chapter 22 organic and biological molecules ap*. ap chemistry lo 2.15 the student is able to...
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Chapter 22
Organic and Biological Molecules
AP*
AP Chemistry
LO 2.15 The student is able to explain observations regarding the solubility of ionic solids and molecules in water and other solvents on the basis of particle views that include intermolecular interactions and entropic effects. (Sec 22.5-22.6)
LO 5.11 The student is able to identify the noncovalent interactions within and between large molecules, and/or connect the shape and function of the large molecule to the presence and magnitude of these interactions. (Sec 22.6)
Chapter 22
Organic Chemistry and Biochemistry
Organic Chemistry The study of carbon-containing compounds and their
properties. The vast majority of organic compounds contain chains or rings of carbon atoms.
Biochemistry The study of the chemistry of living things.
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Section 22.1Alkanes: Saturated Hydrocarbons
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Hydrocarbons Compounds composed of carbon and hydrogen. Saturated: C—C bonds are all single bonds.
alkanes [CnH2n+2]
C C
H
H
H
H
H
H
Section 22.1Alkanes: Saturated Hydrocarbons
Hydrocarbons Unsaturated: contains carbon–carbon multiple
bonds.
C C C
H H
H
H
H
H
C C C
H
H
H
H
Section 22.1Alkanes: Saturated Hydrocarbons
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Isomerism in Alkanes Structural isomerism – occurs when two molecules
have the same atoms but different bonds. Butane and all succeeding members of the
alkanes exhibit structural isomerism.
Section 22.1Alkanes: Saturated Hydrocarbons
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Butane
Section 22.1Alkanes: Saturated Hydrocarbons
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Rules for Naming Alkanes
1. For alkanes beyond butane, add –ane to the Greek root for the number of carbons.
CH3–CH2–CH2–CH2–CH2–CH3 = hexane
2. Alkyl substituents: drop the –ane and add –yl.C2H6 is ethane
C2H5 is ethyl
Section 22.1Alkanes: Saturated Hydrocarbons
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Rules for Naming Alkanes
3. Positions of substituent groups are specified by numbering the longest chain sequentially. The numbering is such that substituents are at lowest possible number along chain. CH3
CH3–CH2–CH–CH2–CH2–CH3
1 2 3 4 5 6
3-methylhexane
Section 22.1Alkanes: Saturated Hydrocarbons
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Rules for Naming Alkanes
4. Location and name are followed by root alkane name. Substituents in alphabetical order and use di–, tri–, etc.
CH3 CH3
CH3–CH2–CH–CH–CH2–CH3
1 2 3 4 5 6
3,4-dimethylhexane
Section 22.1Alkanes: Saturated Hydrocarbons
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First Ten Normal Alkanes
Section 22.1Alkanes: Saturated Hydrocarbons
The Most Common Alkyl Substituents and Their Names
Section 22.1Alkanes: Saturated Hydrocarbons
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Name each of the following:
a)
2,2,4,5-tetramethylhexane
b)
3,6-diethyl-3-methyloctane
H3C C CH2 CH CH2 CH3
CH3
CH3 CH3
CH3
H3C C CH2 CH2 CH CH2
CH2
CH2
CH2CH3
CH3
CH3
CH3
EXERCISE!EXERCISE!
Section 22.1Alkanes: Saturated Hydrocarbons
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Combustion Reactions of Alkanes
At a high temperature, alkanes react vigorously and exothermically with oxygen.
Basis for use as fuels.
4 10 2 2 22C H ( ) + 13O ( ) 8CO ( ) + 10H O( )g g g g
Section 22.1Alkanes: Saturated Hydrocarbons
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Substitution Reactions of Alkanes Primarily where halogen atoms replace hydrogen
atoms.
4 2 3
3 2 2 2
2 2 2 3
3 2 4
CH + Cl CH Cl + HCl
CH Cl + Cl CH Cl + HCl
CH Cl + Cl CHCl + HCl
CHCl + Cl CCl + HCl
hv
hv
hv
hv
Section 22.1Alkanes: Saturated Hydrocarbons
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Dehydrogenation Reactions of Alkanes Hydrogen atoms are removed and the product is an
unsaturated hydrocarbon.
Section 22.1Alkanes: Saturated Hydrocarbons
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Cyclic Alkanes Carbon atoms can form rings containing only C—C
single bonds. General formula: CnH2n
C6H12C4H8 C3H6
Section 22.1Alkanes: Saturated Hydrocarbons
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The Chair and Boat Forms of Cyclohexane
Section 22.2Alkenes and Alkynes
Hydrocarbons
Alkenes: hydrocarbons that contain at least one carbon–carbon double bond. [CnH2n]
CH3–CH=CH2 propene Alkynes: hydrocarbons containing at least one carbon–
carbon triple bond. [CnHn]
CH3–CH2–CΞC–CH3 2–pentyne
Section 22.2Alkenes and Alkynes
Rules for Naming Alkenes
1. Root hydrocarbon name ends in –ene.C2H4 is ethene
2. With more than 3 carbons, double bond is indicated by the lowest–numbered carbon atom in the bond.
CH2=CH–CH2–CH3
1 2 3 4
1–butene
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Section 22.2Alkenes and Alkynes
Rules for Naming Alkynes
Same as for alkenes except use –yne as suffix.
CH3–CH2–CΞC–CH2–CH2–CH2–CH3
3–octyne
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Section 22.2Alkenes and Alkynes
Name each of the following:
a)
2,3,5-trimethyl-2-hexene
b)
6-ethyl-3-methyl-3-octeneCopyright © Cengage Learning. All rights reserved 22
H3C CH CH2 C C CH3
CH3
CH3
CH3
H3C C CH CH2 CH CH2
CH2 CH2CH3 CH3
CH3
EXERCISE!EXERCISE!
