbon chain or ring
suffixindicates the type of hydrocarbon
o ane, ene, yne
certain functional groups
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Naming Alkanes
1. Find the longest continuous carbon chain2. 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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Prefixes
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Alkyl Groups
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More Alkyl Groups
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Examples of Naming Alkanes
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1. Find the longest continuous C chain and use it to determine the base name
Example – Name the alkane
because the longest chain has 5 Cthe base name is pentane
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2. Identify the substituent branches
Example – Name the alkane
there are 2 substituentsboth are 1 C chains, called methyl
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3. Number the chain and substituents
a) determine the end closest to a substituent branch if first substituents equidistant from end, go to next substituent in
b) then assign numbers to each substituent based on the number of the main chain C it is attached to
Example – Name the alkane
both substituents are equidistant from the end
1 2 3 4 5
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Example – Name the alkane4. Write the name in the following order
a) substituent number of first alphabetical substituent followed by dashb) substituent name of first alphabetical substituent followed by a dash
if it is the last substituent listed, no dash use prefixes to indicate multiple identical substituents
c) repeat for other substituents alphabeticallyd) name of main chain
2 4
2,4 – dimethylpentane
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Practice – Name the following
3-ethyl-2-methylpentane
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Practice – Draw and name all nine structural isomers of heptane
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Practice – Draw and name all ninestructural isomers of heptane
• The prefix hept- means 7, so the molecular formula is C7H16
• Start by drawing the carbon skeleton of the straight chain isomer
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Practice – Draw and name all nine structural isomers of heptane
• Take one C off the right end of the straight chain isomer and attach it to the second C in from the left end
• Then keep moving it down the chain, but not past the halfway point
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Practice – Draw and name all nine structural isomers of heptane
• Take one C off the right end of each one-branch chain isomer and attach it to the second C in from the left end
• Then keep moving it down the chainalways keep checking to ensure you do not duplicate
already have
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Practice – Draw and name all nine structural isomers of heptane
• Take one C chain off the right end of 2,2-branch isomer and attach it to the third C in from the left end
• Then keep moving it down the chain• Repeat with other two branch isomers if necessary
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Practice – Draw and name all nine structural isomers of heptane
• Take two C chain off the right end of straight chain isomer and attach it to the third C in from the left end
• Then keep moving it down the chain, but not beyond halfway
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Practice – Draw and name all nine structural isomers of heptane
• Continue the process until you’ve drawn all the isomers
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Practice – Draw and name all nine structural isomers of heptane
• Find the base name of each main chain
Heptane
Hexanes
Pentanes
Butane70Tro: Chemistry: A Molecular Approach, 2/e
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Practice – Draw and name all nine structural isomers of heptane
• Number the main chain from end closest to a substituent
1 2 3 4 5 6 7
1 2 3 4 5 6 1 2 3 4 5 6
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
1 2 3 4 51 2 3 4 5
1 2 3 4
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Hexanes
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Practice – Draw and name all nine structural isomers of heptane
• Name and number the alkyl groups
heptane
2-methylhexane 3-methylhexane
2,2-dimethylpentane 2,3-dimethylpentane 2,4-dimethylpentane
3,3-dimethylpentane3-ethylpentane
2,2,3-trimethylbutaneTro: Chemistry: A Molecular Approach, 2/e
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Practice – Draw and name all nine structural isomers of heptane
• Fill in the hydrogens so each C has four bonds
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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
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Practice – Draw the structural formula of 4-isopropyl-2-methylheptane
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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 Cflat
• Polyunsaturated = many double bonds
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Double Bonds• sp2, trigonal planar
shorter bond lengthsalkene angles a little larger than 120°
• No free rotation around double bond
• Composed of 1sigma and 1 pi () bond
• Not twice as strong as single bond, therefore less stable and more reactive
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Alkenes
