chapter 23: organic chemistry, polymers, and biochemicals chemistry: the molecular nature of matter,...
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Chapter 23: Organic Chemistry,
Polymers, and Biochemicals
Chemistry: The Molecular Nature of Matter, 6E
Jespersen/Brady/Hyslop1
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Carbon ChemistryBonding
Strong covalent bonding to itself and to other non-metal elements
Capable of forming extremely long carbon-carbon chains
Multiple arrangements of
identical molecular formulas
lead to numerous isomers.
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Structural Formula RepresentationsLewis Structure of Pentane
Condensed Structural Formula CH3CH2CH2CH2CH3 pentane
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Structural Formula Representations Lewis Structure of Pentan-1-ol
Condensed Structural FormulaCH3CH2CH2CH2CH2OH 1-pentanol
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Chiral Isomers of CarbonChirality exists when carbon has four unique constituents bond to itself
|||||
Non-superimposable mirror images
C
H
CH3
Cl
Br C
H
Br
Cl
H3C
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Chiral Isomers of Butan-2-ol
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Abbreviated or Bond-Line Structure
Carbon atoms occur at intersection but no symbol used
CH3–CH2–CH3 would appear as:
Non-carbon atoms would appear as symbols
CH3–CH2–CH2–OH would appear as:
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Abbreviated or Bond-Line Structure
Open-Chain CompoundsExamples
butane-1-ol
butane
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
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Abbreviated or Bond-Line Structure of Ring Compounds
Benzene
Chair Form of CylcohexaneCyclohexane
Cyclopropane
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Abbreviated or Bond-Line Structure Heterocyclic Compounds
Piperazine Pyridine Pyrazole
Tetrahydropyran Furan
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning Check1. Draw at least two geometric isomers of
C4H10 using abbreviated structures.
1. Draw the four carbon chain first2. Now rearrange CH3 groups
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!When a chemical formula is written in the following form, CH3CH2CH2COOH, the representation is known as
A. an abbreviated structure
B. a Lewis dot structure
C. a condensed formula
D. an optical isomer
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Functional Groups in Organic Organic families can be defined by
functional groups. Frequently use “R” as a place holder for
alkane-like hydrocarbon groups
R–OH alcohol
R–COOH organic acid
R–O–R’ ether
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Functional Groups in Organic
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning Check
1. Write the abbreviated structure for benzoic acid.
2. What family does C6H5NH2 belong to?
1. 2. amine family
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!Which of the following is an example of an ester?
A.CH3CH2CH2OH
B.
C.
D.16
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Hydrocarbons Hydrocarbon compounds only contain C and
H
Alkanes CnH2n+2 CH3CH2CH3 propane
Alkenes CnH2n CH3CHCH2 propene
Alkynes CnH2n-2 CH3CCH propyne
Aromatic C6H6 benzene Characterized by cyclic delocalized π bonding
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Hydrocarbons Alkanes are defined as saturated
compounds. All singles bond to carbon Cannot add more hydrogen atoms
Alkenes and alkynes are unsaturated compounds. Alkenes have double bonds and H atoms
can be added to the double bond to create a saturated compound.
Alkynes have triple bonds and H atoms can be added to create a saturated compound.
CH2=CHCH3 + H2 CH3CH2CH318
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Aromaticity- Characterized by conjugated bonds in a ring
such as benzene.
- π electrons are delocalized over the ring
- Leads to greater stability than expected
- Properties are different than those of other hydrocarbon families
- Polycyclic examples:
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napthalene anthracene
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Hydrocarbon NomenclatureRules for naming alkanes
Established by IUPAC
1. Name ends in “-ane”2. Complete name uses that of parent compound with constituent groups added.
3. Parent is longest continuous carbon chain.
4. Name of longest chain based on the number of carbons.
5. Carbon atoms are numbered starting at the end that gives the lowest number for the
first branch.20
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Straight Chained Alkanes
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Alkyl GroupsAlkane type groups added to parent chain are known as alkyl groups. Consist of alkane, minus one H atom. Name always ends in –yl
Example
CH4 : now remove one H which yields –CH3
Naming of –CH3
Start with parent name, which is methane
Drop –ane and add –yl So methane becomes methyl group
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Alkyl Groups CH3CH2CH3 yields –CH2CH2CH3 when one H
atom is removed from the end carbon. The name of the aryl group is propyl. Note, you can have another isomer of propyl.