Section 22.2Alkenes and Alkynes
Addition Reactions
Pi Bonds (which are weaker than the C—C bonds), are broken, and new bonds are formed to the atoms being added.
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Section 22.2Alkenes and Alkynes
Halogenation Reactions
Addition of halogen atoms of alkenes and alkynes.
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Section 22.3Aromatic Hydrocarbons
A special class of cyclic unsaturated hydrocarbons. Simplest of these is benzene (C6H6). The delocalization of the electrons makes the benzene
ring behave differently from a typical unsaturated hydrocarbon.
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Section 22.3Aromatic Hydrocarbons
Benzene (Aromatic Hydrocarbon)
Section 22.3Aromatic Hydrocarbons
Unsaturated hydrocarbons generally undergo rapid addition reactions, but benzene does not.
Benzene undergoes substitution reactions in which hydrogen atoms are replaced by other atoms.
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Benzene
Section 22.3Aromatic Hydrocarbons
More Complex Aromatic Systems
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Section 22.4Hydrocarbon Derivatives
AP Learning Objectives, Margin Notes and References AP Margin Notes Acids and bases can serve as catalysts in chemical reactions. See Appendix 7.9 “Acid Catalysis” to learn more about
this acid-catalyzed reaction mechanism.
Section 22.4Hydrocarbon Derivatives
Molecules that are fundamentally hydrocarbons but have additional atoms or groups of atoms called functional groups.
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Section 22.4Hydrocarbon Derivatives
The Common Functional Groups
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Section 22.5Polymers
AP Learning Objectives, Margin Notes and References Learning Objectives LO 2.15 The student is able to explain observations regarding the solubility of ionic solids and molecules in water
and other solvents on the basis of particle views that include intermolecular interactions and entropic effects.
Section 22.5Polymers
Large, usually chainlike molecules that are built from small molecules called monomers.
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Section 22.5Polymers
Common Synthetic Polymers and their Monomers and Applications
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Section 22.5Polymers
Types of Polymerization
Addition Polymerization Monomers “add
together” to form the polymer, with no other products. (Teflon®)
Section 22.5Polymers
Types of Polymerization
Condensation Polymerization A small molecule, such as water, is formed for each
extension of the polymer chain. (Nylon)
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Section 22.6Natural Polymers
AP Learning Objectives, Margin Notes and References Learning Objectives LO 2.15 The student is able to explain observations regarding the solubility of ionic solids and molecules in water
and other solvents on the basis of particle views that include intermolecular interactions and entropic effects. LO 5.11 The student is able to identify the noncovalent interactions within and between large molecules, and/or
connect the shape and function of the large molecule to the presence and magnitude of these interactions.
Section 22.6Natural Polymers
Proteins
Natural polymers made up of -amino acids with molar masses: ~ 6000 to > 1,000,000 g/mol
Fibrous Proteins: provide structural integrity and strength to muscle, hair and cartilage.
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Section 22.6Natural Polymers
Proteins
Globular Proteins: Roughly spherical shape Transport and store oxygen and nutrients Act as catalysts Fight invasion by foreign objects Participate in the body’s regulatory system Transport electrons in metabolism
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Section 22.6Natural Polymers
α-Amino Acids
–NH2 always attached to the α-carbon
(the carbon attached to –COOH)
C = α-carbonR = side chains
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H
C
R
COOHH2N
Section 22.6Natural Polymers
Bonding in α-Amino Acids
There are 20 amino acids commonly found in proteins.
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Section 22.6Natural Polymers
Levels of Structure in Proteins
Primary: Sequence of amino acids in the protein chain. Secondary: The arrangement of the protein chain in the
long molecule (hydrogen bonding determines this). Tertiary: The overall shape of the protein (determined
by hydrogen-bonding, dipole-dipole interactions, ionic bonds, covalent bonds and London forces).
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Section 22.6Natural Polymers
Hydrogen Bonding in α-Helical Arrangement of a Protein Chain
Section 22.6Natural Polymers
Pleated Sheet
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Section 22.6Natural Polymers
Carbohydrates
Food source for most organisms and structural material for plants.
Empirical formula = CH2O Monosaccharides (simple sugars)
pentoses – ribose, arabinosehexoses – fructose, glucose
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Section 22.6Natural Polymers
Some Important Monosaccharides
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Section 22.6Natural Polymers
Carbohydrates
Disaccharides (formed from 2 monosaccharides joined by a glycoside linkage, a C—O—C bond between the rings):
sucrose (glucose + fructose) Polysaccharides (many monosaccharide units):
starch, cellulose
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Section 22.6Natural Polymers
The Disaccharide Sucrose is Formed From α-D-glucose and Fructose
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Section 22.6Natural Polymers
Nucleic Acids
DNA (deoxyribonucleic acid): stores and transmits genetic information, responsible (with RNA) for protein synthesis. (Molar masses = several billion)
RNA (ribonucleic acid): helps in protein synthesis. (Molar masses from 20,000 to 40,000 g/mol)
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Section 22.6Natural Polymers
Nucleotides
Monomers of the nucleic acids. Three distinct parts:
A five–carbon sugar, deoxyribose in DNA and ribose in RNA.
A nitrogen–containing organic base. A phosphoric acid molecule (H3PO4).
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Section 22.6Natural Polymers
Deoxyribose (in DNA) and Ribose (in RNA)
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Section 22.6Natural Polymers
The Organic Bases Found in DNA and RNA
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Section 22.6Natural Polymers
DNA
Key to DNA’s functioning is its double-helical structure with complementary bases on the two strands.
The bases form hydrogen bonds to each other.
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Section 22.6Natural Polymers
Hydrogen Bonding in DNA
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