ethene = ethylene propene = propylene
produced by ripening fruit
C CH
H H
HC C
H
H CH3
H
used to make polyethylene used to make polypropylene
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Physical Properties of Alkenes
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Physical Properties of Alkenes• pi bond electrons not held as tight as sigma,
therefore alkenes are more polarizable than alkanes
• cis generally more polar than trans
• trans lower boiling point
• more carbon groups attached to the double bond = higher boiling pointfor equal numbers of C
• densities similar to alkanes
• trans higher melting point than cismolecules are more symmetrical and pack better
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Alkynes• Also known as acetylenes
• Aliphatic, unsaturated
• CC triple bond
• Formula for one triple bond = CnH2n−2
subtract 4 H from alkane for each triple bond
• Linear shape
• Internal alkynes have both triple bond carbons attached to C
• Terminal alkynes have one carbon attached to H
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Triple Bonds
• sp hybrid50% “s” character
• Linear, 180°
• Composed of 2 pi bonds and 1 sigma
• Shorter than C–C and C=C
• Stronger than C–C, but not 3x as strongCC = 836 kJ/mol, C–C = 368 kJ/mol
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Alkynes
both used in welding torches
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Physical Properties of Alkynes
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Physical Properties of Alkynes
• Higher boiling points than similar sized alkenessimilar size = same number of carbonsmore pi bond = more polarization = higher boiling
point
• Slightly higher densities than similar alkenes
• There are no alkyne cis or trans isomers
• Internal alkynes have higher boiling points than terminal alkyneswith the same number of C
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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
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Examples of Naming Alkynes
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Name the Alkene1. Find the longest, continuous C chain that
contains the double bond and use it to determine the base name
Because the longest chain with the double bond has6 C the base name is hexene
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2. Identify the substituent branches
Name the Alkene
there are 2 substituentsone is a 1 C chain, called methyl
the other one is a 2 C chain, called ethyl
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b) then assign numbers to each substituent based on the number of the main chain C it is attached to
Name the Alkene
1234
5 6
4
3
93
3. number the chain and substituents
a) determine the end closest to the double bond if double bond equidistant from both ends, number
from end closest to the substituents
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Name the Alkene4. Write the name in the following order
a. substituent number of first alphabetical substituent – substituent name of first alphabetical substituent – use prefixes to indicate multiple identical
substituentsb. repeat for other substituentsc. number of first C in double bond – name of main chain
3–ethyl–4–methyl–2–hexene
94
1234
5 6
4
3
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Practice – Name the following
3,4-dimethyl-3-hexene
12
3 4 5 6
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Name the Alkyne1. Find the longest, continuous C chain that
contains the triple bond and use it to determine the base name
Because the longest chain with the triple bond has 7 C the base name is heptyne
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2. Identify the substituent branches
Name the Alkyne
there are 2 substituentsone is a 1 C chain, called methylthe other one is called isopropyl
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Name the Alkyne
98
46
1234567
3. number the chain and substituents
a. determine the end closest to the triple bond if triple bond equidistant from both ends, number
from end closest to the substituents
b. then assign numbers to each substituent based on the number of the main chain C it is attached to
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Name the Alkyne4. write the name in the following order
a) substituent number of first alphabetical substituent – substituent name of first alphabetical substituent – use prefixes to indicate multiple identical
substituentsb) repeat for other substituentsc) number of first C in triple bond – name of main chain
4–isopropyl–6–methyl–2–heptyne46
1234567
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Practice – Name the Following
3,3-dimethyl-1-pentyne
123
4 5
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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 bondstereoisomers
• This is often called cis–trans isomerism
• When groups on the doubly bonded carbons are cis, they are on the same side of the double bond
• When groups on the doubly bonded carbons are trans, they are on opposite sides
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Cis–Trans Isomerism
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Free Rotation Around C─C:No Cis–Trans Isomerism
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No Free Rotation C=C:Cis-Trans Isomerism
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Cis-Trans Isomerism
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The cis and trans isomers are different molecules with different properties.
