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Chapter 22
Organic and Biological Molecules
Chapter 22
Table of Contents
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22.1Alkanes: Saturated Hydrocarbons
22.2 Alkenes and Alkynes
22.3 Aromatic Hydrocarbons
22.4 Hydrocarbon Derivatives
22.5 Polymers
22.6 Natural Polymers
Chapter 22
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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.
Section 22.1
Alkanes: 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 22.1
Alkanes: Saturated Hydrocarbons
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Hydrocarbons
• Unsaturated: contains carbon–carbon multiple bonds.
C C C
H H
H
H
H
H
C C C
H
H
H
H
Section 22.1
Alkanes: 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 22.1
Alkanes: Saturated Hydrocarbons
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Butane
Section 22.1
Alkanes: 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 22.1
Alkanes: 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 22.1
Alkanes: 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 22.1
Alkanes: Saturated Hydrocarbons
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First Ten Normal Alkanes
Section 22.1
Alkanes: Saturated Hydrocarbons
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The Most Common Alkyl Substituents and Their Names
Section 22.1
Alkanes: Saturated Hydrocarbons
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Exercise
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
Section 22.1
Alkanes: 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 22.1
Alkanes: 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 22.1
Alkanes: Saturated Hydrocarbons
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Dehydrogenation Reactions of Alkanes
• Hydrogen atoms are removed and the product is an unsaturated hydrocarbon.
Section 22.1
Alkanes: Saturated Hydrocarbons
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Cyclic Alkanes
• Carbon atoms can form rings containing only C—C single bonds.
• General formula: CnH2n
C3H6, C4H8, C6H12
Section 22.1
Alkanes: Saturated Hydrocarbons
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The Chair and Boat Forms of Cyclohexane
Section 22.2
Atomic MassesAlkenes and Alkynes
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Hydrocarbons
• Alkenes: hydrocarbons that contain a carbon–carbon double bond. [CnH2n]
CH3CH=CH2 propene
• Alkynes: hydrocarbons containing a carbon–carbon triple bond.
CH3CH2CCCH3 2–pentyne
Section 22.2
Atomic MassesAlkenes and Alkynes
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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=CHCH2CH3
1 2 3 4
1–butene
Section 22.2
Atomic MassesAlkenes and Alkynes
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Rules for Naming Alkynes
• Same as for alkenes except use –yne as suffix.
CH3CH2CCCH2CH2CH2CH3
3–octyne
Section 22.2
Atomic MassesAlkenes and Alkynes
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Exercise
Name each of the following:
a)
2,3,5-trimethyl-2-hexene
b)
6-ethyl-3-methyl-3-octene
H3C CH CH2 C C CH3
CH3
CH3
CH3
H3C C CH CH2 CH CH2
CH2 CH2CH3 CH3
CH3
Section 22.2
Atomic MassesAlkenes and Alkynes
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Addition Reactions
• Pi Bonds (which are weaker than the C—C bonds), are broken, and new bonds are formed to the atoms being added.
Section 22.2
Atomic MassesAlkenes and Alkynes
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Halogenation Reactions
• Addition of halogen atoms of alkenes and alkynes.
Section 22.3
The Mole Aromatic Hydrocarbons
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• 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.
Section 22.3
The Mole Aromatic Hydrocarbons
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Benzene (Aromatic Hydrocarbon)
Section 22.3
The Mole Aromatic Hydrocarbons
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• Unsaturated hydrocarbons generally undergo rapid addition reactions, but benzene does not.
• Benzene undergoes substitution reactions in which hydrogen atoms are replaced by other atoms.
Benzene
+ Cl2FeCl3
Cl
Chlorobenzene
+ HCl
Section 22.3
The Mole Aromatic Hydrocarbons
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More Complex Aromatic Systems
Section 22.4
Hydrocarbon Derivatives
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• Molecules that are fundamentally hydrocarbons but have additional atoms or groups of atoms called functional groups.
Section 22.4
Hydrocarbon Derivatives
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The Common Functional Groups
Section 22.5
Polymers
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• Large, usually chainlike molecules that are built from small molecules called monomers.
Monomer Polymer
Ethylene Polyethylene
Vinyl chloride Polyvinyl chloride
Tetrafluoroethylene Teflon®
Section 22.5
Polymers
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Types of Polymerization
• Addition Polymerization Monomers “add together” to form the
polymer, with no other products. (Teflon®)
Section 22.5
Polymers
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Types of Polymerization
• Condensation Polymerization A small molecule, such as water, is formed
for each extension of the polymer chain. (Nylon)
Section 22.6
Natural Polymers
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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.
Section 22.6
Natural Polymers
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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
Section 22.6
Natural Polymers
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-Amino Acids
• –NH2 always attached to the -carbon
(the carbon attached to COOH)
C = -carbon
R = side chains H2N C
H
COOH
R
Section 22.6
Natural Polymers
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Bonding in -Amino Acids
+ H2O
A peptide linkage
• There are 20 amino acids commonly found in proteins.
CNH
H
H
R
C
O
N
H
C
H
R'
CO
OH
Section 22.6
Natural Polymers
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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).
Section 22.6
Natural Polymers
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Hydrogen Bonding in α-Helical Arrangement of a Protein Chain
Section 22.6
Natural Polymers
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Pleated Sheet
Section 22.6
Natural Polymers
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Carbohydrates
• Food source for most organisms and structural material for plants.
• Empirical formula = CH2O
• Monosaccharides (simple sugars)
pentoses – ribose, arabinose
hexoses – fructose, glucose
Section 22.6
Natural Polymers
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Some Important Monosaccharides
Section 22.6
Natural Polymers
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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
Section 22.6
Natural Polymers
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The Disaccharide Sucrose is Formed From α-D-glucose and Fructose
Section 22.6
Natural Polymers
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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)
Section 22.6
Natural Polymers
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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).
Section 22.6
Natural Polymers
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Deoxyribose (in DNA) and Ribose (in RNA)
Section 22.6
Natural Polymers
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The Organic Bases Found in DNA and RNA
Section 22.6
Natural Polymers
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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.
Section 22.6
Natural Polymers
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Hydrogen Bonding in DNA
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