The other isomer’s aryl group is 1-methylethyl, or isopropyl, and is created when the H atom is removed from the non-terminal carbon.
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Nomenclature6. Aryl groups names are prefixed to parent name.
7. Multiple aryl groups on a parent are numbered and named alphabetically.
8. When there are multiple identical groups add di, tri, tetra to the aryl name.
9. If multiple, identical aryl groups are attached to the same carbon repeat the carbon number.
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
ExamplesWhat is the name of the compound
shown?
1. The longest carbon chain (parent) is four. Parent name is butane.
2. Start numbering from the left to get the smallest number for the attached group.
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Examples3. The attached alkyl group is a methyl
group. Thus, the correct name is:
2-methylbutane
What is the name of the following compound?
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Examples The parent chain contains five carbons. Thus, the parent name is pentane. Number from the left to obtain the smallest
number for the first alkyl group.
The alkyl groups are at the 2 and 3 positions. The 2 and 3 positions each contain a methyl
group.27
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Examples Thus, the correct name is: 2,3-dimethylpentane
Let’s consider an alkane with two substituents on the same carbon.
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Examples The parent chain is six carbons long. The lowest correct numbering of positions
is shown below.
There are methyl and ethyl groups attached to carbon 3.
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Examples The correct name is:
3-ethyl-3-methylhexane
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!What is the correct name for the molecule
shown
below?
A. 3-butylpentane
B. 1,1-diethylpentane
C. 3-ethylheptane
D. 5-ethylheptane
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!What is the name of the compound shown
below?
A. 3-methyl-3-methyloctane
B. 3,3-dimethyloctane
C. 2-ethyl-2-methylheptane
D. 6,6-dimethyloctane
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Chemical Properties of Alkanes Alkanes are relatively unreactive
Not reactive in conc. NaOH or H2SO4 at room temperature.
React with hot HNO3
Will react with Cl2 and Br2 to form halogenated hydrocarbons.
Examples are CH3Cl, CH2Cl2 and CHCl3
Can crack molecules like ethane under controlled conditions to form CH2CH2
Will react with O2 to form CO2, CO, and H2O33
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Alkenes and Alkynes Alkenes contain one or more double bonds
General form: CnH2n
Alkynes contain one or more triple bonds General form: CnH2n-2
Non-polar compounds are not water soluble
Examples:
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Ethene or ethylene Ethyne or acetylene
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Alkenes and Alkynes Nomenclature
The parent chain must contain the multiple bond even if it is a smaller chain length than one without a multiple bond
Number from end that gives the lowest number to the first carbon of the multiple bond
The number is given as -x- and placed just before the –ene or –yne of the parent name.
For example, but-2-ene. The double bond starts on carbon 2 of the chain.
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Alkene Examples
Start numbering from the left to get the lowest number for the first carbon with the double bond
The parent is heptene and the correct naming including the double bond location would be hep-2-ene
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Alkene Example
The parent chain is four carbons 2,3-dimethylbut-2-ene
We would not name this 2-methyl-3-methylbut-2-ene
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Naming Polyenes How do we name compounds such as the
following?
This compound contains two double bonds and is known as a diene
We want the lowest number for the first carbon of each of the double bonds
Start numbering from the right
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Naming Polyenes The correct name would be hex-1,3-diene
Three double bonds would be a triene
hex-1,3,5-triene
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Cyclic Alkenes
Number ring to obtain lowest number for first carbon of the double bond
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Cyclic Alkenes Correct name is 1,6-dimethylcyclohex-1-
ene
Other ring examples
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Cyclopentene Cyclooctene
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!What is the correct name for the compound
shown
below?
A. 1,4-dimethylcyclopent-1-ene
B. 1,3-dimethylcyclopent-1-ene
C. 1-methyl-4-methylcyclopent-1-ene
D. 1,3-dimethylcyclo-1-pentene
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!What is the correct structure for 3,3-dimethylpro-
1-ene?
A.
B.
C.
D.
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Geometric Isomers Groups cannot freely rotate about a double
bond Therefore, it is possible to have geometric
isomers
Examples:
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trans-1,2-dibromoethene
cis-1,2-dibromoethene
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Reactions of Alkene Alkenes readily add across the double
bond Examples of an addition reaction:
CH2CH2 + H2 CH3CH3 hydrogenation
CH2CH2 + HCl → CH3CH2Cl
CH2CH2 + H2O → CH3CH2OH
CH2CH2 + Cl2 → CH2ClCH2Cl
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Aromatic Hydrocarbons The most common aromatic compound is
benzene and its derivatives Representation of bonding
Delocalized π bonds create unique stability, called resonance stabilization. The circle in the ring represents delocalization.
