Chapter 22 Organic and Biological Molecules

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. Copyright © Cengage Learning. All rights reserved 2

Section 22.1 Alkanes: Saturated Hydrocarbons Copyright © Cengage Learning. All rights reserved 3 Hydrocarbons  Compounds composed of carbon and hydrogen.  Saturated: C—C bonds are all single bonds. alkanes [C n H 2n+2 ]

Section 22.1 Alkanes: Saturated Hydrocarbons Hydrocarbons  Unsaturated: contains carbon–carbon multiple bonds.

Section 22.1 Alkanes: Saturated Hydrocarbons Copyright © Cengage Learning. All rights reserved 5 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 Copyright © Cengage Learning. All rights reserved 6 Butane

Section 22.1 Alkanes: Saturated Hydrocarbons Copyright © Cengage Learning. All rights reserved 7 Rules for Naming Alkanes 1.For alkanes beyond butane, add –ane to the Greek root for the number of carbons. CH 3 –CH 2 –CH 2 –CH 2 –CH 2 –CH 3 = hexane 2.Alkyl substituents: drop the –ane and add –yl. C 2 H 6 is ethane C 2 H 5 is ethyl

Section 22.1 Alkanes: Saturated Hydrocarbons Copyright © Cengage Learning. All rights reserved 8 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. CH 3 CH 3 –CH 2 –CH–CH 2 –CH 2 –CH methylhexane

Section 22.1 Alkanes: Saturated Hydrocarbons Copyright © Cengage Learning. All rights reserved 9 Rules for Naming Alkanes 4.Location and name are followed by root alkane name. Substituents in alphabetical order and use di–, tri–, etc. CH 3 CH 3 CH 3 –CH 2 –CH–CH–CH 2 –CH ,4-dimethylhexane

Section 22.1 Alkanes: Saturated Hydrocarbons Copyright © Cengage Learning. All rights reserved 10 First Ten Normal Alkanes

Section 22.1 Alkanes: Saturated Hydrocarbons The Most Common Alkyl Substituents and Their Names

Section 22.1 Alkanes: Saturated Hydrocarbons Copyright © Cengage Learning. All rights reserved 12 Name each of the following: a) 2,2,4,5-tetramethylhexane b) 3,6-diethyl-3-methyloctane EXERCISE!

Section 22.1 Alkanes: Saturated Hydrocarbons Copyright © Cengage Learning. All rights reserved 13 Combustion Reactions of Alkanes  At a high temperature, alkanes react vigorously and exothermically with oxygen.  Basis for use as fuels.

Section 22.1 Alkanes: Saturated Hydrocarbons Copyright © Cengage Learning. All rights reserved 14 Substitution Reactions of Alkanes  Primarily where halogen atoms replace hydrogen atoms.

Section 22.1 Alkanes: Saturated Hydrocarbons Copyright © Cengage Learning. All rights reserved 15 Dehydrogenation Reactions of Alkanes  Hydrogen atoms are removed and the product is an unsaturated hydrocarbon.

Section 22.1 Alkanes: Saturated Hydrocarbons Copyright © Cengage Learning. All rights reserved 16 Cyclic Alkanes  Carbon atoms can form rings containing only C—C single bonds.  General formula: C n H 2n C 6 H 12 C4H8C4H8 C3H6C3H6

Section 22.1 Alkanes: Saturated Hydrocarbons Copyright © Cengage Learning. All rights reserved 17 The Chair and Boat Forms of Cyclohexane

Section 22.2 Alkenes and Alkynes Hydrocarbons  Alkenes: hydrocarbons that contain at least one carbon–carbon double bond. [C n H 2n ] CH 3 –CH=CH 2 propene  Alkynes: hydrocarbons containing at least one carbon– carbon triple bond. [C n H n ] CH 3 –CH 2 –CΞC–CH 3 2–pentyne

Section 22.2 Alkenes and Alkynes Rules for Naming Alkenes 1.Root hydrocarbon name ends in –ene. C 2 H 4 is ethene 2.With more than 3 carbons, double bond is indicated by the lowest–numbered carbon atom in the bond. CH 2 =CH–CH 2 –CH –butene Copyright © Cengage Learning. All rights reserved 19

Section 22.2 Alkenes and Alkynes Rules for Naming Alkynes  Same as for alkenes except use –yne as suffix. CH 3 –CH 2 –CΞC–CH 2 –CH 2 –CH 2 –CH 3 3–octyne Copyright © Cengage Learning. All rights reserved 20

Section 22.2 Alkenes and Alkynes Name each of the following: a) 2,3,5-trimethyl-2-hexene b) 6-ethyl-3-methyl-3-octene Copyright © Cengage Learning. All rights reserved 21 EXERCISE!