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Reactions of Hydrocarbons
• All hydrocarbons undergo combustion
• Combustion is always exothermicabout 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 CH3CCCH3(g) + 11 O2(g) → 8 CO2(g) + 6 H2O(g)
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Chemical Energy• Burning hydrocarbons releases heat and light
energyCombustion
• Alkane + oxygen carbon dioxide + water• Larger alkane, more heat released
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Other Alkane Reactions
• Substitutionreplace H with a halogen atominitiated by addition of energy in the form of
heat or ultraviolet light to start breaking bonds
generally get multiple products with multiple substitutions
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Predict the Products and Balance the Equations
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Other Alkene and Alkyne Reactions:Addition
• Adding a molecule across the multiple bond
• Hydrogenation = adding H2
converts unsaturated molecule to saturatedalkene or alkyne + H2 → alkane
generally requires a catalyst
• Halogenation = adding X2
• Hydrohalogenation = adding HXHX is polarwhen adding a polar reagent to a double or
triple bond, the positive part attaches to the carbon with the most H’s
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Addition Reactions
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Practice — Predict the products
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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 resonance hybrid of two structures
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Naming Monosubstituted Benzene Derivatives
• (name of substituent)benzenehalogen substituent = change ending to “o”
• or name of a common derivative
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Naming Benzene as a Substituent
• When the benzene ring is not the base name, it is called a phenyl group
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Naming Disubstituted Benzene Derivatives
• Number the ring starting at attachment for first substituent, then move toward secondorder substituents alphabeticallyuse “di” if both substituents are the same
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Naming Disubstituted Benzene Derivatives
• Alternatively, use relative position prefixortho- = 1,2; meta- = 1,3; para- = 1,4
2-chlorotolueneortho-chlorotoluene
o-chlorotoluene
3-chlorotoluenemeta-chlorotoluene
m-chlorotoluene
4-chlorotoluenepara-chlorotoluene
p-chlorotoluene
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Practice – Name the Following
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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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 moleculegenerally, the reactions that a compound will perform are
determined by what functional groups it hasbecause the kind of hydrocarbon chain is irrelevant to the
reactions, it may be indicated by the general symbol R
CH3—OHR group functional group
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Alcohols• R—OH• Ethanol = CH3CH2OH
grain alcohol = fermentation of sugars in grains
alcoholic beveragesproof number = 2x percentage of alcohol
gasohol• Isopropyl alcohol = (CH3)2CHOH
2-propanol rubbing alcoholpoisonous
• Methanol = CH3OHwood alcohol = thermolysis of woodpaint solventpoisonous
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Naming Alcohols• Main chain contains 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 higher precedence group
present
1 2 3 4 5 6
4-ethyl-4-methyl-3-hex-5-enol
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Practice – Name the following
126
3-ethyl-1-hexanol
1 2 3
4 5 6
12345
1-pent-4ynol
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Reactions of Alcohols
127
Nucleophilic substitutionCH3─OH + HCl CH3Cl + H2O
Acid catalyzed elimination (dehydration)
CH3─ CH2OH CH2═CH2 + H2OH2SO4
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Reactions of Alcohols
128
Oxidation
CH3CH2OH CH3CHO CH3COOH −2 H −2 H
a common oxidizing agent is Na2Cr2O7
Alcohols with very active metals
2 CH3─OH + 2 K 2 CH3O−K+ + H2
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Practice − Complete each reaction
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Practice − Complete each reaction
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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=Opungent gas formalin = a preservativewood smoke, carcinogenic
• Acetone = CH3C(=O)CH3
nail-polish remover
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Aldehyde Odors and Flavors
132
• butanal = butter
• vanillin = vanilla
• benzaldehyde = almonds
• cinnamaldehyde = cinnamon
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• acetophenone = pistachio
• carvone = spearmint
• ionone = raspberries
• muscone = musk
Ketone Odors and Flavors
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Naming Aldehydes and Ketones• Main chain contains C=O
unless COOH present
• Number main chain from end closest to C=O
• For aldehydes, give base name al ending always on C1
• For ketones, give base name one ending and place number of C on chain where C=O attached in front
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Practice – Name the following
135
4-methyl-3-hexenal
12345
12
34 5
5-hydroxy-3-isopropyl-4-methyl-2-hexanone
6
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Reactions• Aldehydes and ketones are generally
synthesized by the oxidation of alcohols
• Therefore, reduction of an aldehyde or ketone results in an alcohol