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Reactions Substitution reactions maintain benzene’s
resonance structure. Addition reactions, like those of alkenes,
destroy resonance structure
Substitution reaction:
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Addition Reaction
Notice that you have reduced the double bonding in the ring and altered the resonance stabilization of the ring
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning Check:What product would form if benzene
reacted with
nitric acid using an appropriate catalyst?
Sulfuric acid is the catalyst A substitution reaction occurs
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Which product is most likely formed when sulfuric
acid reacts with benzene?
A. B.
C. D.
Your Turn!
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Organic Compounds Containing OxygenImportant functional groups:
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Alcohol Ether Aldehyde
Ketone Carboxylic acid Ester
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Alcohols and Ethers Common alcohols: names end in –ol
CH3OH methanol
CH3CH2OH ethanol
CH3CH2CH2OH propan-1-ol If the –OH group was attached to the central
carbon then the alcohol would be propan-2-ol
Alcohols form hydrogen bonds, causing their boiling points to be higher than predicted.
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Alcohols and Ethers Primary alcohols:
Secondary alcohols:
Tertiary alcohols:
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Alcohols and Ethers Common ethers:
CH3OCH3 dimethyl ether
CH3CH2OCH2CH3 diethyl ether
CH3OCH2CH3 methyl ethyl ether
No hydrogen bonding occurs, thus, boiling points are lower than corresponding alcohols
Like alkanes, ethers are not very reactive
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Reactions of Alcohols Alcohols can undergo oxidation to form a
variety of products. Oxidation removes an H atom from the alcoholic carbon as well as the H on the –OH group.
Primary alcohols can be oxidized to aldehydes and carboxylic acids
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Reactions of Alcohols Aldehydes are more readily oxidized than
alcohols
Secondary alcohols can be oxidized to ketones
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Reactions of Alcohols Ketones are not further oxidized Tertiary alcohols have no H atom on the
alcoholic carbon and thus, do not undergo oxidation
Alcohols undergo elimination reactions in the presence of concentrated H2SO4 forming water and alkenes
–OH group readily accepts a proton from sulfuric acid
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Elimination Reaction Dehydration of an alcohol
During the reaction a very unstable carbocation is formed. This ion eliminates a proton to form the alkene.
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Substitution Reactions of Alcohols Using heat and concentrated HBr, HI, or
HCl, a halogen will replace the –OH group
A proton adds to the –OH forming –OH2+
Water leaves and the halogen ion attaches to the carbon site where the –OH was attached
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2-bromo-2-methylpropane
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Aldehydes and Ketones
Naming aldehydes Parent name ends in –al, replacing –e in the
alkane name The aldehyde group is always at the end of a
chain and numbering starts with that end of the chain
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Aldehyde group Keto group
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Naming Aldehydes
Number from the aldehyde end Do not use -1- for aldehyde: 3-methylpropan-1-al, or 3-methyl-1-
propanal would be wrong
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3-methylpentanal
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning CheckWhat is the name of the following
aldehyde?
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4-ethylhexanal
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Naming Ketones Parent name ends in –one Parent chain must contain carbonyl group Numbering so carbonyl carbon has lowest
possible number
4-ethylheptan-3-one
NOT: 4-ethylheptan-5-one63
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!What is the correct name for the aldehyde
shown
below?
A. 2,4-dimethylpentanal
B. 2,4-dimethyl-1-pentanal
C. 2-methyl-4-methylpropanal
D. 2,4-dimethyl-5-pentanal64
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn! - Solution Aldehydes are numbered from the
aldehyde end of the molecule
There are two identical groups, (methyl) so we use –di in the naming
2,4-dimethylpentanal
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!What is the correct name for the ketone
shown
below?