Section 22.2 Alkenes 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. Copyright © Cengage Learning. All rights reserved 22

Section 22.2 Alkenes and Alkynes Halogenation Reactions  Addition of halogen atoms of alkenes and alkynes. Copyright © Cengage Learning. All rights reserved 23

Section 22.3 Aromatic Hydrocarbons  A special class of cyclic unsaturated hydrocarbons.  Simplest of these is benzene (C 6 H 6 ).  The delocalization of the electrons makes the benzene ring behave differently from a typical unsaturated hydrocarbon. Copyright © Cengage Learning. All rights reserved 24

Section 22.3 Aromatic Hydrocarbons Benzene (Aromatic Hydrocarbon)

Section 22.3 Aromatic 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. Copyright © Cengage Learning. All rights reserved 26 Benzene

Section 22.3 Aromatic Hydrocarbons More Complex Aromatic Systems Copyright © Cengage Learning. All rights reserved 27

Section 22.4 Hydrocarbon Derivatives  Molecules that are fundamentally hydrocarbons but have additional atoms or groups of atoms called functional groups. Copyright © Cengage Learning. All rights reserved 28

Section 22.4 Hydrocarbon Derivatives The Common Functional Groups Copyright © Cengage Learning. All rights reserved 29

Section 22.5 Polymers  Large, usually chainlike molecules that are built from small molecules called monomers. Copyright © Cengage Learning. All rights reserved 30

Section 22.5 Polymers Common Synthetic Polymers and their Monomers and Applications Copyright © Cengage Learning. All rights reserved 31

Section 22.5 Polymers Types of Polymerization  Addition Polymerization  Monomers “add together” to form the polymer, with no other products. (Teflon®)

Section 22.5 Polymers Types of Polymerization  Condensation Polymerization  A small molecule, such as water, is formed for each extension of the polymer chain. (Nylon) Copyright © Cengage Learning. All rights reserved 33

Section 22.6 Natural 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. Copyright © Cengage Learning. All rights reserved 34

Section 22.6 Natural 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 Copyright © Cengage Learning. All rights reserved 35

Section 22.6 Natural Polymers α-Amino Acids  –NH 2 always attached to the α-carbon (the carbon attached to –COOH) C = α-carbon R = side chains Copyright © Cengage Learning. All rights reserved 36 H C R COOHH2NH2N

Section 22.6 Natural Polymers Bonding in α-Amino Acids  There are 20 amino acids commonly found in proteins. Copyright © Cengage Learning. All rights reserved 37

Section 22.6 Natural 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). Copyright © Cengage Learning. All rights reserved 38

Section 22.6 Natural Polymers Hydrogen Bonding in α- Helical Arrangement of a Protein Chain

Section 22.6 Natural Polymers Pleated Sheet Copyright © Cengage Learning. All rights reserved 40

Section 22.6 Natural Polymers Carbohydrates  Food source for most organisms and structural material for plants.  Empirical formula = CH 2 O  Monosaccharides (simple sugars) pentoses – ribose, arabinose hexoses – fructose, glucose Copyright © Cengage Learning. All rights reserved 41

Section 22.6 Natural Polymers Some Important Monosaccharides Copyright © Cengage Learning. All rights reserved 42

Section 22.6 Natural 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 Copyright © Cengage Learning. All rights reserved 43

Section 22.6 Natural Polymers The Disaccharide Sucrose is Formed From α-D-glucose and Fructose Copyright © Cengage Learning. All rights reserved 44

Section 22.6 Natural 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) Copyright © Cengage Learning. All rights reserved 45

Section 22.6 Natural 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 (H 3 PO 4 ). Copyright © Cengage Learning. All rights reserved 46

Section 22.6 Natural Polymers Deoxyribose (in DNA) and Ribose (in RNA) Copyright © Cengage Learning. All rights reserved 47

Section 22.6 Natural Polymers The Organic Bases Found in DNA and RNA Copyright © Cengage Learning. All rights reserved 48

Section 22.6 Natural 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. Copyright © Cengage Learning. All rights reserved 49

Section 22.6 Natural Polymers Hydrogen Bonding in DNA Copyright © Cengage Learning. All rights reserved 50