• Common reducing agents are H2 with a Ni catalyst, NaBH4, and LiAlH4
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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
138
polar molecules add across the C=O, with the positive part attaching to O
−
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Practice − Complete each reaction
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Carboxylic Acids
140
• RCOOH• Sour tasting• Weak acids• Citric acid
found in citrus fruit
• Ethanoic acid = acetic acidvinegar
• Methanoic acid = formic acidinsect bites and stings
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Synthesis of Carboxylic Acids
• Made by the oxidation of aldehydes and alcohols
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Naming Carboxylic Acids
• Carboxylic acid group always on end of main chainhas highest naming precedence of functional groups
• C of group always C1position not indicated in name
• Change ending to oic acid
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Examples of Naming Carboxylic Acids
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Practice – Name the following
144
hexanoic acid(aka caproic acid, which
causes foot odor)
2-hydroxy-3-methylbutanoic acid
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Esters
• R–COO–R
• Sweet odor
• Made by reacting carboxylic acid with an alcohol
RaCOOH + RbOH RaCOORb + H2O
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Naming Esters
• Carboxylic acid group always on end of main chainunless carboxylic acid group present
• C of ester group on C1position not indicated in name
• Begin name with alkyl group attached to O
• Name main chain with oate ending
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Naming Esters
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Practice – Name the following
148
isopropyl butanoate
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• 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
Condensation Reactions• A condensation reaction is any organic reaction
driven by the removal of a small molecule, such as water
149
• Esters are made by the condensation reaction between a carboxylic acid and an alcohol
the reaction is acid catalyzed
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Synthesis of Aspirin(Acetylsalicylic Acid)
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Practice – Complete the reaction
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Ethers
152
• R–O–R
• Ether = diethyl ether = CH3CH2OCH2CH3
anesthetic
• Polar molecules
• Used for solvents
• To name ethers, name each alkyl group attached to the O, then add the word ether to the end
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Practice – Name the following
153
isopropyl methyl ether
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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
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Practice – Name the following
155
isopropyl methyl amine
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Amines• Many amines are biologically active
dopamine – a neurotransmitterepinephrine – an adrenal hormonepyridoxine – vitamin B6
• Alkaloids are plant products that are alkaline and biologically active toxicconiine from hemlockcocaine from coca leavesnicotine from tobacco leavesmescaline from peyote cactusmorphine from opium poppies
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Amine Reactions
• Weak basesreact with strong acids to form ammonium salts
RNH2 + HCl → RNH3+Cl−
• React with carboxylic acids in a condensation reaction to form amides
RCOOH + H—NHR’ RCONHR’ + H2O
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Practice – Complete the reaction
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Polymers
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Macromolecules• Polymers are very large molecules made by repeated
linking together of small molecules monomers
• Natural polymers are polymers found in both the living and nonliving environment
• Modified natural polymers are natural polymers that have been chemically altered
• Synthetic polymers are polymers made in a lab from one, two, or three small molecules linked in a repeating pattern plastics, elastomers (rubber), fabrics, adhesives
• Composites are materials made of polymers mixed with various additives additives such as graphite, glass, metallic flakes
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Natural Polymers• Polysaccharides – polymers made of repeating small sugar
molecule units cellulose (cotton) starch
• Proteins – polymers made of repeating amino acid units• Nucleic acids (DNA) – polymers made of repeating nucleotide units
• Natural latex rubber – polyisoprene• Shellac – a resin secreted by lac bugs• Gutta-percha – a polyisoprene latex from the sap of the gutta-
percha plant used to fill space for root canal
• Amber, lignin, pine rosin – resins from trees• Asphalt – polymeric petroleum
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Modified Natural Polymers
• Cellulose acetate – an ester of cellulose and acetic acid rayon film
• Vulcanized rubber – latex rubber hardened by cross-linking with sulfur
• Nitrocellulose – an ester of cellulose with nitric acid gun cotton celluloid
ping-pong balls
• Casein – a polymer of the protein casein made by treating cow’s milk with acid buttons, mouldings, adhesives
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Polymerization
• Polymerization is the process of linking the monomer units together
• There are two processes by which polymerization may proceed – addition polymerization and condensation polymerization