A. 4-methyl-3-ethylhexan-2-one
B. 4-ethyl-3-methylhexan-5-one
C. 3-ethyl-4-methylhexan-2-one
D. 3,4-diethylpentan-2-one66
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn! - Solution Number to give lowest number to keto
group so you start from the right
Alkyl groups are ordered alphabetically so ethyl comes before methyl
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Reactions of Aldehydes and Ketones Aldehydes and ketones add hydrogen
across the C=O bond Process is hydrogenation or reduction
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Carboxylic Acids and Esters
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Naming Carboxlic Acids Name ends in –oic, replacing –e in the
parent name Numbering begins with carboxyl group –COOH or –CO2H is the condensed form
CH3COOH is ethanoic acid (acetic acid)
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Naming Carboxylic Acids Benzoic acid
Propanoic acid
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Naming Esters Name begins with alkyl group attached to
the –O Name of parent acid is separate from the
alkyl group name and –oic is replaced with –ate
Ethyl propanate72
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Learning Check What is the name of the following ester?
Alkyl group is propyl Number, starting with
the ester carbon Propyl 4-methylpentanate
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!What is the correct name for the product
when 3-
methylbutan-1-ol is completely oxidized?
A. 3-methylbutanoic acid
B. 2-methyl-1-butanoic acid
C. 2-methlybutan-1-oic acid
D. 3-methylbutan-1-oic acid
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Reactions of Carboxylic Acids The –COOH is weakly acidic and therefore
reacts with base
RCOOH + OH– → RCOO– + H2O
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Formation of Esters Esters give fruits their characteristic odor
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Saponification Strong base reacts with an ester to form
alcohol and the ester’s anion forms
pentanoate ion
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!Name the ester formed when methanol
reacts with
hexanoic acid.
A. 1-methyl hexanoate
B. methylhexanoate
C. methyl hexanoate
D. methyl hexan-1-oate
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Organic Derivatives of Ammonia Amines are derived from ammonia with
one or more H atoms replaced with organic groups
Like ammonia, amines are weakly basic
Amines react with acids
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Acid Property of Protonated Amines Ethylmethylammonium ion is the
conjugate acid of ethylmethylamine
pKa = 10.76 pKb= 3.24
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Amides General form
Where (H)R indicates either an H atom or an R group attached
Naming The name of the parent acid is amended
dropping the –oic ending and replacing it with –amide
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Example Names of Amides Propanamide
4-ethylhexamide
These are examples
of simple amides
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Synthesis of Simple Amides An organic acid reacts with aqueous NH3 to
form an amide
2-methylpropanoic acid yields 2-methylpropanamide
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Amide Reactions Amides can be hydrolyzed back to their
acid form producing ammonia in the process
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Amide Reactions Urea, an amide, ultimately hydrolyzes to
NH3, CO2 and water
Carbonic acid is formed, which then decomposes to carbon dioxide and water
The overall reaction is:
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Basicity of Amides Amides are not basic like amines The lone pair on the N atom is delocalized
and thus not readily available for donation to a proton
Amides are neutral in an acid-base sense
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Your Turn!What is the correct name for the molecule
shown
below?
A. 4,5-dimethylhexanamide
B. 2,3-dimethyl-6-hexanamide
C. 4-methyl-5-methylhexanamide
D. 4-isopropyl-4-methylpropanamide87
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Organic Polymers Macromolecule made up of small,
repeating units Example, polypropylene
Starting material
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Polymers Repeating unit is called a monomer The reaction to create a polymer is known
as polymerization
Chain Growth Polymers Polymers created by the addition of one
monomer to another monomer Polypropylene is an example of a chain
growth polymer
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Common Polymers
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
General Repeat Unit for Polyvinyl Chloride
This unit is repeated n times to create the polymer
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Step-Growth Polymers Condensation reaction A small molecule such as water is eliminated
when the monomers are joined: Nylon 6,6, for example
Nylon is a copolymer, two different molecules combined
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Dacron-A Polyester Another example of a condensation
copolymer
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Physical Properties Dependent on how polymers pack Branching polymers create non-crystalline,
amorphous solids
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Physical Properties Amorphous polymer of polyethylene is
known as low density polyethelene or LDPE Low molecular mass and low structural
strength Used to make plastic grocery bags
Non-branching polyethylene forms high density polyethylene or HDPE
Strong London forces between chains Strong fibers are formed
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Physical Properties HDPE is lightweight, water repellent,
resists tears Common uses
Strong mailing envelopes Tyvek
Ultrahigh molecular weight polyethlene 3 to 6 million molar mass UHMWPE Used to make very strong polymers Sails, bullet proof vests, bike helmets