• Monomer units may link head-to-tail, or head-to-head, or tail-to-tail during polymerizationhead-to-tail most common regular pattern gives stronger attractions between
chains than random arrangements
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Addition Polymerization
• Monomers add to the growing chain in such a manner that all the atoms in the original monomer wind up in the chainno other side products formed, no atoms
eliminated
• First monomer must “open” to start reactiondone with heat, or the addition of an initiator
• The process is a chain reactioneach added unit ready to add another
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Addition Polymerization of Vinyl Chloride
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Condensation Polymerization
• Monomer units are joined by removing small molecules from the combining unitspolyesters, polyamides lose water
• No initiator needed
• The process is a chain reaction
• Each monomer has two reactive ends, so chain can grow in two directions
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Condensation Polymerization
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Plastics• Plastics are polymer materials capable of being
molded or shaped.Round, hard balls; thin, flexible threads; intricate
molds; or flat sheets.• Plastics have molar mass from 10,000 to
1,000,000 amu• Many plastics are in the “glass” or amorphous
solid statesolid that has semi-fluid characteristicsglass transition temperature is where an
amorphous polymer is converted between rubbery and glassy states
plastics do not melt like an ice cube, they rubberize
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Characteristics of Plastics• Transparent or translucent• Chemical resistance• Thermal and electrical insulators• Low density• Varying strengths
Kevlar• Mold or extrude• Elasticity
regain original shape if quick stress applied• Foamed• Tend to soften when heated
rather than quickly melt
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Synthetic PolymersPolyethylene
HDPELDPE
Polypropylene
Polyvinyl chloride
PolyamidesnylonKevlar
Polyesterspolyethylene terephthalate
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Polyethylene Terephthalate (PET)
• Condensation copolymer of ethylene glycol + terephthalic acidA polyester
• Transparent
• High-impact strength
• Nonreactive with acid and atmospheric gases
• Doesn’t stretch
• Used for soda bottles, Dacron, Mylar
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High Density Polyethylene (HDPE)• Addition polymer with linear chains• Opaque• Denser than LDPE• Mechanically stronger than LDPE• More rigid than LDPE
more crystalline• Higher heat resistance than LDPE• Nonreactive to acids and bases• Absorbs oils and softens• Oxidizes on exposure to air and sunlight• Subject to cracking• Used for containers, caps, bullet-proof vests,
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Poly Vinyl Chloride (PVC)
• Addition polymer• Transparent to opaque• Flame resistant• Low heat resistance• Good chemical resistance• High-impact strength• Quite rigid• Many additives used to modify properties
plasticizer adds flexibility• Used in food wrap, pipes, flooring and wall
covering, toys, hoses, auto trim, squeeze tubes, and appliance housings
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Low Density Polyethylene (LDPE)
• Addition polymer with branched chains
• Lower density, strength, heat resistance (100–125 °C), and rigidity than HDPE
• Used in food, trash, and grocery bags as well as in electrical wire insulation
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Polypropylene (PP)• Addition polymer
• Opaque
• High stretching strength
• High heat resistance (170 °C)
• Excellent chemical resistance
• Flexed almost indefinitely without tearing
• Smooth surface with high luster
• Used in carpets and upholstery; chemical resistant pipes, containers, and tanks; margarine tubs; and medicine bottles
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6Polystyrene (PS)
• Addition polymer
• Low-impact resistance
• Fair strength and stiffness
• Poor chemical resistance
• Transparent, glassy, sparkling clarity
• Moderate heat resistance (90 °C)
• Used in model cars, computer housing, Styrofoam, clear drinking cups, and hard-molded parts
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Acrylics
• Polymethylmethacrylate, PMMA• Low-impact resistance• Good strength and stiffness• Excellent transparency• Excellent scratch resistance• Moderate heat resistance• Addition polymer of methyl methacrylate• Uses include Plexiglas, Lucite, lighting fixtures,
lenses, fiber optic filament, appliance faceplates, decorative signs, and paints
• Also, reduces oil viscosity
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Polycarbonates (PC)• Excellent physical properties
• Excellent toughness
• Very good heat resistance
• Fair chemical resistance
• Transparent
• Condensation copolymer of Bisphenol A and phosgene
• Lexan, Calibre , Makrolon , Panlite
• Used in equipment housings, exterior auto parts, outdoor light fixtures, non-auto vehicle windows, structural parts, medical supply parts, scratch-resistant coatings, eye wear, bullet-proof glass, and DVDs
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Nylon• Condensation copolymer of a diamine with a diacid
polyamidesnylon 6,6
made by condensing 1,6–hexandiamine, H2N–(CH2)6–NH2, with hexandioic acid, HOOC–(CH2)4–COOH
• Good physical propertiesaffected by moisture
• Very good heat resistance• Excellent chemical resistance• Excellent wear resistance
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