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Biochemical molecules Carbohydrates
Structures of glucose, a monosaccharide
Building unit for cellulose and starch
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Disaccharide Sucrose
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Disaccharide Reactions Disaccharide molecules split into
monosaccharides Gal-O-Glu + H2O → galactose + glucose
Polysaccharides Starch is a large polymeric sugar molecule Can be broken down into glucose, which is
used for energy in biochemical reactions Amylose is the structurally simpler glucose
polymer portion of starch
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Disaccharide Reactions Amylose
Amylose +n H2O → n glucose
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Polysaccharides The majority of starch is made up of a
more complex polysaccharide known as amylopectin
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Cellulose A polymer of glucose with different oxygen
bridge orientations We lack an enzyme to digest cellulose
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Lipids Water insoluble natural products Dissolve in non-polar solvents Relatively non-polar with large segments
that are hydrocarbon-like Cholesterol
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Lipids Fats and oils
Triacylglycerols-esters of glycerol and long chain carboxylic acids (fatty acids)
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Fatty Acids
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Triacylglycerols Triacylglycerol example
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Reactions of Triacylclycerols Digestion
Breaks down the triacylclycerol into its three component fatty acids and glycerol. Takes place in base so in fact the fatty acids are in their anion form
Hydrogenation The addition of hydrogen to the double bonds Turns oils into solids
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Soap Castile soap is made from olive oil Olive oil has many different fatty acids
Two major fatty acid constituents are oleic acid, 50-85%, and linoleic acid, 4-20%
Saponification of triacylglcerols using NaOH or other base, and heat, results in salts of the fatty acid components plus glycerol Sodium oleate and sodium linoleate, for example
This product mixture, soap, is thus the result of saponification of triacylglcerols
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Cell Membranes Glycerophospholipids
Diacylclcerols with phosphate unit which is attached to a amino alcohol unit
Contain a hydrophobic, water avoiding, unit and a hydrophilic, water loving, unit
Aggregate together to form lipid bilayers with hydrophilic layers oriented to the outside and inside layers of the membrane
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Cell Membranes
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Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Cell Membranes Membrane also contains protein units,
some which act as ion channels to move select ions in and out of cells
Other proteins act as molecular recognition sites for hormones and neurotransmitters
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Proteins Polypeptides made up of α-amino acids Serve as hormones, neurotransmitters,
and enzymes Essential amino acids are those the
body does not synthesize Basic amino acid
structure:
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Amino Acids
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Lysine
Cysteine
Jespersen/Brady/Hyslop Chemistry: The Molecular Nature of Matter, 6E
Amino Acids Isoleucine
Alanine
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Polypeptides Formation of peptide bond
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PolypeptidesCombining two amino acids forms a dipeptide
Often the amino acids are abbreviated Glycine – Gly Alanine – Ala
A dipeptide of these would then be shown as: Gly-Ala
A few amino acids can be arranged in a very large number of orders leading to many different proteins Gly-Ala-Arg Gly-Arg-Ala Ala-Gly-Arg Plus three more
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Polypeptides and Proteins How many ways can you arrange n
different objects? n ! Therefore 3 amino acids have 6
arrangements
You can also use the same amino acid more than once in a polypeptide
Proteins Consist of polypeptides and usually small
organic molecules They may also incorporate metal ions into
their structure
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Structure of Hemoglobin
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Nucleic Acids RNA – ribonucleic acid DNA – deoxyribonucleic acid
The chemical of a gene Chemical basis of inherited characteristics
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Nucleic Acid Sugars
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Basic Nucleic Acid Structure
Where G is a placeholder for a unique nucleic acid side chain
The sugars are ribose for RNA and deoxyribose for DNA
The groups, G, are: adenine (A), thymine (T), uracil (U), guanine
(G), and cytosine(C)
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DNA - Double Helix Structure A unique arrangement of amino acids
maximized hydrogen bonding resulting in a pairing of strands to form a double helix Base Pairing A only with T
C only with G
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DNA Replication Enzyme catalyzed process unzips the two
strands Arrangement of base pairs dictates
replication pattern
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Polypetide Synthesis Controlled formation of peptide bonds to make
a polypeptide Repeated many times to form polypeptides and
proteins Genetic information is transcribed from DNA in
the nucleus onto RNA (m RNA) This messenger RNA moves outside the
nucleus and through a complex process, using other RNA types, synthesizes a specific protein
The order of amino acid synthesis is coded so that the correct amino acids are made available in the proper sequence
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